Grand dampers

[Dave Nereson]

----- Original Message ----- 
From: "James Perkins" <jimperkins@mac.com>
To: <pianotech@ptg.org>
Sent: Wednesday, September 10, 2003 7:32 PM
Subject: Grand dampers


> 
> Are there any guiding principles for damper types in the low tenor 
> range?
> I don't have originals to work from on this 7' Bechstein and wonder 
> where the split type should change to straight.
> 
> Or is it just experimentation/proof of the pudding etc?
> 
> Also does the practice of applying damper felts in two pieces rather 
> than one continuous piece have a benefit in terms of damping efficiency 
> or is it purely to save felt?
> 
> I would appreciate your comments/advice.
> 
> 
> James Perkins
> 42 Marlee Road
> Parklands
> WA 6210
> Australia
> 
> 08 9581 6354
> Mobile 0401674447
> 
> _______________________________________________
> pianotech list info: https://www.moypiano.com/resources/#archives
> 
    I think most companies use flat damper felts wherever they can, because it's not as expensive to make as the wedge felt.  But (coming down the scale from the treble) there's some point where the flat pieces just don't stop the strings' vibration that well, and that's where they change to wedge type.  Now, how they (or we) decide whether to put the wedge type in front and the flat in back, or vice versa, I don't know;  I've seen it both ways.
    It's hard to experiment without actually gluing them on, in which case you can't get them back off without messing them up a little.  So order extra felt and use a glue that's easily removable.    
    Two pieces of felt (some Kimball verticals have three) damp better than one long piece.  And if a felt sits on a node, it may allow some partial or other to ring obnoxiously -- the seventh partial is notorious for that.  You have to find where that node is, plucking or playing while moving a mute or a finger around in the problem area and decide whether to move that piece of felt forward or back.
    All this assumes both pieces of felt are contacting the strings simultaneously, that the wedge felt doesn't keep the flat felt from contacting the string, that the strings are level, dampers regulated, etc.  In my experience you just have to fuss and tweak, fuss and tweak.  Yet Yamaha glues their damper felt to the heads first, then places the dampers in the piano and and fusses and tweaks from there.  
    --David Nereson, RPT