Raimund, thanks so much. Straight from the horse's mouth. I think I understand
now. The USBPre is ~20dB more sensitive than the ADA8000, so for a given input,
everything registers that much higher up the digital scale.
The noise floor is higher, but every signal is too, by the same amount. This
explains the low modulation on the Behringer - you have to have the gain way up
to get usable signals. Not so on the USBPre (because of the extra 20dB gain
that is always in effect).
Theoretically if the ADA8000 COULD supply enough gain to match the USBPre, it
would clip at 20dB lower, and its noise floor would be 20dB higher, evening
everything out. Got it!
And Mike - I mentioned earlier I don't consider the ADA8000 a piece of field
gear. You're correct, it's mains powered, and it's a rack unit. It sits firmly
inside at all times!
It is fine with dynamic mics except for very faint mains hum sometimes (and a
lack sensitivity when compared to something like...a USBPre 2!). Sound-wise I
find it adds a pleasant bit of top end 'crunchy sparkle' to everything. The
only optical outs are ADAT at 44.1 or 48k.
Hope this helps,
Ben
--- In "Raimund" <> wrote:
>
> 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" <cookcommaben@> 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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