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Re: low voltage DC phantom (was new fi rmware for M-Audio Microtra=

Subject: Re: low voltage DC phantom (was new fi rmware for M-Audio Microtra=
From: Klas Strandberg <>
Date: Thu, 24 Nov 2005 23:08:18 +0100
ck 2496

Well, be happy! Mine works fine when you draw about 1 mA. Then comes more
and more noise the more you draw from it, but not linear. Come and goes.
Used with a phantom powered EM23 it works just fine, but with the PRO6 it
is totally unacceptable.
And that is what I am saying: Both your MT and mine might be within
accepted tolerances, but my phantom power unit might be quite different
from your's.

I will make a sound file comparing a PRO6 handle, phantom powered by the MT=

vs. the same handle running on battery and put on my "crap-page".

I don't mind using precision resistors.

Klas.

At 19:26 2005-11-24, you wrote:
>Klas, you wrote:
>
> >Note that unless you are going to run microphones with output
> >transformers, you don't need to use matched 1% resistors.
>
>Yes, it would perhaps be OK to use less precise resistors. However, a good
>match would also preserve a proper balance of the two input rails of the
>differential microphone preamplifier. Unmatched resistors would degrade th=
e
>"common mode" rejection capabilities of the recorder. This means that
>external noise interference would be canceled out less effectively.
>
>This kind of balance should also be preserved within the microphone or in =
a
>dummy microphone circuit for noise test purposes. So, a test circuit that
>employs an unbalanced connection scheme might produce worse results than a
>balanced microphone. Noise originating from the phantom power circuit is
>usually a common mode signal that can be reduced by the balanced
>preamplifier input.
>
>Klas, this is the reason why I would not over-estimate the bad results you
>got in your test on the MT2496 phantom power. At least the phantom power o=
f
>my own MT2496 is sufficiently clean for operating my phantom-powered (and
>balanced) K6P/ME66 microphone.
>
>Raimund
>
>--
>Highspeed-Freiheit. Bei GMX superg=FCnstig, z.B. GMX DSL_Cityflat,
>DSL-Flatrate f=FCr nur 4,99 Euro/Monat*  http://www.gmx.net/de/go/dsl
>
>
>
>"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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