M-Audio DMP-2 Phantom Power Mod

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
 

ecc83

Well-known member
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.
 

rob aylestone

Well-known member
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.
 

Jannae

New member
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.
 

ecc83

Well-known member
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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