Mass Loading bridges

[Overs Pianos]

>Hi
>
>I am curious as to  just what criteria one uses to <<tune 
>impedance>>.  Is this a trial and error thing or is there a 
>systematic way of  doing this... or is one measureing impedance 
>somehow and calculating how much mass to add and where to add it.
>
>Thanks
>
>RicB

I suppose you were wondering Terry, if this topic would prompt a post 
from down here.

We add a nominal distribution of weight, based on previous 
experience, then fine tune it by listening to the tone in relation to 
that we are seeking. The piano which we are bringing to Rochester 
will have a full system for adding weight wherever it is required. We 
have been building this system into our pianos for some time. I'm not 
going to elaborate on the procedure until after Rochester.

I have mentioned before on the list that I believe there is a 
three-way relationship between soundboard area, stiffness and mass. 
Once a piano is built we have locked up two of the parameters. 
Altering the mass distribution to achieve the desired impedance 
levels is the third variable which we can adjust after the instrument 
is built. Its a wonderful thing I believe. I don't have a formula for 
calculating the desired mass loading. But when you've been listening 
to and adjusting tone using mass, after a while you can hear when, to 
you own mind's ear, a board is lacking in mass. On the other hand it 
is also possible to have too much mass, since this will reduce the 
immediate power. We must make a choice and it will be based on 
'taste'. I believe that some manufacturers are deliberately building 
their instruments with less mass to get that immediate power thing. 
This is unfortunate since the tonal beauty can be much nicer in many 
cases with a little more mass in certain registers. This idea is not 
new. Speaker manufacturers have been varying the mass of drivers, and 
have known about the three way relationship mentioned above, for many 
years.

Ron O.
-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
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Web http://overspianos.com.au
mailto:ron@overspianos.com.au
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