At 8:56 AM +0000 6/29/08, Raimund Specht wrote:
>Hi Rob, you wrote:
>> I doubt that it surprises anyone, but so far, a couple of tests have
>> suggested that LS-10 compromises the performance of most low-noise
>> mics.
>
>Actually, I'm a bit surprised. The absolute noise floor of the K6/ME67
>is -110 dBA and (according to my own measurements) the noise floor of
>the LS-10 is -121 dBA at its maximum gain setting. So, by theory, this
>11 dB margin should make sure that the preamp does not add any
>significant noise.
Hi Raimund--
Numerically, one would think the LS-10's mic pre would be inaudible.
Maybe the battery/phantom powering self-noise discrepancy could
account for some or all of the audible increase in noise when going
from the Sony TCD-D10 pre to the LS-10 pre with the same ME-67 mic?
The D10 has phantom powering.
However, I took a clip of presence with a recording that Debbie made
with NT1-A -> Rolls -> LS-10 and placed it with Vicki's ME-67 ->
LS-10 and to my ears I can hear a similar quality of noise in
both--presumably from LS-10 pre.
https://pantherfile.uwm.edu/type/public/media/NT1A-LS10_ME67-LS10.mov
Granted, I'm trying to evaluate the recorder's pre performance
indirectly and in varied settings, but if the LS-10 does have -3dBu
more noise than the Hi-MD (according to your chart) I would expect to
hear noise from the LS-10's pre with the ME-67 even on battery power.
One can barely detect Hi-MD pre noise with a Sennheiser MKH-40 with
12dB(A) self noise. The noise I consistently get with the NT1-A ->
Rolls -> Hi-MD combination is about 50% from the mics and 50% from
the Hi-MD's pre. Debbie's recording seems to be more than 50% from
the LS-10's pre.
>
>However, the reason for this discrepancy is probably that Vicky used a
>much lower gain setting on the LS-10 (REC LEVEL 2 instead of 10 that I
>used in my test) in order to manage the loudly singing bird. High
>quality professional recorders such as the SONY TCD 10 DAT usually
>exhibit a better noise performance at lower gain settings.
If, as Umshanker suggests, the LS-10's record level is an attenuation
adjustment based on "10" having no attenuation, wouldn't a setting of
"2" just affect the saturation of the recording, not the noise
percentage? That does seem consistent with no improvement in noise
performance at a setting of "2." Rob D.
>
>Another reason might be perhaps that Vickys individual K6/ME67
>microphone creates less noise when powered via external phantom power
>than with the internal battery (which is necessary with the LS-10).
>This increase of noise has been reported by several users (it is
>actually a fault that can be fixed by SENNHEISER).
>
>Regards,
>Raimund
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