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5. Re: Using Line Input/Ext Pre (was Olympus LS-10

Subject: 5. Re: Using Line Input/Ext Pre (was Olympus LS-10
From: "Rob Danielson" danielson_audio
Date: Wed Mar 26, 2008 11:34 pm ((PDT))
At 6:49 PM +0000 3/26/08, Phil Tyler wrote:
>Excellent info Raimund!
>
>Is there any merit in giving results for the line input? The reason 
>I ask is that there seem to
>be a number of people using separate mic pre-amps and the info might 
>be useful?
>
>Phil
>

Hi Phil--
Its always smart to ask and confirm, but the engineering should be 
fairly straight-forward for Olympus and the other manufacturers to 
provide very low-noise performance using the -10dB "line" input set 
at unity gain. To match FR2-LE or Hi-MD performance, one would need 
an external pre with comparable noise performance and the cost of 
these is as much or more than the recorders.  If you have SD MP-2 or 
Mix Pre that you aren't using, hook it up to the line input on an H2 
and you _should_ have a very high quality combo. As a reference, the 
lower cost portable pres folks are suggesting have noise performance 
around that of the LS-10 so there's not much point in that route if 
lower noise is sought. A good percentage of the pres have only 40dB 
gain which many would find too low for nature recording.

Based on Raimund's noise spec for the LS-10, one would need mics with 
around 15dB(A) self- noise or lower to hear the noise from the 
LS-10's mic pre at maximum gain. That number drops to around 12dB(A) 
for Hi-MD and the FR2-LE's pre noise is likely to be inaudible with 
quietest mics we typically use.

It adds bulk, but one can use a Rolls PB224 portable phantom supply 
and connect lower-noise mics like the AT-3032's to the 3.5mm mic 
input. The recorder's noise would be audible with these mics but the 
noise performance should be much improved compared to that of mics 
with >16dB(A) self-noise.  Rob D.
-- 




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