Electret Mic Pre-amp

Discussion in 'General Electronics Chat' started by AetherNZ, Aug 18, 2010.

  1. AetherNZ

    Thread Starter Member

    Mar 23, 2008
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    I am carrying out a few acoustics experiments with electret mics. I am currently using the attached preamp circuit and measuring magnitude and phase using a 1Mohm Zin impedance analyzer, which works fine. I need to start carrying out the same experiments on a vector network analyzer with a 50ohm input impedance. My current preamp circuit is getting loaded down by the VNA.

    The VNA has a +30 dBm +-7 V MAX input @ 50 ohm, so ideally this would be taken into account with voltage limits ect.

    Any suggestions on what type of amp circuit I could use? Low noise is especially important across as a wide frequency band if possible (20 Hz - 30 kHz +).

    I found these circuits posted by Audioguru and SgtWookie:

    [​IMG]

    [​IMG]

    Thanks a lot! :D
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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  3. AetherNZ

    Thread Starter Member

    Mar 23, 2008
    21
    0
    How well would that chip handle the 50 ohm load and be able to supply close the the +30dBm to get full scale measurements?

    I came across this high current op-amp that seems suitable: TS921?
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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