Hi Rob,
There is definitely a lot of uncertainty basing findings on manufacturers s=
pec. The main purpose was to come up with a easy reference based on manufac=
turers specs rather than an absolutely accurate account of mic performance.=
List members are frequently referred to the Rane148.html page to "look u=
p the numbers on the charts".
On 31/03/2010, at 5:19 PM, Rob Danielson wrote:
>
> Rode NT-1A 25 5 -118.83 -128.8 dBu YES, A-weighted
> Rode NT-2A 16 7 -120.70 -130.7 dBu?? Side by
> side, the 2A is noisier than the 1A. In practice one could get by
> with a slightly "noisier" pre, not a "quieter" one and one would not
> need -130.7 dBu (A weighted).
There is no question that the NT-2A has a higher level of self-noise, but b=
ased on the published specs if you recorded both the NT-1A and NT-2A at id=
entical gain settings on the same recorder the recorded mic noise floor of =
the NT-2A _should_ be lower in terms of of dbFS than the recorded noise flo=
or of the NT-1A. I'd be interested to see your results of such an unadjuste=
d comparison.
>
> MKH-40 25 12 -111.83 -121.8 ?? A few years back when we
> were trying to get a input noise measurement for Hi-MD recorders, a
> few folks independently noted that one could barely detect the input
> noise of the pre at high gain using an MKH-40. Raimund (and others)
> measured the Hi-MD recorders at -124dBu (A weighted). For pre
> transparency with that mic, I'd go with a pre measure EIN of -125dBu
> or higher, not -122dBu.
I think the HiMD tests done by Richard Mudhar on www.wildlife-sound.org mig=
ht provide an answer to that quandary. The test measured the MZ-NH700 with=
sensitivity set high and gain at 28 and found the EIN was -116dBu. (see: =
http://www.wildlife-sound.org/equipment/himd/himdmyths_meas.html ) This was=
compared with the noise output of the MKH-40 mics, and the HiMD noise was =
found to be 4-5dB lower than the MKH40 above 1Khz. This level of difference=
is less than the 6-10dB safety margin suggested by Rane and tally's with t=
he observations of audible preamp noise you relate. This suggests that eit=
her the HiMD preamps noise floor increased quite rapidly as gain was lowere=
d from maximum or that John Beales original testing (the figures listed on =
Raimund's chart) with RMAA gave a EIN that was inaccurate. As far as I'm a=
ware there has been little testing done to check input noise at typical rec=
ording levels vs full gain. Such tests might explain some of the anomalous =
results we see with lower gain settings.
cheers
Paul
|