CA3086 VCA

This is the exact same circuit as the CA3046 VCA but uses a CA3086 transistor array. Because the transistors in the CA3086 aren't matched as good, the offset trimmer had to be increased to 10k.
The results show that there is no performance difference between the CA3046 and CA3086 as long as you trim the DC offset. Without trimming, the CA3086 has a lot higher offset error, which result in control voltage bleedthrough.

Noise & signal attenuation

Red = signal bleedthtrough at 0V CV. Blue = 10V CV, no signal. Green = 0V CV, no signal.

Distortion (THD+N) vs. input level

Frequency response

Test results

Dynamic range 10 V CV, no signal  83 dBr A
  0 V CV, no signal 107 dBr A
  0 V CV, 1kHz 10 V p-p in 88 dBr A
  0 V CV, 2 kHz 10 V p-pin  80 dBr A
  0 V CV, 10 kHz 10 V p-pin  64 dBr A
  Headroom (over 10V p-p)  5 dB
CV bleedthrough with careful trimming 5 mV



The CA3086 is fully usable, but if you can get the CA3046, it the better part.


Low CV bleedthrough

Fairly low distortion over a wide range of signal levels

Fairly high signal bleedthrough