Turtlerock Forum

Anyone know ho to achieve this? I have some cardioid electret capsules and want to put a pair back to back and reverse the phase of the rear to make a true figure 8 pattern, but the capsules only have a ground and a +ve. If it was something like a ribbon I could use an output transformer on each, but I'm trying to make something small enough to mount on a dslr camera shoe to get like a Blumlein pair, and be powered by the camera. Any ideas out there?
Thanks.

treat them as two mics and mix them later to get fig 8

Hi Rob,
only got 2 tracks on the camera, so need to do it on the way in.
Might not be possible I guess without some sort of electronic balancing
and phase reversal in a little external box.
Thanks.

Depending on the volts available, perhaps an unity gain inverting opamp would do the trick for you. If you get a dual opamp DIP8 single supply package (eg LM358 which can run on just 3V up to 32V) you could even put the other channel through a non-inverting opamp as well to buffer both electets. I'm thinking 4 resistors, a couple of MKT 100n caps to smooth the power at the opamp Vcc and Vee pins, Bob's yer uncle.

No comment as to whether this is a good idea or not, it's just a way to do what you want to do.

Thanks Chris.
Something along those lines is probably the only way to get the back capsule inverted.
Hoping to keep it small.
I guess the zooms can mount on a camera shoe so electronics in a small box with
capsules on top could be possibility. Oh well.
Cheers,

Andy

You might be able to pick up and old flash unit, Cashies etc, that will mount on the shoe and provide an enclosure for the electronics.

Good idea Bob.
Thanks.

I second the Bob idea for an enclosure, and you could veroboard it along these lines - it would be quite small

Thanks Chris!
Cheers.