3-pin electret wiring for plugin power

[Question]

Hello

What is the correct wiring for 3-pin electrets with this schematic for MD's plugin power mic input?

Any ideas will be appreciated

Regards

Edited November 19, 2005 by Question

[greenmachine]

3 wire connection (FET connected as source follower):

A=audio out

B=ground

C=Vcc (power supply +)

---------------------------------------------

Conventional 2 wire connection (compatible with plug-in power, but distorts at moderate SPLs):

C=positive (audio out + plug in power)

A+B=ground

[Question]

Thanks for reply

I wonder if this wiring helps SPL a little bit or cause more distortion/hiss

A = Output + plugin power

B+C = Ground

[greenmachine]

I'm afraid your suggestion wouldn't work, but if you would use

A=gnd

B+C=positive (outer shell=positive, needs to be isolated properly!)

you would basically have a 2-wire source follower connection, But with a parallel 4k resistor (RL) at the output, which can't be removed and works like an attenuator. Unlike the conventional 2-wire hookup, there's no preamplification in this mode, which makes it less sensitive, RL works as an additional attenuator. The source follower connection usually allows for higher SPLs, but attenuation of the microphone output (which can't be removed in this case) in theory degrades the signal to noise ratio. The lower output level might help to avoid preamp overload though. Although this particular capsule seemingly is intended for 3- wire connection, you might want to give it a try.

[Question]

Thanks for all info

Regards

Edited November 9, 2005 by Question