Good evening, since May of last year I purchased a second-hand Yamaha C3 in excellent condition from a well-known and highly regarded authorized dealer in the area. The serial number is between 4900000 and 5000000, so according to some research, it dates back to the early 90s. A few days after its arrival, it started making a very unpleasant metallic noise only on certain keys and, without anyone touching it, a few days later it suddenly stopped. This situation repeated itself several times throughout last summer; the problem would manifest suddenly from evening to morning and go away without anyone intervening. After an entire winter without problems, a few days ago the noise reappeared, and taking the opportunity to tune the piano, the tuner (the same person who sold it to me) came and tried to fix this problem as best as possible, which, after a few days of absence, reappeared this morning. I want to specify that the piano is kept in the best possible condition; nothing has ever been placed on it or accidentally dropped inside. Honestly, I don't know what to think anymore; the dealer himself assured me that if the problem could not be resolved, he would be willing to replace the instrument, which for the moment I consider the last possibility as it is not a very convenient operation.
It is difficult to evaluate from a distance. The causes can be various. First of all, the sound, as much as one can hear from an MP3, seems good to me.
It could be a problem with the hammer voicing/intonation
it could be a problem with sympathetic resonators. This can be remedied by placing small felt dampers on the part of the string that is supposed to resonate.
It could be, although unlikely on a new instrument, noise from the soundboard and/or glue issues on the bridges (one must try pressing the bridge in the position of the strings concerned and listen to see if it disappears)
Lastly, the optimal strike point may have shifted.
Yamaha has impregnated hammers and therefore develops, especially on the forte, a timbral progressivity that is typical of impregnated hammers: The sound is designed to be heard in a hall. However, with skillful voicing, the sound can be made a little softer, without sacrificing the general timbre intended by the Manufacturer.
You most likely also captured the problem via mp3; by pressing the bridge in the position of the strings that cause these problems, the noise disappears. However, the louder I play, the more force must be applied to the bridge (I think that's obvious). How could I resolve this?
It could be a minimal and invisible detachment of the bridge and/or one of the braces (braces are transverse wooden strip reinforcements visible under the soundboard).
Try pressing from underneath on the brace corresponding to the point where pressure was applied from above. And check if the noise disappears.
If so, it is advisable to replace the instrument.
Hypothesis: The vibrations come and go, therefore, depending on the variation in humidity and temperature (precisely because the detachment could be minimal, micro, and naturally invisible and undetectable).
As I repeat, I am nonetheless formulating hypotheses.
Yes, most likely this is the problem; there really wouldn't be any other repair alternatives, considering that I still have assistance and the technician is a professional? Thank you very much anyway, you have been very helpful.
If there are screws under the strings, under the soundboard, try tightening them. It is possible that the problem will disappear.
Another thing: ensure that the piano rests on its three legs without any unevenness. Otherwise, try to compensate. It is possible that the problem will disappear.
The difficult part is identifying exactly where the problem is located, the precise point.
Furthermore, over time, after many years, the soundboard undergoes a slight compression, decreasing the load contrast (for this reason too, the soundboard tension should be decreased in the long run!) and the problem could increase.
The screws under the strings are not there, but there are those under the soundboard. The situation had improved a lot this morning so for the moment, since the problem seems to have been almost totally resolved, I prefer not to intervene. However, from what I understand, it seems that the best alternative is a replacement of the instrument...
