Understanding Preamp Gain Structure With Mics

[bgavin]

Given: AT4040 has an open circuit sensitivity of -32dB/25.1mV in relation to 1 volt / 1 Pascal.

Amplifying this signal, or raising it +32dB to 0dB produces a 1 volt output.

Question: does this mean the preamp must provide 32dB of gain to amplify the mic output to near line level?

If so, then the mic sensivity specs are a good indication of the preamp gain requirements.

Taking a worse-case example, the Beyer M201 dynamic full-range mic. It is rated at -58dB/1.2mV. Does this mean the preamp must have 60dB of gain to accomodate this mic?

What I'm getting at is, if an engineer wants to use Beyer M201 mics, his preamps should be capable of delivering 60dB gain, or it will never produce full output (LINE) level from the preamp.

[acorec]

Originally posted by bgavin
Given: AT4040 has an open circuit sensitivity of -32dB/25.1mV in relation to 1 volt / 1 Pascal.

Amplifying this signal, or raising it +32dB to 0dB produces a 1 volt output.

Question: does this mean the preamp must provide 32dB of gain to amplify the mic output to near line level?

If so, then the mic sensivity specs are a good indication of the preamp gain requirements.

Taking a worse-case example, the Beyer M201 dynamic full-range mic. It is rated at -58dB/1.2mV. Does this mean the preamp must have 60dB of gain to accomodate this mic?

What I'm getting at is, if an engineer wants to use Beyer M201 mics, his preamps should be capable of delivering 60dB gain, or it will never produce full output (LINE) level from the preamp.

Yes, you are right. See "The Big Mic Pre-amp Thread" at Harvy Gerst's forum in PSW. This thread has ALL of the heavyweights like Dan K, MQ and a guy from Neve. I highly recommend reading this thread for all the secrets of mic-pre design and building.

[bgavin]

What/Where is PSW?

[Big Kenny]

prosoundweb.com
make it one of your favorites
it has lots of great info
In HIs Name
BK