Thanks for the input David. I suppose I was more 'interested' than 'worried=
' about the results I was getting and in a way gratified that a somewhat fr=
owned-upon box such as the ADA8000 can acquit itself as well as it does!
The USBPre does in fact have a 15dB pad which I ignored for this exercise, =
but which is handy. I've run into limiter release problems in the past with=
a Tascam HDP2 which clamped down for a moment (pause) and then let everyth=
ing back up again, very distracting. The SD limiters I find are much more w=
ell behaved and 'invisible' but unfortunately the USBPre doesn't yet do lim=
iter linking.
I like your idea of making the rain sound 'wet' rather than just a hiss, I'=
ll try that out in some large-leaved and puddly areas during one of the ine=
vitable Darwin downpours.
Yes, the weighting issue does apply, and in that regard (not that I know ho=
w to measure it) the USBPre wins with a smoother and softer sounding noise =
profile, whereas the ADA has a much sharper hiss (in addition to some 50Hz =
hum).
BTW and out of interest what recorder are you running with your MKHs?
Cheers,
Ben
--- In "Avocet" <> wrote:
>
> > 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?
>
> Ben,
>
> For a start, the noise figures of both are well below acoustic noise
> levels or even the dynamic range of the listener's ears. The cost of
> the equipment is irrelevant. What is more imporatant is its
> reliability in adverse conditions and ease of use, battery life, etc.
>
> An input clipping level of -7.5dB may mean an input attenuator may be
> needed if using high gain mics, especially if you are recording
> thunder. BTW an impressive sound is a tropical storm approching
> through canopy forest even without thunder. Also get near water to
> make rain sound wet. Experiment with letting the peak thunderclaps
> distort and here is a never-quoted parameter which is the recovery
> time after an overload. A limiter "dropout" after a peak is very
> uncomfortable. It may be better to record at low level and
> clip the waveform later. If you hnow what your mic and mixer noise
> sounds like, you can set the record level so the background noise just
> swamps the system hoise.
>
> The problem with relying on RMS noise figures is that these may not be
> a good guide to noise as heard on a recording. LF noise, for instance,
> is usually swamped by acoustic LF background but hiss is much more
> prominent. The preferred weighting for noise is the "468" curve which
> peaks at about 11KHz by around +12dBs. Few manufactureres quote this
> as it gives noise figures around 11dB higher than the meaningless A
> weighting.
>
> Dummy loads can make a big difference to measured figures but the
> actual output impedance of mics varies from 50 Ohm to 2KOhm, so a
> dummy load of 150 to 200 Ohms is only a starting point. Alternatively,
> you can do noise measurrements with a zero load and open circuit which
> will also give the "equivalent noise impedance" of the input stage.
>
> In my book the real noise test is with a particular mic in a quiet
> place and by listening. You may be able to distinguish the mic hiss
> from the input hiss in which case the input stage is noisy. With my
> MKH's a power spectrum shows an upturn in the noise from around 8KHz
> upwards which is thermal noise from the mic and possibly the air
> itself. You can't get quieter than that.
>
> David
>
> David Brinicombe
> North Devon, UK
> Cogito cogito ergo cogito sum - Ambrose Bierce
>
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