EQ revision

[PRR]

> to raise from 10khz to 12khz (a more usable "silkiness" frequency), switch from 2n2 to 1n5?

Actually 1n83333.

But these circuits are very gentle slopes. You may not hear a difference.

Put in a couple terminal points so you can try different caps on real sources.

 

[PRR]

> audible oscillation that changes in pitch when i adjust the eq controls

The stray capacitance on the Inverting inputs must be VERY small. In particular, you can't have a foot of wire from pin 2 to the LF pot wiper. Likewise everything on pin 6 must be tight. Keep it short!

> can/should i put 22pf stabilizer caps over R35 and R38?

47pFd here may help. But you need to minimize stray capacitance first.

> will that not affect the eq freq's?

It will roll-off supersonics. Figure: your HF cap is about 2nFd or 2,000pFd, what difference is another 47pFd?

 

[Kev]

cool ... :thumb:
keep us posted

 

[Consul]

Umm, just out of curiosity, is this a mod to the Calrec EQ, or a different circuit?

If this was mentioned, my apologies. I must have missed it. Thanks!

 

[PRR]

> how could i make the HF filter a bit steeper??

Use a more complicated EQ network. This one is very tame, even lame. Last time I saw one like this was for a car radio. There are better schemes for artistic music manipulation.

 

[tmbg]

is there a standard design for an inductorless eq design with variable center and Q? Most of the filtering I'm familiar with has the Q as a design factor, and isnt simple to vary...