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Post by jman on Jun 30, 2007 1:36:53 GMT -7
Rolls mp13 mic pre
Behringer ecm8000
Are these the best choice for about $110?
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Post by ThomasW on Jun 30, 2007 9:02:21 GMT -7
If you have a duplex soundcard in the PC, yes those are the things you need.
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Post by jman on Dec 26, 2007 20:37:38 GMT -7
Finally got them today. Unfortunately I'm getting very little signal and a lot of noise. The Rolls only puts out 12V phantom and the Behringer is spec'd as needing 15-48 so it may be a few volts too low. I can't measure anything with it.
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Post by ThomasW on Dec 26, 2007 21:23:47 GMT -7
According to the pdf listing the Rolls factory specs, the phantom power is 21 volts. The amount of voltage need to power the preamp is 12 volts.
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Post by jman on Dec 27, 2007 14:36:55 GMT -7
I can get a Behringer UB1002 for $40, will this work no problem?
I have to crank the Rolls pre and run sweeps at 95db to get anything vaguely usable in REW and I'm not sure I trust the results.
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Post by ThomasW on Dec 27, 2007 15:32:07 GMT -7
The Rolls MP13 has been recommended component for many years and you're the first person I'm aware of to say they've had a problem with it...
So....
Are you sure the problem isn't with the soundcard, drivers or software settings, whatever?
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Post by jman on Dec 27, 2007 15:55:28 GMT -7
I think the other parts are ok. I tested the ecm8k on my Digidesign Mbox and it works fine there with gain only half way up. But then when I try the rolls as pre to the mbox line-in, it's just as low as when using the soundcard (2 different pc's, 3 different soundcards total). I emailed Rolls tech support but I don't expect a fast/useful reply. The Rolls just doesn't seem to be boosting the ecm8k properly. Also, my Sure SM57 works fine on the Rolls but it doesn't need phantom power, so that's an unknown variable still.
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Post by jman on Dec 31, 2007 18:43:34 GMT -7
My friend took the Rolls apart and we did some measurements. At the actual XLR there is a pawltry 5.2V of phantom power, which is why the mic is barely working. The schematic does not match the MP13 as they have made some changes since. At one point it measures 31V and then it goes through a transistor (not on the original schematic) and then suddenly there is only 5V left. So basically the unit is defective or they've screwed up the unit with the changes made. Waiting for a reply on their support email now  |
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Post by jman on Feb 9, 2008 12:28:08 GMT -7
My friend inspected the rolls again and found that the transistor was actually shorted by a bad solder joint. He resoldered it and it works fine now.
Nice quality control!
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