Sitars and Waveshaping

tim at tim at
Thu Jan 22 09:30:54 CET 1998

O.K. Chaps here is some stuff that may be usefull.


The sympathetic strings are effectively tuned to C,B,D,E,F,G,A,B,C.  Note
that this is not the well tempered scale but the ratio scale.  The
implications of this are that it sounds better in some keys than others 
(some sitar players retune their sitars for certain pieces).

The Indian scale (carnatic) has 23 distinct notes.  These are not all used in
a given scale and yes you can get away with C major again.  If you want
more info on scales try a book on Ragas or a teach yourself book on the
harmonium or sitar (Pantaj publish some), you could also try a search for

O.K. The notes are:

	Name		Cents		Equal tempered
	sa				0				C
	ra				90				
	ri				112			C#+12
	ru				182			
	re				204			D+4
	ga				294			
	gi				316			D#+16
	gu				386			
	ge				408			E+8
	ma				498
	mi				520			F+20
	mu				590			
	me				610			F#+10
	pa				702			G+2
	dha			792			
	dhi			814			G#+14
	dhu			884
	dhe			906			A+6	
	na				996
	ni				1018			A#+18
	nu				1088
	ne				1110			B+10	
	sa'			1200			C	

Wave Shaping

For more information on peicewise linear approximation (funtion fitting) etc
try the following.

Journal of the Audiuo Engineering Society  Vol 24, No 6,  pp446-454.

Electronotes #69 pp8-13  How to build the stuff described above.

Analog Devices   Non Linear Circuit Handbook, has loads of stuff.  I'm not
sure if it's still available but
you could get them for free from AD or a distributor.

Serge Wave Multiplier

Andre Storeur described the chips used in it on Analog Heaven.

A few Guesses:

>From this the 1st stage uses a 3080 as the distrotion element (Bob Moog uses
this in a patent for a fuzz box)
the clipping switch controls the signal level to the input of the 3080.

Stage 2 sounds like a function fitter for sure.  Does anyone who has one want
to re-engineer this section (please)?

The third stage  has to be cascaded full wave rectifiers with a variable dc
bias, as described by Serge in his patent.

I would love to know if the above is correct.  Any suggestions?



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