Electret Microphone Stereo PreAmp - Strange Behaviour

[hgg]

Hi,

I finally bought the Primo EM172 Capsules which turned out to be very nice indeed.
Extremely sensitive and the noise decreased substantially.  I am recording voice
1 meter away from the microphones with excellent clarity.  I am now doing some tests
with different kinds of capacitors (electrolytics vs polypropylene) to see if they really
make any difference in audio quality.  I will power the preamp with 6V from 4 1.5V AA
batteries.  The Primo capsules need 5V.  I will also try a 9V battery and a lower gain
if that further decreases the noise.

[Zero999]

Juku, Hero666 thank you for your replies.

Yes, it will be a high pass filter. The cut-off frequency can be calculated using the following formula:

F_C = 1/(2pi*RC)

Don't forger that changing the value of the red resistor will also affect the bandwidth of the circuit, as it's in series with a capacitor.

In what way though?  High pass filter again?

So how can you go about solving this problem?
What about if instead of the blue 10k pot I use a larger value like 100k?
Maybe this way the filtering effect will be much smaller since the resistances are greater.

It's a non-inverting amplifier.
http://en.wikipedia.org/wiki/Operational_amplifier_applications#Non-inverting_amplifier

The formula for calculating the cut-off is the same as above.

I don't think it would be a problem.