Pro Audio Design Forum

Nice work John. Very simple using two duals. I think keeping the RC network in there is a good thing.

I think we'd need a pan kill of at least 70 dB or more since that's about what a conventional pan pot would produce.

The perhaps flaky data sheet I looked at was something like 8-10 nV/rt hz for those opamps. FWIW something like a 5532 driving the CV would very likely be more than adequate sonically and cheap. The 33078/33079 is more like 4.5 nV/rt Hz: http://www.onsemi.com/pub_link/Collateral/MC33078-D.PDF Not t...

John - After thinking about it I went "oops." Yes the DC performance will only be as good as the op amp.

The MC33178/33078/79 are dirt cheap, low Vos and low noise. I'd blow off the passive pad, large C and just drive Ec with the op amp. Less parts to stuff.

Using a low noise transistor as an emitter follower I can pad down the opamp noise, and deliver a pretty low output impedance.

OK, I follow you there. But wouldn't this also pad down the output offset allowing "looser" (and higher output impedance) quads like a TL074?

Thanks for this....

I dusted off my thinking cap, last night, and I can't figure out why not just add a simple unity inverter to split the CV for symmetrical drive?

That's what I was thinkin' too. Looks like an MC33179/MC33079 quad would seem ideal or two duals.

We put a bunch of simple build options in the original 10 LED GR meter: Diode rectifier, constant current, Vreg etc. That board generated more support questions, due to it's options, than all the Pico Compressors combined. And you're right that a balanced insert adds another line receiver. I think s...

I had completely forgotten about BI Technologies pots from TT Electronics. They recently ran an ad in the AES Journal and will be exhibiting at NAMM. They've built a product web page just for Pro Audio:

http://www.bitechnologies.com/ProAudio/ ... /index.htm

John - I think anyone wanting/needing dynamics on a per-channel basis could just do it ahead of the line input. Having a CV insert seems feature-creepish and I doubt anyone would use it. For the added interconnect overhead there would be a lot more mileage if it just had a TRS insert send/return in ...

I am speaking from the cuff and don't know if the PICO has a easy to implement feed forward mode. Since the VCA is feeding a summing bus, feedback topology is not available The Pico is a feed-forward topology. I wouldn't put a compressor in the unit however. I can see that with 100 dB cutoff how on...