At 9:05 PM +0000 4/20/06, oryoki2000 wrote:
>Rob Danielson wrote:
>
>> Given a rating of -115 dBU EIN for the outboard pre, its not likely
>> to perform as well as mic pre in the Sony HiMD's. I can ask Chris at
>> SP about this claim...-115 dBu EIN is "borderline" performance for
>> many of the condensor mics we use
>
>Yes, please ask your contact at Sound Professionals to clarify their
>claim that a preamp with EIN of -115dBU sounds less noisy than a
>minidisc mic preamp.
>
>Let me display my poor understanding of the dBU scale: If the
>SP-Gigatracker has a preamp EIN of -115dBU and the Sound Devices 722
>has a preamp EIN of -131 dBU, does the Gigatracker have twice as much
>self-noise?
>
>--oryoki
1 dB =3D a change in volume that a person can easily distinguish. The
higher the negative number, the lower the noise.
I estimate the EIN for the HiMD mic pres between -125dBu and -128dBu.
For reference, this is almost quiet enough to amplify the signals
from Rode NT1-A's (6dBA self-noise) without adding noise. (I hear
the noise to be about 50% from the NT1-A mics and 50% from the HiMD
pre).
Assuming range of 10dBu between the SP pre (-115 dBu) and the HiMD
pre (-125 dBu), that's around 10 audible "steps" in the volume of the
noise.
Another question to ask is, would the mic pre's noise mask my mics?
The Rane 148 tabulator says the noise of the HD-P2's pre (EIN-116
dBu) is high enough to be heard in the signal of a MKH-30/40 pair.
HiMD, with 10 dBu less noise, is inaudible behind a mkh 30/40 pair.
The 722's pre is inaudible behind NT1-A's.
Playback volume and the kinds of sounds you record can play a big
role, though. I play low dynamic recordings quite loud. If you record
dynamic sounds, like loud calls, you probably play your recordings
much quieter. In these cases, 10dB can be insignificant. Rob D.
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