The Duplex affect --an experiment

[David Love]

Agreed.  I think the one thing about tuned duplexes (rear duplexes that is,
I'm in total agreement about the contributions, if you can call it that, of
front tuned duplexes) is that they necessarily are shorter.  One of the side
issues that you mention is backscale length.  If one of the goals of a tuned
rear duplex is to create the illusion of greater sustain then a better and
more direct benefit might be realized by increasing the backscale length,
which means untuning it, so that the bridge is not tied down so much.  The
direct benefits of that seem to be far greater than the indirect benefits of
a tuned rear duplex, all other things being equal by which I mean that the
rear duplex is not muted.  As far a Dale's and Bob's experiment goes, it
concurs with my findings that muted rear duplexes seem to have a drier sound
than unmuted ones.  The same thing might very well be true of rear segments
that sit on rest felt on the plate rather than aliquots or directly on the
hard surface of the plate itself.  

David Love
davidlovepianos at comcast.net 
www.davidlovepianos.com

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Ron Nossaman
Sent: Wednesday, November 14, 2007 7:28 AM
To: Pianotech List
Subject: Re: The Duplex affect --an experiment



> I thought the recent discussions were about whether a _tuned_ duplex was 
> worth much, not so much whether the duplex itself should be open or not. 

Not only the recent discussion, but all those many many others 
stretching back in time. In other words, it's been hashed over 
in considerable detail many times.


>  I have had similar experiences in which the capo section duplexes were 
> braided and removing the braid seemed to have some effect.  Similarly, 
> I've had experiences where the tenor and bass backscales were unbraided 
> and were making too much noise vibrating sympathetically when unwanted.  
> There does seem to be a crossover point where the free and sympathetic 
> duplex is loud enough to be "sensed" but not so loud as to be heard, if 
> you catch my meaning.  

I typically don't braid tenor back scales until I've heard the 
piano at pitch and with the dampers installed. When you get 
the banshees wailing from the open tails, and something keeps 
groaning after the dampers are down, it's time to braid 
whatever it takes to bring it into line. Yes, I braid the 
tenor through the bass strings.



>It seems pretty clear that the duplex or 
> backscale area is an area that can and does respond sympathetically.  
>  The question of whether it's important that it's tuned or not is 
> another matter.  Did you happen to test whether or not they were tuned? 
> 
> David Love

Exactly. It's not much of a stretch hearing the difference 
between muted and open duplexes, both front and rear. I don't 
recall anyone ever advocating muting duplexes except when 
absolutely nothing else would work. Incidentally, taping off 
the speaking lengths produces interesting results too. 
Meanwhile, I'd like once again to point out that with the 
exception of open low tenor back scales, the tuned front 
duplex is the real abomination, and the bane of our existence 
in trying to eliminate the zings, whistles, and wails they 
produce in the capo sections as they deliver their benefits. 
Untuned back scales actually add more to the sound and sustain 
than tuned rear duplexes, for no other reason than that the 
segments are longer. Otherwise, the rear duplex (top half of 
the scale), tuned or not, is fairly benign and helpful if you 
don't braid it off.
Ron N