Pianotech

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Follow-up question: Is there a spec on how far dampers are supposed to lift?

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Follow-up question: Is there a spec on how far dampers are supposed to lift?

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Matteo - Yes, it's that "certain kind of touch". Inspection of the parts during that kind of play revealed that what's happening is that I almost subconsciously feel the bump just before escape and letoff, and the micro pause that I am creating at that point is just enough to allow the hammer to continue to move and strike the strings lightly. But since the jack has not yet completed its move when the hammer bounces back, the action still has to complete its move. When the jack finally does escape at letoff the hammer strikes the string as originally intended, but now it's a second strike from the same key movement. 

To be clear, it's not the hammer bouncing off the jack after the action has completed its move and the hammer bounces off the strings. And it's not a backcheck problem. Jacks are set so that there is a small visible space between the jack and the knuckle when all key and action movement is completed. 

Yes, like you, with a little concentration I am able to actually create this phenomena on most pianos. Upright and grand. 

I disagree that adjusting the dampers to lift earlier would help. The whole idea of having the dampers lift no earlier than half way through the blow is to take advantage of the momentum of the key and hammer movement already in process and reduce the sudden increase in weight as the dampers engage and start to lift. However, (Wim and Charles), adjusting the damper springs to make them lighter sounds like a good idea. I'll see if I can find Don Mannino's article. 

Scott - I realize that what I'm feeling is the moment the jack actually starts to move under the knuckle. A little Teflon powder on the knuckle could possibly reduce that, yes. Good suggestion. 

Nathan - The problem with the sustain pedal being involved is, I'm sure, my own playing technique. (I'm sure that being a piano tech and a beginning piano player I'm being far too technical and analytical in my approach to learning to play. 🙄 ) If I wind up pedaling at about the same time as the jack is about to escape it's adding an additional change in overall touch, at exactly the wrong moment, that simply makes it a bit easier to unintentionally create that micro pause in key play that causes the double strike. 

Follow-up question: Is there a spec on how far dampers are supposed to lift?

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

UPDATE: I received a call from Lisa Weller, also suggesting damper spring tension as the culprit. She had me do a test to make this determination. I lightly played a C chord, in the middle of the piano, first with the pedal engaged and then with the pedal released. Did it feel different? Yes! As she surmised, the keys were noticeably heavier with the pedal off then when on. She suggested that when damper spring tension is properly adjusted the difference between pedal on and pedal off should be minimal, if not actually unnoticeable. I understand how this could, in fact, be the cause of my double striking problem. Time to dig out my Hart tool and make some adjustments. 

Thanks, all. 

Matteo - Yes, it's that "certain kind of touch". Inspection of the parts during that kind of play revealed that what's happening is that I almost subconsciously feel the bump just before escape and letoff, and the micro pause that I am creating at that point is just enough to allow the hammer to continue to move and strike the strings lightly. But since the jack has not yet completed its move when the hammer bounces back, the action still has to complete its move. When the jack finally does escape at letoff the hammer strikes the string as originally intended, but now it's a second strike from the same key movement. 

To be clear, it's not the hammer bouncing off the jack after the action has completed its move and the hammer bounces off the strings. And it's not a backcheck problem. Jacks are set so that there is a small visible space between the jack and the knuckle when all key and action movement is completed. 

Yes, like you, with a little concentration I am able to actually create this phenomena on most pianos. Upright and grand. 

I disagree that adjusting the dampers to lift earlier would help. The whole idea of having the dampers lift no earlier than half way through the blow is to take advantage of the momentum of the key and hammer movement already in process and reduce the sudden increase in weight as the dampers engage and start to lift. However, (Wim and Charles), adjusting the damper springs to make them lighter sounds like a good idea. I'll see if I can find Don Mannino's article. 

Scott - I realize that what I'm feeling is the moment the jack actually starts to move under the knuckle. A little Teflon powder on the knuckle could possibly reduce that, yes. Good suggestion. 

Nathan - The problem with the sustain pedal being involved is, I'm sure, my own playing technique. (I'm sure that being a piano tech and a beginning piano player I'm being far too technical and analytical in my approach to learning to play. 🙄 ) If I wind up pedaling at about the same time as the jack is about to escape it's adding an additional change in overall touch, at exactly the wrong moment, that simply makes it a bit easier to unintentionally create that micro pause in key play that causes the double strike. 

Follow-up question: Is there a spec on how far dampers are supposed to lift?

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

UPDATE: I received a call from Lisa Weller, also suggesting damper spring tension as the culprit. She had me do a test to make this determination. I lightly played a C chord, in the middle of the piano, first with the pedal engaged and then with the pedal released. Did it feel different? Yes! As she surmised, the keys were noticeably heavier with the pedal off then when on. She suggested that when damper spring tension is properly adjusted the difference between pedal on and pedal off should be minimal, if not actually unnoticeable. I understand how this could, in fact, be the cause of my double striking problem. Time to dig out my Hart tool and make some adjustments. 

Thanks, all. 

Matteo - Yes, it's that "certain kind of touch". Inspection of the parts during that kind of play revealed that what's happening is that I almost subconsciously feel the bump just before escape and letoff, and the micro pause that I am creating at that point is just enough to allow the hammer to continue to move and strike the strings lightly. But since the jack has not yet completed its move when the hammer bounces back, the action still has to complete its move. When the jack finally does escape at letoff the hammer strikes the string as originally intended, but now it's a second strike from the same key movement. 

To be clear, it's not the hammer bouncing off the jack after the action has completed its move and the hammer bounces off the strings. And it's not a backcheck problem. Jacks are set so that there is a small visible space between the jack and the knuckle when all key and action movement is completed. 

Yes, like you, with a little concentration I am able to actually create this phenomena on most pianos. Upright and grand. 

I disagree that adjusting the dampers to lift earlier would help. The whole idea of having the dampers lift no earlier than half way through the blow is to take advantage of the momentum of the key and hammer movement already in process and reduce the sudden increase in weight as the dampers engage and start to lift. However, (Wim and Charles), adjusting the damper springs to make them lighter sounds like a good idea. I'll see if I can find Don Mannino's article. 

Scott - I realize that what I'm feeling is the moment the jack actually starts to move under the knuckle. A little Teflon powder on the knuckle could possibly reduce that, yes. Good suggestion. 

Nathan - The problem with the sustain pedal being involved is, I'm sure, my own playing technique. (I'm sure that being a piano tech and a beginning piano player I'm being far too technical and analytical in my approach to learning to play. 🙄 ) If I wind up pedaling at about the same time as the jack is about to escape it's adding an additional change in overall touch, at exactly the wrong moment, that simply makes it a bit easier to unintentionally create that micro pause in key play that causes the double strike. 

Follow-up question: Is there a spec on how far dampers are supposed to lift?

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

UPDATE: I received a call from Lisa Weller, also suggesting damper spring tension as the culprit. She had me do a test to make this determination. I lightly played a C chord, in the middle of the piano, first with the pedal engaged and then with the pedal released. Did it feel different? Yes! As she surmised, the keys were noticeably heavier with the pedal off then when on. She suggested that when damper spring tension is properly adjusted the difference between pedal on and pedal off should be minimal, if not actually unnoticeable. I understand how this could, in fact, be the cause of my double striking problem. Time to dig out my Hart tool and make some adjustments. 

Thanks, all. 

Matteo - Yes, it's that "certain kind of touch". Inspection of the parts during that kind of play revealed that what's happening is that I almost subconsciously feel the bump just before escape and letoff, and the micro pause that I am creating at that point is just enough to allow the hammer to continue to move and strike the strings lightly. But since the jack has not yet completed its move when the hammer bounces back, the action still has to complete its move. When the jack finally does escape at letoff the hammer strikes the string as originally intended, but now it's a second strike from the same key movement. 

To be clear, it's not the hammer bouncing off the jack after the action has completed its move and the hammer bounces off the strings. And it's not a backcheck problem. Jacks are set so that there is a small visible space between the jack and the knuckle when all key and action movement is completed. 

Yes, like you, with a little concentration I am able to actually create this phenomena on most pianos. Upright and grand. 

I disagree that adjusting the dampers to lift earlier would help. The whole idea of having the dampers lift no earlier than half way through the blow is to take advantage of the momentum of the key and hammer movement already in process and reduce the sudden increase in weight as the dampers engage and start to lift. However, (Wim and Charles), adjusting the damper springs to make them lighter sounds like a good idea. I'll see if I can find Don Mannino's article. 

Scott - I realize that what I'm feeling is the moment the jack actually starts to move under the knuckle. A little Teflon powder on the knuckle could possibly reduce that, yes. Good suggestion. 

Nathan - The problem with the sustain pedal being involved is, I'm sure, my own playing technique. (I'm sure that being a piano tech and a beginning piano player I'm being far too technical and analytical in my approach to learning to play. 🙄 ) If I wind up pedaling at about the same time as the jack is about to escape it's adding an additional change in overall touch, at exactly the wrong moment, that simply makes it a bit easier to unintentionally create that micro pause in key play that causes the double strike. 

Follow-up question: Is there a spec on how far dampers are supposed to lift?

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Matteo - Yes, it's that "certain kind of touch". Inspection of the parts during that kind of play revealed that what's happening is that I almost subconsciously feel the bump just before escape and letoff, and the micro pause that I am creating at that point is just enough to allow the hammer to continue to move and strike the strings lightly. But since the jack has not yet completed its move when the hammer bounces back, the action still has to complete its move. When the jack finally does escape at letoff the hammer strikes the string as originally intended, but now it's a second strike from the same key movement. 

To be clear, it's not the hammer bouncing off the jack after the action has completed its move and the hammer bounces off the strings. And it's not a backcheck problem. Jacks are set so that there is a small visible space between the jack and the knuckle when all key and action movement is completed. 

Yes, like you, with a little concentration I am able to actually create this phenomena on most pianos. Upright and grand. 

I disagree that adjusting the dampers to lift earlier would help. The whole idea of having the dampers lift no earlier than half way through the blow is to take advantage of the momentum of the key and hammer movement already in process and reduce the sudden increase in weight as the dampers engage and start to lift. However, (Wim and Charles), adjusting the damper springs to make them lighter sounds like a good idea. I'll see if I can find Don Mannino's article. 

Scott - I realize that what I'm feeling is the moment the jack actually starts to move under the knuckle. A little Teflon powder on the knuckle could possibly reduce that, yes. Good suggestion. 

Nathan - The problem with the sustain pedal being involved is, I'm sure, my own playing technique. (I'm sure that being a piano tech and a beginning piano player I'm being far too technical and analytical in my approach to learning to play. 🙄 ) If I wind up pedaling at about the same time as the jack is about to escape it's adding an additional change in overall touch, at exactly the wrong moment, that simply makes it a bit easier to unintentionally create that micro pause in key play that causes the double strike. 

Follow-up question: Is there a spec on how far dampers are supposed to lift?

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Matteo - Yes, it's that "certain kind of touch". Inspection of the parts during that kind of play revealed that what's happening is that I almost subconsciously feel the bump just before escape and letoff, and the micro pause that I am creating at that point is just enough to allow the hammer to continue to move and strike the strings lightly. But since the jack has not yet completed its move when the hammer bounces back, the action still has to complete its move. When the jack finally does escape at letoff the hammer strikes the string as originally intended, but now it's a second strike from the same key movement. 

To be clear, it's not the hammer bouncing off the jack after the action has completed its move and the hammer bounces off the strings. And it's not a backcheck problem. Jacks are set so that there is a small visible space between the jack and the knuckle when all key and action movement is completed. 

Yes, like you, with a little concentration I am able to actually create this phenomena on most pianos. Upright and grand. 

I disagree that adjusting the dampers to lift earlier would help. The whole idea of having the dampers lift no earlier than half way through the blow is to take advantage of the momentum of the key and hammer movement already in process and reduce the sudden increase in weight as the dampers engage and start to lift. However, (Wim and Charles), adjusting the damper springs to make them lighter sounds like a good idea. I'll see if I can find Don Mannino's article. 

Scott - I realize that what I'm feeling is the moment the jack actually starts to move under the knuckle. A little Teflon powder on the knuckle could possibly reduce that, yes. Good suggestion. 

Nathan - The problem with the sustain pedal being involved is, I'm sure, my own playing technique. (I'm sure that being a piano tech and a beginning piano player I'm being far too technical and analytical in my approach to learning to play. 🙄 ) If I wind up pedaling at about the same time as the jack is about to escape it's adding an additional change in overall touch, at exactly the wrong moment, that simply makes it a bit easier to unintentionally create that micro pause in key play that causes the double strike. 

Follow-up question: Is there a spec on how far dampers are supposed to lift?

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Geoff,

I've encountered this problem with more new Yamahas than I would care to admit. The bump may be caused by waring parts, or it could be regulation.  The double striking is most likely caused by not enough aftertouch. Try to make minor changes until you find what will work best. I would probably start with changing key dip from 10mm to 10.5mm. 

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Geoff,

I have a U1, and a few years ago I brushed powder into all the hammer butts. That made the bump very difficult to feel (but I don't mind it). Try it on an end key and see if that improves the feel.

Geoff,

I've encountered this problem with more new Yamahas than I would care to admit. The bump may be caused by waring parts, or it could be regulation.  The double striking is most likely caused by not enough aftertouch. Try to make minor changes until you find what will work best. I would probably start with changing key dip from 10mm to 10.5mm. 

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Hi Geoff,

For some background, I have been a professional pianist far longer than a technician.  Teaching piano is still my primary income.

Obviously, there is some great technical advice here, but I want to approach it from a piano playing perspective.

Assuming your piano regulation is not incredibly far out of spec, pianists always have to overcome some level of "bump" in the key.  Often, less experienced pianists approach quiet playing by pressing the key both slowly and with very little weight.  It is the lack of weight that is the primary problem here since a lack of arm weight will be susceptible to feeling the key weight differences as the key moves to the bottom.  Instead, try approaching quiet playing by thinking of your finger as an extension of your arm.  This virtually eliminates the different resistances of the key at various points of its cycle.  Additionally, try not thinking of the key as something that only moves down and up (even though it does).  Try pressing down and forward, which will slow the rate of the key while you maintain the same rate of movement in your hand.  Similarly, you can press the key down and backward as well. 

Not all the fingers can center the arm weight equally well without using wrist angle.  For example, finger 3 will have you centered and it's easy to evenly distribute arm weight over the key.  Finger 5 is more difficult, unless you tilt the wrist/forearm to the right, centering the arm weight over that finger. This is a little overly simplistic, but hopefully it gets the point across.  Also, for more melodic quiet playing, try not to have "lost motion" from finger to key.  Your finger should be touching the key before moving the key.  This is especially important when playing the 1st finger since it is so much larger and stronger.

Another thing to try-- often times we suspend arm weight from the shoulders when it should be centered over the keys.  If you are conscious about relaxing your shoulders, try playing softly while exhaling.  Often times this will allow much more controlled soft playing.

There is another type of soft playing which involves very rapidly moving fingers, but I doubt that is related to the issue at hand (no pun intended).

Hopefully some of this makes sense-- it's much easier demonstrated than explained without visuals.

Geoff,

I have a U1, and a few years ago I brushed powder into all the hammer butts. That made the bump very difficult to feel (but I don't mind it). Try it on an end key and see if that improves the feel.

Geoff,

I've encountered this problem with more new Yamahas than I would care to admit. The bump may be caused by waring parts, or it could be regulation.  The double striking is most likely caused by not enough aftertouch. Try to make minor changes until you find what will work best. I would probably start with changing key dip from 10mm to 10.5mm. 

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Tim - Thanks for your perspective. I know that technique is probably more than just partly responsible for what I'm experience so your advice is helpful. I do understand your descriptions of the methods you are suggesting and will try them all out. - Thanks

Hi Geoff,

For some background, I have been a professional pianist far longer than a technician.  Teaching piano is still my primary income.

Obviously, there is some great technical advice here, but I want to approach it from a piano playing perspective.

Assuming your piano regulation is not incredibly far out of spec, pianists always have to overcome some level of "bump" in the key.  Often, less experienced pianists approach quiet playing by pressing the key both slowly and with very little weight.  It is the lack of weight that is the primary problem here since a lack of arm weight will be susceptible to feeling the key weight differences as the key moves to the bottom.  Instead, try approaching quiet playing by thinking of your finger as an extension of your arm.  This virtually eliminates the different resistances of the key at various points of its cycle.  Additionally, try not thinking of the key as something that only moves down and up (even though it does).  Try pressing down and forward, which will slow the rate of the key while you maintain the same rate of movement in your hand.  Similarly, you can press the key down and backward as well. 

Not all the fingers can center the arm weight equally well without using wrist angle.  For example, finger 3 will have you centered and it's easy to evenly distribute arm weight over the key.  Finger 5 is more difficult, unless you tilt the wrist/forearm to the right, centering the arm weight over that finger. This is a little overly simplistic, but hopefully it gets the point across.  Also, for more melodic quiet playing, try not to have "lost motion" from finger to key.  Your finger should be touching the key before moving the key.  This is especially important when playing the 1st finger since it is so much larger and stronger.

Another thing to try-- often times we suspend arm weight from the shoulders when it should be centered over the keys.  If you are conscious about relaxing your shoulders, try playing softly while exhaling.  Often times this will allow much more controlled soft playing.

There is another type of soft playing which involves very rapidly moving fingers, but I doubt that is related to the issue at hand (no pun intended).

Hopefully some of this makes sense-- it's much easier demonstrated than explained without visuals.

Geoff,

I have a U1, and a few years ago I brushed powder into all the hammer butts. That made the bump very difficult to feel (but I don't mind it). Try it on an end key and see if that improves the feel.

Geoff,

I've encountered this problem with more new Yamahas than I would care to admit. The bump may be caused by waring parts, or it could be regulation.  The double striking is most likely caused by not enough aftertouch. Try to make minor changes until you find what will work best. I would probably start with changing key dip from 10mm to 10.5mm. 

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Here are a couple of citations of Mannino in the Journal, discussing pros and cons of adjusting vertical damper spring tension:

October 2009 Journal pg 12, Q&A topic "Bobbling Hammers" - Mannino discusses the damper springs.
Also January 2011, pg 8, he comments on adjusting upright damper springs.

Tim - Thanks for your perspective. I know that technique is probably more than just partly responsible for what I'm experience so your advice is helpful. I do understand your descriptions of the methods you are suggesting and will try them all out. - Thanks

Hi Geoff,

For some background, I have been a professional pianist far longer than a technician.  Teaching piano is still my primary income.

Obviously, there is some great technical advice here, but I want to approach it from a piano playing perspective.

Assuming your piano regulation is not incredibly far out of spec, pianists always have to overcome some level of "bump" in the key.  Often, less experienced pianists approach quiet playing by pressing the key both slowly and with very little weight.  It is the lack of weight that is the primary problem here since a lack of arm weight will be susceptible to feeling the key weight differences as the key moves to the bottom.  Instead, try approaching quiet playing by thinking of your finger as an extension of your arm.  This virtually eliminates the different resistances of the key at various points of its cycle.  Additionally, try not thinking of the key as something that only moves down and up (even though it does).  Try pressing down and forward, which will slow the rate of the key while you maintain the same rate of movement in your hand.  Similarly, you can press the key down and backward as well. 

Not all the fingers can center the arm weight equally well without using wrist angle.  For example, finger 3 will have you centered and it's easy to evenly distribute arm weight over the key.  Finger 5 is more difficult, unless you tilt the wrist/forearm to the right, centering the arm weight over that finger. This is a little overly simplistic, but hopefully it gets the point across.  Also, for more melodic quiet playing, try not to have "lost motion" from finger to key.  Your finger should be touching the key before moving the key.  This is especially important when playing the 1st finger since it is so much larger and stronger.

Another thing to try-- often times we suspend arm weight from the shoulders when it should be centered over the keys.  If you are conscious about relaxing your shoulders, try playing softly while exhaling.  Often times this will allow much more controlled soft playing.

There is another type of soft playing which involves very rapidly moving fingers, but I doubt that is related to the issue at hand (no pun intended).

Hopefully some of this makes sense-- it's much easier demonstrated than explained without visuals.

Geoff,

I have a U1, and a few years ago I brushed powder into all the hammer butts. That made the bump very difficult to feel (but I don't mind it). Try it on an end key and see if that improves the feel.

Geoff,

I've encountered this problem with more new Yamahas than I would care to admit. The bump may be caused by waring parts, or it could be regulation.  The double striking is most likely caused by not enough aftertouch. Try to make minor changes until you find what will work best. I would probably start with changing key dip from 10mm to 10.5mm. 

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Here is what Mannino wrote:

Don Mannino, RPT:
A tentative player (i.e., most relative
beginners) will experience bobbling the most, because he does
not play the key smoothly all the way to the bottom. More
experienced pianists sometimes sit down at the same piano,
play a quiet piece of music, and have no problem. I've done
this in the past, and it added to the frustration of the piano's
owner to have me play it and say, "Hmmm, seems okay to
me…." Bad move on my part.
The best diagnostic test is to have the pianist play
something that causes bobbling and watch if the damper
pedal is in use. It will almost always occur when the damper
pedal is not in use, meaning the fingers are being stopped by
the damper springs in combination with the jack springs. If
you then ask the player to mash the damper pedal down and
hold it, then play the same music, you should find that the
bobbling has stopped. If it still occurs, recheck regulation
and friction.
The solution in almost all cases, once you have confirmed
that the standard regulation points are good (letoff, blow,
key height and dip, capstans, backchecks), is to look at the
damper timing and move it away from the jack contact with
the letoff button. Damper timing should be at half of the
hammer blow, which should be early enough to make sure
that damper lift comes sufficiently before the jack contact. In
some cases, damper lift can be made slightly earlier to help
prevent bobbling, but this does make the touch feel heavier
when the pedal is not being used. When damper lift is correct,
the player's fingers will naturally overcome the damper spring
tension well before letoff occurs, and the finger will play the
key through the full stroke.
Many pianos are built with too much damper spring
tension. This can be regulated, but it is best to do it with the
action out of the piano, in an action cradle, tilted back with
the dampers facing up. I place a stack of my old key weights
on the damper head at the center point, and find the pressure
that balances the spring tension right at the rest point of the
dampers. Spring tension increases as the dampers are pressed
back, so I find the weight that makes the treble damper start
to float at the starting point. I observe the tension over four
or five notes. At some point in the tenor, the tension will get
suddenly higher because the spring gauge has changed. This is
the critical point, in the middle of the piano, where bobbling
happens. At the very least, smoothing the transition by
weakening the heavy springs in the tenor to match the light
treble spring tension will be a huge improvement.
If the pianist is having trouble throughout the piano, then
lowering the tension by five grams or so, while also smoothing
out any transitions, then also regulating the damper lift timing
carefully, will be the end of the complaint.
To adjust tension, use your grand repetition spring
tool. Flex the spring down (with the action in the cradle as
described above) to weaken it, disengage it and pull it above
the damper levers to strengthen it. With experience, you can
do a decent job just using your finger to test spring tension,
but double check yourself occasionally with the weights.
Warning: In many pianos, weakening the spring tension
will cause lots of damper noises and weak damping! So don't
go overboard–weaken them only enough to smooth out
irregularities, or to very slightly weaken them over all. You
should plan on some follow-up damper alignment work. One
reason companies make the springs so strong is because it
saves time when regulating dampers! Shameful, I know, but
still true.
Before putting the action back in the piano, apply some
Teflon (TFL-50, Slide-All, etc) to the spoons and damper lift
rod. Ideally, these should be polished and smooth, so look for
any glue deposits to clean off first. Simply press the dampers
back, and spray the Teflon from the can using the little plastic
nozzle extender tube. A paint brush with liquid McLube
444 works very well also, if you like to avoid aerosols.
Once the dampers are re-adjusted to work well, and
damper timing is set carefully (Do you have a forked-blade
type spoon bender?), your bobbling should be eliminated.
There are two basic action configurations in use
today. I'm not sure what the correct names are for the different
action types, so I call them American and European. Asian
pianos almost always use the European style, and this has
become the most common style of upright action in new
pianos today.
In the American design, the hammer spring is relatively
strong, the jack springs are relatively weak, and the damper
spring does not affect the touch very much. This is a smooth
working and very reliable action design, but does not by
nature repeat quite as well as the European type.
In the European design, the jack springs must be strong,
and the hammer springs are weak. As I've described above,
the damper spring has a larger impact on the touch in this
design, because the player isn't already compressing that heavy
hammer spring. When working well, this system repeats a
little better, and many feel the tone quality is more expressive
and controllable.
The European design is also more sensitive to other
factors, such as spring tensions and friction. Hammer center
friction that is too low can contribute to bobbling at times,
and if the above spring and damper regulation doesn't fix
the problem, one can pick an especially bad bobbling note,
pull the hammer, and see if the friction is close to zero. If so,
pin it for four grams friction or so (measured at the flange
screw hole) and try it again. If that fixes the problem, you
have the solution.
In doing some testing in recent months, I have confirmed
that these actions really need their strong jack spring tension.
It is tempting to try weaker jack springs to stop bobbling,
but the repetition will really be bad, especially in slow to
medium-speed repetition. In a related issue, insufficient
aftertouch can also lead to repetition problems, because the
jack spring is not being compressed enough. Upright actions
rely on the jack spring to help to push the wippen (and
therefore the key) down when the player lifts the finger. If
the spring is weak, or if the spring has not been compressed
enough, the repetition rate will be poor. Gravity alone (using
the mass of the key weights at the back of the keys) is much
too slow to do a good job of letting the note repeat.

Here are a couple of citations of Mannino in the Journal, discussing pros and cons of adjusting vertical damper spring tension:

October 2009 Journal pg 12, Q&A topic "Bobbling Hammers" - Mannino discusses the damper springs.
Also January 2011, pg 8, he comments on adjusting upright damper springs.

Tim - Thanks for your perspective. I know that technique is probably more than just partly responsible for what I'm experience so your advice is helpful. I do understand your descriptions of the methods you are suggesting and will try them all out. - Thanks

Hi Geoff,

For some background, I have been a professional pianist far longer than a technician.  Teaching piano is still my primary income.

Obviously, there is some great technical advice here, but I want to approach it from a piano playing perspective.

Assuming your piano regulation is not incredibly far out of spec, pianists always have to overcome some level of "bump" in the key.  Often, less experienced pianists approach quiet playing by pressing the key both slowly and with very little weight.  It is the lack of weight that is the primary problem here since a lack of arm weight will be susceptible to feeling the key weight differences as the key moves to the bottom.  Instead, try approaching quiet playing by thinking of your finger as an extension of your arm.  This virtually eliminates the different resistances of the key at various points of its cycle.  Additionally, try not thinking of the key as something that only moves down and up (even though it does).  Try pressing down and forward, which will slow the rate of the key while you maintain the same rate of movement in your hand.  Similarly, you can press the key down and backward as well. 

Not all the fingers can center the arm weight equally well without using wrist angle.  For example, finger 3 will have you centered and it's easy to evenly distribute arm weight over the key.  Finger 5 is more difficult, unless you tilt the wrist/forearm to the right, centering the arm weight over that finger. This is a little overly simplistic, but hopefully it gets the point across.  Also, for more melodic quiet playing, try not to have "lost motion" from finger to key.  Your finger should be touching the key before moving the key.  This is especially important when playing the 1st finger since it is so much larger and stronger.

Another thing to try-- often times we suspend arm weight from the shoulders when it should be centered over the keys.  If you are conscious about relaxing your shoulders, try playing softly while exhaling.  Often times this will allow much more controlled soft playing.

There is another type of soft playing which involves very rapidly moving fingers, but I doubt that is related to the issue at hand (no pun intended).

Hopefully some of this makes sense-- it's much easier demonstrated than explained without visuals.

Geoff,

I have a U1, and a few years ago I brushed powder into all the hammer butts. That made the bump very difficult to feel (but I don't mind it). Try it on an end key and see if that improves the feel.

Geoff,

I've encountered this problem with more new Yamahas than I would care to admit. The bump may be caused by waring parts, or it could be regulation.  The double striking is most likely caused by not enough aftertouch. Try to make minor changes until you find what will work best. I would probably start with changing key dip from 10mm to 10.5mm. 

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Jason - This is GREAT! I am going to print this out to study it a bit more. But I have a question.

>Damper timing should be at half of the
hammer blow, which should be early enough to make sure
that damper lift comes sufficiently before the jack contact.

Since the jack is responsible for moving the hammer, how can damper timing be set using half the blow distance as a guide without jack contact? Without jack contact there can be no hammer movement. 

Here is what Mannino wrote:

Don Mannino, RPT:
A tentative player (i.e., most relative
beginners) will experience bobbling the most, because he does
not play the key smoothly all the way to the bottom. More
experienced pianists sometimes sit down at the same piano,
play a quiet piece of music, and have no problem. I've done
this in the past, and it added to the frustration of the piano's
owner to have me play it and say, "Hmmm, seems okay to
me…." Bad move on my part.
The best diagnostic test is to have the pianist play
something that causes bobbling and watch if the damper
pedal is in use. It will almost always occur when the damper
pedal is not in use, meaning the fingers are being stopped by
the damper springs in combination with the jack springs. If
you then ask the player to mash the damper pedal down and
hold it, then play the same music, you should find that the
bobbling has stopped. If it still occurs, recheck regulation
and friction.
The solution in almost all cases, once you have confirmed
that the standard regulation points are good (letoff, blow,
key height and dip, capstans, backchecks), is to look at the
damper timing and move it away from the jack contact with
the letoff button. Damper timing should be at half of the
hammer blow, which should be early enough to make sure
that damper lift comes sufficiently before the jack contact. In
some cases, damper lift can be made slightly earlier to help
prevent bobbling, but this does make the touch feel heavier
when the pedal is not being used. When damper lift is correct,
the player's fingers will naturally overcome the damper spring
tension well before letoff occurs, and the finger will play the
key through the full stroke.
Many pianos are built with too much damper spring
tension. This can be regulated, but it is best to do it with the
action out of the piano, in an action cradle, tilted back with
the dampers facing up. I place a stack of my old key weights
on the damper head at the center point, and find the pressure
that balances the spring tension right at the rest point of the
dampers. Spring tension increases as the dampers are pressed
back, so I find the weight that makes the treble damper start
to float at the starting point. I observe the tension over four
or five notes. At some point in the tenor, the tension will get
suddenly higher because the spring gauge has changed. This is
the critical point, in the middle of the piano, where bobbling
happens. At the very least, smoothing the transition by
weakening the heavy springs in the tenor to match the light
treble spring tension will be a huge improvement.
If the pianist is having trouble throughout the piano, then
lowering the tension by five grams or so, while also smoothing
out any transitions, then also regulating the damper lift timing
carefully, will be the end of the complaint.
To adjust tension, use your grand repetition spring
tool. Flex the spring down (with the action in the cradle as
described above) to weaken it, disengage it and pull it above
the damper levers to strengthen it. With experience, you can
do a decent job just using your finger to test spring tension,
but double check yourself occasionally with the weights.
Warning: In many pianos, weakening the spring tension
will cause lots of damper noises and weak damping! So don't
go overboard–weaken them only enough to smooth out
irregularities, or to very slightly weaken them over all. You
should plan on some follow-up damper alignment work. One
reason companies make the springs so strong is because it
saves time when regulating dampers! Shameful, I know, but
still true.
Before putting the action back in the piano, apply some
Teflon (TFL-50, Slide-All, etc) to the spoons and damper lift
rod. Ideally, these should be polished and smooth, so look for
any glue deposits to clean off first. Simply press the dampers
back, and spray the Teflon from the can using the little plastic
nozzle extender tube. A paint brush with liquid McLube
444 works very well also, if you like to avoid aerosols.
Once the dampers are re-adjusted to work well, and
damper timing is set carefully (Do you have a forked-blade
type spoon bender?), your bobbling should be eliminated.
There are two basic action configurations in use
today. I'm not sure what the correct names are for the different
action types, so I call them American and European. Asian
pianos almost always use the European style, and this has
become the most common style of upright action in new
pianos today.
In the American design, the hammer spring is relatively
strong, the jack springs are relatively weak, and the damper
spring does not affect the touch very much. This is a smooth
working and very reliable action design, but does not by
nature repeat quite as well as the European type.
In the European design, the jack springs must be strong,
and the hammer springs are weak. As I've described above,
the damper spring has a larger impact on the touch in this
design, because the player isn't already compressing that heavy
hammer spring. When working well, this system repeats a
little better, and many feel the tone quality is more expressive
and controllable.
The European design is also more sensitive to other
factors, such as spring tensions and friction. Hammer center
friction that is too low can contribute to bobbling at times,
and if the above spring and damper regulation doesn't fix
the problem, one can pick an especially bad bobbling note,
pull the hammer, and see if the friction is close to zero. If so,
pin it for four grams friction or so (measured at the flange
screw hole) and try it again. If that fixes the problem, you
have the solution.
In doing some testing in recent months, I have confirmed
that these actions really need their strong jack spring tension.
It is tempting to try weaker jack springs to stop bobbling,
but the repetition will really be bad, especially in slow to
medium-speed repetition. In a related issue, insufficient
aftertouch can also lead to repetition problems, because the
jack spring is not being compressed enough. Upright actions
rely on the jack spring to help to push the wippen (and
therefore the key) down when the player lifts the finger. If
the spring is weak, or if the spring has not been compressed
enough, the repetition rate will be poor. Gravity alone (using
the mass of the key weights at the back of the keys) is much
too slow to do a good job of letting the note repeat.

Here are a couple of citations of Mannino in the Journal, discussing pros and cons of adjusting vertical damper spring tension:

October 2009 Journal pg 12, Q&A topic "Bobbling Hammers" - Mannino discusses the damper springs.
Also January 2011, pg 8, he comments on adjusting upright damper springs.

Tim - Thanks for your perspective. I know that technique is probably more than just partly responsible for what I'm experience so your advice is helpful. I do understand your descriptions of the methods you are suggesting and will try them all out. - Thanks

Hi Geoff,

For some background, I have been a professional pianist far longer than a technician.  Teaching piano is still my primary income.

Obviously, there is some great technical advice here, but I want to approach it from a piano playing perspective.

Assuming your piano regulation is not incredibly far out of spec, pianists always have to overcome some level of "bump" in the key.  Often, less experienced pianists approach quiet playing by pressing the key both slowly and with very little weight.  It is the lack of weight that is the primary problem here since a lack of arm weight will be susceptible to feeling the key weight differences as the key moves to the bottom.  Instead, try approaching quiet playing by thinking of your finger as an extension of your arm.  This virtually eliminates the different resistances of the key at various points of its cycle.  Additionally, try not thinking of the key as something that only moves down and up (even though it does).  Try pressing down and forward, which will slow the rate of the key while you maintain the same rate of movement in your hand.  Similarly, you can press the key down and backward as well. 

Not all the fingers can center the arm weight equally well without using wrist angle.  For example, finger 3 will have you centered and it's easy to evenly distribute arm weight over the key.  Finger 5 is more difficult, unless you tilt the wrist/forearm to the right, centering the arm weight over that finger. This is a little overly simplistic, but hopefully it gets the point across.  Also, for more melodic quiet playing, try not to have "lost motion" from finger to key.  Your finger should be touching the key before moving the key.  This is especially important when playing the 1st finger since it is so much larger and stronger.

Another thing to try-- often times we suspend arm weight from the shoulders when it should be centered over the keys.  If you are conscious about relaxing your shoulders, try playing softly while exhaling.  Often times this will allow much more controlled soft playing.

There is another type of soft playing which involves very rapidly moving fingers, but I doubt that is related to the issue at hand (no pun intended).

Hopefully some of this makes sense-- it's much easier demonstrated than explained without visuals.

Geoff,

I have a U1, and a few years ago I brushed powder into all the hammer butts. That made the bump very difficult to feel (but I don't mind it). Try it on an end key and see if that improves the feel.

Geoff,

I've encountered this problem with more new Yamahas than I would care to admit. The bump may be caused by waring parts, or it could be regulation.  The double striking is most likely caused by not enough aftertouch. Try to make minor changes until you find what will work best. I would probably start with changing key dip from 10mm to 10.5mm. 

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?

Jason - This is GREAT! I am going to print this out to study it a bit more. But I have a question.

>Damper timing should be at half of the
hammer blow, which should be early enough to make sure
that damper lift comes sufficiently before the jack contact.

Since the jack is responsible for moving the hammer, how can damper timing be set using half the blow distance as a guide without jack contact? Without jack contact there can be no hammer movement. 

Here is what Mannino wrote:

Don Mannino, RPT:
A tentative player (i.e., most relative
beginners) will experience bobbling the most, because he does
not play the key smoothly all the way to the bottom. More
experienced pianists sometimes sit down at the same piano,
play a quiet piece of music, and have no problem. I've done
this in the past, and it added to the frustration of the piano's
owner to have me play it and say, "Hmmm, seems okay to
me…." Bad move on my part.
The best diagnostic test is to have the pianist play
something that causes bobbling and watch if the damper
pedal is in use. It will almost always occur when the damper
pedal is not in use, meaning the fingers are being stopped by
the damper springs in combination with the jack springs. If
you then ask the player to mash the damper pedal down and
hold it, then play the same music, you should find that the
bobbling has stopped. If it still occurs, recheck regulation
and friction.
The solution in almost all cases, once you have confirmed
that the standard regulation points are good (letoff, blow,
key height and dip, capstans, backchecks), is to look at the
damper timing and move it away from the jack contact with
the letoff button. Damper timing should be at half of the
hammer blow, which should be early enough to make sure
that damper lift comes sufficiently before the jack contact. In
some cases, damper lift can be made slightly earlier to help
prevent bobbling, but this does make the touch feel heavier
when the pedal is not being used. When damper lift is correct,
the player's fingers will naturally overcome the damper spring
tension well before letoff occurs, and the finger will play the
key through the full stroke.
Many pianos are built with too much damper spring
tension. This can be regulated, but it is best to do it with the
action out of the piano, in an action cradle, tilted back with
the dampers facing up. I place a stack of my old key weights
on the damper head at the center point, and find the pressure
that balances the spring tension right at the rest point of the
dampers. Spring tension increases as the dampers are pressed
back, so I find the weight that makes the treble damper start
to float at the starting point. I observe the tension over four
or five notes. At some point in the tenor, the tension will get
suddenly higher because the spring gauge has changed. This is
the critical point, in the middle of the piano, where bobbling
happens. At the very least, smoothing the transition by
weakening the heavy springs in the tenor to match the light
treble spring tension will be a huge improvement.
If the pianist is having trouble throughout the piano, then
lowering the tension by five grams or so, while also smoothing
out any transitions, then also regulating the damper lift timing
carefully, will be the end of the complaint.
To adjust tension, use your grand repetition spring
tool. Flex the spring down (with the action in the cradle as
described above) to weaken it, disengage it and pull it above
the damper levers to strengthen it. With experience, you can
do a decent job just using your finger to test spring tension,
but double check yourself occasionally with the weights.
Warning: In many pianos, weakening the spring tension
will cause lots of damper noises and weak damping! So don't
go overboard–weaken them only enough to smooth out
irregularities, or to very slightly weaken them over all. You
should plan on some follow-up damper alignment work. One
reason companies make the springs so strong is because it
saves time when regulating dampers! Shameful, I know, but
still true.
Before putting the action back in the piano, apply some
Teflon (TFL-50, Slide-All, etc) to the spoons and damper lift
rod. Ideally, these should be polished and smooth, so look for
any glue deposits to clean off first. Simply press the dampers
back, and spray the Teflon from the can using the little plastic
nozzle extender tube. A paint brush with liquid McLube
444 works very well also, if you like to avoid aerosols.
Once the dampers are re-adjusted to work well, and
damper timing is set carefully (Do you have a forked-blade
type spoon bender?), your bobbling should be eliminated.
There are two basic action configurations in use
today. I'm not sure what the correct names are for the different
action types, so I call them American and European. Asian
pianos almost always use the European style, and this has
become the most common style of upright action in new
pianos today.
In the American design, the hammer spring is relatively
strong, the jack springs are relatively weak, and the damper
spring does not affect the touch very much. This is a smooth
working and very reliable action design, but does not by
nature repeat quite as well as the European type.
In the European design, the jack springs must be strong,
and the hammer springs are weak. As I've described above,
the damper spring has a larger impact on the touch in this
design, because the player isn't already compressing that heavy
hammer spring. When working well, this system repeats a
little better, and many feel the tone quality is more expressive
and controllable.
The European design is also more sensitive to other
factors, such as spring tensions and friction. Hammer center
friction that is too low can contribute to bobbling at times,
and if the above spring and damper regulation doesn't fix
the problem, one can pick an especially bad bobbling note,
pull the hammer, and see if the friction is close to zero. If so,
pin it for four grams friction or so (measured at the flange
screw hole) and try it again. If that fixes the problem, you
have the solution.
In doing some testing in recent months, I have confirmed
that these actions really need their strong jack spring tension.
It is tempting to try weaker jack springs to stop bobbling,
but the repetition will really be bad, especially in slow to
medium-speed repetition. In a related issue, insufficient
aftertouch can also lead to repetition problems, because the
jack spring is not being compressed enough. Upright actions
rely on the jack spring to help to push the wippen (and
therefore the key) down when the player lifts the finger. If
the spring is weak, or if the spring has not been compressed
enough, the repetition rate will be poor. Gravity alone (using
the mass of the key weights at the back of the keys) is much
too slow to do a good job of letting the note repeat.

Here are a couple of citations of Mannino in the Journal, discussing pros and cons of adjusting vertical damper spring tension:

October 2009 Journal pg 12, Q&A topic "Bobbling Hammers" - Mannino discusses the damper springs.
Also January 2011, pg 8, he comments on adjusting upright damper springs.

Tim - Thanks for your perspective. I know that technique is probably more than just partly responsible for what I'm experience so your advice is helpful. I do understand your descriptions of the methods you are suggesting and will try them all out. - Thanks

Hi Geoff,

For some background, I have been a professional pianist far longer than a technician.  Teaching piano is still my primary income.

Obviously, there is some great technical advice here, but I want to approach it from a piano playing perspective.

Assuming your piano regulation is not incredibly far out of spec, pianists always have to overcome some level of "bump" in the key.  Often, less experienced pianists approach quiet playing by pressing the key both slowly and with very little weight.  It is the lack of weight that is the primary problem here since a lack of arm weight will be susceptible to feeling the key weight differences as the key moves to the bottom.  Instead, try approaching quiet playing by thinking of your finger as an extension of your arm.  This virtually eliminates the different resistances of the key at various points of its cycle.  Additionally, try not thinking of the key as something that only moves down and up (even though it does).  Try pressing down and forward, which will slow the rate of the key while you maintain the same rate of movement in your hand.  Similarly, you can press the key down and backward as well. 

Not all the fingers can center the arm weight equally well without using wrist angle.  For example, finger 3 will have you centered and it's easy to evenly distribute arm weight over the key.  Finger 5 is more difficult, unless you tilt the wrist/forearm to the right, centering the arm weight over that finger. This is a little overly simplistic, but hopefully it gets the point across.  Also, for more melodic quiet playing, try not to have "lost motion" from finger to key.  Your finger should be touching the key before moving the key.  This is especially important when playing the 1st finger since it is so much larger and stronger.

Another thing to try-- often times we suspend arm weight from the shoulders when it should be centered over the keys.  If you are conscious about relaxing your shoulders, try playing softly while exhaling.  Often times this will allow much more controlled soft playing.

There is another type of soft playing which involves very rapidly moving fingers, but I doubt that is related to the issue at hand (no pun intended).

Hopefully some of this makes sense-- it's much easier demonstrated than explained without visuals.

Geoff,

I have a U1, and a few years ago I brushed powder into all the hammer butts. That made the bump very difficult to feel (but I don't mind it). Try it on an end key and see if that improves the feel.

Geoff,

I've encountered this problem with more new Yamahas than I would care to admit. The bump may be caused by waring parts, or it could be regulation.  The double striking is most likely caused by not enough aftertouch. Try to make minor changes until you find what will work best. I would probably start with changing key dip from 10mm to 10.5mm. 

Yamaha YUS1, 2008. 

While I experience this bump on most pianos to varying degrees, I seldom have complaints about it from piano owners. My problem with this piano is that it is mine. I purchased it new, and then started taking lessons. Figured that since I was tuning them I should probably know how to play them. The bump that happens when a key is part way down and finally starts to move the damper is preventing me from being able to play softly. If I'm not very careful to absolutely smoothly press the key down clear to the bottom I frequently get a slight double strike. It's worse when the sustain pedal is involved. It's driving me nuts. I'm having trouble deciding whether it's my own playing technique that is bad or if it's that darn bump that distracts me.

Yamaha regulation specs were set and the bump was crazy. But a year or so ago I tuned a customers Yamaha U1 upright and really liked the response. I measured everything and took those measurements home and set my U1 up as closely as possible to them. Great improvement. But still not enough for me not to pretty much unconsciously experience that bump on quiet notes and cause it to lightly double strike. 

Dip is 10mm. Lost motion is at minimum. Letoff is sooner than spec because I'm trying to keep things quiet. Dampers start to move just past halfway hammer blow distance. Jack set just lightly in front of specs, (it escapes sooner than later). Damper lift with pedal is exactly the same is when playing, except the black keys move the damper just a teeny tiny bit more. 

How far the pedal moves, and how much lost motion is in the pedal, pretty much determines how far the dampers are going to lift with the pedal. Short of increasing pedal lost motion, which I don't want to do, the only way to limit damper lift with the pedal is to reduce pedal movement with additional hard felt under the pedal. That, along with adjusting damper spoons to accommodate less pedal movement is what I'm thinking of trying next. Theoretically I'm supposed to know what I'm doing, but damper spoon adjustment is not an easy task so I thought I would inquire here before diving in to that task. Don't want to have to do it twice, ya know? 

Thoughts?