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MathGroup Archive 2009

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Help Developing a Demonstration Project

  • To: mathgroup at smc.vnet.net
  • Subject: [mg104336] Help Developing a Demonstration Project
  • From: BenT <brtubb at pdmusic.org>
  • Date: Wed, 28 Oct 2009 04:07:06 -0500 (EST)

Generically there are string instruments from 3 to 12 strings that I
know of from around the world which the Demonstation Project that I
want to create would attempt to support (although with allowances to
limiting chords which have more notes than their are strings to
display them (less the root, which can be assumed to most likely be
played by a bass instrument after all). Thus the guitar (6, 7 and 12
strings), lutes and the Chapman Stick "touchboard' (with 10 strings)
can play virtually any 6-7 part chord type (i.e. 13th chords) if
desired. Intruments with few strings like the Strings (violin octet,
and standard types), as well as banjo (4 and 5 string), ukelele and
mandolin will be restricted to "lower" chord types. Consider:

Consider the standard "tertian" (expansion one, in Schillinger's
terminology) system of chord structures relating to the major scale
degree sequence of 1 3 5 7 2(9) 4(11) 6(13).

The chromatic chord/scale itself can be named thusly
M13 add #5 b9 #9 #11 b13

Thus, depending upon the number of strings which an instrument with
directly affect the "highest" chord type that is can play.

(1) 3-strings  => triads only or sevenths without the fifths
(2) 4-strings  => 7th, and 9th chord (without the roots)
(3) 5-strings => 9th, and 11th (without the root)
(4) 6-strings => 11th, and 13th (without the root)

FYI, the general chord type "families" are [using major scale degrees
for general reference]
based on these "primitive" structures. They can all be "extended" by
the tertian structure refered to above.

Major [M, or Maj] [1,3,5]
minor [m, min, or -] [1,b3,5]
suspended [1,4,5]
augmented [M (#5)] [1,3,#5]
diminished [dim, m(b5)]
augmented 7 [aug7, 7(#5)
[dominant] 7
diminished 7th [dim7, 7b9]
 #5] (7th) => related to 7(#5) with 6 symmetric
minorMajor
ambiguous [a "catch all" of all others without 3rds, 4ths, 5ths AND
7ths;
  which in fact are inversions of one of the other types]

As to the Demos GUI, it should have inputs for

(1) chord types [upto 2000+ are possible in ONE key, although
technically many are inversions to others in other keys, which are
more "consonant" and thus "rational" to be named with respect to their
respective roots <g>]

(2) instrument/custom number of strings (3-10) [the 12-string guitar
can be treated like a 6-string for fingering purposes)

(3) tuning (from several standard tunings)
   (a) fourths [custom]
   (b) fifths [custom]
   (c) guitar [EADGBE]
   (d) violin,mandolin [GDAE]
   (e) viola, tenor banjo, cello [CGDA]
   (f) 4-string bass [EADG]
   (6) 6-string bass [BEADGC]
   (c) 10-string Stick [EADGC F#BEAD]

The output of course will include

(1) a chord diagram grid box which will have a standard 5 "box"
vertical fret range using "dots" (dark circles) AND perhaps an
unfilled [or colored] circle to indicate the Root note (if present)
  [Personnally I prefer a darkenned circle with another circle around
it for the added emphasis.]

(2) the [generic major] scale degree (and "b" or "#" prefix if needed)
of each note above each string's vertical position on the grid

(3) no finger numbers or fret postions will be needed because of (2)
fortunately; the player will be assumed to be competent enough to know
where to play it from the above info, thus they are transposable to
ANY key

This will NOT be simple to say the least but VERY convenient! If you
know anyone else interested in working on this PLEASE spread the word
<GRIN>.

--- Benjamin Tubb


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