Harpsichord

Hi,

We have a Dowd French Double (after Blanchet) here at SFSU that somehow managed to survive at high pitch since 1969 without the wrestplank tearing out. But we are always having trouble with damper felts - they tend to curl off to the side and stop damping (mostly in the bass). It's easy enough to flip them over to the other side or just replace them with fresh felt - but what causes them to curl? And is there a way to prevent this?
-------------------------------------------
Israel Stein RPT
A-Major Piano Services
Albany, CA 94706
510-558-0777
custos3@comcast.net

-------------------------------------------

Israel,

Here is an expert you could ask about this:  

Henrik Broekmann at hubharp.com. (Hubbard Harpsichords; a competitor but Hubbard and Dowd once studied together).   He is very generous with assistance.

-------------------------------------------
Larry Lobel
Petaluma CA
707-762-5800
-------------------------------------------






Original Message:
Sent: 08-22-2011 16:44
From: Israel Stein
Subject: "curling" damper felts

Hi,

We have a Dowd French Double (after Blanchet) here at SFSU that somehow managed to survive at high pitch since 1969 without the wrestplank tearing out. But we are always having trouble with damper felts - they tend to curl off to the side and stop damping (mostly in the bass). It's easy enough to flip them over to the other side or just replace them with fresh felt - but what causes them to curl? And is there a way to prevent this?
-------------------------------------------
Israel Stein RPT
A-Major Piano Services
Albany, CA 94706
510-558-0777
custos3@comcast.net

-------------------------------------------

Ah, good old Henrik...  He once gave our Boston chapter (when I was there) a really nice technical session at the Hubbard workshop (before they moved from Waltham Square to Sudbury) on what sort of nasty things happen to harpsichords when they are copied from 18th-century originals but kept at A=440 (and what they do at the shop to restore them). That's why I am amazed that our Dowd is still intact... Henrik has the driest sense of humor coupled with the greatest deadpan - he had us rolling with laughter for two hours...

I wouldn't call Frank Hubbard and Bill Dowd "competitors" - they both started out as friends at Harvard (English Lit, I think), got bored of Academe and went to study harpsichord building in England with the Dolmetches and others. Starting out on their own at copying historical examples (which nobody else at the time was doing) as partners in a shop, they later started their own shops back in Massachusetts - Frank in an old mansion in Waltham (I got to visit what used to be his shop when tuning a piano for a concert series in that mansion - Lyman Mansion) and Bill in South Boston. I got to visit both shops - Bill was still running his (he was an ornery old cuss by then, griping about what he called "Hysterical accuracy" - referring to "historical" tuning pins and other such "authentic" and (in his mind, unnecessary) complications. Frank  died in 1976, and the shop was being run by his widow Diane at the time that I was working on an unfinished Hubbard Fortepiano kit (which I got from Chistine Lovgren which she got from Bill Garlick when he went to Steinway) and was always coming around for parts. Eventually she offered me a job - which I declined (wasn't ready for all that woodworking) and which she eventually gave to Dave Doremus. You here, Dave? (Never finished the kit - sold it to Peter Sykes, and it's still probably lying around somewhere at the First Congregational Church of Cambridge...)

OK, so much for reminiscing in public. I figured I would bother Henrik with more complicated stuff - I was thinking that someone here like Dave or Fred or Horace or Anne could handle this one...

-------------------------------------------
Israel Stein RPT
A-Major Piano Services
Albany, CA 94706
510-558-0777
custos3@comcast.net

-------------------------------------------






Original Message:
Sent: 08-22-2011 18:55
From: Larry Lobel
Subject: "curling" damper felts

Israel,

Here is an expert you could ask about this:  

Henrik Broekmann at hubharp.com. (Hubbard Harpsichords; a competitor but Hubbard and Dowd once studied together).   He is very generous with assistance.

-------------------------------------------
Larry Lobel
Petaluma CA
707-762-5800
-------------------------------------------






Original Message:
Sent: 08-22-2011 16:44
From: Israel Stein
Subject: "curling" damper felts

Hi,

We have a Dowd French Double (after Blanchet) here at SFSU that somehow managed to survive at high pitch since 1969 without the wrestplank tearing out. But we are always having trouble with damper felts - they tend to curl off to the side and stop damping (mostly in the bass). It's easy enough to flip them over to the other side or just replace them with fresh felt - but what causes them to curl? And is there a way to prevent this?
-------------------------------------------
Israel Stein RPT
A-Major Piano Services
Albany, CA 94706
510-558-0777
custos3@comcast.net

-------------------------------------------

I believe the main cause of damper curl is register changing. I don't often find it on registers that don't shift (upper manual 8', harpsichords with one set of jacks). The problem becomes acute when the off position puts the end of the damper past the string or with just barely a corner on the string - so it falls. When the dampers in the off position have fallen off their strings, what is going to happen when the register is turned on? They will be pushed against the string, causing curling. Then when each jack is played, the damper will again be on the string (if it didn't curl too much). This phenomenon is also an issue with respect to turning on the register all the way. If a bunch of dampers have fallen, they act as a spring keeping the register from being turned on all the way, so often a number of notes are weak or don't sound at all.

The solution is careful workmanship: cut all the plectra precisely cut to length, so that they ghost (meaning that if the register is at a certain point between on and off, all the plectra will just brush their strings); now set off so that the plectra just clear the strings (a little extra for insurance); damper felts are set/cut (however you install them) so that they are just the right length to avoid damping the neighboring string when on, and still to be on the string when off. The difference in position between on and off is very small. This avoids the problem, doesn't entirely solve it. The mere abrasion of on/off will eventually cause some curling and denting.

More details are in the handout and powerpoint from a class I gave at Rochester, posted here. In the pdf see page 6.

Israel: "It's easy enough to flip them over to the other side or just replace them with fresh felt - but what causes them to curl? And is there a way to prevent this?"
-------------------------------------------
Fred Sturm
University of New Mexico
fssturm@unm.edu
"The true sign of intelligence is not knowledge, but imagination." - Einstein
-------------------------------------------


\

Fred is right that the curl happens because the dampers are being pushed against the strings when the associated register is engaged. 

It can be delayed by being carefully setting the height of the damper flags to cruise their way across the top of the string instead of shoving into them.  You'll still be getting some slight friction, so after enough years, curl will happen.  I'd replace with new felt.  It will look and last better.

You can avoid this problem with mouse-ear instead of flag dampers, but your Dowd jacks are not set up for that, and your users would have to accept the reality that the strings of "off" registers, were allowed to vibrate sympathetically, a touch concept for modern ears.

Best,  Anne

-------------------------------------------
Anne Acker
Owner
Savannah GA
912-704-3048
-------------------------------------------






Original Message:
Sent: 08-22-2011 20:53
From: Fred Sturm
Subject: "curling" damper felts

I believe the main cause of damper curl is register changing. I don't often find it on registers that don't shift (upper manual 8', harpsichords with one set of jacks). The problem becomes acute when the off position puts the end of the damper past the string or with just barely a corner on the string - so it falls. When the dampers in the off position have fallen off their strings, what is going to happen when the register is turned on? They will be pushed against the string, causing curling. Then when each jack is played, the damper will again be on the string (if it didn't curl too much). This phenomenon is also an issue with respect to turning on the register all the way. If a bunch of dampers have fallen, they act as a spring keeping the register from being turned on all the way, so often a number of notes are weak or don't sound at all.

The solution is careful workmanship: cut all the plectra precisely cut to length, so that they ghost (meaning that if the register is at a certain point between on and off, all the plectra will just brush their strings); now set off so that the plectra just clear the strings (a little extra for insurance); damper felts are set/cut (however you install them) so that they are just the right length to avoid damping the neighboring string when on, and still to be on the string when off. The difference in position between on and off is very small. This avoids the problem, doesn't entirely solve it. The mere abrasion of on/off will eventually cause some curling and denting.

More details are in the handout and powerpoint from a class I gave at Rochester, posted here. In the pdf see page 6.

Israel: "It's easy enough to flip them over to the other side or just replace them with fresh felt - but what causes them to curl? And is there a way to prevent this?"
-------------------------------------------
Fred Sturm
University of New Mexico
fssturm@unm.edu
"The true sign of intelligence is not knowledge, but imagination." - Einstein
-------------------------------------------


\

Thank you, Anne and Fred. All the felts were replaced last summer, because a lot of them were curling - a few of the new ones are starting to curl again... I'll go over the damper flags and reset the  "troublemakers" as you describe.

-------------------------------------------
Israel Stein RPT
A-Major Piano Services
Albany, CA 94706
510-558-0777
custos3@comcast.net

-------------------------------------------

A few more thoughts about harpsichord dampers:

Definitely extra quality bushing felt - stiffer, less apt to wear as fast.

The bottom should be as smooth as possible. If it is fuzzy at all, trim with damper scissors. This is to allow for smooth sliding back and forth on the string when the registers are changed.

Ditto for the "leading edge" corner, so there won't be fuzzy bits interfering with the neighboring string. A crisp corner.

Choose a felt as thick as will comfortably fit in the slot without forcing. Forcing is a bad idea, especially with jacks that have snap-in tongues. What you are doing is spreading the slot, which levers out a bit of delrin on the outside of the slot, which levers in on the gap where the tongue rides. Result: tongues that aren't free enough, repetition failure (trills). This applies especially to Kingston harpsichords (ask me how I know).

When installing the felt, you slide a length of felt down the slot, a little long, then pull carefully back until it protrudes just about 1.5 - 2 mm beyond the end of the plectrum (ie, the plectra need to be ghosted first). This takes some practice in sighting with the right angle and judgment, but once you learn it, it makes things better and faster. Then you just slice the felt down the back of the jack.

String spacing can be a big issue. If the neighboring strings are tight together, it becomes impossible to have enough felt overhang to have the felt on the string with the jack in off position. If there are a couple offenders, it can be worth the trouble to pull the nut pin(s) and reposition.

Magnification is a very good idea. I use those magnifiers that look sort of like welding goggles for voicing plectra and for damper work. And for buff stop leather work. My days of pretending my eyesight is wonderful are past. I'd like to have some of those magnifiers my dental hygienist wears, that have two lenses so you don't have to put your work within 6-8 inches of your eyes. A bit pricey, the ones I have found available, so I haven't made that plunge yet. If anyone knows of some reasonably priced ones, please let us all know.

-------------------------------------------
Fred Sturm
University of New Mexico
fssturm@unm.edu
"The true sign of intelligence is not knowledge, but imagination." - Einstein
-------------------------------------------

Fred and Anne,

Here is a puzzler for you. I went and adjusted all the damper flags on the Dowd as you suggested. Half-way through the job I realized that most of the problem dampers were on the front 8 - which does not move (it's the only register on the bottom manual). Any other ideas?

It's the first day of classes here at SFSU, BTW, and I am spending half my time directing traffic - new students trying to find their way in this labyrinth of a building with a totally incomprehensible room numbering system...

-------------------------------------------
Israel Stein RPT
A-Major Piano Services
Albany, CA 94706
510-558-0777
custos3@comcast.net

-------------------------------------------






Original Message:
Sent: 08-22-2011 20:53
From: Fred Sturm
Subject: "curling" damper felts

I believe the main cause of damper curl is register changing. I don't often find it on registers that don't shift (upper manual 8', harpsichords with one set of jacks). The problem becomes acute when the off position puts the end of the damper past the string or with just barely a corner on the string - so it falls. When the dampers in the off position have fallen off their strings, what is going to happen when the register is turned on? They will be pushed against the string, causing curling. Then when each jack is played, the damper will again be on the string (if it didn't curl too much). This phenomenon is also an issue with respect to turning on the register all the way. If a bunch of dampers have fallen, they act as a spring keeping the register from being turned on all the way, so often a number of notes are weak or don't sound at all.

The solution is careful workmanship: cut all the plectra precisely cut to length, so that they ghost (meaning that if the register is at a certain point between on and off, all the plectra will just brush their strings); now set off so that the plectra just clear the strings (a little extra for insurance); damper felts are set/cut (however you install them) so that they are just the right length to avoid damping the neighboring string when on, and still to be on the string when off. The difference in position between on and off is very small. This avoids the problem, doesn't entirely solve it. The mere abrasion of on/off will eventually cause some curling and denting.

More details are in the handout and powerpoint from a class I gave at Rochester, posted here. In the pdf see page 6.

Israel: "It's easy enough to flip them over to the other side or just replace them with fresh felt - but what causes them to curl? And is there a way to prevent this?"
-------------------------------------------
Fred Sturm
University of New Mexico
fssturm@unm.edu
"The true sign of intelligence is not knowledge, but imagination." - Einstein
-------------------------------------------


\

Are the dampers low relative to the string, i.e. lots of up pressure from the string, i.e. the jacks are hanging from the strings?  The jacks should be resting on the keys, not hanging from the strings.

Otherwise it is probably a phenomenon of the damper felt itself. What are you using?  Is it humid where you are?  Since the register and its jacks are fixed in position, I would recommend using an angle cut for those instead of the horizontal flag position.  Works better and is more forgiving.


AA

-------------------------------------------
Anne Acker
Owner
Savannah GA
912-704-3048
-------------------------------------------






Original Message:
Sent: 08-23-2011 14:18
From: Israel Stein
Subject: "curling" damper felts

Fred and Anne,

Here is a puzzler for you. I went and adjusted all the damper flags on the Dowd as you suggested. Half-way through the job I realized that most of the problem dampers were on the front 8 - which does not move (it's the only register on the bottom manual). Any other ideas?

It's the first day of classes here at SFSU, BTW, and I am spending half my time directing traffic - new students trying to find their way in this labyrinth of a building with a totally incomprehensible room numbering system...

-------------------------------------------
Israel Stein RPT
A-Major Piano Services
Albany, CA 94706
510-558-0777
custos3@comcast.net

-------------------------------------------






Original Message:
Sent: 08-22-2011 20:53
From: Fred Sturm
Subject: "curling" damper felts

I believe the main cause of damper curl is register changing. I don't often find it on registers that don't shift (upper manual 8', harpsichords with one set of jacks). The problem becomes acute when the off position puts the end of the damper past the string or with just barely a corner on the string - so it falls. When the dampers in the off position have fallen off their strings, what is going to happen when the register is turned on? They will be pushed against the string, causing curling. Then when each jack is played, the damper will again be on the string (if it didn't curl too much). This phenomenon is also an issue with respect to turning on the register all the way. If a bunch of dampers have fallen, they act as a spring keeping the register from being turned on all the way, so often a number of notes are weak or don't sound at all.

The solution is careful workmanship: cut all the plectra precisely cut to length, so that they ghost (meaning that if the register is at a certain point between on and off, all the plectra will just brush their strings); now set off so that the plectra just clear the strings (a little extra for insurance); damper felts are set/cut (however you install them) so that they are just the right length to avoid damping the neighboring string when on, and still to be on the string when off. The difference in position between on and off is very small. This avoids the problem, doesn't entirely solve it. The mere abrasion of on/off will eventually cause some curling and denting.

More details are in the handout and powerpoint from a class I gave at Rochester, posted here. In the pdf see page 6.

Israel: "It's easy enough to flip them over to the other side or just replace them with fresh felt - but what causes them to curl? And is there a way to prevent this?"
-------------------------------------------
Fred Sturm
University of New Mexico
fssturm@unm.edu
"The true sign of intelligence is not knowledge, but imagination." - Einstein
-------------------------------------------


\

Acker "The jacks should be resting on the keys, not hanging from the strings."

Yes, that is another wrinkle, having to do with staggering as well. I'd say the damper should be hanging on the string, but the weight of the jack should also be supported at the same time by the felt on the back of the key. It is a matter of balance. If the plucking point (distance the jack/key moves before the plectrum contacts and plucks the string) is low (that distance is relatively long), the damper bottom surface should not be close to the plectrum, but should be raised. What you want to see is the jack move right when the key moves, not a lost motion condition (which means the jack is hanging by the damper). But the damper has to be low enough to damp. It's a fine balance to have it right.

Practically speaking, if the register is fixed, it doesn't really matter if the felts are curling, as long as they damp. Curling becomes a problem mostly when the register is mobile. And rather than cut them at an angle, you can just pull up on the leading edge and change the angle of insertion in the slot.
-------------------------------------------
Fred Sturm
University of New Mexico
fssturm@unm.edu
"The true sign of intelligence is not knowledge, but imagination." - Einstein
-------------------------------------------

Anne,

Thanks again. We are using thick, dense English key bushing cloth (from Pianotek) - that's what we stock here.
I do have those dampers adjusted so that they damp the string - and no lower. Any firmer contact with the keys, and they will be singing all over the place (just adjusted a bunch in the bass that were singing...) As far as humidity - well, we are here in fogland, Southwestern corner of San Francisco, less than a mile from the Pacific. The University is built in what used to be San Francisco's water reservoirs - before they dammed up the Hetch Hetchy valley (near Yosemite) and started piping water from there... So, humidity is a problem when the building heat is off (just tuned it down from the stratosphere to something resembling A=440). I guess I will start cutting dampers on a slant once they start curling again - the 4-foot dampers are already cut that way...


-------------------------------------------
Israel Stein RPT
A-Major Piano Services
Albany, CA 94706
510-558-0777
custos3@comcast.net

-------------------------------------------






Original Message:
Sent: 08-23-2011 14:55
From: Anne Acker
Subject: "curling" damper felts

Are the dampers low relative to the string, i.e. lots of up pressure from the string, i.e. the jacks are hanging from the strings?  The jacks should be resting on the keys, not hanging from the strings.

Otherwise it is probably a phenomenon of the damper felt itself. What are you using?  Is it humid where you are?  Since the register and its jacks are fixed in position, I would recommend using an angle cut for those instead of the horizontal flag position.  Works better and is more forgiving.


AA

-------------------------------------------
Anne Acker
Owner
Savannah GA
912-704-3048
-------------------------------------------






Original Message:
Sent: 08-23-2011 14:18
From: Israel Stein
Subject: "curling" damper felts

Fred and Anne,

Here is a puzzler for you. I went and adjusted all the damper flags on the Dowd as you suggested. Half-way through the job I realized that most of the problem dampers were on the front 8 - which does not move (it's the only register on the bottom manual). Any other ideas?

It's the first day of classes here at SFSU, BTW, and I am spending half my time directing traffic - new students trying to find their way in this labyrinth of a building with a totally incomprehensible room numbering system...

-------------------------------------------
Israel Stein RPT
A-Major Piano Services
Albany, CA 94706
510-558-0777
custos3@comcast.net

-------------------------------------------






Original Message:
Sent: 08-22-2011 20:53
From: Fred Sturm
Subject: "curling" damper felts

I believe the main cause of damper curl is register changing. I don't often find it on registers that don't shift (upper manual 8', harpsichords with one set of jacks). The problem becomes acute when the off position puts the end of the damper past the string or with just barely a corner on the string - so it falls. When the dampers in the off position have fallen off their strings, what is going to happen when the register is turned on? They will be pushed against the string, causing curling. Then when each jack is played, the damper will again be on the string (if it didn't curl too much). This phenomenon is also an issue with respect to turning on the register all the way. If a bunch of dampers have fallen, they act as a spring keeping the register from being turned on all the way, so often a number of notes are weak or don't sound at all.

The solution is careful workmanship: cut all the plectra precisely cut to length, so that they ghost (meaning that if the register is at a certain point between on and off, all the plectra will just brush their strings); now set off so that the plectra just clear the strings (a little extra for insurance); damper felts are set/cut (however you install them) so that they are just the right length to avoid damping the neighboring string when on, and still to be on the string when off. The difference in position between on and off is very small. This avoids the problem, doesn't entirely solve it. The mere abrasion of on/off will eventually cause some curling and denting.

More details are in the handout and powerpoint from a class I gave at Rochester, posted here. In the pdf see page 6.

Israel: "It's easy enough to flip them over to the other side or just replace them with fresh felt - but what causes them to curl? And is there a way to prevent this?"
-------------------------------------------
Fred Sturm
University of New Mexico
fssturm@unm.edu
"The true sign of intelligence is not knowledge, but imagination." - Einstein
-------------------------------------------


\