Duplex Tuning - mysteries and realities?

[Alan W Deverell]

Thanks Ron - your reply explains a lot and thanks for correcting my
"MOE" inserted wrongly (just stiffness was adequate/appropriate).

In summary, can we assume from your comments that:

1) DUPLEX adds "colour" to the tone of any piano ?
2) DUPLEX "tuning" is mostly garbage ?
3) Except for the adjustment of downbearing, Duplex "wedges" serve no
significant purpose?
4) It is/maybe desirable to "mute" the duplex strings during tuning ?

I have another post from Dr Clive Woods which has some interesting
information - see extra post to this subject.

>-----Original Message-----
>From: owner-pianotech@ptg.org
>[mailto:owner-pianotech@ptg.org]On Behalf
>Of Ron Nossaman
>Sent: Sunday, June 14, 1998 1:35 AM
>To: pianotech@ptg.org
>Subject: Re: Duplex Tuning - mysteries and realities?
>
>>I have been seeking a technical and practical clarification
>>about the DUPLEX question raised briefly on Piano-Tech last week.
>>
>>Quite obviously the effect of Duplex on the note diminishes as the
>>proportion of speaking length to tuned string length becomes smaller
>>and the stiffness of the strings themselves increases. Yet, I
>>have observed duplex wedges going well past points where I
>>would have considered any inducement to sympathetic resonance or
>>harmonics would have been identified let alone capable of being
tuned!
>
>The apparent stiffness of the string changes, but the MOE is
>constant for the material, regardless of length or diameter. While
some
>duplexes possibly are too short to add much to the sound, and, in
fact, >are more probably constraining soundboard movement, they do
serve to >establish a string termination height, and down bearing at
the bridge..
>
>>
>>The whole question of sympathetic resonance in strings between
>>hitch-pin and bridge and the value of Aliquot strings in
>>Bluthner etc. seems to be confused by inconsistency between
>>manufacturers and Piano people generally.
>>
>>1) What do you believe are the merits, if any, in duplex ?
>*More sound.
>
>>2) Should felt wraps be threaded through un-tuned bridge-to-hitchpin
>>strings on pianos without duplex wedges ?
>*Only if they are noisy enough to detract from the desired sound, or
>interfere with the tuning (S&S model D, for one).
>
>>3) Should Aliquot strings be removed from Bluthners ?
>*No opinion, I haven't played with one.
>
>>4) What desirable partials and/or un-desirable harmonics are excited
>>into these Duplexed areas.
>*I don't really know. The purpose of the duplex is to make
>noise. It isn't necessarily 'tuned' to anything specific, and there
>isn't necessarily any correlation between pitch of any given note and
>the pitch of it's corresponding duplex. For any note struck in the
>piano, some duplex segment, somewhere in the scale, will respond.
>Serendipity sometimes supersedes intent.
>
>>5) How does a Duplexed string effect the practicalities of
>>Tuning the Piano itself ?
>*It adds more garbage to work around. If you mute off the
>duplexes when tuning, you notice how clear and clean the piano sounds
>during the process, and how shallow and lifeless the result is. When
you >uncover the duplex, the piano comes back to life. I don't
normally mute >duplexes when tuning, but
>I've run into a few instances where it was necessary,
>particularly in the
>front duplex.
>
>>6) add more questions ..... ?
>>
>>The following observations have been made by a UK corespondent and I
>>will be interested in comments from Technicians on Piano-Tech.
Neither
>>my Bechstein C or Ehrbar have tunable duplex and there seems to be a
>>complete lack of definitive instructions for tuning the wedges on
>>Yamaha and Steinway etc.
>>
>>-----Original Message-----
>>From: Dr. Clive Woods
>>Sent: Saturday, June 13, 1998 5:11 AM
>>To: Alan W Deverell
>>Subject: P.S. Re: Tuning Duplex
>>
>>It occurs to me that in some makes (Bechstein? Bosendorfer? Seiler?
>>Grotrain?) there are not wedges for the Duplex scale,
>--snip--
>>Ever seen a piano with _front_ duplexes? Same idea, but it
>>is the bit
>>on the keyboard side of the plate bridge that is duplexed. An old
>>Steinway B in Sheffield Cathedral is like this. It sounds terrific,
>>but I'm not sure how much is due to the duplexes! Theoretically this
>>should have much less effect, of course, so it was very quickly
>>dropped by Steinway.
>>
>>Clive
>
>*The reason there are no instructions for tuning these
>duplexes is pretty straight foreword. There isn't much point. The
>designer either had a devilishly clever and obscure reason for
placing >the aliquots where he did,
>or it was done entirely arbitrarily. The resulting sound, in
>either case, is going to be very similar.
>
> Ron