[sdiy] New TOG board: $0.02 needed

[Tim Ressel]

--- On Tue, 1/6/09, Nicholas Gregorich <nicksdsu at mac.com> wrote:

> If you control amplitude in the FPGA then you need a DAC
> (rather than just an output pin) and a way to control the
> amplitudes (MIDI or ADC).
> 
> I think part of the beauty of a Walsh generator is that you
> can actually put it in a small CPLD and build a mixer,
> that's it. No development kits  needed.

Wow. This as getting heavy. A Walsh TOG!? Hmm. If we keep it to a manageable number of coefficients, say 8 per note, 104 output lines. It is doable, but like I sed, wow. I think the only way to do the mixer is with digital pots. This is a pricey way to go but very controllable digitally. Another possibility is to use a sea of 4051's that combine coefficients through resistors. 

My official pronouncement: A Walsh-based poly synth is possible. And the attempting it will build gobs of character and be handy if you're trying to get disability money from the government. So naturally, I'm in.

I think the thing to do is play with a monotonic Walsh and get a feel for just how many coefficients are needed for a decent system. 

--TimR