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Re: New noisy mic amps!

Subject: Re: New noisy mic amps!
From: "Rob Danielson" danielson_rob
Date: Thu Aug 31, 2006 10:12 am (PDT)
At 3:33 PM +0200 8/31/06, Klas Strandberg wrote:
>
>Hi Rob, there is a lot to say here, I will try limit myself as much as I c=
an:
>
>I talked to some guys here, familiar with modern electronic industry  In
>brief they said:"The IC-designers have been sitting at their computers,
>making "elegant" designs, saving parts and money. They don't notice if it
>works well or not until it is too late."
>
>Being more respectful:
>I have seen the Sony diagrams. They don't say much, but might explain why
>inputs have changed "in principal".
>The explanation might be in how the High and Low mic inputs are designed.
>
>Before: The first transistor was set for max
>gain and - thereby - lowest noise.
>If the mic output was too strong, you added a -20db attenuator circuit
>before the first transistor - still running on max gain / lowest noise.
>Now: When you hold up the Edirol R-09, with it's built in microphone in
>front of a pop-band, (or Sony HiMD's with a Sony stereo mic) there is no
>need to run the first transistor at max gain. It will distort. It is enoug=
h
>to vary the gain from mid to low.
>For naturesound people this is really bad.

No doubt the pre design could be better even not
considering the PIP restrictions.  I just don't
want people  to get the idea that there's the
"flaw, " in Hi-MD makes it worse than old MD or
other $<350 recorders. In side by side tests, my
$115 NH700  the Hi-MD was less noisy than my Sony
D-7, D-8, My Sharp MT-90,  MT-190 and the M-Audio
Microtracker.

Makes a lot of sense that the Low/High
sensitivity circuit is involved, but  a number of
us on the list were shocked in July by tests that
showed the "Low" gain setting works really well
at eliminating distortion/overload when louder
sounds were recorded with with vanilla EMC PIP
mics.  I had always thought the low setting was
just a pad.


>
>About EM23, external powering and phantom power:
>I have many times said that the EM23 has a "average" sound quality, simila=
r
>to ME62 and other 15-20 mm omnis. (HQ sound quality is MKH, Schoeps etc.)
>
>But used with plug in power, it could be made much smaller and handier tha=
n
>EM62 etc.
>That was the whole point with it.

And portability/small mass is a huge factor!
Personally, I prefer your the response curve of
your EM-23's to that of Senn 62's and your
packaging could be smaller.  A separate "body
pack" design  where the pre is separate from the
heads, like the MBHO 603's could be very popular.
A pair of me-62's  are $90USD, so maybe you could
be competitive.


>
>It is not at all difficult to make a small preamp to EM23, but then you
>loose the point with it. There will be an extra box, an extra battery to
>worry about, an extra switch to check and an extra cost.
>
>As it looks, you can use it without preamp, but you cannot =96 as before =
=96 be
>sure that you use it's low noise performance. It might be destroyed by the
>recorder's low-sensitive and noisy mic inputs.
>One doesn't know that, and that is what bothers me.
>
>I have thought of testing different HiMD's, but such a test is possibly
>irrelevant. Sony models sold in the US are not the same models as in Europ=
e
>(Asia??) and some Sony diagrams have previously shown different circuitry
>for US models than for European.
>And being "on the border" one must even consider individual variations.
>Remember that resistors and capacitors have a tolerance of +/- 10 to +/-
>40% !!!

I wasn't aware of this. All I have to go on is
the NH-700 I tested from Australia. It matches
the performance of my 2 other Hi-MD's. I've
shared and compared Hi-MD /NT1-A recordings with
several people in England and I can't hear
anything in the noise performance of their
recordings that isn't totally familiar.

>Again I want to point out that there were TWO different problems involved:
>First the low plug in power, which I could cope with, using another FET-IC=
.
>Then- now, 2006 - the low sensitivity + mic input noise. (R-09 is the wors=
t
>here.)

I guess I'd have to determine whether its time to
re-look at the EM-23 and consider loosing the
PIP powering option or doing only on an as-is
basis. Dan says it works fine with the older
Sharps-- so keeping a unit around for those
recorders is fine. But it seems like each new low
cost recorder brings too many surprises. Some
offer 24 bits yet only 34-42 dB of gain. Go
figure.  Looks like the states of PIP are not
going to get better or more similar.
Manufacturer's, even Sony, include a power module
for their better ECM's.

>I have made the tests similar to other "clock-tick" tests presented here.
>It is an easy and reliable method.
>"Correct" means that what you shall hear is the mic self noise.
>"Incorrect" means that you hear the recorder's mic amp noise.

Understood. If you can do another test a mic with
12<dBA self noise or lower then we can compare it
to Hi-MD performance too. :-D Rob D

>
>I will get back to this topic as soon as I have something to report.
>
>Klas.
>

--
Rob Danielson
Peck School of the Arts
University of Wisconsin-Milwaukee
http://www.uwm.edu/~type/audio-art-tech-gallery/





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