[Harp-L] Re: Altered reed shapes

["Doug H" <dough.harpl@xxxxxxxxx>]

Great information Rick!

However, there are a few terms relating to accordians that I don't understand.  For example "cassotto",  "cassotto tone chamber",  "reed shoe",  "reed block" and "cabinet".

Is there a spot on the web that would clairfy these terms, and maybe teach me a bit about accordians in general?  Thanks in advance for any info.

Doug H
  ----- Original Message ----- 
  From: Rick Epping 
  To: harp-l@xxxxxxxxxx 
  Sent: Wednesday, August 11, 2010 1:24 PM
  Subject: [Harp-L] Re: Altered reed shapes


  >
  >
  > The spectrographs of all the harmonica reeds I studied while conducting
  research for Hohner showed what appears to be a low signal to noise ratio;
  that is, the amplitude of the dissonant overtones was very low compared to
  that of the consonant overtones.  The amplitude of the dissonant overtones
  only increased significantly when the harmonica reed was blown loud enough
  to start distorting.  I believe that what makes harmonica reeds sound thin
  and reedy is the relatively high amplitude of the upper partials, or
  consonant overtones, and not so much that of the dissonant overtones.



  Some aspects of reed design that can influence the strength of the upper
  partials compared to the 1st partial, or fundamental tone, are: 1. Reed
  thickness (especially the thickness of the reed at its edge) - a thin reed
  will have stronger upper partials than a thick reed.  2. Reed dimensions - a
  narrow reed will have stronger upper partials than a wide reed.  3. Reed
  plate thickness - a thin reed plate will produce stronger upper partials
  than a thick reed plate.  English-made concertina reed shoes are undercut to
  create the effect of a thin reed plate, giving these instruments their
  characteristic reedy tone.



  I believe that what is at least as influential as the reed to the tone of an
  instrument is that of the instrument design and construction.  For example,
  clarinet accordion reeds in cassotto are identical to those in the same
  instrument that are not in cassotto, yet the tone of cassotto reeds is
  significantly warmer and rounder than those not in cassotto.  This is
  because the cassotto tone chamber shifts energy from the upper partials to
  the fundamental, making the fundamental actually louder than that of the
  same reed not in cassotto.  While playing a harmonica note into a microphone
  to produce spectrograph, I found that going from an uncupped note to a
  cupped note caused the amplitude of the upper partials to decrease and that
  of the fundamental partial to increase, just like an accordion's tone
  chamber.  Similarly, the reeds of an XB-40 are identical to those of a
  chromatic yet, due mainly to the XB-40's internal valve chamber, the XB-40
  produces more of the fundamental tone and less of the upper partials than a
  chromatic, giving it a warmer, rounder and loud, but less bright tone.



  Italian accordions might be characterized as having a warm, pure and round
  tone compared to German accordions, which tend to be more bright.  Here are
  some possible reasons: 1. Italian reeds tend to be thicker and stiffer than
  German reeds (this need not affect response, as stiff reeds can be given
  less offset than more flexible reeds).  2. Italian cabinets are generally
  thicker and heavier than German cabinets, and can absorb more of the upper
  partials.  Likewise, Italian reed blocks may be heavier than German reed
  blocks, having the same effect.  3. Italian accordions more often use
  leather reed valves and German accordions usually use PVC reed valves.  The
  heavier, softer, rough-surfaced leather valves absorb more upper partials
  than the thin, reflective PVC valves.  Lastly, 2-voice tremolo tuning on
  German accordions is usually faster than the standard 2-voice, Violin tuning
  common to Italian accordions.  This also helps to give German accordions a
  brighter tone compared to the more pure tone of Italian accordions.



  Some harmonicas can be overly bright, especially harmonicas that have been
  customized for maximum performance.  But in general, most players might
  prefer a somewhat bright instrument, where there is a greater possible range
  of tonality by means of hand cupping.  A bright harmonica can be made warmer
  and more fundamental in tone by means of cupping, but less can be done while
  playing to make a harmonica with a predominantly mid-range tone more bright
  sounding.



  Rick