Piano: Steinway M, Built in the 50's

I have yet to figure out what is causing the buzz. The buzz is concentrated around the 5th octave and it's most pronounced on notes C5 and D5. It also becomes more pronounced when the temperature falls. There also happens to be a crack in the soundboard that passes under the bridge and where the notes buzz. I have pressed on the soundboard where the crack is and it doesn't make any change. I have also pressed on the ribs and no change as well. I don't think it's coming from the action but I did tighten all the screws. I also tried removing the music desk, fallboard, etc and no change. There are no light fixtures close by that could be rattling so I'm pretty sure it's coming from piano. The buzz also seems to be the loudest at the soundboard crack but it's really hard to tell for sure. And yes, I did blow the piano out with 120 psi of air pressure.

Any ideas on where the buzz might be coming from? Any tips on diagnosing a difficult to find buzz like this?

Here's a sound file to give a better idea on how the buzz sounds like.
Listen to the buzz

And yes, I'll let you all know once it's figured out.

Here's a better recording of it.

Click Here

Now that it has warmed up, the buzz has become a lot more subdued.

Whats the name of the first song you played on the new recording? Thats a song I want to learn but dont know the name. That buzz would drive me crazy though. I would have said the crack in the soundboard but im not sure, it still could be the crack. Maybe some Pictures could help. The easy thing to do would be to call your piano technician

Sounds like a loose rib or bridge, but it could be anything. Check the sostenuto. I once had a key up-stop bolt that sounded wooden. took me a while to find it.

Thanks I'll check that.

Here are some pictures of the crack. Notice how the crack extends under the bridge. It's those notes that are buzzing. Pushing on the crack doesn't seem to have any effect on the buzz.







Kinderszenen by Robert Schumann

Did you get to the bottom of this buzz and/or what have you eliminated as the cause?

No I haven't. The hardest problem I'm having is locating / pinpointing the exact location of the buzz. I've got a mechanics stethoscope but still haven't been able to find anything definite. However, I do know that the notes that buzz are the ones closest to the crack that extends under bridge. The buzz also seems to be louder in that area. Pushing down on the bridge in that area or pushing up on the soundboard from below in that area doesn't do anything.

If someone has some tricks on how to locate buzzes, I would like to know. Someone should invent a buzz detector.

The fact that the buzz occurs in notes that are located in the same vicinity is a clue (not frequency dependent). This, to me, would tend to rule out a "sympathetic" vibration in some object located adjacent to, or in, the piano, and, instead, point to something directly in this particular location. I would try going underneath, locating the soundboard crack and following it to the rib. At that point, try wedging a shim of some sort between the two, (the board and rib), and see what happens. Also, try gently tapping the bridge pins down and then seating the strings.
After listening to your recording, I'd also suggest checking the proximity of the damper wires to the strings of those notes. They too could be rubbing against the vibrating string and would sound similar to what I believe I am hearing.

Your playing is beautiful. Even with the buzz. Isn't Schumann great?