How can you tell if a diaphram went bad?

[sidecarjoeg]

I have a Rode NT1000 and the output on it is really really low. I have a second one which I actually bought new years ago and the output is what I would expect. I compared AC voltages on the output of the diaphrams and the good one gets me around 50mv just by singing a medium volume into it. The bad one gets around 12mv by singing loudly into it. Both are getting 50vDC on the DC in pin. These are large diaphram condensers, btw. I hope the one diaphram isn't bad... I use these as my drum overheads and they aren't terribly cheap. Is there a way to tell if it is the diaphram or the caps? There are only 5 caps in the circuit, looks like at least 2 of them are being used to filter the phantom power. Any thoughts?

[dgatwood]

Originally Posted by sidecarjoeg

I have a Rode NT1000 and the output on it is really really low. I have a second one which I actually bought new years ago and the output is what I would expect. I compared AC voltages on the output of the diaphrams and the good one gets me around 50mv just by singing a medium volume into it. The bad one gets around 12mv by singing loudly into it. Both are getting 50vDC on the DC in pin. These are large diaphram condensers, btw. I hope the one diaphram isn't bad... I use these as my drum overheads and they aren't terribly cheap. Is there a way to tell if it is the diaphram or the caps? There are only 5 caps in the circuit, looks like at least 2 of them are being used to filter the phantom power. Any thoughts?

Check and make sure you don't have a short from the output to ground or something. Failing that, you might also loosen the wires and retighten them to see if there is corrosion or a loose screw connection or similar. Be really careful if the capsule is center-terminated (screw in the middle of the diaphragm), though. If you over-tighten such a screw, you can wrinkle the diaphragm.

If neither of those tips help, then yeah, I suspect the capsule is either partially shorted or severely mis-tensioned or both.

[ermghoti]

You start finding babies.

[witzendoz]

I would contact Rode direct and ask them about the problem. It's been a while since I talked to them, but I had a nt1 that started to become noisy, it was out of warranty but they said send it in. They returned it fixed no charge.

Cheers

Alan.