Hi all,
I just received a Korg MR-1, SN 000617, Firmware version 1.0.0.
You can see and read something at http://www.korg.co.jp/Product/DRS/MR-1/
I started playing with it with the hope to be able to do wideband
recordings because DSD technology claims a bandwidth greater than
100kHz when clocked at 2.8MHz (MR-1), and more than 200kHz at 5.6MHz
(MR-1000), in both case with no aliasing problems because the
sampling rate is much higher than any audio component coming in.
By using special software (at present very expensive) it is possible
to down-convert a DSD stream to a more conventional PCM formats up to
384kHz/24bits. The software coming with the MR-1 allows conversion up
to 192kHz/24bit with very limited options. Just conversion PCM<>DSD.
MR-1 specs state 100 kHz bandwidth within 1dB. The bandwidth
information is true, but with a significative roll-off on both analog
out (where it is possible to choose among three different lowpass
filters) and PCM converted files.
But the greatest disadvantage of DSD technology, in particular in
this specific implementation, is that it introduces a lot of noise
above 20-30 kHz. With the MR-1 the SNR is around or greater than 120
dB in the audio range, but only 50 dB above 50 kHz. Probably MR-1000
with 5.6 MHz sampling will perform a bit better with noise more
shifted towards high frequencies.
This is intrinsic in DSD technology, but can vary depending on the
implementation of noise shaping algorithms used to move hiss from
audio range to those frequencies we can't hear. As this happens in
the AD conversion stage, there is limited possibility to smooth the
noise in postprocessing.
With Korg DSD you can choose among three operating modes:
1 - full DSD recording by getting the DSD output of the recorder (you
have to face with a smooth low pass filtering)
2 - DSD recording then conversion to PCM: the program AudioGate works
well but it is limited to max 192 kHz. This way you get 96 kHz
bandwidth with almost no aliasing, but you pay this with only 50 dB
of SNR in the upper half bandwidth. Conversion to 384 kHz is not
implemented (yet?).
3 - PCM recording: I don't know why, but it performs like any other
PCM recorder with aliasing similar to that of the Tascam DP2 plus
increased background noise above 30 kHz.
I'm in a very preliminary stage of evaluation. I can't say yet if it
sounds really good or not in the audio range. I'm now just evaluating
its suitability for wideband bioacoustic recordings. Later on I'll
try to evaluate its "pure audio" capabilities (hints are welcome).
Back to general features of this recorder:
Good points:
- easy to operate (with REC Level exception), good display
- apparently good audio quality, no strange noises or interferences
- by pressing the REC button it enters in prerecording condition with
level display active
Weak points:
- the stereo mic I received has capsules with many dB of difference
in sensitivity
- no phantom power, only PIP with on/off switch (but I can't evaluate
how good is it - Klas any hint for a PIP test ?)
- two separate mini-jack (3.5mm mono) inputs for left and right, thus
you need an adapter cable for your stereo mic plug. A switch allows
to select mic or line.
- recording level control: it is needed to access the menu to set the
level! press menu button, rotate the wheel to scroll to Rec Level,
press the wheel to enter, press and then rotate the wheel to set L
level, press the wheel to exit L channel, rotate the wheel to switch
to R channel, press and then rotate the wheel to set R level, then
press menu button twice to exit. Rec level range is -95.5dB to
+31.5dB in both MIC and LINE IN modes.
- there is no prerec buffer... at least, I don't see any option for
setting it (and my manual is japanese only)
- when selecting a new recording mode the display is not updated
until REC is pressed
- can't be recharged through USB connection.
- besides suitability for wideband recordings, I'm worried by the
high frequency noise that come out from line outputs: when connected
to my power amplifier and I turn up the level knob, I see the VU
meters move just for the unaudible high frequency noise!! The high
frequency noise is also visible in PCM converted files and it
disturbs a lot when editing as the noise masks the envelope of quiet
sounds and silences.
As already stated I can't say about audio range quality yet. In the
meanwhile you can look at my preliminary tests
at (http://www.unipv.it/cibra/res_techtest_uk.html). The page will
be updated with MR-1 tests this afternoon and during the next weekend.
If you have hints for additional tests, please let me know!
Gianni
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Gianni Pavan
Centro Interdisciplinare di Bioacustica e Ricerche Ambientali
Universita' degli Studi di Pavia, Via Taramelli 24, 27100 PAVIA, ITALIA
Phone +39-0382-987874 Fax +39-02-700-32921
Email
Web http://www.unipv.it/cibra
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CIBRA organizes the XXI IBAC Congress, Pavia, 15-18 September 2007
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