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Re: MT2496/Mic2496?/Motu Pre Test Questions

Subject: Re: MT2496/Mic2496?/Motu Pre Test Questions
From: Gianni Pavan <>
Date: Thu, 20 Oct 2005 09:19:30 +0200
At 18.17 19/10/2005, you wrote:

>Hi Gianni--
>
>I'm having problems with my posts going through. Anyway, here are
>some questions I wanted to ask you. Feel free to fwd/post  your
>answers if you wish, too. Great Test!  Sorry for the inconvenience. Rob D.
>
>  =3D =3D=3D
>
>Interesting testing Gianni, thanks a lot.
>
>Bob Cain did a computation for the mic2496 more than a year ago
>which concludes, "the pre equivalent noise (due to their EIN related
>back through the [MKH-40's mic's sensitivity of 25mV/Pa]) would be
>12 dBA for the mic2496."  The mic2496's mic pre came out
>considerably nosier than the MP2. I'm wondering if there is
>consistency between Bob's computation and your findings. When you write:
>
>>Thus, to evaluate the real mics noise I used the Mic2496 digitally
>>connected to the PDAudio system based on an old iPaq (the MT2496
>>could be used for digital recording as well) or the MOTU.
>
>are you using the Mic2496's A-D mic pre circuit to compare the
>mics?  If so, shouldn't there be masking of the noise produced by
>the NT1-A if Bob's value is right? If not, perhaps you're using
>another pre circuit to come up with the absolute mic self noise rankings?

I made the test with the mics directly connected to the Mic2496 or to
the MOTU or to the MT2496.
With Mic2496 and MOTU I saw the Rode is the quietest mic; of course
it could have been affected by the Mic2496 noise floor and by the
postprocessing gain required to equal the bips amplitude with those
recorded by the MOTU.
Next week I'll do some more tests to compare the Mic2496 with the
MOTU Traveler by lowering the input gain on the MOTU to equal the
levels produced by the Mic2496.

>re:
>>  "the Mic2496 offers greater gain and less noise than the MT2496.."
>
>Is it possible that the "digital boost" in the MT2496's menu
>setting  is the "Hi Setting" to obtain the higher ~55dB gain?

I don't know how much gain I really set on the MT2496. I used the H
setting (new firmware, of course) but avoided to use the digital
boost (27dB) available in the menus.

The level recorded by the MT2496 was the lowest, the MOTU was the highest.

>If you did use the higher gain setting and you are getting a similar
>equivalent 12db(A) self noise equivalent for the Mic2496's mic pre,
>it seems pretty clear that the MT2496's TRS mic pre is not as
>suitable as other pres we have become accustomed to for nature
>ambient recording in quiet settings.
>
>I also find it surprising that the MOTU's pre noise performance
>would be only a 6-7dB improvement over the Mic2496. Thanks again, Rob D.

I'll check this again in a direct comparison. Maybe I'll check a
Roland UA25 too.

Feel free to write if you have further doubts or something to suggest,
all the best
Gianni

--------------------------------------------------------------
Gianni Pavan
Email 
Centro Interdisciplinare di Bioacustica e Ricerche Ambientali
Universita' degli Studi di Pavia
Via Taramelli 24, 27100 PAVIA, ITALIA
Tel        +39-0382-987874
Fax        +39-02-700-32921
Web       http://www.unipv.it/cibra


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"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
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