> My current conjectures are
> 1) Perhaps something strange about the ATRAC compression (not too
> likely, in my opinion) or
> 2) (as stoatwizard suggested) something about the way the mics are
> powered (an external box with 9 V battery and a few tiny electronic
bits
> I haven't identified yet).
>
Actually I have been chasing something similar, and I have come to the
conclusion that I accused the thomann phantom unit unfairly. My MKH
30/40 are now
powered off 6 8.4V batteries in series, with a diode drop of .6V to be
about 50V. Within Sennheiser's spec of 48V+/-4V.
I was recording a firecrest in a bush, and this is a quiet sound, so
the HiMD was flat out. I have posted the raw recording and a sonogram
on
http://www.suffolkbirds.co.uk/article/49/mkh-hf-noise-blues-firecrest-in-a-=
bush
and there really does seem to be a lot of 17kHz wideband noise,
particularly on the MKH30.
I have got this down a bit by soldering jump wires from pin1 to the
shell tag on the XLRs, but it appears to be very much like Steve's
issue. Am I asking too much of these mics - would you normally expect
the noise floor to exhibit a band of HF noise like this? No TVs within
100 yards, no computer at all, car ignition was off, not overhead
power lines. There is a coastguard station about half a mile away with
a VHF marine radio, but the 18kHz noise band is replicatable at home
20 miles from the recording site, just harder to see in the ambient noise.
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