Thanks! It occurred to me to test for this when I had the MT in my
hands,...wish I had. There are quite a few clues pointing what you
found, except, this may be an inconsistency: When I compared
NT1A->Rolls->HiMD to NT1A->MP2->MT (balanced line in), the HiMD
(using its mic inputs) had noticeably less noise. Granted that line
input was better,but not what one would expect.
http://www.uwm.edu/~type/Mic%20Preamps/MicroTrack_NH900_722Comp2_IMA4.mov
Perhaps the wiring in the MT is such that the phantom circuit affects
the line level amp performance? If not, this suggests to me that the
noise is coming from another source, perhaps in addition to the mic
pre and/or phantom.
One clarification. From my test, it seems its not just the 3.5mm jack
with gain problems for quiet location recording, the XLR inputs
sensitivity is 21dB lower than HiMD's. Rob D.
= = =
At 4:24 PM +0100 11/20/05, Klas Strandberg wrote:
>Hi all. This weekend I have visited a friend of mine, who has been working
>with phantom power devices half off his life. 100% expert on the topic.
>We made all kinds of tests of the MT.
>I will make a very brief summary.
>
>There is "nothing" seriously wrong with the 24/96 microphone preamps,
>except that the 3,5 mm input is insensitive.
>
>But the phantom power is a really bad. The chopper adds lots of noise and
>is very unstable. If it happens to works fine with your mic when you test
>it, it doesn't mean it will work fine when the temperature changes or when
>battery voltage goes down a bit.
>
>This is only one example of the tests we did: The cold pin was connected
>via 22mfd and 100 ohms to ground. 10kOhms to the phantom power rail. Just
>as usual, standard design. Then we put a 220n condensor over the 100 ohms
>resistor and found that the noise increased by several db.
>Such a device cannot be used. A change of only 100 Ohms source impedance
>shouldn't have any impact at all on recorder noise. (the expected is rather
>the opposite, lower noise)
>
>So if you happen to like the use of a 24/96 - get a low noise self powered
>microphone or a phantom power design that works.
>The Telinga PRO6, for example, can be used with the 9v power box.
>
>Klas.
>
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>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
>
--
Rob Danielson
Film Department
University of Wisconsin-Milwaukee
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