[sdiy] 'Reverse' connected 2164 approach for HP filter stage purpose..

[Tom Wiltshire]

On 11 Mar 2014, at 13:26, Jean-Pierre Desrochers <jpdesroc at oricom.ca> wrote:
> 
> BTW is there anybody who used the 'reverse' connected 2164 approach
> for HP purpose like the first 2 stages hre ?
>> http://www.arcenson.com/public/2164_BP_filter.JPG
> 
> Didn't check it on breadboard so far...
> 
> JP


I haven't seen it before. The only VCA HP stage I know of is in one of the THAT VCA application notes, where they show a 1-pole SVF used as a HPF. Basically, a mixer followed by a VC-integrator, with the integrator output taken back to the mixer.

I think I saw it first in one of the others, but it's also shown here:

http://www.thatcorp.com/datashts/AES13-031_Digitally_Controllable_Audio_Filters.pdf

Incidentally, there's a SVF in there with the 'phase lead' compensation components shown, and also an extremely "alternative" way of controlling the Q in an SVF by moving the CVs of the two integrators apart. Interesting stuff.

HTH,
Tom