M-Audio DMP-2 Phantom Power Mod

J

Jannae

New member
Hello dear Home-Recording-Members,
I´ve recently bought a good working M-Audio DMP-2 for 30€ and would like to mod the phantom power. I´ve measured only 40V and it would be great, if someone knows a good way how to modify the DMP-2, so it puts out 48 (+/- 2) Volts. I´m experienced in soldering, but I don´t have a schematic for this unit. I have a lot of pictures of the board, if it would help.
Does someone have a solution?

Thank you and greetings from Germany,
Jan
 
Is your measurement of 40V at the XLR, pins 2 and 3 to pin 1 and no load? If so that is way out of the standard of + or - 4V and a current delivery of 10mA (mind you, many AIs cannot manage 10mA!) However I doubt that 4V loss will cause you any problems. Take the XLR apart on a cable and use it with a microphone, be handy to know the current draw of the mic but that can often be hard to find. Now check the voltages. If you get about 14-16V on pins 2 and 3 AND the mic performs well, I would not worry.

In any case there is probably nothing you can do about it! The "48V" almost certainly derives from a DC-DC converter and they are sealed units with no adjustment. Just maybe they use an IC and a 'diode pump' circuit in which case there might be a set preset but most unlikely.

If the low spook voltage IS causing a problem you can use the money you saved to buy an external supply but beware! There are some crap units about.

Dave.
 
I'm with Dave - few microphones are that touchy about the absolute voltage - as long is it's there. Very few now have huge current requirements, so before you waste time doing this, I'd just give it a try and 99% would be a good success rate. Lots of people never ever notice they don't actually have 48V.
 
Thanks for your replies!
I'm sorry I haven't answered before. The voltage drops when I have a condenser mic connected (Okatva Mk012) from 50v to 40v. With two mics only 38V. I'm just thinking that it could affect the sound if it doesn't stay stable. Maybe I put in some higher value caps in the power supply.
 
Assuming you are measuring that 40V at the XLR that means the mic is pulling around 3mA which is about what I would expect of many modern mics. The further 2 V drop with another mic indicates that the phantom power supply has an internal resistance of about 7 Ohms, again, about what I would expect for a general, 'knockabout' interface.

You have nothing to worry about. It AIN'T broke!

Dave.
 
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