The Duplex affect --an experiement

[Richard Brekne]

Hi Dale.

Very late in  on this one... but just so.  I've listened to both fans 
and anti-duplexers both front and back and taken both as seriously as I 
can.  My own judgement is that if the things are appropriately adjusted, 
then the sound of the instrument is most definitely enhanced.  Really 
cant see how anyone can come up with any other conclusion myself.  
Well... I can understand that some may not like the contribution the 
finely adjusted front duplex makes... but then to each their own.  I 
like it.

As far as your experiment is concerned.  You didnt mention whether any 
attempt was made to <<tune>> the rear duplex and if so what you did.  I 
know tuning the rear duplex is a hot item... but I recently conclusively 
confirmed that the thing is most definitely <<tuneable>> and in fact the 
tension on these lengths is more stable then the speaking lengths as 
long as your usual tuning technique does not  involve large movements of 
the tuning pins. 

As for getting the front duplex working well... and appropriately 
adjusted... I again recommend Ed McMorrows book.  He does explain in 
easy language the basic physics of how the thin capo profile works to 
allow the string to flex about the termination. This is essential to a 
good functioning duplex. Otherwise its hard to avoid getting all kinds 
of what most folks would call string noise.

Cheers
RicB


    Duplexers
      AS  a follow up to my original post
       Last night we had a roundtable discussion at our chapter  meeting
    regarding my experience as listed below.
      As you can imagine, in a group of independent piano technicians 
    there were
    a variety of opinions & intelligent conjecture offered.
      My contention was that if the duplex scale is such a great
    invention  it
    should produce a noticeable effect upon the listener & content of
    the  sound
    emanating from any piano with a duplex scale should be enhanced.
      The short version is that Bob Davis suggested an experiment
    which,  any one
    with a roll of masking tape can do.
      Our test subject, was 1953 Steinway B with an original  board,new
    strings &
    action.  The voicing is in the range of what  many people would find
    acceptable. We enlisted one of members to play the same  piece of
    music after taping
    off the three rear duplex bars. As he played we took  of the tenor
    area tape.
    The clarity sustain & flavor of the piano tone was  greatly more
    appreciated by
    all present and of all areas & most pronounced  of the 3 individual
    sections.
         We then did the same thing with capos section 2  & 3. Similar
    result in
    capo 1. Capo 2 was less obvious but still  preferred.(i.e. .increased
    sustain,clarity & color. We taped off the  front duplexes as well &
    a similar outcome
    was observed though not nearly as  pronounced.  One thing to note
    about the
    front duplexes and that is that on  this 1953 B the draft angles are
    significantly steepr than most B I've  encountered & bleed thru is
    not an issue & sustain
    is good. Also lightly  pressing your finger on the front duplexes
    really
    kills the sustain as it  apparently limits the rocking of the string
    across the
    capo string contact  area.
      In our follow up assessments I was surmising that the more
    efficient  &
    strong the tone of a sound board is
    the greater the duplex effect may be.
      So try it yourself & see if it's just smoke & mirrors.   Whether
    it is a
    desirable affect....... is your call.
      I personally like it.
        Dale