Search found 5 matches

by Ian DuRieu
Thu Aug 07, 2008 9:30 am
Forum: Pro Audio Design
Topic: Graeme Cohen - Microphone Amplifier History and Design
Replies: 10
Views: 32265

Re: Graeme Cohen - Microphone Amplifer History and Design

mediatechnology wrote:when did the dbx 2150 VCA get introduced
Speaking of dbx VCAs, I have an old dBx 163 circuit where the VCA was done in discrete components.
It used 2 dual transistors. 2SA798 & 2SC1583
Any interest in seeing the circuit?

JR: I'd be interested in seeing the "cool stuff".

Cheers
Ian DuRieu
by Ian DuRieu
Thu Aug 07, 2008 1:03 am
Forum: Pro Audio Design
Topic: Graeme Cohen - Microphone Amplifier History and Design
Replies: 10
Views: 32265

Re: Graeme Cohen - Microphone Amplifer History and Design

emrr wrote:Nice compilation. Here are some corrections:
Thanks for the corrections.
The PDF file at http://leonaudio.biz/AES/Aug-15-2006/ae ... ug_15f.pdf has been updated.
by Ian DuRieu
Sat Aug 02, 2008 10:48 am
Forum: Pro Audio Design
Topic: Benchmark Mic Preamp from 1984 - Active Preamp History
Replies: 39
Views: 64326

Re: Benchmark Mic Preamp from 1984 - Active Preamp History

AFAIK the 5534 per it's specification won't drive 300 ohms rail to rail. According to Graeme, the input op amps only swing half rail making the use of 300R resistors possible. These op amps are also running class A in so far as their outputs are always sinking. I asked Graeme some time ago about us...
by Ian DuRieu
Sat Aug 02, 2008 7:49 am
Forum: Pro Audio Design
Topic: Benchmark Mic Preamp from 1984 - Active Preamp History
Replies: 39
Views: 64326

Re: Benchmark Mic Preamp from 1984 - Active Preamp History

I guess "E" stands for earth (?) Yes, "E" is the earth/common/ground point. I don't see much market for a stand alone mic preamp. What about all those studios who need to get a mic or two into their HDD recorder? I used one just the other week to run an AKG condensor mic into a laptop. It is true t...
by Ian DuRieu
Fri Aug 01, 2008 9:31 pm
Forum: Pro Audio Design
Topic: Benchmark Mic Preamp from 1984 - Active Preamp History
Replies: 39
Views: 64326

Re: Benchmark Mic Preamp from 1984 - Active Preamp History

Hi JR, Passing the common mode through to the output doesn't really strike me as a benefit. It sounds like you may have only seen figure 4 as posted by others. This is only the input stage. Please see Figure 1 on page 2 of the PDF file for the full circuit which includes a pair of 4 resistor diff am...