Singing Strut

[Delwin D Fandrich]

Charles E Faulk wrote:

> Del,
>
> I looked at the 6' Petrof grand today, and it does indeed have a 'singing
> strut'. The owner was quite prepared for me. He first played E-flat 3 for
> me, kind of a staccato hit, and sure enough the strut rang out like a
> large tuning fork. Then he rapped the offending strut with his fist and
> made it ring again.
>
> I checked for any defective damping. There was none.
>
> This particular Petrof has a nose bolt located at the rear of the case
> just under the juncture of the first two long struts which flair out in a
> V-shape to the front. The only other nose bolt is under the third strut
> which begins the third section of the piano. Both the two long strut are
> rather thin which I guess explains how one of them can vibrate.
>
> Looks like Petrof needs to do a serious redesign on their plates.
>
> Thanks for your input.
>
> Charles Faulk
> Manhattan, KS

-----------------------------------

Charles,


Well, so much for iron being "acoustically dead" as we were always taught. I found it very interesting to see what was
happening in the various parts of a piano plate once I was able to get an accelerometer on one. Acoustically dead, indeed!

What is being done to remedy the situation with this particular piano? Is it under warranty or is it something you and the
customer are going to have to deal with? If the latter, feel free to contact me privately if you think my ideas might be of
any help.

While this might be a bit tricky to solve on an existing piano, from a plate design standpoint these things are usually
easier to fix than you might think. If this is a fluke, the manufacturer probably won't be overly concerned about it, but if
they have had a series of complaints about the problem, then some relatively simple plate pattern changes are definitely in
order.

Del