S&S D Duplex

[Tony Caught]

Hi David,

In some instances the answer is yes. It will depend on the piano and wether
the duplex system was designed as the scale/iron frame was designed, or
wether it is an add on, or in fact who designed it.

Have been following this topic only briefly as I am not totally wrapped in
the twangy sound that you get if they have never been adjusted properly.
Which appears to be the norm. Still, sound is a personal thing.

Look at an electric guitar and see were the pickups are, Gibson are
different from Fender. The sounds are different because they are enhancing
certain harmonics. This is different to the strike point of 1/8th or 1/9th
or whatever the string length (which also gives a different sound) because
it is picking up the strings harmonics from various points that may not
match specific harmonics but just give the sound that the designer wants.

With a piano's string the bridge is set in accordance to the designed scale
with only a reasonable amount of thought in the string's tail. However it's
the tail of the string that is going to denote how much the bridge will move
and which harmonics will be accentuated in the main string.

Even when the tail is muted the tail still vibrates and allows the bridge to
move but the vibrations because the tail is muted is not self sustaining.

Most of the Duplex bars you see have staggered contact points ( not in a
straight line with the bridge) and it is obvious that the shortest distance
between the bridge and the Duplex bar is going to control how the bridge is
going to vibrate in that area.

I once asked 'how come C1 on some pianos sounds more like a G note?' The
answer is that the short tails on the strings in the bass cause the G
harmonics of the C1 string to come out stronger.  This same effect is
happening right through the piano.  The short tail in the treble is also
affecting the stiffness of the soundboard by restricting the bridge.

Who was it that said 'The duplex has been added to pianos in an attempt to
cover up the deficiencies created in the construction of the modern
soundboard'.

Sorry Avery, I digress, yes moving the duplex back towards the bridge by
just a few mm's would make a difference. What else would make a difference
is bedding the duplex properly onto the iron frame and putting a brass shim
or two under the duplex to decrease the downbearing on the bridge. This may
even overcome some of the killer octave effect that is also present in the
same areas.

Regards

Tony

Tony Caught
Darwin Australia
caute@bigpond.com




----- Original Message -----
From: "David Love" <davidlovepianos@earthlink.net>
To: "Pianotech" <pianotech@ptg.org>
Sent: Wednesday, November 20, 2002 2:42 PM
Subject: Re: S&S D Duplex


> The question was hardly frivolous.  My question had to do with whether it
> was more important to try and establish longer backscale length at the
> expense of a tuned duplex.  By moving the duplexes back toward the hitch
> pins you can gain several mm's of backscale length.  I was inquiring
whether
> those added mm's would make any difference.
>
> These are just questions Dan, I'm not attacking you personally.  It would
be
> nice if you desensitized a bit.
>
> David Love
>
>
> ----- Original Message -----
> From: <Duplexdan@aol.com>
> To: <pianotech@ptg.org>
> Sent: November 19, 2002 8:26 PM
> Subject: Re: S&S D Duplex
>
>
> David Love,
>
> Quick answer to a quick and frivolous question: If yo don't think the
duplex
> is important at all, why bother moving it either way?
>
> Dan Franklin