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Greetings to all!

I own a 1927 Steinway AIII that I purchased about 4 years ago. Ever since the purchase, I noticed that the second F, the one directly to the right of the metal bar, has a different sound. It sounds like there is a knock on wood at impact.

Since the purchase, I had a reputable technician replace the hammers, shanks, wippens, felts. Then last year I had the bass strings replaced.

My piano tech went through many things, but the second F still sounds different, there is that knocking sound.

The hammers and wippens were exchanged to find out if it was the voicing/hammer, but the knocking was still there, on the second F.

The voice is there with or without pedal.

Glide bolts were checked for knocking, they were fine.

The key pins were checked, they were fine.

The sound is not there at all when the key is depressed with the action out of the case.

Recently, I made this interesting discovery. I removed the metal plate on the left cheek to allow the action to slide in and out very slightly, and pushed the entire action a little bit to the back, I managed to push it in very slightly, maybe 1/32".

What I noticed then is that the knocking sound is softer, but spread over to the neighboring higher keys, the F#, G, and very little on the G#. So instead of having the 2nd F sounding differently, I can adjust it to 3 or 4 keys sounding slightly different.

Does anybody here have any idea what it is? I have read a posting here about Steinway model A having this issue, that may be solved by voicing, but I have tried a few other model As and didn't notice this difference in sound.

I would really appreciate your comments. Thanks in advance.

Tim Firman

I would have to hear the sound. Have you checked the fitting between the front rail and the key bed?

Like Dave wrote I would also check the key frame. Even if there is no sound at the glide bolts they might be turned down too far. I have seen pianotuners turning down the glide bolts to adjust the key level!
Turn up the glide bolts and adjust them again.

A very long screwdriver to test the setting of the back of the frame, if it is raised at that location there is usually a problem to regulate correctly the glide bolt corresponding.

anything can twist in a STeinway , then some warping can install.

The keyframe can be regulated separately for a good adjusting at the front, the back and for a good hold in the beckets at its back. (a good job !)

The tubular frame can be warped (or a rail can be cracked), a shim under a action frame feet can be necessary (rare but it happens)

The keyframe is prone to warp because of the pressure of the glide bolts , but also because there is a good force coming from the action return spring (left pedal)
Then the thinner part of the back of the frame (where the left pedal becket inserts when the action is pushed in) is the place where a warp occurs on old pianos, most often.

Once those hard wood assembly warps it is not easy to get them back in shape.
I have often left the stack in an unusual stress to allow it to warp back, it can work after some months an a few corrections.

Is it related to the numerous techs that screw the glide bolts to raise the center of the keys (when new balance paper punchings should be used) I am unsure.

But Steinway keyframe are better raised from the 2 extremes than the center (as many grand pianos in fact) Center bolts may have a very moderate and well evened pressure...

THe left pedal may be kept TIGHT always, without any play. At last it can refrain the strength of that huge spring, then the keyframe is eventually less compressed from the side.

It could also be a loose hammerhead. That's happen to me a few times.

Yes , or a loose hammer pin, but the techs hear that very easily, even on videos sometime.

Your responses are much appreciated.

The hammers and the pins have been checked, and they are fine. As a matter of fact, they were loose in the beginning, after the action rebuild, but now they are fine.

Also the technician pulled out the action and tried to duplicate the knocks, but it was not there. I am pretty sure it has to do with how the action sits on the bed.

I am going to experiment with the glide bolts. Is that true that they are not supposed to stick out at all? Do they have to be aligned with the wood frame?

Thanks again.

Please dont touch to the glide bolts. I helped once a customer by phone to regulate them (they where stressed to the point the front of the keybed was knocking)

the glide bolt change the key height, the key dip, AND the light stress that is desired in a Steinway (in a German one anyway)

They change the tone , from percussive/woody to unfocused. and when they are optimally evened there is a bonus !

The worst voicing is done when a too tense keyframe is corrected by heavy voicing to get rid of percussion

They may be checked at every tuning, but on Steinways anyway, after some time they dont move (on many other instruments they have to be tweaked at the dry season then back)

Very little techs are really trained to check them with the good /coherent and specific Steinway method.

I would not try to modify that on a Steinway your piano is designed with torque/stress almost everywhere, if you have only one note that is knocking and none around wait to find a tech that can analyse that correctly.

Indeed on older Steinway the stress in the action is almost none, but the wood of the keyframe is now hard , it will not accept the same level of torque than when new.

What you can do is bump strong on the stretcher and under the keybed to listen if there is any rattle. Push very lightly on the left pedal first to suppress any noise from the lyra.

You can locate the rattle a little by bumping on different places, on a recent/in good condition Steinway, the case and perimeter around the action tones a little like a drum.

You can bump on the stretcher while lightly put a finger on the white keys in front, if something is vibrating you will feel it in your hand.

THe noise is most probably a warped keyframe who knock against a becket because there is too much play in the vertical dimension . If the back of the keyframe is pushed down the front of the keys will not be leveled once the glide bolt pressure will be regulated (less turned)
You could see that this glide bolt is more protuberating.

This is not easy to correct.

More simply, the noise may come from the damper system.

Many techs, once they understand how creative can be the use of the glide bolts, tend to over use them, and I find numerous pianos where the action have been stressed while it was not intended to, the next season the tone get hard and too woody, or the touch. There are limits in all those tricks...

I hope you are afraid to touch those things by now

Ah there is a last possibility which is that the tail of that hammer rubs on the backcheck when you play strong enough. then the tone of that not is too strong and percussive.
It can happen if the new hammers have longer tails than the precedent, and that backchecks have not been lowered..

Yes a recording (of more than the offending note) or video could possibly help..

I usually do not respond to vague problems like this, because there is much more that can be learned by actually being with the piano, but if the problem is with the keyframe, it may be necessary to remove all the keys and fit it back into the piano to find out exactly where it is.

It will be necessary....

I had an issue like the OP and one time it turned out to be a very small staple that had fallen into the piano and worked it's way under the keys. It drove me nuts until I finally removed the action and found it.

Tim,
Did your tech actually check if the key frame fits exactly?

Could it be a problem with the felt on the damper upstop rail?

It could be the up-stop rail itself from maybe going to high too right there...

BDB is right.... Pure guess work going on from all of know it all's! HAH!

I spy.............a problem.................

Thank you again to all who responded.

Kamin: I will follow your recommendation and not touch the glide bolt at all. Thank you so much for the multiple responses.

Pianolive: I will ask my technician, but I think he already checked this area.

BDB: I am in San Rafael, and I noticed you are not too far away. Would you be willing to inspect my piano?

Proper bedding of the action can only be done by removing the action stack and keys from the key frame. After you place the key frame back into the piano, the glide bolts should be turned upward. Then, using a thin piece of paper under the bolt, turn down the bolt until it just grabs the paper as you're pulling it away from under the bolt.

Assuming there aren't any other fit issues with the key frame to the key bed, the keys and action stack can then be put back onto the key frame.

This would conclude a correct bedding procedure, with regulation to follow, if necessary.

I was taught (granted from a Yamaha class with the very flexible keyframes) that bedding should be done with at least the stack screwed on, and, in my mind, as many keys as possible on the frame.

The stack may be rigid enough to warp the keyframe slightly, and change the bedding of the action. Also, it is good to check bedding with the sustain pedal firmly pressed down, as the keybed may slightly distort when this stress is put on the lyre (that idea came from a Steinway class, and it can introduce an unwanted knock in some pianos).

You can get close with the stack off, but final fit should be done with the stack on.

As for the keys, well, it just makes me feel better if they're in the action when I'm bedding it. It may not make a difference.

Regards,

Daniel you are right, and on a Yamaha the action stack is more rigid than on a Steinway, but in the end the weight and the stress from the screwed stack makes the things different.

But without the keys the adjustment of the back lip can be checked.

It can be a noise coming from the damper upstop rail or felt or screws, or whatever, but as it was said that using the pedal did not modify the noise, I resort to others things.

Regulating the glide bolts on a Steinway may be done by a Steinway tech (Steinway trained, and certified)
I exaggerate a tad, would not have said so a few years before but this is way too much specific.

For just one note, however unless the stack us vibrating strong enough only with that note, the defects due to bad bedding are felt more in a few notes than one only, and heard in tone, too (anyway with European voiced hammer sit is clearly felt in tone, even if mostly it change the touch).

With video and recording, but more speaking with the customer at the phone, I was able to detect some kind of trouble. What surprised me that it was 90% of the time incorrect use of the glide bolts that caused the defects. After some well reputed techs worked on the piano some time, I even once find hammer tails rub left unsuspected for one year on a new piano.


Then , bedding is not given, it change with the seasons , and the tech have to train to ascertain the quality of the bedding in a few minutes as it will decide of the voice of the piano for a huge part .

A tick is often difficult to locate drop of glue misplaced, strange element in the action)
I had some with the upstop rail indeed and the fact that it move to next notes when the action is pull makes me think this is the correct thing to check. How much play up do have the dampers when a sharp or a white key is at full dip ?)

How far from the strings are the flat dampers when a white key is at full dip.

When the sustain pedal is engaged those kind of knocks are hidden in the resonance noise, you may use a rag or a cloth on the strings yo damp them, to listen if you hear it with sustain pedal engaged/not and without tone)

The damper upstop rail can be making a very audible clack

Working on a warped keyframe can be very difficult and time consuming.

Push the other direction with moisture, make saw lines, use wedges, etc...

Sometime dismounting the balance rail helps, you can also shim under it so to avoid too large thicknesses of cardboard punchings.

In the end the perfect fit of the back of the frame is less important than balance and front but it can make a little zone less responsive (hence another one a bit too strong)

Also, the perfect evening of weight/pressure from the action to the keybed gives a real plus to the touch and feel of the instrument (some more sensitive to that than others).