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Re: Preamp noise calculations

Subject: Re: Preamp noise calculations
From: Rob Danielson <>
Date: Mon, 3 Apr 2006 21:55:10 -0500
Thanks for starting the process Bruce!

The HD-P2 at EIN -115dBu seems low and 46.2dB gain. Could that be true?

The PMD's with EIN=3D-121 dBu seems high and, again, 48 dB gain is
surprisingly low.

But who really knows? That's why I'm hoping we can figure out a way
for bench testing or carefully documented reports. I notice the Mix
Pre is EIN figure is unweighted. Here's the chart (very) in-progress:

https://pantherfile.uwm.edu/type/public/temporary/Recorder_Specs.htm

As folks come across better or additional numbers, please email them
to me. I probably left some obvious recorders out. Should we include
some of the older DAT's for reference,.. like the Sony M-1 and Tascam
DA-P1?  Rob D.


Bruce wrote:

>Here is a quick run-through of the popular preamps, using published
>specs:
>
>MixPre reported values: gain=3D66 dB, EIN=3D-126 dBu, Max.=3D+22 dBu
>
>MT2496 reported values: s/n=3D-98 dBu, max.=3D+4.3 dBu, input=3D-14dBu,
>gain=3D34 dB. Calculated values: EIN=3D-112 dBu (98 dB below -14 dBu).
>
>Fr-2 reported: s/n=3D87 dB at input=3D-60 dBu. Calculated: EIN=3D-147 dBu =
(an
>impossibly low number, -141 dBu is the electron noise at 50 ohms)
>
>HD-P2 reported: noise=3D-55 dBu at input of -60 dBu, max=3D+13.8 dBu,
>gain=3D+46.2 dB. Calculated: EIN=3D-115 dBu.
>
>722 reported: EIN=3D-130 dBu (150 ohm), max=3D+16 dBu, gain =3D70 dB.
>
>670/671 reported: s/n=3D65 dB, input =3D 1.2mV (=3D-56 dBu). Calculated:
>EIN=3D-121 dBu, gain=3D48 dB.
>
>How do these EIN values compare with your experience? All I have is a
>670 and a minidisk.
>
>Bruce
>


--
Rob Danielson
Film Department
University of Wisconsin-Milwaukee

[Non-text portions of this message have been removed]



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