Portable two-band Parametric EQ (ESP/Urei 545)

[JohnRoberts]

It was a real prototype on PCB and metal enclosure, the fpot scraping a lot but with my circuit shown in post #74. Some crazy 1:290 apparently and the OPA1642 (3mV voltage offset per datasheet). With the 1:25 I'm planning now it might be no problem, I hope. Or I might try something else,
Isn't the current noise of the NE5532 too high for this? Considering the high resistor values everywhere. Never tried it. The AD712 produced my favorite sounding EQ curves of what I've tried, but voltage noise specs ended up scaring me off.

I typically used bifet opamps (like TL07x) in parametric SVF designs.

JR

 

[abbey road d enfer]

I typically used bifet opamps (like TL07x) in parametric SVF designs.

JR

The problem with TLO7X is noise voltage. I deemed them not suitable for my 5 and 9-band parametrics. With typical 5k resistors at the input, the noise du to noise urrent is less than that due to noise voltage.
However, today there are FET opamps with noise voltage comparable to 5532.
OPA1652 and even better OPA1656, both only in SOIC package.