> Thanks for starting the process Bruce!
>
> The HD-P2 at EIN -115dBu seems low and 46.2dB gain. Could that be true?
I don't know if it's right, but here is how I figured it: from the manual
specs, "Noise level Trim Max (22 Hz to 22 kHz): Up to -55 dBu MIC to LINE
out." TRIM MAX is defined as -60 dBu, so adding them together should give
the noise floor of -115 dBu. It's a very odd and to my mind unreliable way=
of getting it, but it's the only way I can see of getting it from the
published information. The specs report the same gain for the MIC and LINE=
inputs, so something is screwy with their numbers. Sometimes I wonder if th=
e
manufacturer even knows what the numbers really are.
>
> The PMD's with EIN=3D-121 dBu seems high and, again, 48 dB gain is
> surprisingly low.
48 dB is the mic gain before the level controls, then there is another stag=
e
of unspecified LINE-level gain. The total gain must be higher, but it takes=
48 dB of gain to get the MICs up to the LINE levels. The EIN comes from: MI=
C
s/n=3D65 dB using an input signal of 1.2mV. 1.2mV is -56 dBu, so that puts =
the
noise at -121 dBu. According to the published figures.
What I can't figure is why everyone uses different signal levels when
reporting s/n ratios. Marantz uses -56 dBu, others use -60 dBu, one used -1=
4
dBu (guess who's ratio looks the best?).
I've looked for any specs from Edirol that might give a hint as to EIN, but=
can't find anything. At all. Not for the R-1 or the R-4. There is a mention=
of the R-4 resudual noise (85 dBu), but it's measured in a way that
minimizes the mic preamp stage (input shorted, mic level minimum). They
aren't measuring the noise in the presence of a signal, just the noise in
the output. I don't know what to do with that. It's an "EON" (equivalent
output noise).
Anyway, here are some more preamps:
Core Sound Mic2496:
Max input =3D -2.6 dBu (yep, that's negative), EIN reported to be -132
to -137, a few dB higher than thermal electron noise (unlikely with the bes=
t
mics, and impossible with the high-impeadance mics they sell). Total gain a=
modest 53 dB.
Nagra BB+:
They say a signal from -52 dBu to -38 dBu will give a full-scale recording,=
and that the mic has a 50 dB dynamic range, so if we assume the DR is
limited by noise (in other words, if we assume the s/n =3D 50 dB) then the =
EIN
is -102 dBu. That can't be right for a company with that reputation.
Nagra ARES-C:
I don't get this at all. They report the sensitivity in mV/hPa
(hectapascal???), which seems more like a mic measurement than a preamp. EI=
N
by the same assumption is -117 dBu.
HHB PortaDisc:
Report -122 dBu, with -52 dBu max MIC input, so s/n=3D70 dB, I can't calcul=
ate
the clipping level.
>
> 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:
I didn't even think to check for weighting and how it differs between
unweighted and A-weighted.
>
> 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.
>
>
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