[sdiy] Weird Vocoder project

[Tom Wiltshire]

On 28 May 2007, at 09:29, JH. wrote:

>> Any opinions out there? Is this
>> totally insane? Thanx in advance.
>> Rig
>
> I don't know about this particular EQ, but _normally_ the filters  
> in EQs
> aren't steep enough for the "typical" vocoder effects.
> May give _other_, possible interesting results, but I wouldn't be  
> overly
> optimistic.

A 31-band EQ is going to have 1/3 octave bands, which will require  
fairly high Q filters. So if you _can_ build a vocoder from a graphic  
EQ, I'd say you've started with the best one for the job, given that  
you're unlikely to find one with narrower bands than that.

For the VCAs, I'd personally be inclined to use SSM 2024 Quad VCA  
chips, one of the few SSMs that is still in production. In fact,  
Juergen used these chips in his interpolating scanner circuit. 31  
VCAs is only 8 chips, and the associated circuitry isn't complicated.

Good luck with it!

Tom