Mad Man Rambles about Noise Generators

[Scott Gravenhorst, Synthaholic]

>Don Tillman writes:
>Back to the topic.  I think you're referring to that large string of
>0's (and later 1's) all in a row, right?  I'm pretty sure this is what
>causes that thumpa effect.

I think you're right.

>
>When I first proposed a VCO driven feedback shift register to AH a
>long while ago, the idea was to make the harmonic structure of the VCO
>waveform far more complex.  So for that, the string of 0's is just
>more fundamental tone.

I wasn't on the list then, but this is intriguing.  Of what size 
register were you thinking?  I can see where one could take advantage 
of the sort term repeatability of a very short (2,3,4,5,6 bits) 
register.  One would want to be able to patch the bits to the XOR gates 
as well as into the data inputs of a DAC to change the wave shape.  Am 
I on the right track?  Sorry if you're repeating something explained 
earlier.  This sounds cool.  

>
>It sounds like you're using this more as a noise source, and you want
>to get rid of the string of 0's.

Yes, but the above adds new dimensions.  I built the prototype as a 
dual purpose module, 1: noise   2: an extra VCO.  When using it as a 
VCO it would be very nice to have a complex waveform generator as you 
described.

>  Okay.  I'm guessing you tap off just the last two SR stages.

4 taps on a 16 bit register.  16, 15, 13 & 4

>  If you tapped off other stages in the middle, I beleve you'll 
>eliminate that string of 0's.  Obvously you'll want one tap at the 
>very end.  Some combinations of taps drastically reduce the length of 
>the sequence, so you'll want to either do a quickly simulation or bone 

>up on error correction theory to be sure.

Any good book suggestions for error correction ?

-- 
-- Scott G., Synthaholic

If at first you don't succeed, keep suckin' 'til you do suck seed.
                                                 -- Curly Howard
What else can happen?
       -- Howard (Never call me Howie) Bradley