Hi Ben,
I have neither the USBPre2 nor the ADA8000. However, the noise levels should be
compared at absolute voltage levels (dBu), not relative dBFS levels. According
to your measurements, the absolute input referenced noise floors (EIN) would be
as follows:
USBPre 2: -60dBu - 67dBFS = -127 dBu
ADA8000: -41dBu - 85dBFS = -126 dBu
The lower clipping level at the minimum gain setting of -7.5dBu vs. +13dBu
reveals that the USBPre 2 generally provides a higher gain than the ADA8000
(even if the relative gain ranges are almost equal).
A higher maximum gain will always reduce the clipping level at that setting.
So, the clipping level at the maximum gain setting is just a measure of the
maximum gain (= sensitivity) of a recorder. This means that a lower clipping
level is usually a good thing (because it indicates the sensitivity of the
recorder).
Regards,
Raimund Specht
-- In "doctorobotnik" <>
wrote:
>
>
>
> Okey dokey, the text did go weird. Here is the data in sentence form.
>
> At max gain, the USBPre 2 (U2) clips with an input level of -60dBu. The
> ADA8000 (A8) clips at -41dBu.
>
> At min gain, U2 clips at -7.5dBu, A8 clips at +13 dBu.
>
> The RMS noise floor of the U2 at max gain is -67dBFS, for the A8 it is
> -85dBFS.
>
> The noise floor of the U2 at min gain is -106.5dBFS, for the A8 it is
> -103dBFS.
>
> The gain range between min and max gain is 50dB for the U2, and 51dB for the
> A8.
>
> --- In "doctorobotnik" <cookcommaben@>
> wrote:
> >
> >
> >
> >
> >
> >
> > 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" <cookcommaben@>
> > 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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