False Beats / Loose pins

[Farrell]

I brought up this topic a while back and didn't get the response I was 
looking for (or at least I don't think so - or maybe I just missed it - or I 
don't remember it). My recollection of information presented by Del Fandrich 
in one of his Small Piano Design classes (and please forgive me and correct 
me if I am wrong here Del) was that some aspect of soundboard design can 
affect the susceptibility of a piano to false beat production. I think it 
was the fundamental frequency of the soundboard in that area of the scale - 
but it could have been impedance or something else. The situation was that 
if the particular characteristic (fundamental frequency?) of the soundboard 
is higher of lower (or maybe just out of range) than any particular 
string(s) in the same area, the piano may be inclined more or less toward 
false beats.

Still, it is some defect that is the direct cause of the false beat - like a 
loose bridge pin or a nick in the wire or whatever - or at least a 
combination.

So in your case, this Bosendorfer may well have a soundboard that is 
designed such that it is not prone to false beats - so much so that it can 
have a loose bridge pin and still sound clean.

At the other extreme are many cheap spinet pianos that have clean wires, 
tight bridge pins, etc. and still are absolutely loaded with false beats. 
Presumably the designs of these soundboards are such that they are very 
prone to false beats - maybe the tiny piano case is the cause! Or maybe the 
horrible soundboard design can in itself cause the false beats.

Many (if not most) pianos lie somewhere in the middle. Their soundboard 
design is such that they are moderately prone to false beats. If strings are 
clean and straight and terminations are tight, you get a clean sound. But if 
something such as bridge pins come loose, you get the false beats.

Can anyone clarify this issue? Del? Ron N.? Anyone that has attended Del's 
Small Piano Design class (and understood and remembered everything - or at 
least this item)? Or, of course, maybe my memory isn't all that good. I 
think it's pretty good, but I really don't remember........  ;-)

Terry Farrell

----- Original Message -----
> Ran into a classic example today of why I am skeptical to the idea that 
> loose bridge pins are the direct cause of false beats.  This was a small 
> Bosendorfer grand 170ish in size and getting old. I can get the 
> particulars if anyone wants them after Easter.  There were loose pins all 
> over the place and particularilly in the upper treble. Good sized hairline 
> cracks around the bridge pins here and there, lots of space on the string 
> side of the pin between the pin and wood of the bridge pin holes.  I 
> loosened a few strings just to be sure and you could pull the pins out 
> with your fingers.  Now if that dont fit the description of loose pins I 
> dont know what does.  However.... this was one of the cleanest sounding 
> pianos I've ever come across.  False beats of the sort being identified 
> with loose pins were virtually non existant, and for that matter there 
> wasnt a whole lot of falsness of anykind.
>
> The only marked difference between this instrument and most that I see was 
> the diameter of the bridge pins.  They were big and looked to be the same 
> size over the entire long bridge. I didnt have my micrometer along today, 
> but they were the size you usually see in the bass bridge on most 
> instruments.
>
> So you tell me... loose pins are the direct cause of false beats ??? Then 
> how do you explain this instrument ? Its not the only example I can pluck 
> ... but its about the most pronounced I've found up to now.
>
> Cheers
> RicB