Search found 6 matches

by dfiction
Thu Aug 16, 2018 8:03 pm
Forum: Pro Audio Design
Topic: THAT 2162 VCA Control Circuitry
Replies: 12
Views: 11272

Re: control circuitry for THAT 2162

What matters from a control viewpoint (maximum attenuation) is the voltage. From that perspective the divider reference can be either ground or Vcc/2 as long as you calculate the divider with the correct end-point voltage. If you have other things that reference Vcc/2, like the VCA, op amps etc., t...
by dfiction
Thu Aug 16, 2018 5:54 pm
Forum: Pro Audio Design
Topic: THAT 2162 VCA Control Circuitry
Replies: 12
Views: 11272

Re: control circuitry for THAT 2162

Yes, just use Vcc as Vin to the divider and set the divider output to whatever maximum attenuation you want. Then buffer that divider with another op amp. I would use Vcc/2 as the reference for the lower end of the divider. I'll give it a try. However, I'm confused, because R5 is connected to GND, ...
by dfiction
Thu Aug 16, 2018 5:38 pm
Forum: Pro Audio Design
Topic: THAT 2162 VCA Control Circuitry
Replies: 12
Views: 11272

Re: control circuitry for THAT 2162

Okay, I'm starting to get a feeling for what you're saying. so this new op amp would be a unity gain buffer like the other three—but how do i figure out the values of this new voltage divider you're suggesting I add? simply calculate the max attenuation I want and calculate it Vin as Vcc? And, shoul...
by dfiction
Thu Aug 16, 2018 2:29 pm
Forum: Pro Audio Design
Topic: THAT 2162 VCA Control Circuitry
Replies: 12
Views: 11272

Re: control circuitry for THAT 2162

Make the lower end of P2 fed from a low-impedance voltage source. (Op amp output.) (The upper end of P2 should continue to be a voltage source as well.) Do you mean, stick another buffer in there? ie, the bottom end of P2 would go into an op amp buffer, and then the output of that would drive R5 in...
by dfiction
Thu Aug 16, 2018 1:14 pm
Forum: Pro Audio Design
Topic: THAT 2162 VCA Control Circuitry
Replies: 12
Views: 11272

Re: control circuitry for THAT 2162

Thanks for joining us! Have a look here and see if this is useful "Resistors Provide Nonlinear Pot Tapers," Mark Rumreich EDN November 13 1986. : http://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=12&t=866#p10260 Though the VCA control taper is linear dB I can see how some r...
by dfiction
Wed Aug 15, 2018 6:51 pm
Forum: Pro Audio Design
Topic: THAT 2162 VCA Control Circuitry
Replies: 12
Views: 11272

THAT 2162 VCA Control Circuitry

Hey everyone! I'm new to this forum and I have enjoyed reading everyone's wisdom here. So many cool circuits. I wanted to share a problem I ran into with a VCA i'm working on–There are so many wise mentors here, and I'm sure many of you have licked this problem before. I'm doing some work with the T...