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Posted By: Will M Ringing overtones on certain notes - 04/17/21 11:25 PM
Hey team,

I’m learning to maintain my own piano at the moment - a nice old Weinbach upright that’s in generally great condition.

I have an issue I can’t figure out on several adjacent notes - the C one octave below middle C, and the notes on either side.

The strings were just tuned, but when played they each produce what sounds like a harmonic / overtone.

When I release the key this overtone keeps ringing loudly, even though the damper is returning to the string.

I feel like this is an issue with the damper not correctly damping the strings, but I feel (maybe incorrectly) that I can hear the overtone as soon as they key is pressed... it just becomes more obvious when the string is muted.

I’ve experimented and I’m confident the overtone is coming from the strings of each particular note - as I can mute it by touching them - so I don’t think it’s coming from anywhere else in the piano.

I’ve made a short video demonstrating the problem: [video:youtube]https://youtube.com/shorts/NKJcYmQWzuo?feature=share[/video]

Would love some advice on diagnosing and fixing this!
Posted By: BDB Re: Ringing overtones on certain notes - 04/18/21 12:25 AM
It sounds like there is something touching the strings.
Posted By: Will M Re: Ringing overtones on certain notes - 04/18/21 02:21 AM
As best I can see, the only thing touching these strings is the hammer and damper.

They’re slightly weird strings - it’s a cluster of 3-string notes where I think most pianos use two strings.
Posted By: Maximillyan Re: Ringing overtones on certain notes - 04/18/21 06:17 AM
You must shall see your bass bridge.(it's wood shelf down under bass strings). May be anything metal thing there,
regards, Max
Posted By: BDB Re: Ringing overtones on certain notes - 04/18/21 06:19 AM
Trichords are common down to the B an octave below middle C.

You would have to check the entire length of the strings. You can usually see from the top of the strings to the damper, and you can check from the bridge to the bottom of the keybed by removing the bottom board, but then there could still be something behind the action. Are the damper springs in place?

But it could be something else.
Posted By: Chris Leslie Re: Ringing overtones on certain notes - 04/18/21 11:37 AM
There is a rumbling sound on the lower notes, but also those notes are not damping very well. Those dampers need adjusting. Then, we have that rumble.
Posted By: David Boyce Re: Ringing overtones on certain notes - 04/18/21 08:34 PM
That rumble is very peculiar. Could something have fallen down the back of the piano and be wedged against the soundboard?
Posted By: Chris Leslie Re: Ringing overtones on certain notes - 04/18/21 09:49 PM
Originally Posted by David Boyce
That rumble is very peculiar. Could something have fallen down the back of the piano and be wedged against the soundboard?

Yes. For the rattle I would definitely check that something foreign is not contacting the soundboard, both at the back of the piano along the bottom, and inside at the bottom.

Those dampers will still need adjusting.
Posted By: Will M Re: Ringing overtones on certain notes - 04/19/21 12:15 AM
I'm sorry guys. I didn't listen to the recording loudly enough.

That rattling / rumbling noise is a microphone artefact from my phone. The piano itself isn't doing that ... it's just that the dampers aren't cleanly finishing the note.
Posted By: Will M Re: Ringing overtones on certain notes - 04/19/21 01:00 AM
The issue seems to be that these dampers aren’t damping one of the three strings, always one of the outside ones.

I’ve tried manually pressing the damper against the string and it doesn’t make much difference without a fair bit of force, so it feels like the damper isn’t shaped right, so is snugly against two strings and lightly touching the third.

Visually the dampers seem to be pretty neatly aligned with the strings, but clearly something is amiss.
Posted By: P W Grey Re: Ringing overtones on certain notes - 04/19/21 01:58 PM
You are correct that the dampers are not working well right there. Unfortunately this is a common problem on vertical pianos due to design requirements (longer strings...smaller dampers...less than ideal placement, etc). The damper felt is doubtlessly not as soft and fkexible as it once was, and has acquired the shape of the unison from many moons ago.

Be forewarned that ANY adjustment made here could possibly make things worse than tbey already are (sorry, but that's just the way it is sometimes). The ideal thing would be to replace the offending dampers with new felt and fit them as required. However in lieu of that, you can try nudging the string that is not damping over a little to get closer to the felt. Be careful though since you may end up creating a bigger problem as the felt tries to adapt. Another (possibly safer) way is to use a sewing needle to jab away at the felt to try to soften it up a little and maybe expand it slightly.

There are other things possible but I hesitate to get into them since it is somewhat specialized.

Peter Grey Piano Doctor
Posted By: Will M Re: Ringing overtones on certain notes - 04/19/21 09:03 PM
Thank you - this is super helpful.

I’ve tried needling the felts, tightening the damper springs, and fiddling with the alignment. Needling made a slight difference but not massively, nothing else seemed to matter.

I also spent some time fiddling with the damper head alignment by tweaking the wires or unscrewing and twisting the damper head. It was possible to make the problem worse, and I could switch which string in the unison isn’t damping, but I couldn’t fix it (although I can restore it to where I started).

I’ve noticed about half the dampers have been recently replaced. Most of the dampers that haven’t are working OK, but I’ve noticed a slight buzzing or rattling when damping a unison. It’s nothing that bothers me - but it maybe suggests all these unchanged dampers are too old and hard?

I reached out to my local piano tech supply store, and they recommended I check the “damper centre pins” before buying new felts.

I can’t find anything telling me what this refers to. Do they maybe go by another name?
Posted By: David Boyce Re: Ringing overtones on certain notes - 04/19/21 10:12 PM
It's referring to the centre pins in the damper flanges, the little wooden hinges that secure the dampers to the action rail. The suggestion is that if those centres are tight, the dampers might not be moving properly.
Posted By: P W Grey Re: Ringing overtones on certain notes - 04/20/21 02:00 AM
Personally, I don't think the pins have any bearing on the matter. Based on the totality of what you have said I think you "simply" need nice new felt in that area. And well fitted to the unisons.

Peter Grey Piano Doctor

Just an opinion though
Posted By: Chris Leslie Re: Ringing overtones on certain notes - 04/20/21 05:18 AM
You might also check that the damper springs are firm and that the spring grooves are clean.
Also check that the sustain pedal is not over adjusted.
Check that if you push the strings back by about 1 or 2mm that the dampers move back with the string and keep contact.
Posted By: Will M Re: Ringing overtones on certain notes - 04/20/21 09:26 PM
Originally Posted by P W Grey
Personally, I don't think the pins have any bearing on the matter. Based on the totality of what you have said I think you "simply" need nice new felt in that area. And well fitted to the unisons.

Peter Grey Piano Doctor

Just an opinion though

I believe you are right.

I’ve pulled the action out, and all the dampers seem to be moving fluidly and have a fair bit of spring tension. There’s no sign of anything amiss with the problem dampers - they seem (reassuringly) consistent with the others.

I might try (temporarily) swapping two damper heads, just to see if that changes the nature of the issue.

I’m still going to bring in a technician to give a more experienced once-over to the piano, and help with anything I can’t realistically do myself.
Posted By: Will M Re: Ringing overtones on certain notes - 04/20/21 09:28 PM
Originally Posted by Chris Leslie
You might also check that the damper springs are firm and that the spring grooves are clean.
Also check that the sustain pedal is not over adjusted.
Check that if you push the strings back by about 1 or 2mm that the dampers move back with the string and keep contact.

Dampers seem to be seating nicely when I press the strings. I have the pedal adjusted to keep a fair bit of lost motion (personal preference) - so it’s probably under-adjusted more than anything.

I’ll give the spring grooves a clean and see what difference that makes, if any. It can’t hurt!
Posted By: Chris Leslie Re: Ringing overtones on certain notes - 04/21/21 02:08 AM
Do these notes have flat dampers or wedge?
If they are flat then converting to wedges should improve the damping.
If they are wedges then adjustment can be very tricky. They do need to be just right and may take some fiddling to get there. Also, the strings may need a little spacing to fit the dampers.
Posted By: BDB Re: Ringing overtones on certain notes - 04/21/21 02:23 AM
I went back and listened to the video again, and the distortion from the mike was what I was hearing, that and the double-striking on the D. Everything else is so subtle that I cannot say that there is a problem. Post a clean recording and maybe I can understand what you are talking about. If you would photograph the hammers and dampers, instead of just the key, that would provide more clues.
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