Low Phantom Power

  • Thread starter Thread starter BGulliver512
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BGulliver512

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Hi everyone,

I have a Peavey PV8 USB mixer board that I acquired new not too long ago. I don't use it much for recording but it's nice to have a portable board.

The board has a global phantom switch which says it provides +48V in the manual. When I turn the phantom switch on and check the voltage between the XLR pins with a voltmeter, however, it's close to +13.5 V, which is not even close to the stated 48 V. (Turning off phantom, these pins show 0 V, as would be expected.)

I don't understand why the board is only giving me 13 V phantom power when it clearly advertises 48 V. Have I got a defective board, or is there something I'm missing?

My separate tube pre-amp with phantom power turned on measures 44 V when I test it in the same way, which is much more reasonable.

I've primarily dealt with dynamic mics in the past so I don't have much experience with phantom power. I'm getting two condensers in the mail on Wednesday though so I thought I better figure out how it works.

Any help would be appreciated.
 
I'm using the adapter that was supplied with the console, which is a "15V 0-1.2A (set at 1.0A)" power supply. I doubt if I have any other 15-16 V AC adapters but I'll check.

Thanks though, good suggestion. I hadn't thought to check the power source.

EDIT: Actually my board appears slightly different than the one in that manual. Whereas that manual says to use 16 VAC 1 amp, the back of my board says 15 VDC 500 mA.
 
Could be defect or design. Shoot an email off to Peavey, their support is usually pretty good.
 
dumb question??? between which pins did you test??? you should see the voltage between pin 1 (ground) and both pins 2-3...
 
48V was really necessary "years ago" when condensers had mass quantities of discrete components and a noticable power draw in order to drive this circuitry cleanly while giving the necessary headroom.

Modern condensers, particularly the less costly ones, are designed around extremely low power surface mount components, and in fact often have a small linear power supply that drops the phantom 48V down to something else - 12, 15, 18, 24V or something in that range. This also reduces cost because they can use components rated for a lower voltage - particularly capacitors.

I don't know enough about the peavey units to be able to say if it's supposed to be like that (misprint) or if it's defective or broken. But, with some mics, it doesn't matter anyway.
 
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