Topic: Question: mic pads, passing phantom power?

[illconditioned]

Does anyone know of a mic pad circuit that will still pass phantom power?

I've got a Beyerdynamic MC833 single point (MS/XY) mic, but the outputs are really hot.  I need to take off 10-20dB right at the input.  The mic (apparantly) can run off less than 48V, minimum of 11V@4.2mA.

In particular, I'd like to run this thing into the Fostex FR-2LE, but right now the thing just distorts like crazy at even moderately.  Fortuanatley, I've discovered that it does work, eg., into the Edirol R4 _line_ input.

Thanks,
  Richard

[DSatz]

ill, the usual H-pad circuit passes 48-Volt phantom power just fine. It's just three resistors--one in each audio lead and one spanning the two audio leads. The series resistors (the ones that go in the audio leads) are normally less than 20% of the 6.8 kOhm of the pair of resistors in the phantom power supply itself, so with any reasonably designed in-line pad, everything should be within spec as long as those two resistors have equal value to each other.

Just make sure that you use the pads at the input to the recorder, not at the output of the microphones--it actually makes a difference, especially with longer runs of cable. Also, with 12-Volt phantom powering the situation may be different, since the phantom resistors are of much lower value in that case, so the series resistors in the pad have a correspondingly greater chance of starving the microphone.

--best regards

[wbrisette]

I know the AudioTechnica version passes phantom as does the Shure version. As stated previously, most are just resistor networks, so they don't affect the power.

Wayne

[illconditioned]

ill, the usual H-pad circuit passes 48-Volt phantom power just fine. It's just three resistors--one in each audio lead and one spanning the two audio leads. The series resistors (the ones that go in the audio leads) are normally less than 20% of the 6.8 kOhm of the pair of resistors in the phantom power supply itself, so with any reasonably designed in-line pad, everything should be within spec as long as those two resistors have equal value to each other.

Just make sure that you use the pads at the input to the recorder, not at the output of the microphones--it actually makes a difference, especially with longer runs of cable. Also, with 12-Volt phantom powering the situation may be different, since the phantom resistors are of much lower value in that case, so the series resistors in the pad have a correspondingly greater chance of starving the microphone.

--best regards

Thanks for the info?


OK, I think I just found a webpage: http://www.uneeda-audio.com/pads/

I'm aiming for a 20dB pad, so I'll use 680R for the two series resistors and 150R for the bridge resistor.
I'll post back here (eventually) with results...

  Richard