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Buzzy 26th December 2010 06:32 AM

Need help with mic preamp
Hi I am building a mic preamp for measurement mic. I am trying to build rod elliot's project 93. The schematic i am building with is figure 6 which is found here Recording and Measurement Microphones

I am using a 9V battery to power it. In the page he says that C5 and C6 should be reversed when using battery power. Is reversing C6 correct ? Its like the positive of C6 is connected to ground. I am confused if it should be this way.

Any help is appreciated. thanks.

Frank Berry 26th December 2010 09:06 PM

The instructions are correct. Reverse the polarity of C5 and C6. You must also eliminate R10 and R11.

Buzzy 9th January 2011 09:34 AM

Thanks for clarifying. I have built the mic preamp and I am using it. I paired it with a projects unlimited mic. The specs are here AOM-4544L-R

The mic works only when i hold the mic close enough. I actually built the mic to do some measurements of my speaker. I think the mic preamp does not have enough amplification. Is it possible to increase the gain or is this mic just can't be used ?

teleman 24th January 2011 12:54 AM

I think you'd be better off using a Panasonic WM61A capsule in Linkwitz mod!
Gives excellent results & is widely used as a measuring mic by many DIYers.The auther,Rod Elliott himself has used this mic in this project.

jorgovanko 21st April 2017 08:49 PM


if i use this mic preamp ( current URL Recording and Measurement Microphones ) with external power supply which give ~+9V (LM317, discrete PSU or something similar), is this the same as well as to use battery (have to eliminate R10 and R11 and reverse the polarity of C5 and C6)?


tataylino 27th April 2017 04:14 AM

Correct! R10 and R11 are only used to get power from mixer's phantom power supply. reverse c5 and c6 also

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