The advantage I found with an external pre-amp hooked to an RH1 was
that you eliminate some of the digital hash that the internal preamp
seemed to pickup.
I found that when the RH1 spins up the MD at the beginning of a
recording there is an obvious whine that will break through the noise
floor on the internal preamp. John Beale also did some tests that
illustrated the write noise produced by the recorder.
http://beale.best.vwh.net/measure/audio/RH1-noise/index.html
That said an external preamp will only really provide a benefit if
it offers a noise floor that matches or betters the internal mic pre.
cheers
Paul
On 28/03/2008, at 1:53 AM, Rob Danielson wrote:
> One should be able to determine from ballpark numbers whether a
> particular, lower-cost external pre will improve the performance of a
> given a recorder/mic combination. The time I ran the numbers with the
> better external mic pre made by Sound Professionals ( ~$250USD), the
> answer was, "no."
>
> Two conditions must be met:
>
> (1) The mics must have fairly low self-noise or they will mask the
> the recorder's pre noise anyway. The self-noise of WL183's at
> 22.5dB(A), for example, cannot be improved by using any external mic
> pre or any "better" recorder. One needs mics with no more than
> 17dB(A) self-noise, something closer to 14dB(A) is safer.
>
> (2) For the noise bed of the external mic pre to be inaudible
> "behind" that of the mics' self-noise, the pre's noise bed needs to
> be 7 to 10 dB(A) lower.
>
> The noise floor of the lower cost external mic pres I've seen are in
> the -97 to -110 dBu range. This is not low enough to offer
> significant or any improved noise performance. I tend to use the
> noise for a Hi-MD recorders' mic pre, -124dBUv as the maximum amount
> of noise I can live with in a pre for nature recording.
|