Dan Dugan wrote:
> May be a residue of the RF in the mike beating against some clock
> (computer or dc-dc converter) in the recorder. It happens with just
> one equipment combination? Is phantom on in the MP-2? Phantom
> supplies sometimes have dc-dc converter residue in them.
Phantom is off, although the MP-2 has a power supply that's much the
same as I understand it. However, the whine goes away completely if you
disconnect either mic. And it's not connected with the MP-2 or
Portadisc, it will do it with either independently.
>>BTW, with that value cap I'm getting more low end than I know what to do
>>with. I'm picking up the gas turbine power plant 3 miles away as a
>>steady rumble.
>
>
> Sometimes you get what you ask for...the 110 is designed for infrasound.
Actually I'm interested in having this low end for some things. It's
more like the 110's don't overload on low sounds, and they don't poop
out, the rest of my equipment gives up before they do. They do pick up
full range just fine, up to 19.8 kHz, where everything cuts out. Just if
you don't want the infrasound, you will have to apply a good high pass.
> After more experiments to discover what combinations do or don't make
> the whine, Sennheiser service should be helpful.
I found the other one I'd got, I got two pairs originally thinking I'd
keep one pair in a sass permanently and have the other two for other
projects. Though different mics have slightly different whine, all 4 do
it. Kind of rules out damaged mics I think.
I made up a Y splitter and took the stereo cable out with two singles
replacing it, no change.
I've tried caps just about everywhere, and disconnecting various combos.
I also took out all electrical links to the mics and put together power
off a 2nd battery. Even moved components away from each other. I sure
can't see how it's doing it.
I can get it to vary some with changes in supply voltage, but no null point.
Sennheiser service were the ones that came up with the sheet I have on
powering it. And at the time I got the impression they knew no more than
that. But they are about the next to try.
Really annoying, because behind the whine is a really nice sound.
Walt
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