Pro Audio Design Forum

True about the drop-out beween positions. In the mic preamp the gain drops to unity for a few ms between steps but it wasn't too audible. Your mastering situation however would require seemless switching. I think that was the motivation for bruno2000 (live) to use pots in his preamp build.

OK, got it. Absence of serial errors is the key IMHO.

I wished I had some of the old Kay Elemetrics attenuators...

+1 what JR. said.

The predecessor to the iPad was the hPad. Both trace their origins to garages.

http://www.amazon.com/Hewlett-Packard-F ... 654&sr=8-1

I did the calculations for the potentiometer style attenuator. I even learned Reverse Polish Notaion to do it. Thanks iPAD! I ordered the resistors and did a mock up. The good news is that I basically got it right. The bad news is that even with .1% resistors the accuracy varies more than 0.2dB per...

JR. makes a good point about Ibias. WRT the 1646 and 120X I don't recall what the typical bias current is. For 124X line receivers (FWIW PNP input) I recall it to be about 900 nA max so it would be high enough - in some cases - to click when switched. For the 1646, to maintain LF balance, I wouldn't...

OK, good. Removing the 300R in front of the 1646 should improve both it's noise floor and output balance.

Thanks for posting this matthias. The design does look very simple, clean and useful. One thing I would examine is R76 and the 300R source impedance (at LF) that is presented to the 1646 input. Ideally you'd like to see something driving a 1646 that's <<100R and ideally directly from the output of a...

The other record companies went crazy trying to figure out what we'd done."

I'm finding this hard to believe. Seems like most engineers would have figured it out as soon as they heard it.

I was going through some stuff that JR sent me and found this DOD R870 schematic. Thanks for the databook and notes John. I'm organizing my own collection, the books that crazynightowl gave me, and what you sent. I hope to get the more interesting finds scanned and linked. This one's a start: https:...

I just got around to recording a quick 4 pole demo using four cascaded all-pass sections shown below. The final output is direct + all-pass mono output also summed using a THAT1240. The middle control range (and octaves) were used for this particular cut making it sound a little dark and thin. At ab...