[pianotech] Tuning the duplex sections

[David M. Porritt]

Well, like about everyone else I have no scientific evidence for the
theories I've adopted along the way.  Having said that however, generally
all the energy available comes from the hammer striking the speaking length
of the string.  In the ideal world, all that energy would go directly
through the bridge into the sounding board.  Any energy that "bleeds" across
to the duplex (either front or back) is lost for our primary purpose.  I
would rather keep it in the speaking length as much as possible.

While it is undeniable that the front duplex does cause additional sound,
frequently that sound is a high pitched obnoxious sound.  It's also not
under my control nor under the control of the pianist.  It's the random
nature of the front duplex that really bothers me.  It's not like a highly
desirable sound that can't be created elsewhere.  If you don't have a front
duplex - or even if you mute it - you can get more brilliance with a harder
hammer and that _is_ under your control.  Maybe I've just become a control
freak in my old age, but I don't like things that just happen.

dave

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of David Love
Sent: Tuesday, March 15, 2011 5:08 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] Tuning the duplex sections

Then I guess I'm not sure what your point was.  Since the board transmits
energy back to the strings the rear duplexes will contribute to the overall
sound in some, albeit, small way and muting them will remove something, I've
heard that happen and have removed the braiding accordingly.  If they are
tuned or untuned the energy from the board will still excite those lengths
and put their energy back into the loop.  If they are tuned there might be
something added by virtue of them being in sympathy with other frequencies.
Whether that added amount is significant enough to hear the difference when
comparing tuned and untuned rear duplexes, I don't know.  It might depend on
the length of the rear duplexes.  With rear duplexes that are significantly
shorter and stiffer than the speaking lengths (like on many Steinways) it
probably makes less difference than if they are tuned exactly as the
speaking length is as is the case with some Yamahas, for example.  

So there are really three aspects: there's the fact that the rear duplexes
receive energy from the soundboard and contribute in some way to the overall
envelope.  In addition to that they may be tuned or untuned which may also
contribute more or less but that amount may or may not be significant.  And
then there's the length and/or specific frequencies to which the rear
duplexes are tuned.  How you separate the contribution of each of those
factors I don't know.   

David Love
www.davidlovepianos.com


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Ron Nossaman
Sent: Tuesday, March 15, 2011 9:45 AM
To: pianotech at ptg.org
Subject: Re: [pianotech] Tuning the duplex sections

On 3/15/2011 9:22 AM, David Love wrote:
> See my other post in response to JD but if the soundboard is transmitting
> energy back to the strings then it may not matter if the duplexes are
tuned
> or not, they will react to the energy being provided by the soundboard
> either way.
>
> David Love
> www.davidlovepianos.com

Of course the soundboard is transmitting energy back to the strings - 
all of them at once.

My comment was concerning Frank's mention of muting duplexes, which 
wasn't being discussed at all.

I agree it likely doesn't matter if the rear duplexes are tuned or not, 
and have been saying that every chance I get for a whole lot of years 
both on list and off.

The front duplexes are a different animal altogether from rear duplexes 
and discussions of "duplex" should differentiate each time they are 
mentioned - front duplex, rear duplex.
Ron N