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Need help with mic preamp
Need help with mic preamp
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Old 26th December 2010, 06:32 AM   #1
Buzzy is offline Buzzy  Singapore
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Join Date: Apr 2007
Default 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.
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Old 26th December 2010, 09:06 PM   #2
Frank Berry is offline Frank Berry  United States
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The instructions are correct. Reverse the polarity of C5 and C6. You must also eliminate R10 and R11.
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Old 9th January 2011, 09:34 AM   #3
Buzzy is offline Buzzy  Singapore
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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 ?
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Old 24th January 2011, 12:54 AM   #4
teleman is offline teleman  Norway
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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.

Last edited by teleman; 24th January 2011 at 01:03 AM.
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Old 21st April 2017, 08:49 PM   #5
jorgovanko is offline jorgovanko  Serbia
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Join Date: Feb 2010

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)?

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Old 27th April 2017, 04:14 AM   #6
tataylino is offline tataylino  Philippines
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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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