"The cheapest little chip amp has a better noise
performance than the best mic amps 10-15 years
ago. You can presume [the mic input] is good,
(low noise) enough."
-Klas Strandberg 3/25/05
5 years ago, on the advice of several pro
recordists, I bought a $700 external mic preamp
and a $1200 pair of condenser mics and soon
joined the chorus citing the consumer MD/DAT mic
pre circuit as the weakest link in coaxing low
noise performance-- especially using high gain in
quiet places. I didn't have any better
explanation why the noise dropped so dramatically
in my recordings . A couple of years ago, the
$200 Rode NT1-A mic appeared with ~6dBA self
noise and ~25mv/Pa sensitivity. I bought a pair
and became interested in whether one could
assemble a much lower cost, low noise
mic-pre-recorder system out of the many options
out there. I tried several lower cost external
mic pres, mods and started running hi gain record
tests to pin down the inconsistences I was
getting with mics connected to the HiMD mic
input. Klas Srandberg took a look at these tests
and kept insisting that the mic input circuit was
not responsible for the noise. How to test this?
Dan Dugan sent me some nice Denecke PS-2 phantom
power supplies to try but they created a fizz
that I could not eliminate. I ordered parts to
build a portable unit using 5 X 9volt batteries
based on a schematic drawn up by Klas, when I ran
into Paul Dickinson who told me that Ross Corp
had just come out with a beefier, battery powered
phantom supply for only $70 that I might want to
try.
http://www.music123.com/Rolls-PB224-Dual--Phantom-Power--Adaptor-i11829.mus=
ic?source=3Dfroogle
Well, it looks like there could finally be a way
to hear/assess the noise floor of the HiMD mic
pre.=A0
In the test movie, there are four tests, back to
back that are so close in performance that you
might think there's only one sound sample! Listen
carefully, the audio changes occur at the same
time as the change in the picture. The gear
set-ups compared in the first four tests are:
1) NT1A-s Mics->722 Sound Devices Recorder
2) Same Mics-> using Rolls PB244 Phantom power
supply-> 722 Sound Devices Recorder.
3) Same Mics-> Sound Devices MixPre -> Line input Sony HiMD NH900 recorder
4) Same Mics-> using Rolls PB244 Phantom power
supply-> 3.5mm Mic Input Sony HiMD NH900 recorder
The next two tests include familiar
PIP-compatible friends-- the Shure 183's and Rode
NT-4's for comparison.
Finally, I couldn't resist juxtaposing the $2800
(1) package with the $700 (4) package.
4mb version with compressed sound
http://www.uwm.edu/~type/Mic%20Preamps/RollsPB224-%3eHiMDMicPreIMA.mov
8.4 mb version - uncompressed sound:
http://www.uwm.edu/~type/Mic%20Preamps/RollsPB224-%3eHiMDMicPreAIF.mov
The QuickTime movie should stream in your browser
if you have a fast connection or you can download
the movie(s) by going to the directory at:
http://www.uwm.edu/~type/Mic%20Preamps/
and look alphabetically for the links
RollsPB224-_3eHiMDMicPreIMA.mov
or
RollsPB224-3eHiMDMicPreAIF.mov
to right-click( mac option-click) on.
Think I'll go pour a single malt whiskey now.
Seems more affordable. May I be the first to
toast Klas?! Rob D.
=3D =3D =3D
At 12:58 PM +0100 3/25/05, Klas Strandberg wrote:
>No, not too early, cause nowadays there is no reason to make a mic input
>noisy. You can presume it is good (low noise) enough.
>
>The cheapest little chip amp has a better noise performance than the best
>mic amps 10-15 years ago.
>
>The design challenge is to make a mic preamp running on 1/ low voltage, 2/
>low current consumption, still 3/ good headroom and 4/ low noise.
>
>All "walkman" size recorders that I know of sacrifices the headroom in
>favour of low noise.
>
>Klas.
>
>
>
>At 03:42 2005-03-25, you wrote:
>
>>Might be too early to conclude the R-4's mic pre quality is good
>>enough for the general sensitivity of "todays" mics. Of course,
>>Volker's thunderstorm is not a good recording situation for judging
> >noise. Side-by-side comparison tests with known gear can be very,
>>very telling. It could also be the R-4, like the R-1, is designed
>>more for music recording with a mic pre gain of 40dB compared to the
>>~55-60dB we're used to with MD's. That would be consistent with the
>>Oades' report. Rob D.
>>
>> =3D =3D =3D =3D =3D
>>
>>At 2:21 AM +0100 3/25/05, Klas Strandberg wrote:
>> >At 00:45 2005-03-25, you wrote:
>> >
>> >>It would be great if they could specify what they mean by not so grea=
t?
>> >
>> >I agree! Again: ALL mic inputs today are good enough if you use high o=
utput
>> >microphones!! Most microphones today are such high output mic's! What =
is
>> >the problem??
>> >
>> >Klas.
>> >
>> >
>> >>I actually purchased an Edirol R4 recently.
>> >>It was the Oade page that made me aware it existed.
>> >>According to my dealer I am one of only few people to have one in Ger=
many.
>> >>
>> >>My main interest in bying it is to make the switch away from DAT as w=
ell
>> >>as the 4 channel opportunity.
>> >>
>> >>My (couple of days) experience so far is quite positve.
>> >>
>> >>I've done 4 channel early spring birdsong recordings with a modified =
4
>> >>channel Jecklin disc (2 Audio Technica AT3031, 2 Audio Technica AT303=
2),
>> >>that I like very much.
>> >>With my mid class surround system, I feel in the middle of the forest=
.
>> >>
>> >>Coming from Sony DAT and Sharp MD mic preamps, I am satisfied, but I =
am by
>> >>no means short of a recording professional.
>> >>My main interest in recording is ambience anyway.
>> >>Just today I did a recording of the first spring Thunderstorm from my
>> >>balcony with a stereo Jecklin setup (AT3032 again).
>> >>And I really rocks.
>> >>
>> >>In case there is anyone who would like to have more detail about the
>> >>Edirol R-4 or even sound samples, just let me know.
>> >>I would also be interested in an exchange of experience with other us=
ers.
>> >>
>> >>
>> >>Volker
>> >>
>> >>
|