Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Resonance, a little too weird for me

I'm trying to improve my over dampers but it's weird. Even damping the 3 strings with my finger is not totally effective. There's a resonance that sings on throughout the piano. Even quickly damping all the strings with my hand it's still there. What is it kind folks?

To me, all overdampers do that. Poor damper condition or adjustment in general won't help, but the design also doesn't allow efficient damping as I am sure you are well aware. All the slightly leaking strings combine to create a wash of sound. Sometimes the action , or just the damper assembly, is not pushed up far enough to the strings. Just how bad is it? Can you post an example?

I just happen to have posted this at the ABF: https://www.box.com/s/bkltozppwlqbun4hmnfw I've had a PM which explains the middle of the strings still vibrate even though I've stopped the top of the string with my finger.

Sounds like a birdcage piano. These pianos were designed to have the non fully damped "old Timey", sound. You will not get modern piano style damping on these pianos. One must either like the sound or move on to a different piano.

Jim Ialeggio

Could it be that it is the sympathetic vibration of the 'birdcage' damper wires themselves? Just a thought.

The physics of vibrations on struck strings are such that-the ideal place to damp a struck string is the same place it was struck. Over-dampers are far from the striking point-and all vertical pianos except ones made with the dampers on the opposite side of the strings from the hammers have less effective damping.

An overdamper piano does sound a little like it is in a large acoustic space and they may have used that as a selling point. Pointing out that "this piano has concert hall resonance".

Actually the dampers are quite close to the striking point:


And as it turns out it doesn't matter where I dampen, the effect is still there. Here's a recording: https://www.box.com/s/yoqibyh22kim7itf1dew You can hear me put my thumb on after about a second. Maybe all pianos do this?

edit: I see, my under damper piano does it too, but to a much lesser extent. Conclusion? It must be the sound board and a particular Pleyel thing?

The dampers are too close to the top termination point. That does not damp the lower harmonics as well.

In addition, the piano is old. Whatever provides the force pressing the dampers against the strings is not as strong as it used to be. The dampers have undoubtedly been moved from side to side many times, so the grooves that have developed in them have not always lined up with the strings in the same way, resulting in uneven pressure on each of the strings in a unison. The ones with less pressure leak. This happens with underdampers when the action has been removed from the piano too many times, particularly with old felt that has lost its resilience.

You are never going to get new piano performance from an old, poorly designed piano.

Now that is fighting talk! This is a Pleyel Pianino - something Chopin always had by his side! I'm not looking for new piano performance (for that I play my Geyer or Schiedmayer), I'm looking to get to it's original sound. Should I replace the dampers? Is there a 're-newing' process?

Maybe it belongs back at Chopin's side.

Here's the snippet with a good mike and as a wav: https://www.box.com/s/6c4omxleqkshm7sq2v8q

In the picture, the dampers look a little uneven in height. Also there appears to be several mm of gap between the dampers and the hammers. Some appear to contact the strings above the termination points which would be useless. There could be more room for new and larger dampers which, when correctly adjusted, could improve damping efficiency. Also, harder than normal damper felt seems to work better in these circumstances.

You could replace them with softer less compacted felt and it looks like there even might be room to extend them slightly longer out towards the hammer. As others have mentioned, this leakage is quite common for this type of piano, especially with the dampers so close to the termination point, you might make it a bit better or similar to "new' condition with replacement and possibly some better positioning/fitting to the strings.

If you stop the strings with your thumb near the strike point, the sound should cease. The reason it isn't, is probably sympathetic vibration from all the other strings that aren't being damped properly. In this sample, are the dampers engaged, or have you taken the action away to pluck the string? If you perform the same experiment, and after you damp the string you pluck with your thumb, damp the notes on all the octaves below it, does that make a difference? It might not just be the octaves - try the set of octaves a fifth below, or a fifth above etc.

(you shouldn't really be touching the strings with your thumb - moisture and grease from your skin can corrode the strings, increasing the problems you have with false beats)

Whatever you find, you've got your work cut out to make those dampers work more effectively. The only real way to do it would be to replace the damper felt, and even then you will be a long way from finished as they will all need to be bent manually to engage the strings as close to the strike point as possible without interfering with the hammers. It is a tedious and frustrating task!

I have seen many overdampers that do not bleed below the treble break, but some damper bleed is inevitable from the top section of the dampers.

It definitely isn't the strings. It's the sound board somehow.

It can't be the soundboard on its own - it doesn't have the resonances that would sustain a note for that long. The soundboard is designed to project sound energy, not hold it.

There are definitely strings still vibrating even after you damped those that you plucked in the sample you gave.

I think Phil probably hit it with sympathetic vibration. You are correct, the sound is coming from the sound board, but the energy to excite the soundboard comes from the strings through the bridge. When you hit one string, all the strings want to vibrate sympathetically. You can hear this in any piano when you listen to the difference between holding a long sustain on a single note, and striking a single note with the pedal raising all the dampers. You get a fuller more resonant sound in the later case because all the strings are free to vibrate and all kinds of different harmonics on different strings get excited.

So in this case you know that your dampers are leaky, presumably not just on the string you are striking but on all the other strings as well. So even if the dampers are engaged on the other strings, and even if you stop the vibration of the struck string manually all the other strings will continue to vibrate through their leaky dampers resulting in the carry over.

Rob

You would assume that, but I pluck a note, damp it, run my hand over the entire 'harp' and it's still there!

That tells me you have the action out when you are plucking the string. The resonance of the piano will be very high in this situation - stopping the sound with your hand won't work unless you can mute all the strings at once!

Or am I wrong here - is the action in place with the dampers doing their job to the best of their ability in that sound sample?

You're right, I have the action pulled back. Surely after I've stopped all the strings they can't re-start?