In article ,
Alan S. wrote:
Is anyone here still using AKG C451 mics, or remembers using them?

Hi Alan ;-) Yes indeedy - I also have a few.


I've had my 4 for some time but am becoming more and more aware of a low
level hum on the output. The hum gets worse the more of them that are
plugged in to the mixer. If only one is faded up, the hum gets worse as
others are plugged in. At first I thought the phantom power supply was
giving trouble but I have now tried them on two different mixers and a,
stereo, standalone mic pre-amp (M-Audio) with similar results. I
wondered if one of them was drawing too much current and dragging the
PS down but it doesn't seem to matter which combination of mics I use.

Properly designed phantom should be immune to a dead short since standoff
resistors are used at each mic input. That's not to say all mixers have
properly designed phantom.


I think the hum is
100 hertz, which still suggests PS but on three differant i/ps?

Both mixers and the standalone are fine when used with dynamic mics.

The C451s are long in the tooth so are they prone to draw high current
as they age? Or am I barking up the wrong tree altogether?

Not one I've come across.

Any suggestions, polite ones, would be appreciated.

It does sound like a PS fault to me - have you tried other phantom powered
mics? Have you access to a scope to look at the DC?

--
*Never underestimate the power of very stupid people in large groups *

Dave Plowman London SW
To e-mail, change noise into sound.