[sdiy] VSM201 Vocorder Question

[Magnus Danielson]

Hi Tim,

Each filter section has 2 poles, just count the capacitors.
Looks like Sallen&Key or VCVS without looking too much at the transistor 
setup. Just look here:

https://en.wikipedia.org/wiki/Sallen%E2%80%93Key_topology#Application:_Bandpass_filter

Looks like a 6 pole band-pass filter. Looking at the slopes, it does not 
seem to have distributed the poles to create a flat pass-band, nor the 
peaked response used in some vocoders to increase the slopes, to the 
cost of higher Q and thus longer release time and hence impact on 
intelligibility of speach.

Cheers,
Magnus

On 01/04/2016 09:10 PM, Tim Ressel wrote:
> Another question. Perhaps a filter/transistor expert can educate me. The
> BP filters are 3-sections each. I assume these are 3 pole filters, yes?
>
> --TimR
>
> On 1/4/2016 10:05 AM, rburnett at richieburnett.co.uk wrote:
>> Simon, thanks for the clarification and detailed explanation.  My
>> apologies for the confusion caused.  Familiarity with the Roland
>> Vocoder way of doing things, German annotated schematics and about 2
>> hours sleep were all contributing factors!
>>
>> -Richie,
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>