when connecting an unbalanced, self-powered (or non-powered) microphone to a balanced input, the ideal approach is to balance the connection at the microphone output by connecting the unbalanced output to one modulation lead and imitating the microphone's output impedance as precisely as possible and connecting that impedance between ground and the other modulation lead. It isn't necessary to use a transformer or active circuitry at the microphone end to create balance; all that's needed is for the impedance to ground to be equal between the two legs of the circuit.
Wow, right, let me try and get my head around this!
Just read the wikipedia Balanced Audio article - should have done that sooner
By the way, I just grabbed a UA-5 off ebay (whoooo!
), so that's what we're working with, that and the microtrack.
I'm a little confused, will the UA-5/MTII will be subtracting Hot and Cold signals? so we need to reverse the polarity of one signal coming from the AT822? Is this the role of the 'modulation lead'? I couldn't find any info on what this might be. Or are you saying that it's not necessary to do any inverting, just match impedances? Where does the 200 Ohm resistor go exactly?
the signal lead is going to ground through the AT822 (200 Ohms)? And we want the shield to just run to the ground of the preamp. So we need to split the signal at some point between each capsule and the amp input, and make the cold signal go to ground through a 200 Ohm resistor at the preamp end?
That's the best I can do for now, but I'm sure I'm probably way off!
Thanks for bearing with me
it is quite easy to rip the head off the AT822/825 mic, add a 4.7k resistor to each capsule and power it with plug-in-power, from something like an Edirol R09. I've got three of these mics, two AT822 were chopped, and the third, an AT825, was left for phantom powering.
Just so I'm clear, this is preferable to battery power because (apart from the mic being smaller of course), it's getting more voltage, ~5V rather than 1.5V, and this improves performance, like a battery box does...?
Now I think about the small voltages we're dealing with here, I suppose it must be impossible to run the AT822 on a comparatively massive 48V - would it just fry the electronics?
Wheee, this is fun, can't wait to get my AT822, and UA-5!!! whoo whoo whoo whoo