Balanced electret microphone circuit

[scone]

Does anyone have experience with the Balanced electret microphone circuit found on this page ? I am planning on building a measurement mic with the panasonic WM-61A capsule, and I need to modify it to use phantom power so I can use my mixer as a preamp. I don't have any experience with electret mics, and I was wondering... are they all the same? Reason I ask is because the above link is a generic circuit with no mention of what capsules it will and will not work with.

 

[gmphadte]

one is here, I don't know how useful...

 

[Shaun]

This looks promising

http://www.edn.com/contents/images/83001di.pdf


Chek out page 100.

HTH

 

[scone]

Thanks for the responses. I've been reading about circuits that use phantom power to drive mic capsules for a while now, and the more I read, the more it makes me want to scrap the whole idea of using phantom power, and to instead stick with something really simple (battery).

I did eventually find some critique of the circuit I linked above in case anyone is interested. And I quote:

Chris' circuit puts the microphone element across the phantom powered input and uses a pair of PNP transistors running as emitter followers to drive the line. My objection to this circuit is its total dependence on the CMRR of the balanced input as neither side of the microphone element is grounded; you must replace the cable with 2C shielded twisted pair.

I doubt it would make too much of a difference, but in any case I never found anything which tells me whether or not the panasonic capsules would work well in the circuit so I'm moving on. It was originally designed as a mod to the Radio Shack PZM anyway.

So from the complicated to the simplest and it looks like Linkwitz's mod to the WM-61A capsule is about as straightforward as it gets. (http://www.linkwitzlab.com/images/graphics/microph1.gif) I'm planning on using his b) circuit and from what I understand, I can simply plug the output of the circuit into my pre-amp and I'm set. Someone please tell me if I'm wrong... it's very late and my brain is confused by the FET spec sheets I've been reading all night.