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Re: Preamp for PIP mics

Subject: Re: Preamp for PIP mics
From: "Eric Benjamin" ericbenjamin2
Date: Tue Dec 8, 2015 4:12 pm ((PST))
I think that we need more information.  Do you intend this preamp to go bet=
ween the PIP microphone and an existing PIP input?

PIP has some fundamental limitations. It is basically defined by a 3 Volt s=
upply and a 2k pullup resistor. The resistor gives rise to a minimum noise =
floor, and the 3 V supply limits the maximum voltage to about 1 V rms. If t=
hose were the only limitations then the performance could be very good. A s=
o called battery box helps by allowing a higher battery voltage and perhaps=
 a higher value pullup resistor. As an example, the Primo EM172 is spec&#39=
;d at -28 dBV/Pa and 80 dB SNR and 122 dB SPL maximum acoustic level. But t=
hat is with a 5V supply and a 3.9 k resistor. With 3V and 2k all of those s=
pecs will degrade slightly.

You could build a battery box with those values and get the specified perfo=
rmance from the mic capsule. But there will still be a limitation on the ma=
ximum signal that can be accepted by the preamp in the recorder. That is, t=
he preamp will clip. If you only want to record quiet sounds, then the over=
load will probably not occur.

To do a complete job on the interface design we need more info on your micr=
ophones and recorder.




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