Eric measured 47 volts output from the Rolls under load. I've run two
CAD 179's on a Rolls for hours with no performance loss and these mcs
pull ~13ma each. Scott's Rolls, mics or his recorder might be working
improperly but I (along with many other recordists) can report
Scotts' problem its not from a design flaw in the Rolls. Rob D
At 12:58 PM -0400 9/2/06, Walter Knapp wrote:
>Posted by: "Klas Strandberg"
>
>> Rob, - as far as I know, the MKH mic's use much more current than the m=
ic's
>> you have tested with the Rolls.
>> It might very well be that the Rolls start to generate noise when that =
high
>> current is being squeezed out of it.
>
>The MKH, except for the 80 & 800 use 2ma current, which is fairly low
>for studio mics. The 80 & 800 use 3ma. These currents are well below the
>official specs for a phantom power supply. Sennheiser's rating is for
>the phantom to be 48 volts plus/minus 4 volts. I've used them down to 36
>volts with no problem. Though I was not measuring the calibrated noise
>level. By ear they were fine.
>
>Portable phantom power supplied from low voltage batteries is often a
>problem. You might want to check the Rolls phantom power voltage under
>load and see just what you are supplying. The unloaded voltage won't
>tell you, it will draw down under load.
>
>Walt
>
If the Rolls has basic supply current problems, we would known about
them long ago,...
Eric Benjamin measured the voltage at the output pins of the Rolls at
Message: 47.
Subject: 6 V. We run CAD 179 mic's on Rolls all the time at school. I
think the CAD's pull ~13ma each. We can predict with confidence that
Scotts' problem its not the result of a design flaw in the Rolls. Rob
D.
--
Rob Danielson
Peck School of the Arts
University of Wisconsin-Milwaukee
http://www.uwm.edu/~type/audio-art-tech-gallery/
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