Pianotech

I had a kind of "aha!" experience on the week-end, when in working on a number of pianos in preparation for an event, the implications of the idea of a gradient of tone in voicing stood out to me more clearly.  I was working with a 1990 Steinway B, noting how nicely the tone quality progressed from one dynamic level to another, when I realized that I was enjoying precisely what was eluding me on other pianos I have been struggling with in recent days.

In a number of cases, the work that I do in voicing maintenance produces exactly what I want.  Conservative reshaping of the upper shoulders of hammers on several instruments has dialed back the growing stridency in the middle dynamics without taming the forte.  A new set of Abel hammers from Bolduc that I installed in a reworked 1916 Nordheimer are performing well.  In the latter case, I did some needling in the lower shoulders before installation, and did not have to do a whole lot more than that.

On some other instruments, however, I seem to be faced with a simple choice between stridency at all dynamic levels and a lack of power at forte levels.

When dealing with a set of strident hammers that is well into its service life, my first move is to remove material near the strike area, shortening the lengths of the grooves, while seeking to restore something resembling the original curved profile of the crown.  Sometimes this is enough, but sometimes it isn't.  My second move is often to use a single needle, inserting it near or at the end of each string groove, angling away from the center line of the hammer.  I typically do this at both ends of each groove.  If the hammer is particularly resistant to the insertion of the needle, I might first do an insertion just outboard of the end of the string groove first.  This usually gives access to a less strident tone at lower dynamic levels.  However, in a number of instances, the focus of the forte has been lost.

On one occasion I worked to restore the lost power by using a mild solution of B-72 just outboard of the string grooves, but in time this resulted in a return of the strident tone at all dynamic levels.

I do wonder what needs to be modified in my approach, but I also wonder what other factors are contributing to my experience.  Some of these pianos have lost a significant degree of the original impedance of their soundboards.  How does this factor in?  Some have replacement hammers that I regard as being beyond the appropriate weight.  I suspect this plays into the picture as well, though I do understand that there are specific strategies in voicing heavier hammers.

In a few weeks I will be revisiting a Yamaha U1 in a small-town community hall.  Last time I visited it, if I recall correctly, I felt like it was screaming at me, and I did some voicing, probably both reshaping the hammers and doing some needle work.  The response of the users was that the piano lost its ability to speak into the space the way they wanted it to.  I will bring along my B-72, but I'm hoping I can do more than put it back into the strident state in which I found it last time.

I look forward to your comments.  I think I'm poised to learn something.  Thanks for any input you might have.

Floyd,

It is interesting you have observed many impressions of aging pianos as I. There are many aspects to those problems. Aside from the hammer filing you mentioned which could contribute to tonal deterioration including the shorter filed hammer not striking on the proper strike line or not striking at a 90-degree angle there are other possible issues. Issues you have touched upon.

It is common knowledge in the audio business that low frequencies suck up the most energy, i.e. the fundamentals. There is a low frequency in the tonal equation we tend to forget, that being the hammer impact frequency. That frequency is so low it would be equated to one hertz per second or even one hertz per two seconds. In other words, a great amount of low frequency energy is projected in such a short time we tend to dismiss it because we focus our attention on the string fundamental and harmonics. Keep in mind, the piano is a percussion instrument.  As with percussion instruments, the percussive attack is part of the tonal quality that defines a particular instrument. The high pitch attack we hear in chimes or the low frequency attack we hear in kettle drums are part of the qualitative identifier.

With pianos, the low frequency attack power level increasingly dissipates through the sound board as the piano ages. This is caused by the low impedance you identified. This low impedance favors the low impact frequency, and we begin to hear the tonal envelope emanating as a thud when the hammer strikes the string. So much low frequency energy has been drawn down by the soundboard it leaves less and less energy for the rest of the tonal envelope and we identify the piano as having a loss of power and sustain.

That's my guess, being thousands of miles from your pianos.

PS. Sorry I can't give you more encouraging suggestions, but do not despair, on the horizon there may be a way to increase the impedance of a sound board without replacement.

Roger

I had a kind of "aha!" experience on the week-end, when in working on a number of pianos in preparation for an event, the implications of the idea of a gradient of tone in voicing stood out to me more clearly.  I was working with a 1990 Steinway B, noting how nicely the tone quality progressed from one dynamic level to another, when I realized that I was enjoying precisely what was eluding me on other pianos I have been struggling with in recent days.

In a number of cases, the work that I do in voicing maintenance produces exactly what I want.  Conservative reshaping of the upper shoulders of hammers on several instruments has dialed back the growing stridency in the middle dynamics without taming the forte.  A new set of Abel hammers from Bolduc that I installed in a reworked 1916 Nordheimer are performing well.  In the latter case, I did some needling in the lower shoulders before installation, and did not have to do a whole lot more than that.

On some other instruments, however, I seem to be faced with a simple choice between stridency at all dynamic levels and a lack of power at forte levels.

When dealing with a set of strident hammers that is well into its service life, my first move is to remove material near the strike area, shortening the lengths of the grooves, while seeking to restore something resembling the original curved profile of the crown.  Sometimes this is enough, but sometimes it isn't.  My second move is often to use a single needle, inserting it near or at the end of each string groove, angling away from the center line of the hammer.  I typically do this at both ends of each groove.  If the hammer is particularly resistant to the insertion of the needle, I might first do an insertion just outboard of the end of the string groove first.  This usually gives access to a less strident tone at lower dynamic levels.  However, in a number of instances, the focus of the forte has been lost.

On one occasion I worked to restore the lost power by using a mild solution of B-72 just outboard of the string grooves, but in time this resulted in a return of the strident tone at all dynamic levels.

I do wonder what needs to be modified in my approach, but I also wonder what other factors are contributing to my experience.  Some of these pianos have lost a significant degree of the original impedance of their soundboards.  How does this factor in?  Some have replacement hammers that I regard as being beyond the appropriate weight.  I suspect this plays into the picture as well, though I do understand that there are specific strategies in voicing heavier hammers.

In a few weeks I will be revisiting a Yamaha U1 in a small-town community hall.  Last time I visited it, if I recall correctly, I felt like it was screaming at me, and I did some voicing, probably both reshaping the hammers and doing some needle work.  The response of the users was that the piano lost its ability to speak into the space the way they wanted it to.  I will bring along my B-72, but I'm hoping I can do more than put it back into the strident state in which I found it last time.

I look forward to your comments.  I think I'm poised to learn something.  Thanks for any input you might have.

Floyd,

It is interesting you have observed many impressions of aging pianos as I. There are many aspects to those problems. Aside from the hammer filing you mentioned which could contribute to tonal deterioration including the shorter filed hammer not striking on the proper strike line or not striking at a 90-degree angle there are other possible issues. Issues you have touched upon.

It is common knowledge in the audio business that low frequencies suck up the most energy, i.e. the fundamentals. There is a low frequency in the tonal equation we tend to forget, that being the hammer impact frequency. That frequency is so low it would be equated to one hertz per second or even one hertz per two seconds. In other words, a great amount of low frequency energy is projected in such a short time we tend to dismiss it because we focus our attention on the string fundamental and harmonics. Keep in mind, the piano is a percussion instrument.  As with percussion instruments, the percussive attack is part of the tonal quality that defines a particular instrument. The high pitch attack we hear in chimes or the low frequency attack we hear in kettle drums are part of the qualitative identifier.

With pianos, the low frequency attack power level increasingly dissipates through the sound board as the piano ages. This is caused by the low impedance you identified. This low impedance favors the low impact frequency, and we begin to hear the tonal envelope emanating as a thud when the hammer strikes the string. So much low frequency energy has been drawn down by the soundboard it leaves less and less energy for the rest of the tonal envelope and we identify the piano as having a loss of power and sustain.

That's my guess, being thousands of miles from your pianos.

PS. Sorry I can't give you more encouraging suggestions, but do not despair, on the horizon there may be a way to increase the impedance of a sound board without replacement.

Roger

I had a kind of "aha!" experience on the week-end, when in working on a number of pianos in preparation for an event, the implications of the idea of a gradient of tone in voicing stood out to me more clearly.  I was working with a 1990 Steinway B, noting how nicely the tone quality progressed from one dynamic level to another, when I realized that I was enjoying precisely what was eluding me on other pianos I have been struggling with in recent days.

In a number of cases, the work that I do in voicing maintenance produces exactly what I want.  Conservative reshaping of the upper shoulders of hammers on several instruments has dialed back the growing stridency in the middle dynamics without taming the forte.  A new set of Abel hammers from Bolduc that I installed in a reworked 1916 Nordheimer are performing well.  In the latter case, I did some needling in the lower shoulders before installation, and did not have to do a whole lot more than that.

On some other instruments, however, I seem to be faced with a simple choice between stridency at all dynamic levels and a lack of power at forte levels.

When dealing with a set of strident hammers that is well into its service life, my first move is to remove material near the strike area, shortening the lengths of the grooves, while seeking to restore something resembling the original curved profile of the crown.  Sometimes this is enough, but sometimes it isn't.  My second move is often to use a single needle, inserting it near or at the end of each string groove, angling away from the center line of the hammer.  I typically do this at both ends of each groove.  If the hammer is particularly resistant to the insertion of the needle, I might first do an insertion just outboard of the end of the string groove first.  This usually gives access to a less strident tone at lower dynamic levels.  However, in a number of instances, the focus of the forte has been lost.

On one occasion I worked to restore the lost power by using a mild solution of B-72 just outboard of the string grooves, but in time this resulted in a return of the strident tone at all dynamic levels.

I do wonder what needs to be modified in my approach, but I also wonder what other factors are contributing to my experience.  Some of these pianos have lost a significant degree of the original impedance of their soundboards.  How does this factor in?  Some have replacement hammers that I regard as being beyond the appropriate weight.  I suspect this plays into the picture as well, though I do understand that there are specific strategies in voicing heavier hammers.

In a few weeks I will be revisiting a Yamaha U1 in a small-town community hall.  Last time I visited it, if I recall correctly, I felt like it was screaming at me, and I did some voicing, probably both reshaping the hammers and doing some needle work.  The response of the users was that the piano lost its ability to speak into the space the way they wanted it to.  I will bring along my B-72, but I'm hoping I can do more than put it back into the strident state in which I found it last time.

I look forward to your comments.  I think I'm poised to learn something.  Thanks for any input you might have.

I had a kind of "aha!" experience on the week-end, when in working on a number of pianos in preparation for an event, the implications of the idea of a gradient of tone in voicing stood out to me more clearly.  I was working with a 1990 Steinway B, noting how nicely the tone quality progressed from one dynamic level to another, when I realized that I was enjoying precisely what was eluding me on other pianos I have been struggling with in recent days.

In a number of cases, the work that I do in voicing maintenance produces exactly what I want.  Conservative reshaping of the upper shoulders of hammers on several instruments has dialed back the growing stridency in the middle dynamics without taming the forte.  A new set of Abel hammers from Bolduc that I installed in a reworked 1916 Nordheimer are performing well.  In the latter case, I did some needling in the lower shoulders before installation, and did not have to do a whole lot more than that.

On some other instruments, however, I seem to be faced with a simple choice between stridency at all dynamic levels and a lack of power at forte levels.

When dealing with a set of strident hammers that is well into its service life, my first move is to remove material near the strike area, shortening the lengths of the grooves, while seeking to restore something resembling the original curved profile of the crown.  Sometimes this is enough, but sometimes it isn't.  My second move is often to use a single needle, inserting it near or at the end of each string groove, angling away from the center line of the hammer.  I typically do this at both ends of each groove.  If the hammer is particularly resistant to the insertion of the needle, I might first do an insertion just outboard of the end of the string groove first.  This usually gives access to a less strident tone at lower dynamic levels.  However, in a number of instances, the focus of the forte has been lost.

On one occasion I worked to restore the lost power by using a mild solution of B-72 just outboard of the string grooves, but in time this resulted in a return of the strident tone at all dynamic levels.

I do wonder what needs to be modified in my approach, but I also wonder what other factors are contributing to my experience.  Some of these pianos have lost a significant degree of the original impedance of their soundboards.  How does this factor in?  Some have replacement hammers that I regard as being beyond the appropriate weight.  I suspect this plays into the picture as well, though I do understand that there are specific strategies in voicing heavier hammers.

In a few weeks I will be revisiting a Yamaha U1 in a small-town community hall.  Last time I visited it, if I recall correctly, I felt like it was screaming at me, and I did some voicing, probably both reshaping the hammers and doing some needle work.  The response of the users was that the piano lost its ability to speak into the space the way they wanted it to.  I will bring along my B-72, but I'm hoping I can do more than put it back into the strident state in which I found it last time.

I look forward to your comments.  I think I'm poised to learn something.  Thanks for any input you might have.

I had a kind of "aha!" experience on the week-end, when in working on a number of pianos in preparation for an event, the implications of the idea of a gradient of tone in voicing stood out to me more clearly.  I was working with a 1990 Steinway B, noting how nicely the tone quality progressed from one dynamic level to another, when I realized that I was enjoying precisely what was eluding me on other pianos I have been struggling with in recent days.

In a number of cases, the work that I do in voicing maintenance produces exactly what I want.  Conservative reshaping of the upper shoulders of hammers on several instruments has dialed back the growing stridency in the middle dynamics without taming the forte.  A new set of Abel hammers from Bolduc that I installed in a reworked 1916 Nordheimer are performing well.  In the latter case, I did some needling in the lower shoulders before installation, and did not have to do a whole lot more than that.

On some other instruments, however, I seem to be faced with a simple choice between stridency at all dynamic levels and a lack of power at forte levels.

When dealing with a set of strident hammers that is well into its service life, my first move is to remove material near the strike area, shortening the lengths of the grooves, while seeking to restore something resembling the original curved profile of the crown.  Sometimes this is enough, but sometimes it isn't.  My second move is often to use a single needle, inserting it near or at the end of each string groove, angling away from the center line of the hammer.  I typically do this at both ends of each groove.  If the hammer is particularly resistant to the insertion of the needle, I might first do an insertion just outboard of the end of the string groove first.  This usually gives access to a less strident tone at lower dynamic levels.  However, in a number of instances, the focus of the forte has been lost.

On one occasion I worked to restore the lost power by using a mild solution of B-72 just outboard of the string grooves, but in time this resulted in a return of the strident tone at all dynamic levels.

I do wonder what needs to be modified in my approach, but I also wonder what other factors are contributing to my experience.  Some of these pianos have lost a significant degree of the original impedance of their soundboards.  How does this factor in?  Some have replacement hammers that I regard as being beyond the appropriate weight.  I suspect this plays into the picture as well, though I do understand that there are specific strategies in voicing heavier hammers.

In a few weeks I will be revisiting a Yamaha U1 in a small-town community hall.  Last time I visited it, if I recall correctly, I felt like it was screaming at me, and I did some voicing, probably both reshaping the hammers and doing some needle work.  The response of the users was that the piano lost its ability to speak into the space the way they wanted it to.  I will bring along my B-72, but I'm hoping I can do more than put it back into the strident state in which I found it last time.

I look forward to your comments.  I think I'm poised to learn something.  Thanks for any input you might have.

I had a kind of "aha!" experience on the week-end, when in working on a number of pianos in preparation for an event, the implications of the idea of a gradient of tone in voicing stood out to me more clearly.  I was working with a 1990 Steinway B, noting how nicely the tone quality progressed from one dynamic level to another, when I realized that I was enjoying precisely what was eluding me on other pianos I have been struggling with in recent days.

In a number of cases, the work that I do in voicing maintenance produces exactly what I want.  Conservative reshaping of the upper shoulders of hammers on several instruments has dialed back the growing stridency in the middle dynamics without taming the forte.  A new set of Abel hammers from Bolduc that I installed in a reworked 1916 Nordheimer are performing well.  In the latter case, I did some needling in the lower shoulders before installation, and did not have to do a whole lot more than that.

On some other instruments, however, I seem to be faced with a simple choice between stridency at all dynamic levels and a lack of power at forte levels.

When dealing with a set of strident hammers that is well into its service life, my first move is to remove material near the strike area, shortening the lengths of the grooves, while seeking to restore something resembling the original curved profile of the crown.  Sometimes this is enough, but sometimes it isn't.  My second move is often to use a single needle, inserting it near or at the end of each string groove, angling away from the center line of the hammer.  I typically do this at both ends of each groove.  If the hammer is particularly resistant to the insertion of the needle, I might first do an insertion just outboard of the end of the string groove first.  This usually gives access to a less strident tone at lower dynamic levels.  However, in a number of instances, the focus of the forte has been lost.

On one occasion I worked to restore the lost power by using a mild solution of B-72 just outboard of the string grooves, but in time this resulted in a return of the strident tone at all dynamic levels.

I do wonder what needs to be modified in my approach, but I also wonder what other factors are contributing to my experience.  Some of these pianos have lost a significant degree of the original impedance of their soundboards.  How does this factor in?  Some have replacement hammers that I regard as being beyond the appropriate weight.  I suspect this plays into the picture as well, though I do understand that there are specific strategies in voicing heavier hammers.

In a few weeks I will be revisiting a Yamaha U1 in a small-town community hall.  Last time I visited it, if I recall correctly, I felt like it was screaming at me, and I did some voicing, probably both reshaping the hammers and doing some needle work.  The response of the users was that the piano lost its ability to speak into the space the way they wanted it to.  I will bring along my B-72, but I'm hoping I can do more than put it back into the strident state in which I found it last time.

I look forward to your comments.  I think I'm poised to learn something.  Thanks for any input you might have.

The reality is that it's always an interaction between hammer and soundboard impedance and both change over time.  Hammers wear, get less resilient, develop different compression/decompression characteristics and all that affects how they deliver energy to the string and how they rebound off the string affecting both timbre and, to some degree, the filtering properties that are especially important in the treble section.

Soundboards do change impedance characteristics throughout their life and even with humidity cycles.  Riblets won't be a perfect substitute for lost crown or lower impedance because the spring-like qualities that allow the board to stiffen under compression to achieve the requisite level are only part of the story. The potential energy stored in this soundboard spring that is under a certain amount of compression is not the same as adding stiffness by effectively beefing up the rib scale. It might help, in some cases, but it's not a substitute for a fully crowned board that is compressed.  

That means that not only are hammer selections critical in the initial phase of the piano's life but that choice that might have been right then may not be right now that the board has aged. Often that can be dealt with through judicious voicing procedures but sometimes the changes in the hammer and soundboard that occur with age are going in the same direction, less liveliness, less spring, however you want to call it, and those things can't be physically restored.  

At a certain point in a piano soundboard's life, the choice of hammer, and opting for a new, more suitable hammer, is probably the best route. Generally, with lower impedance you will want somewhat softer and somewhat lighter and more resilient (springy), to mitigate the percussive nature of the changing SB and to get the hammer off the string faster to reduce filtering and help, to some degree with sustain, or at least sustain perception.  

As to what specific treatment needs to be applied to aging hammers short of replacing them, it will depend a lot one what the hammer is, what's been done to it already, and how much life it has left in it.  While we can always make things better, sometimes better will not be enough. Shape is critical and affects hammer string contact time and filtering.  But as we reshape the hammer from wear, the hammer dimensions have also been reduced--there is less felt over the molding.  Sometimes that can be a benefit if there was too much there to begin with.  That's often the case with Steinway factory hammers, certainly from previous decades.  But sometimes there will be compromise in the shock absorber nature of hammers with that reduction and that's hard to mitigate. If weight is reduced to the detriment of power, especially in the lower end of the piano, that can be added back easily using mini binder clips or even lead insertions into the molding.  But usually, a lighter hammer will benefit an aging soundboard somewhat.  Building back in the shock absorber by needling high or low shoulder certainly helps but becomes shorter and shorter lived the more the hammer dimensions are reduced.

It should be kept in mind that everything we do in the voicing procedure is destructive to the integrity the hammer.  Either we're adding chemicals that destroy the felt's natural resilience, or we are needling the felt and reducing the tension in the hammer by stretching the fibers apart.  That has benefits in terms of reducing the level of stiffness in the hammer when it is too "hard", but we can't un-needle a hammer to restore tension if we decide we need it back. 

So, at a certain point we may have to cut our losses and rethink what needs to be there based on the characteristics of the existing SB and make the best choice possible when it comes to replacing them.  Long answer to the question of what are best practices, but I think there is no simple answer or general protocol that can address every situation, unfortunately.   

I had a kind of "aha!" experience on the week-end, when in working on a number of pianos in preparation for an event, the implications of the idea of a gradient of tone in voicing stood out to me more clearly.  I was working with a 1990 Steinway B, noting how nicely the tone quality progressed from one dynamic level to another, when I realized that I was enjoying precisely what was eluding me on other pianos I have been struggling with in recent days.

In a number of cases, the work that I do in voicing maintenance produces exactly what I want.  Conservative reshaping of the upper shoulders of hammers on several instruments has dialed back the growing stridency in the middle dynamics without taming the forte.  A new set of Abel hammers from Bolduc that I installed in a reworked 1916 Nordheimer are performing well.  In the latter case, I did some needling in the lower shoulders before installation, and did not have to do a whole lot more than that.

On some other instruments, however, I seem to be faced with a simple choice between stridency at all dynamic levels and a lack of power at forte levels.

When dealing with a set of strident hammers that is well into its service life, my first move is to remove material near the strike area, shortening the lengths of the grooves, while seeking to restore something resembling the original curved profile of the crown.  Sometimes this is enough, but sometimes it isn't.  My second move is often to use a single needle, inserting it near or at the end of each string groove, angling away from the center line of the hammer.  I typically do this at both ends of each groove.  If the hammer is particularly resistant to the insertion of the needle, I might first do an insertion just outboard of the end of the string groove first.  This usually gives access to a less strident tone at lower dynamic levels.  However, in a number of instances, the focus of the forte has been lost.

On one occasion I worked to restore the lost power by using a mild solution of B-72 just outboard of the string grooves, but in time this resulted in a return of the strident tone at all dynamic levels.

I do wonder what needs to be modified in my approach, but I also wonder what other factors are contributing to my experience.  Some of these pianos have lost a significant degree of the original impedance of their soundboards.  How does this factor in?  Some have replacement hammers that I regard as being beyond the appropriate weight.  I suspect this plays into the picture as well, though I do understand that there are specific strategies in voicing heavier hammers.

In a few weeks I will be revisiting a Yamaha U1 in a small-town community hall.  Last time I visited it, if I recall correctly, I felt like it was screaming at me, and I did some voicing, probably both reshaping the hammers and doing some needle work.  The response of the users was that the piano lost its ability to speak into the space the way they wanted it to.  I will bring along my B-72, but I'm hoping I can do more than put it back into the strident state in which I found it last time.

I look forward to your comments.  I think I'm poised to learn something.  Thanks for any input you might have.

My approach when doing this kind of "major maintenance" voicing is to repeat what I have done earlier when "pre-voicing": deep needle the shoulders in a pattern that follows the grain of the felt fibers to the degree possible, opening them up, as opposed to inserting needles at right angles through the layers. The tip of the needle is placed on the surface of the hammer, then pressed in, as opposed to stabbing. This results in far less tearing of fibers compared to creation of springy cushion, by pulling the fibers apart and allowing the natural crimp to be released. I follow a pattern that rotates around the shoulders, leaving a sharpish point of untouched felt just above the tip of the molding. 

I will have filed the hammers in the interim, so the re-needling process will be penetrating deeper into the core of the hammers.

I have found that this treatment consistently maintains a wide tonal gradient, increasing upper partial mix with increased force of blow, and restoring the lower end of the spectrum when playing pianissimo. See attached photo for needle pattern.

The reality is that it's always an interaction between hammer and soundboard impedance and both change over time.  Hammers wear, get less resilient, develop different compression/decompression characteristics and all that affects how they deliver energy to the string and how they rebound off the string affecting both timbre and, to some degree, the filtering properties that are especially important in the treble section.

Soundboards do change impedance characteristics throughout their life and even with humidity cycles.  Riblets won't be a perfect substitute for lost crown or lower impedance because the spring-like qualities that allow the board to stiffen under compression to achieve the requisite level are only part of the story. The potential energy stored in this soundboard spring that is under a certain amount of compression is not the same as adding stiffness by effectively beefing up the rib scale. It might help, in some cases, but it's not a substitute for a fully crowned board that is compressed.  

That means that not only are hammer selections critical in the initial phase of the piano's life but that choice that might have been right then may not be right now that the board has aged. Often that can be dealt with through judicious voicing procedures but sometimes the changes in the hammer and soundboard that occur with age are going in the same direction, less liveliness, less spring, however you want to call it, and those things can't be physically restored.  

At a certain point in a piano soundboard's life, the choice of hammer, and opting for a new, more suitable hammer, is probably the best route. Generally, with lower impedance you will want somewhat softer and somewhat lighter and more resilient (springy), to mitigate the percussive nature of the changing SB and to get the hammer off the string faster to reduce filtering and help, to some degree with sustain, or at least sustain perception.  

As to what specific treatment needs to be applied to aging hammers short of replacing them, it will depend a lot one what the hammer is, what's been done to it already, and how much life it has left in it.  While we can always make things better, sometimes better will not be enough. Shape is critical and affects hammer string contact time and filtering.  But as we reshape the hammer from wear, the hammer dimensions have also been reduced--there is less felt over the molding.  Sometimes that can be a benefit if there was too much there to begin with.  That's often the case with Steinway factory hammers, certainly from previous decades.  But sometimes there will be compromise in the shock absorber nature of hammers with that reduction and that's hard to mitigate. If weight is reduced to the detriment of power, especially in the lower end of the piano, that can be added back easily using mini binder clips or even lead insertions into the molding.  But usually, a lighter hammer will benefit an aging soundboard somewhat.  Building back in the shock absorber by needling high or low shoulder certainly helps but becomes shorter and shorter lived the more the hammer dimensions are reduced.

It should be kept in mind that everything we do in the voicing procedure is destructive to the integrity the hammer.  Either we're adding chemicals that destroy the felt's natural resilience, or we are needling the felt and reducing the tension in the hammer by stretching the fibers apart.  That has benefits in terms of reducing the level of stiffness in the hammer when it is too "hard", but we can't un-needle a hammer to restore tension if we decide we need it back. 

So, at a certain point we may have to cut our losses and rethink what needs to be there based on the characteristics of the existing SB and make the best choice possible when it comes to replacing them.  Long answer to the question of what are best practices, but I think there is no simple answer or general protocol that can address every situation, unfortunately.   

I had a kind of "aha!" experience on the week-end, when in working on a number of pianos in preparation for an event, the implications of the idea of a gradient of tone in voicing stood out to me more clearly.  I was working with a 1990 Steinway B, noting how nicely the tone quality progressed from one dynamic level to another, when I realized that I was enjoying precisely what was eluding me on other pianos I have been struggling with in recent days.

In a number of cases, the work that I do in voicing maintenance produces exactly what I want.  Conservative reshaping of the upper shoulders of hammers on several instruments has dialed back the growing stridency in the middle dynamics without taming the forte.  A new set of Abel hammers from Bolduc that I installed in a reworked 1916 Nordheimer are performing well.  In the latter case, I did some needling in the lower shoulders before installation, and did not have to do a whole lot more than that.

On some other instruments, however, I seem to be faced with a simple choice between stridency at all dynamic levels and a lack of power at forte levels.

When dealing with a set of strident hammers that is well into its service life, my first move is to remove material near the strike area, shortening the lengths of the grooves, while seeking to restore something resembling the original curved profile of the crown.  Sometimes this is enough, but sometimes it isn't.  My second move is often to use a single needle, inserting it near or at the end of each string groove, angling away from the center line of the hammer.  I typically do this at both ends of each groove.  If the hammer is particularly resistant to the insertion of the needle, I might first do an insertion just outboard of the end of the string groove first.  This usually gives access to a less strident tone at lower dynamic levels.  However, in a number of instances, the focus of the forte has been lost.

On one occasion I worked to restore the lost power by using a mild solution of B-72 just outboard of the string grooves, but in time this resulted in a return of the strident tone at all dynamic levels.

I do wonder what needs to be modified in my approach, but I also wonder what other factors are contributing to my experience.  Some of these pianos have lost a significant degree of the original impedance of their soundboards.  How does this factor in?  Some have replacement hammers that I regard as being beyond the appropriate weight.  I suspect this plays into the picture as well, though I do understand that there are specific strategies in voicing heavier hammers.

In a few weeks I will be revisiting a Yamaha U1 in a small-town community hall.  Last time I visited it, if I recall correctly, I felt like it was screaming at me, and I did some voicing, probably both reshaping the hammers and doing some needle work.  The response of the users was that the piano lost its ability to speak into the space the way they wanted it to.  I will bring along my B-72, but I'm hoping I can do more than put it back into the strident state in which I found it last time.

I look forward to your comments.  I think I'm poised to learn something.  Thanks for any input you might have.