Pro Audio Design Forum

mediatechnology wrote:The NE570 is still made by ON Semiconductor in SMT. The IC is still very popular in cordless phones and wireless mics.

Forgot to mention stomp boxes. Does Cool Audio make the NE570 too? Hmm...

The NE570 is still made by ON Semiconductor in SMT. The IC is still very popular in cordless phones and wireless mics. Link to ON Semi NE570 applications: https://www.onsemi.com/PowerSolutions/supportDoc.do?type=AppNotes&rpn=NE570 The ON NE570 datasheet is here: https://www.onsemi.com/pub_link/C...

I wonder if we used 4 caps with two pair in series each connected opposite polarity with one pair + to +, and the other pair - to -. It seems this should both protect against DC and could cancel distortion. It seems a little Rube Goldberg, but this is fringe audio design. :D It may be interesting t...

I'm not sure how protective the reverse breakdown path would be.

Well it might not be. If the even-order distortion cancellation that Sam writes about works it still might be a good reason to use it. One more test for the null-tester.

While I wouldn't expect huge terminal voltages in the mic pre gain leg (same voltages pretty much as the inputs), I have run these down to single digit ohms so surely low impedance, and perhaps several mA of peak current. These are often polarized and 6.3V. They can see amps of fault current and du...

I don't know if you've followed Sam Groner's work in this area. I think his current preference is to parallel two electrolytic caps, back to back, with one by definition reverse polarity. On his bench, he reports a first order cancellation of some distortions. JR It's been awhile since I followed S...

JR. You might want to go back and re-read my post. Not because you missed anything but it may have changed due to editing. (There's some combination of keystrokes that will completely nuke a post and I've done that a lot lately. So I edit/re-edit/submit out of fear of losing it.) The best solution i...

I think I want to make a capacitor null tester. As JR and I have both discussed elsewhere, the terminal voltage developed across a coupling capacitor is usually very small until low frequency cut off is reached. At low frequencies, the reactance begins to become significant relative to the load resi...

Roland - For set and forget you might just want to use the auto non-linear capacitor if you want an RMS compressor. To emulate an SSL feedback peak limiter you could use a pair of untrimmed 2181C or 2180C VCAs for the sidechain along with the 4301s for the main path. Wayne

I finally got around to scanning some of the material JR sent me.

This is the 1981 Signetics Compander Product Guide with applications.

https://www.ka-electronics.com/Images/p ... _Guide.pdf

Thanks, John.