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Re: a preamp survey

Subject: Re: a preamp survey
From: Klas Strandberg <>
Date: Fri, 13 Feb 2004 23:49:09 +0100
Thanks Rob, obviously you have thought a lot about this.

But still:

I have recordings of atmos only, distant birds and perhaps a woodpecker
coming in nearby every 45 sec or so.
The mic is a Telinga MPS1 with a self noise around 6 dbA.

Still, with only 6dbA noise - the noise I hear is mic noise, not Tascam DAP=
1
preamp noise.

When using EM23, the omni with a self noise around 14 dbA, what I hear is o=
f
course mic noise, not preamp noise, using a simple and inexpensive Sharp MD=
...?

"Sound quality" is another issue here, - whether using a preamp and line
input "sounds better" or not.
The only thing I would like to be cleared out (finally, if possible) is if
there is any facts supporting that there is better noisefigures to gain, an=
d
how this relates to output voltage of the microphone and it's self noise.

Like - using a MKH20 (10 dbA) - is there a lower noise with a good preamp
than directly into the Tascam or HHB??

Klas.

At 14:43 2004-02-13 -0600, you wrote:
> wrote:
>>All: This preamp question comes up now and then.
>>
>>Has anyone really investigated how bad the mic inputs are of different MD=
's
>>and DAT's?
>>Has anyone tested how sensitive a microphone must be, (output voltage) to
>>run over the noise of the standard MD mic amps??
>>
>>My little idea is that there is not much use of preamps (to improve noise
>>level) as most microphones today have either enough output voltage or mak=
e
>>so much self-noise that a preamp won't help.
>>
>>So: What is the advantage spending lots of money on a preamp and how do y=
ou
>>know that for sure??
>
>
>Don't you think that most folks who are talking about noise are
>trying to record soft sounds? With your dish and a nearby healthy
>bird at 30 yards, your Portadisk mic pre gain must be well below max.
>Going the extra mile to lower noise comes from people interested in
>recordings where the local acoustics are part of the image.  For
>their surround projects, my students are moving mics away from sound
>sources to capture more of the space-- a very different practice than
>trying to isolate all sounds except junk "presence" tracks of 20
>years ago. Of course, this is not a new desire or technique, but it
>is much more common and people have modest budgets. The MD mic pre is
>the weakest link. There are mics with high output, 6 to 18dB(A) self
>noise, the ability to record in high humidity and wind for $200.
>
>Some numbers that have proven to be very useful estimates for us are:
>
>Consumer MD mic pres with the gain set at maximum have an equivalent
>self noise of 20-25dB(A).The Walkman DAT's are in the same
>neighborhood.
>
>Tascam DA-P1 with the mic gain set at maximum has an equivalent self
>noise of 12-14db(A). Based on comments on this list and others, the
>Portadisk mic pre at full gain might be around 10-12dB(A) but I've
>never had one to compare.
>
>The MP-2 has a self noise of about 4-5dB(A)
>
>The Audio Buddy Mic Pre has an equivalent self noise of about
>12-14dB(A) when the gain is set to max.
>
>Bob Cain (micbuilders llst) derived one or two of these numbers, I've
>ear-tested them with many mics and have found them pretty accurate in
>determining whether an investment is likely to lower noise.  Being
>able to use the line input of an MD recorder is itself a big
>advantage. Even a 25dB(A) mic will sound a bit cleaner using a $300
>Mic pre like the Edirol UA-5. A mic with 18dB(A) self noise through a
>decent pre will sound considerably cleaner. Some of us use pres in
>the 5-12dB(A) range to better enjoy the low noise of great mics-- and
>that is why somone would consider a $700 mic pre for an MD recorder.
>It's a bit overkill, and it seems odd, but there aren't too many
>alternatives.
>
>Many of the lower cost and better mic pres have maximum gain in the
>neighborhood of 45-55dB which means 10-15dB less gain than the folks
>cranking their MP-2's to the max.  In quiet settings, that's huge.
>I've been trying to get the DC power and phantom power issues solved
>with the Audio Buddy which is a very decent sounding $90 pre with
>60dB of gain.  That would fill a big void with the $200 low noise mic.
>
>
>>And for which microphones??
>
>It would take quite a bit calculation to put all the mics and pres on
>one standard because, as you point out, its not just noise but mic
>output/sensitivity too. We'd also need apples and apples numbers for
>the pres and the -10dB line inputs.
>
>As a ballpark guide, the Rode NT-3 seems to consistently ou-tperform
>the MT-90 mic pre. This mic has 17 dB(A) self noise and 12 mV/Pa
>sensitivity.  In theory, there's no point in spending more on a mic
>that specs better than this without considering a better recorder or
>a mic pre. When you consider that many nature recordists and natural
>space recordists find their way to an ECM-MS957 stereo with 25 dB(A)
>self-noise with and considerably lower sensitivity or DIY Panasonic
>WM-61a capsules with 32 dB(A), its easy to see why people start
>imagining what another few hundred could do,.. For me, a $90 portable
>pre with 12d(A) self noise would mean  students would have much
>better access to low noise recording rigs.
>
>Rob D.
>
>
>--
>Rob Danielson
>Film Department
>University of Wisconsin-Milwaukee
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
>
>
>
Telinga Microphones, Botarbo,
S-748 96 Tobo, Sweden.
Phone & fax int + 295 310 01
email: 
       



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