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

Subject: Re: Using Line Input/Ext Pre (was Olympus LS-10)
From: "Rob Danielson" danielson_audio
Date: Sun Mar 30, 2008 6:20 pm ((PDT))
Hi Bill-
Re:
http://www.soundprofessionals.com/cgi-bin/gold/category.cgi?item=3DSP-PREAM=
P

Pre -117 dBu (unweighted) =3D -122 dBu (A weighted)
ME-66  [10dB(A) and 50mV/Pa]
Sennheiser ME66 mic computes to -108 dBu

122 - 108 =3D 14dBu which is a comfortable margin. See
http://rane.com/note148.html below Table 3, "...use Table 3 to map
out a preamp's A-weighted noise to show the combinations that add
insignificant noise. If you use a -10 dB difference figure as a
guide, then the preamp's noise amounts to less than 0.4 dB increase. "

One concern about the Sound Pro pre is, "42dB gain for recording
quiet sounds,.."  42 dB gain is minimal. 60 dB would be much more
suitable for this application. The ME66 has more output but probably
not enough to compensate. You could ask Chris at Sound Pro if you can
buy one and test it out and return it if it doesn't meet your needs.
Or,.. (shudder), you can buy a good condition, used Hi-MD for less, I
bet. It has 75dB gain and -124 dBu.  Rob D.

  =3D =3D =3D =3D =3D

At 6:06 PM +0000 3/30/08, William Ruscher Jr. wrote:
>Quoting from the Sound Professionals product description of the 9V
>preamp that goes for $179.00
>" Signal to noise ratio: 117 dBu EIN unweighted (quieter than built-
>in Walkman preamps) ".
>Rob, I am uncertain that condition (2) would be met for me to benefit
>using this preamp with the combination of my Edirol R-09 and
>Sennheiser ME66 mic, although condition (1) would certainly be met
>with the ME66.
>The preamp's noise floor is better than the Edirol's ( at -106dBu )
>but not better than the ME66 (?). I really don't know what the noise
>floor is on the preamp of my Sony Walkman MZ-NF810 recorder, or if my
>recordings (noise floor) would improve from purchasing this preamp.
>I am a bit confused on comparing the dBu numbers , between recorders
>and mics. Thanks in advance for attempting to help straighten me out
>on this, and for all the information that you provided.
>
>Regards,
>
>Bill
>
>--- In
><naturerecordists%40yahoogroups.com>=
m,
>Rob Danielson <>
>wrote:
>>
>>  At 10:13 AM +0000 3/27/08, Philip Tyler wrote:
>>  >Thanks Rob, I was enquiring as there have been a number of people
>>  >looking at using external pre-amps in an effort to improve the
>>  >performance of some of the solid state recorders around or that
>they
>>  >already own. Now if they ever need to replace their recorder with
>a
>>  >new one, and as they are already in possession of a
>reasonable 'low
>>  >noise' mic pre-amp, then it might be more cost effective to buy
>one
>>  >of the less expensive recorders and continue to use their current
>>  >mic pre-amp
>>
>>  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.
>>
>>  >So I was thinking that some indication the device delivers on its
>>  >line-in might prove useful? (I like to keep in mind that there are
>a
>>  >number of enthusiasts that pursue their hobby on a 'tight' budget
>  > >and it may be that the difference in price between the various
>>  >recorders can make a big difference to them, also not forgetting
>>  >size.)
>>  >
>>  >I agree that the line-in 'should' produce decent results, but you
>>  >can never be too sure due to some of the shenanigans some
>>  >manufacturers get up to :-))
>>
>>
>>  I have used the -10dB line inputs on more than 10 MD and DAT
>>  recorders with a Sound Devices MP-2 as a the mic pre. Its a sad
>>  over-sight on the part of a manufacturer if a newer recorder does
>not
>>  meet these standards. The -10 line input on Sharp and Sony MD
>>  recorder will allow one to make great recordings IF a very high
>>  quality mic pre is used "up front." They are expensive unless one
>>  makes on DIY. Some may remember that Klas' "on the cheap" external
>>  mic pre box for unbalanced mics turned out to have more noise than
>>  that of the Hi-MD's pre. In short, the cheap external pres that say
>>  they have "low-noise," seem to be referencing higher sound levels
>>  than those we encounter.
>>
>>  Curiously, all of these new recorders could include mic pres with
>>  noise performance on par with those in the Hi-MD units. There seems
>>  to be a lack of awareness and priority on the manufacturers' part,
>>  not prohibitive production costs. See discussion
>>
><http://bioacoustics.cse.unsw.edu.au/archives/html/naturerecordists/200>ht=
tp://bioacoustics.cse.unsw.edu.au/archives/html/naturerecordists/200
>6-07/msg00192.html
>>  regarding the $4 mic pre ad component, the AK-5356VN-L, used in the
>>  Hi-MD recorders.
>>
>>  Could we be applying more pressure on these manufacturers to
>include
>>  low-noise, high-gain mic preamps in their recorders? I personally
>>  think so. The demand seems to be growing rather than diminishing.
>>
>>  >Another thing I am beginning to see as an advantage to these
>>  >'point-and-shoot' style recorders is the versatility they can
>offer.
>>  >I am a fan of the MZ RH1 due to its small size, but it lacks
>>  >microphones. So having a device that would allow you to go into
>the
>>  >field which you can use hand held to capture material when you
>were
>>  >not after 'ultimate' quality.. But would then lend itself to being
>>  >used with an external pre when you wanted to say 'take more care'
>>  >over what you were recording would seem an ideal tool.
>>
>>  I'm not a fan of built-in X-Y arrays for any sound sources further
>>  than a few feet away. I'd rather use body-worn mics when hiking and
>>  be completely hands-free. Why use noisy mics at any time in quiet
>>  locations? Time and circumstance are too precious.
>>
>>  There was a intriguing quest proposed a while back to liberate the
>>  omni mic capsules and circuitry from the larger AT-3032 housing and
>>  re-house them more like Klas's has with the EM-23's,.. Curt Olson
>>  found he could remove the circuitry from the metal case of the Art
>>  Phantom III unit ($60USD) without problem. Seems like there's a
>neat,
>>  low-profile. low-noise mic project or product waiting to be made. :-
>)
>>  Rob D.
>>
>>
>>  >
>>  >I for one often go birdwatching, and carrying a tripod and
>telescope
>>  >over my shoulder and a pair of binoculars around my neck, don't
>>  >fancy adding a recording kit as well as I walk around. But
>something
>>  >like the Olympus which would slip into a shirt pocket by the looks
>>  >of it would be great. Ideally I would like it to be a dual purpose
>>  >device so on those occasions when I wanted to record an ambience
>>  >using low noise microphones it was able to deliver the goods. It
>>  >would also serve as a memo recorder, which I carry anyway, to
>record
>>  >the birds seen on my wanderings. But at the moment my Sony MZ RH1
>is
>>  >still going strong so I wont be buying anything new for a while :-(
>>  >
>>  >Phil
>>  >
>>
>>
>>  --
>>
>>
>>
>
>


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