--- In Rob Danielson <> wrote:
> Your input noise numbers seem better than Richard's for his NH700
> http://www.wildlife-sound.org/equipment/himd/himdmyths_meas.html
> and Bruce's for his NH800:
>
http://bioacoustics.cse.unsw.edu.au/archives/html/naturerecordists/2006-04/=
msg00301.html
Hi Rob,
Thank you for the feedback! Your excellent pages on HiMD recording (
http://www.uwm.edu/~type/audio-reports/HiMD/index.htm ) were my
inspiration to buy the RH1.
The subjective terms on the measurements page were auto-generated by
RMAA. They are not relevant to this test and I have removed them.
I did a "bench test" with resistive attenuators, no real microphones
were involved. I am not an audio professional (my background is
engineering and applied physics). My personal gear hasn't been
calibrated in several years but all three multimeters and my digital
scope agreed on a 1 kHz test signal to within 0.2 dB, so I hope their
absolute accuracy isn't too far off.
My reported noise level is for the ~80% of the time that the MD motor
is not spinning. It gets about 2 dB worse when it spins up; see also
http://beale.best.vwh.net/measure/audio/RH1-noise/index.html
I had the in-unit display ON during recording. I suspect some
high-frequency noise spikes might be reduced had I turned it off.
(measurement notes:)
------------------------------------------------
1 kHz sine from Protek B-801 sig gen:
Tek TDS210 scope: 4.00 Vac RMS (+12.04 dBV)
Fluke 77: 3.93 Vac (+11.89 dBV)
RS 22-168a meter: 4.02 Vac (+12.08 dBV)
Tek DMM916: 3.96 Vac (+11.94 dBV)
------------------------------------------------
Echo MIA control panel sets output level (+4 dBu or -10 dBV)
plus master fader from +0 dB to -40 dB.
Echo Audio MIA line out 1 kHz sine @ +4 dBu setting
measured by Tektronix TDS210 scope
-40 dB: 60.6 mVac
-20 dB: 0.625 Vac
-10 dB: 1.98 Vac (+5.93 dBV)
-5 dB: 3.54 Vac
-3 dB: 4.44 Vac
-1 dB: 5.61 Vac
+0 dB: 6.29 Vac (+15.97 dBV)
Echo Audio MIA line out @ -10 dBV setting
-20 dB: 0.153 mVac
-10 dB: 0.485 Vac
-6 dB: 0.787 Vac
-5 dB: 0.883 Vac (-1.08 dBV) <=3D=3D TEST LEVEL
+0 dB: 1.57 Vac (+3.92 dBV)
------------------------------------------------
L: HOSA XLR att #1: -25.13 dB + JPB cable -40.07 dB =3D -65.2 dB
R: HOSA XLR att #2: -25.10 dB + JPB cable -40.10 dB =3D -65.2 dB
-1.08 dBV + -65.2 dB =3D -66.28 dBV
however the gain of the RH1 did not precisely match the signal at
0 dBFS. By comparing output and input files, I determined that the RH1
file 0 dBFS was actually -65.78 dBV or -63.58 dBu at the input for the
test data reported here:
http://beale.best.vwh.net/measure/audio/MZ-RH1_Mic_30_150Z.htm
regards,
John
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