At 19:07 2005-11-20, you wrote:
>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
I can't play your .mov files.
>Perhaps the wiring in the MT is such that the phantom circuit affects
>the line level amp performance?
Is it possible to have it line in with the phantom power on? Guess it is.
Then I wouldn't be surprised if it is like you say. You can leave the
inputs open, - when you switch the phantom power on and off you always hear
the very typical kind of noise it produce for about a second or so.
Klas.
>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.
> >
>
>
>
>
> >
> >
> >
> >
> >
> >
> >
> >"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
>
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
>
Telinga Microphones, Botarbo,
S-748 96 Tobo, Sweden.
Phone & fax int + 295 310 01
email:
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