Re: Copying Op Amps to Make Mic Amps

Wow ...3 threads at same time for mic amps.

>"Improved mic amp posted on Rapidshare"
>"A Better Microphone Amplifier Yet"
>"Is S.E.D. actually sci.electronics.dummies"
>
>I'm surprised mic amps are a lively topic on here.
>I thought it would be a beaten to death topic like audio power
>amplifier design.
>Also, by now shouldn't the ultimate microphone amp be a well known
>cookbook circuit?.
>Ever since "Mary had a little lamb" (history) there's been plenty of
>time to master mic amps.
>Is mic amp design still in fuzzy land?
>
>Copying Op Amps to Make Mic Amps
>I'm sure the best op amp topologies have been thought out by
>designers.
>How about just (partially) copying a very good op amp internal design
>with discrete low noise transistors for the front end mic circuit?
>I recall somebody posted that it's the IC process that creates noisy
>transistors in op amps.

Analog ICs typically use lots of transistors and few resistors or capacitors, the reverse of most discrete design. And they can match the transistors for offset and beta orders of magnitude better than you can with discretes. That's why a simple-looking analog integrated circuit may have hundreds of transistors. So the designs are usually quite different.

Some analog processes can use transistors as good as anything you can buy as discretes. Opamps like LT1028 have noise below 1 nv/rt hz.

John

Yeah, but you don't have integrated ferrite beads!

John