DIY microphone

[454Casull]

My apologies if this is in the incorrect forum - it does not seem like there is one perfect choice for this type of topic. Anyways, what I had in mind was a DIY microphone, just something I could try to build and fool around with (but of course not something of poor quality).

My interest was piqued when I came across this:

http://linkwitzlab.com/sys_test.htm#Mic

Sure enough, the cartridge can be had for pocket change, and I believe I can do the mod Linkwitz mentions without too much trouble (but if anybody wants to help me out now, by all means...)

However, what I'm wondering is if a pre-amp is necessary with the WM-61a cartridge.

http://www.panasonic.com/industrial/...61_a_b_dne.pdf

Also, is the cartridge for unbalanced or balanced operation? Or both? This is something I never really understood.

[I_Forgot]

Those cartridges are unbalanced.

I made a dummy-head binaural mic using some Linkwitz modified cartridges. You can see some pictures here: http://mark.rehorst.com
I haven't added any text to support the pix, but they are prtetty self explanatory.

I shock mounted the cartridges inside the dummy head, then stuffed the head with strips of cloth. One of these days I'll get around to posting some audio I've recorded with it. Binaural is great with headphones.

I_F

[Geek]

The simple one I use.

Go nuts

[Geek]

Whole unit - plumber's delight

[454Casull]

Bear with me, if you would. Circuits were never my thing.

There are two terminals to the mic cartridge. I can see where to connect the active output, but where do I connect the other one?

The 9V battery powers the mic as well?

EDIT: After looking more carefully, it seems like the ground/shield of the coax cable is soldered to the branch that goes off to the right, while the center conductor goes up.

OK, so wikipedia tells me that electret cartridges usually come with built-in preamps, so does your circuit just provide the power for it?

[Geek]

Hi 454,

Yup, electret's are two, sometimes three terminal. This circuit works with the two terminal ones and supplies a "phantom" power to it.

I've tried it with a couple of carts, an el-cheapo and an unobtanium one with similar performance to expensive testing mics. The circuit doesn't seem too picky...

Originally posted by 454Casull
OK, so wikipedia tells me that electret cartridges usually come with built-in preamps, so does your circuit just provide the power for it?

Yup, provides power and some gain and line buffering. I've tried it on three boxes, a Mac, Win and Linux and related speaker measuring software and it functions nicely on all three.

I have not had a chance to calibrate the microphone, but it seemed well enough when tested against a reference fullrange that had a calibrated sweep done of it.

Cheers!