Search found 572 matches
- Sun Dec 13, 2009 9:23 am
- Forum: Pro Audio Design
- Topic: op amp gain; vary Rg or Rf, and why?
- Replies: 28
- Views: 42246
Re: op amp gain; vary Rg or Rf, and why?
next dumb question. The C in series with RG, almost always seen on the ground side. Is that placement important? If placed on top of the R, or even between two R's, do we have a biased condition that causes problems? Leakage enough to still cause DC gain? I could keep this rework more simple if I co...
- Wed Dec 09, 2009 4:17 pm
- Forum: Pro Audio Design
- Topic: op amp gain; vary Rg or Rf, and why?
- Replies: 28
- Views: 42246
Re: op amp gain; vary Rg or Rf, and why?
the gain stage has to drive the total Rf+Rg to ground in parallel with input impedance of following circuits Obvious enough, I hadn't thought about that part. These are mostly 75 ohm output rated op amps, and the following circuits are 600 ohm at minimum, mostly 10K. So not a problem. Back to the d...
- Wed Dec 09, 2009 7:17 am
- Forum: Pro Audio Design
- Topic: op amp gain; vary Rg or Rf, and why?
- Replies: 28
- Views: 42246
Re: op amp gain; vary Rg or Rf, and why?
When attempting to get best s/n at high gain you want low total impedance in feedback network (Rf and Rg in parallel). The pot varying the leg to ground give you lowest impedance at highest gain. The above hits the nail on the head. Amazing how I can dig through a stack of books, and browse the web...
- Tue Dec 08, 2009 8:05 pm
- Forum: Pro Audio Design
- Topic: op amp gain; vary Rg or Rf, and why?
- Replies: 28
- Views: 42246
Re: op amp gain; vary Rg or Rf, and why?
Safari is cutting off the right side of the image here, but Firefox is showing everything.
- Tue Dec 08, 2009 8:04 pm
- Forum: Pro Audio Design
- Topic: op amp gain; vary Rg or Rf, and why?
- Replies: 28
- Views: 42246
Re: op amp gain; vary Rg or Rf, and why?
When attempting to get best s/n at high gain you want low total impedance in feedback network (Rf and Rg in parallel). The pot varying the leg to ground give you lowest impedance at highest gain. That's finally in layman's terms. Perhaps it makes more sense to fix a constant Rf value, and use S3 fo...
- Tue Dec 08, 2009 2:38 pm
- Forum: Pro Audio Design
- Topic: op amp gain; vary Rg or Rf, and why?
- Replies: 28
- Views: 42246
Re: op amp gain; vary Rg or Rf, and why?
Yep, these use Grayhill MBB switches, and I have 5 channels that have survived to this late date; 35+ years.
- Tue Dec 08, 2009 1:38 pm
- Forum: Pro Audio Design
- Topic: op amp gain; vary Rg or Rf, and why?
- Replies: 28
- Views: 42246
op amp gain; vary Rg or Rf, and why?
I was working on some early '70's RCA preamps with transformer input (15K sec), which use a discrete op amp in non-inverting mode. I note RCA chose to have Rg be a set value, and varied Rf via a stepped control, along with tailored Cf's. In almost every other similar preamp I've encountered, Rf is f...
- Wed Dec 02, 2009 3:36 pm
- Forum: The Peabody Lounge
- Topic: The Mad Tea Party: free xmas single
- Replies: 1
- Views: 5487
The Mad Tea Party: free xmas single
We did these tracks as extras when we made the ZOMBIE BOOGIE Halloween record earlier this year. We cut these songs live in their living room over a weekend. Guitarist is also playing the drums at the same time. Generous abuse of Pico mono and stereo comps on this one, though maybe hard to tell, as ...
- Thu Nov 19, 2009 7:35 pm
- Forum: Build
- Topic: ms matrix- at last
- Replies: 8
- Views: 32955
Re: ms matrix- at last
That's what I'm planning for one set! Dual mono, or M/S stereo.MikoKensington wrote: throw it between two mono Picos to make a M/S compressor.
- Wed Oct 28, 2009 10:04 am
- Forum: Pro Audio Design
- Topic: +24Vdc from +/-15Vdc
- Replies: 2
- Views: 6441
Re: +24Vdc from +/-15Vdc
I'll report back, smoke or no.....