Back again. Here are the numbers I've got from my rudimentary testing.
Apologies in advance if the text formatting goes wierd.
USBPre 2 ADA8000
max input level at max gain -60 -41 dBu
max input level at min gain -7.5 +13 dBu
noise floor RMS at max gain -67 -85 dBFS
noise floor RMS at min gain -106.5 -103 dBFS
gain range 50 51 dB
The figures in my original post were off by a few digits due to memory leakage.
It's important to note that this isn't some kind of stealth attack on the
USBPre 2, and I don't consider the ADA8000 a piece of field recording gear, and
that I'm not taking into account the 'sound' of the two units, this is mainly
about dynamic range. I swear I'm not trolling!
The main thing that concerns me is that at max gain, the Behringer can handle a
higher input level while simultaneously having a lower noise floor. It would be
good to hear from someone that could state situations in which this would be
beneficial. Honestly, it would make me feel better about this box of mine with
the lovely metering...
--- In "doctorobotnik" <>
wrote:
>
> Hi all,
>
> This is my first post after lurking for several years.
>
> I'm a recordist/audio engineer who mainly does audio post and sound design.
> I'm currently planning a trip to Darwin in northern Australia to record the
> tropical wet season, specifically the thunderstorms.
>
> I made a similar trip last year and there wasn't much storm activity during
> the period I was there so I ended up with mostly frog and insect tracks (not
> a bad thing).
>
> On that trip I was running 2 x AT4022 > MixPre > PCM-M10. For this year's
> trip I've bought a SD USBPre 2 which will probably be paired with a Tascam
> DR680.
>
> Some preliminary tests I've done on the USBPre are concerning me slightly,
> particularly in that my Behringer ADA8000 mic pre/adat interface seems to
> outperform the USBPre in several important respects. (bear with me on this!)
>
> I don't have the measured figures handy (they're at home), but the crux of
> the matter is that at max gain, with a dummy load (a SM58 with its capsule
> leads shorted), the USBPre's RMS noise floor is about 25dB higher than the
> Behringer (approx -60dBFS USBPre vs -85dBFS Behringer).
>
> The max input levels show a similar difference. I fed a 1kHz sine wave out of
> my Emu 1212m, peaking at -1dBFS (which I believe equates to an analog output
> level of +19dBu), over balanced lines into both devices' mic inputs. By
> lowering the software master fader I could see the max level each device
> could accept. At max gain the USBPre clipped at about 20dB lower than the
> Behringer (can't remember figures, will post later if people want)
>
> So it would appear that at max gain the USBPre has a far lower dynamic range
> than its cheapo comparison box.
>
> Does anyone know why this would be the case?
>
> I haven't done a direct test with my main mics yet but initially these
> results are a bit disconcerting. I've seen Raimund's excellent recorder tests
> and am interested to see how or if my results fit into his framework.
>
> I'm interested in hearing your opinions, and thanks for reading this far!
>
> Ben
>
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