What I meant by "not much extra work" is the design, not the soldering
together. It's only one envelope follower and one VCA to design, then
it's copied and pasted 39 times to make the PCB layout. I was thinking
about putting 20 of each onto a board. One board would also have extra
circuitry for the voiced/unvoiced logic.
I went with the staggered knobs. I've got the panel all marked out,
now I need to drill 44+44+4 holes. Gulp.
On 28-Jul-08, at 5:44 PM, John Mahoney wrote:
> At 12:48 PM 7/28/2008, Scott Juskiw wrote:
>> I'm considering creating a PCB (or two) that would have all the
>> additional circuitry needed to make a "modular vocoder". You'd need
>> two of the JH string filters to make this work (and a few patch cords
>> to hook it all up). You could build a standalone vocoder and
>> eliminate
>> all the patching, but then you wouldn't be able to use the JH string
>> filter "as is". I'd like to at least try it. I designed a vocoder
>> back
>> in the mid 1980s but never got it completed. The JH string filter
>> already has the necessary mixer and the filters have 10-turn trimmers
>> for calibration, that got me thinking it wouldn't be all that much
>> extra work to make a vocoder.
>
> Wow, interesting! Personally, I would not say that 40 VCAs and 40
> envelope followers are "not much extra work" :-) although I
> understand that at least the 40-band filters are taken care of.
>
> (BTW, I might be interested in PCBs with, say, 4 VCAs or EFs per
> board. Are you planning anything like that?)
>
>
>> Here are some other uses for the string filter separate outputs:
>>
>> 1. extracting vocal formants
>> 2. spectral processing of individual bands
>> 3. using specific bands to trigger envelope generators
>
> Indeed. However, these functions can generally be performed by a few
> bandpass filters. I'd rather use the 2U to house 3 or 4 manual BP
> filters, like a pair of Blacet dual filters
> (http://www.blacet.com/DF.html), instead of a 40-jack array.
>
> But, that's me. As an observer, I'd enjoy seeing someone else build a
> 40-band analog vocoder!
>
> Oh: I prefer the panel design on which the jacks are staggered like
> the knobs.
>
> John