DMP-3 problem with humming

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minimal me

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Went in to GC for guitar strings on Memorial Day and came out with one of these for $119. (That price certainly solved the issue of waiting to spend a little more on the RNP.) Had a GREAT time with it for about two weeks, big improvement for me, read the thread on this price and really felt smart. Boo-yeah.

But then one night channel A had a hum. I went back and swapped it for a new one, and this one has a similar hum problem right out of the shrink wrap, so now I'm wondering if it's me.

This new one only hums if I fill up both channels - removing the mic input from either channel stops the problem. (The previous one hummed in channel A no matter what I put there.) Just for superstition, I've tried plugging it in in a different location and got the same result.

Is it me or did I get two lemons in a row? And if it's me, what's the fix?
 
the RNP costs 4x more than the DMP3 , yet the DMP3 performs at least 80-90% as well.....Id say its a great bargain.....
 
I have two MXL 2003's and 3 POS cables. Problem is, I can't get any ONE mic/cable combo to make the hum, whereas absolutely ANY combo of two mics and cables causes it. Also, I don't get a hum when I run the same gear through my POS mixer.

I don't want to spend more money on cables until I'm sure I need 'em.
 
bring it back and let them test it there.....

worry about cables later....I have crap cables and it doesnt bother me much........

worry about getting a working DMP3 first because they rock.....
 
Check you wireing with a cheap tester from Home Depot. Then correct the problem (loose ground causes this).
 
i got one awhile ago, and the B channel makes a staticy noise when i turn the knob. it hasn't effected the sound of the recording, but it's super annoying.
 
just wanted to say i got one of those dmp3's last week for $120 too. and there's no audible hum at any setting on the preamp or my mixer.

however, with "high gain" selected on the dmp3, there is quite a bit more general noise than i was expecting. had to fiddle with the faders on my mixer and the volume on the preamp to get the noise down to usable levels.

so, i would say, the dmp3 is definitely NOT a silent amp. on "low gain" the noise is MUCH less though.

but for $120, there's not much to complain about, huh? :)

so, if you have hum, i would say you have some kind of other problem in your studio. bad cables. bad grounding. bad electricity. lots of em interference. whatever.... but the chances of both dmp3's being bad are pretty low.

remember, the power supply is that stupid wall-wart.... and the electricity is being carried via a really thin not-even-twisted-pair cable to the dmp3 itself.... it's quite possible you have something going on down there too.
 
i'm not trying to be a jerk, this is meant to be helpful...

is this possibly your first 'nice' pre? if so, good pres are more detailed and tend to pick up all the noise in the room. hence, if you have a fairly noisy room they will amplify that noise as well as the good noise coming out of the microphone. i've found the DMP3 to be a little noisy, but nothing i would really complain about. it might just be your room noise that it's picking up.
 
Very definitely this is my first "nice" pre, so I've got no ego at all invested in the cause of the problem. But if it were room noise, then one mic would hear that just as well as two, and this second box only hums when I use two mics.

Also, the first box was "right" for two weeks and I used it a bunch, so I know what it's supposed to (not) sound like. The hum is direct and intrinsic, like an old guitar amp, rather than, say, the sound of inadvertently amplifying a rumbling appliance (I turn off my A/C when I lay miked tracks).

Also, I had another idea. Rather than driving all the way back to GC, first I'm going to see whether I get the hum when I plug in at my neighbor's house. If not, then that points toward a grounding issue in my house. And if so, then it's off to the dealer, where I can try other cables and mics as necessary, and maybe end up with a 3rd box. (I know the odds are long on this, but it could be that I got two from the same bad batch, right?)

I really like this danged preamp. The price was very right, and it made my sound improve pretty dramatically. I want to make it work for me.
 
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