Electrical Engineer Question (or anyone else)

[imacgreg]

I have been looking at the Panasonic 1/4" electret capsules and I am interested in buying a couple and tinkering around with them, but I hava a question. It looks like the output of the the capsule is just a hot and ground, are all mics like this right out of the capsule? If you could take a '57 capsule out, would it only have a hot and ground? If so, where does the balancing of the signal take place? I am assuming in the mic but how would I hook up the panasonic guy to a balanced output? With a xformer?

Thanks in advance,
Ian

 

[skippy]

Yup- usually a transformer, but sometimes transformerless differential buffer amps are used (for condnser mics that already have active electronics in them, anyway). For just hacking around, a transformer will be a *boatload* easier to deal with.

Here's a very nice transformer-based schematic, from the Crown PZM web site:

http://www.crownaudio.com/pdf/mics/125576.pdf

And if you want to buy a pair, and play around with switchable patterns, here's a nice transformerless design. You can also scrap one of the two capsules, and just build their follower and buffer sections with no pattern switching, of course:

http://www.cadmics.com/pdf_files/e200_manual.pdf

Hope that helps...

 

[barefoot]

On his web site Siegfried Linkwitz (some obscure electrical engineer ) describes the classic modification to the Panasonic electret microphone cartridge http://www.linkwitzlab.com/sys_test.htm. I don't think he invented this mod, but he gives a very nice description of the procedure.


barefoot

 

[skippy]

That gets a 404 these days, but here's the link to the actual schematic...

http://www.linkwitzlab.com/images/graphics/microph1.gif

Certain details (like the actual differential buffer) are left as exercises for the interested student, but that's half the fun!

 

[barefoot]

Just a typo. http://www.linkwitzlab.com/sys_test.htm

Here's and alternative circuit I came up with based on Linkwitz's "b" schematic and basic designs found in AD application notes. I drew it quickly so Skippy, maybe you can look for bugs. It should have very high performance, but will probably eat up batteries like crazy.

barefoot