Soundboard compression ridges

[Amy Baldinger]

I am bidding on 2 rebuilding jobs:  1)  Steinway M - extensive rebuild, lots of new action parts and restringing.  2) M&H BB just restringing and maybe damper felts.   These will be my first restringing jobs I've done on my own (I've done many for another tech in his shop).  Both soundboards sound good - no apparent issues that I can tell.  But both have small compression ridges.  Question for the group - are compression ridges signs of trouble?  What should I look for (listen for) to better assess the condition?   Is it something that is always repaired when restringing?  The M&H owner doesn't want the piano moved and will likely opt not to restring if it also requires removing the plate to repair the SB.

 

One additional factor - I live on an island and it would be hard (expensive) to get a more experienced tech out here to help evaluate.  But that is an option.

Thoughts/advice/insight would be appreciated.

[Terry Farrell]

Hello Amy,

Compression ridges, like soundboard cracks, are signs of soundboard damage. Damage can mean several things. It can mean that there is damage, but the soundboard still functions at a high or acceptable level. At the other end of the spectrum it can be indicative of soundboard failure. Or it can suggest something in between. But one thing it is, is reason for a closer evaluation.

You say the soundboards sound good. Have you evaluated the killer octave area closely? Listening for volume drops, decreased sustain and/or distortion at forte levels of play? I would certainly recommend taking some soundboard crown and downbearing measurements in the killer octave area. If all that looks good, then it should be reasonable to expect good results from restringing.

Let us know what the results are of your further evaluation if you'd like more input.

BTW - what island? Maybe I'll sail over and take a look if you'd like! ;-)

Terry Farrell

[Blaine Hebert]

I am wading into treacherous and turbulent waters here but allow me to voice my opinion:

I have seen many compression ridges on fine new pianos.  I have never observed one of those pianos develop a sound board problem, but that doesn't mean I have followed those exact pianos for the 25 to 50 years that a crack can take to develop.

My personal opinion is that it represents a condition of excessive humidity and over expansion of the sound board and is not an indication of any actual failure.

With the design of soundboards today, with ribs installed perpendicular to the grain, there is little room for expansion or contraction.  Any modern sound board, when placed under conditions greatly different from its manufacture can and probably will develop some type of defect.  A pressure ridge is not necessarily one to be concerned about (IMHO), though visually alarming it is probably harmless and could even be an indicator of proper manufacturing and storage.

I am well aware that I may be subjected to "vigorous dissent" for this opinion.

I have seen pianos well over 100 years old where the ribs were installed at less than 90 degrees and show no signs of cracks.  It is a shame that this technique has been lost for the sake of a theoretical improvement.

Blaine Hebert

[Terry Farrell]

On Mar 6, 2015, at 12:42 AM, Blaine Hebert wrote:

I am wading into treacherous and turbulent waters here but allow me to voice my opinion:

Treacherous and turbulent? I don't understand.

I have seen many compression ridges on fine new pianos.

As have I.

I have never observed one of those pianos develop a sound board problem,

And I've seen cars with wobbly wheels and I've never seen one fall off. Doesn't mean some haven't fallen off.

but that doesn't mean I have followed those exact pianos for the 25 to 50 years that a crack can take to develop.

And what would that mean? I suppose a crack might commonly be an indicator of more damage than a pressure ridge, but really it's pretty much the same in its ultimate significance - an indicator that damage consisting of crushed soundboard panel cells has occurred.

My personal opinion is that it represents a condition of excessive humidity and over expansion of the sound board

Exactly correct.

and is not an indication of any actual failure.

It's in indication that the soundboard performance may be degraded from new. It may not be degraded. It may be degraded somewhat. The soundboard may have degraded so much that failure would be a good descriptive term.

With the design of soundboards today, with ribs installed perpendicular to the grain, there is little room for expansion or contraction. 

Pretty darn close to zero!  Good call.

Any modern sound board, when placed under conditions greatly different from its manufacture can and probably will develop some type of defect. 

By conditions, I presume you are referring to environmental conditions - specifically, relative humidity levels. As for likelihood of develop some type of defect, maybe yes, maybe no. Much depends on the design of the soundboard. Boards such as the ones in question are compression crowned soundboards and indeed are quite subject to defect caused by extremes (and sometimes not so extreme) of humidity. Sometimes they fail in the factory - or at least the showroom floor. At the other extreme of soundboard design are rib-crowned and supported soundboards. These come pretty close to being immune from failure due to extremes (or at least normally occurring) of humidity. Like can still develop and defect - like a crack - but even still, they are much less prone to that as well.

So be careful when you say "modern soundboard" - as if they are all of the same design. Some have components that are radically different in some aspects of their function from others.

A pressure ridge is not necessarily one to be concerned about (IMHO),

Correct. But it is an indicator of damage and the soundboard should be evaluated more closely.

though visually alarming it is probably harmless and

Maybe yes and maybe no. In itself it is not a problem, but rather it is an indicator of damage.

could even be an indicator of proper manufacturing and storage.

Wow. Okay, time for........ Oh, now maybe I see what you meant about treacherous and turbulent. My intentions here are purely constructive. I have to say this statement is pure wrong. Pressure ridges may well be an unavoidable result of "proper" manufacturing to a particular design. And it may well be an indicator of close adherence to a specific design (i.e. compression crowned board) - but only because damage and perhaps failure is so consistently predictable in compression crowned soundboards. If you want to call that proper manufacturing and storage, I guess you can.

I am well aware that I may be subjected to "vigorous dissent" for this opinion.

Correct.

I have seen pianos well over 100 years old where the ribs were installed at less than 90 degrees and show no signs of cracks. 

Correct. And I've seen 100 year old compression crowned soundboards with ribs at or near 90 degrees with no cracks. By less than 90 degrees, I presume you are talking about less than 45 degrees or thereabouts.  I don't think many of these 160+ year old designs would hold up very well to a modern scale - they likely didn't even hold up very well to their generally much lower tensioned string scales. I don't think they really make a good comparison.

With a rib-crowned and supported soundboard design one can keep the ribs near(ish) 90 degrees (some of these designs have a fanned rib array with the high treble and bass pretty far from 90 degrees) by designing and constructing differently from compression-crowned boards and hopefully after 100 years not be all cracked up - and hopefully still performing well. Like you said about 25 years to observe a crack developing, I haven't sat around for 100 years to see how well a rib-crowned and supported soundboard holds up - but I think it will hold up well.

And just in case you are not familiar with rib-crowned and supported soundboard design, perhaps a better term for compression-crowned soundboards would be panel-crowned and supported soundboard design.

It is a shame that this technique has been lost for the sake of a theoretical improvement.

Gotta disagree here - at least if the desire is to have a "modern" piano. If one were to want to make a piano that sounded like an 18th Century piano, perhaps it might be a shame. Very different beast though.

Terry Farrell

[Nathan Monteleone]

> But both have small compression ridges.  Question for the group - are compression
> ridges signs of trouble?  What should I look for (listen for) to better assess
> the condition?

This is what I've been taught and read. If it's off base someone please correct me:

Probably the biggest concern if you see compression ridges is that the same forces that create them can ultimately cause rib separations. Compression ridges alone don't cause any serious problems; rib separations do.

So you would need to check for rib separation under the compression ridge using a feeler gauge or something similar. If found, they can and should be repaired, but it's a lot easier to do so with the strings out so it should be part of the restringing job.

[Nathan Monteleone]

> So you would need to check for rib separation under the compression ridge
> using a feeler gauge or something similar. If found, they can and should be repaired

... Of course if the plate is in the way of repairing the separation adequately, you'd have to remove it...

[Joseph Garrett]

Not necessarily.<G>
Joe

Captain of the Tool Police
Squares R I
gpianoworks.com

[Terry Farrell]

And yes, that might fix a rib/panel separation, but you may still have a failed or failing soundboard.

Terry Farrell

[Ron Nossaman]

On 3/6/2015 10:32 AM, Nathan Monteleone wrote:
> Probably the biggest concern if you see compression ridges is that
> the same forces that create them can ultimately cause rib
> separations. Compression ridges alone don't cause any serious
> problems; rib separations do.
>

> So you would need to check for rib separation under the compression
> ridge using a feeler gauge or something similar. If found, they can

> and should be repaired, but it's a lot easier to do so with the
> strings out so it should be part of the restringing job.

This is not just in answer to this particular post, but to the universe
in general, since the misconceptions are universal.

By the time ribs start coming loose, the soundboard has been dead for a
whole lot of years. The huge majority of the pianos we service in the
field have very poorly functioning soundboards. Since that's what we
hear, that's what we accept as normal and right. In field service, we
accept a lot of what we find and press on unless the board looks like a
corn crib, sounds like a kazoo, and you can discern the wallpaper or rug
pattern looking through the gaps.

In reality, ribs are rarely loose regardless of the compression ridges
and cracks, but the soundboard is very often sick anyway. In compression
crowned boards, like our revered Steinwayvarius, the crown and required
stiffness comes purely from panel compression. As the panel wood is
crushed (compression ridges) and cracked by RH% swings, seasonal or
otherwise, the board loses stiffness and it loses crown. Killer octave
tonal problems become obvious to even the most generous and accepting
tech, and measurement of crown and bearing there shows the board has
collapsed. Whether ridges or cracks are evident or not, when the bearing
and crown is gone and a firm blow in the killer octave produces a short
distorted and percussive attack (even after your best shot in lifting
and leveling strings and performing your most special voicing Voodoo),
the board is shot. As long as no one complains, you're fine. Leave it
alone. But if you're asked to rebuild a piano that has these
characteristics, the board needs to be replaced. You can't save it by
shimming, though you can make it considerably less bad by epoxying the
top surface. This limits compressibility of the panel and adds enough
stiffness to make a positive difference. But please not on an otherwise
good piano that's getting a new action, bridge work, back action, and
what you would call a thorough rebuild. An extensive rebuild on a decent
piano with soundboard problems as described deserves a real soundboard,
which means replacing it.

A good and efficient soundboard produces a wonderful and rich tonal
spectrum (with an appropriate hammer). The sound envelope is a gentle
slope from the attack through a surprisingly extended dwell to a
gradually diminishing decay. Most of what we hear is a much lesser
version, with a narrowed spectrum lacking clean fundamental, with a
tonal envelope going from a short spike attack dropping abruptly to a
short or non existent dwell, followed by a steep and typically shortened
decay. It's the difference in tone production between a big expensive
stereo system and a transistor radio with a 2" speaker. When a 7' grand
of good quality sounds like a Kimball console, there is obviously a
problem and a new set of hammers won't fix it.

The best alternative to compression crowned soundboards is a rib crowned
and supported board, where the ribs act as structural beams supplying
both stiffness and crown support as if the panel wasn't even there. The
panel is under very little if any compression, and won't deteriorate
nearly as badly as the compression crowned panels. Nor will it cause the
crown to flatten or the tone to deteriorate like CC boards demonstrably
do in areas that have seasons.

Ron N