I just made a quick comparison between the new Marantz PMD 671 (that is
capable of recording at 24bit/96kHz) and the SoundDevices 722 recorders in
conjunction with a pair of Rhode NT1-A microphones (sensitivity: 25 mV/Pa,
equivalent noise: 5dBA).
Inspired by Rob Danielson's test arrangement, I placed the two microphones
on the desk in my office (microphone spacing about 10 inches). There was a
ticking alarm clock at a distance of about one meter and a small tweeter
producing a constant reference tone of 1 kHz.
I first recorded the reference tone. I then switched the speaker off and
subsequently replaced the left microphone by a resistor of 180 ohms
connected to the pins 2 and 3 of the XLR connector (and additionally two 6k8
resistors between pins 1 - 2 and 1 - 3 in order to draw a current from the
phantom power supply circuit). I did this procedure with both recorders
under exactly the same conditions. Unfortunately, there was some additional
ambient noise (hum and distant jets).
The recording settings were as follows:
- sample rate: 44.1 kHz
- bit depth: 16 bit (dithering enabled on the SD722)
- approximate recording level of the 1 kHz reference tone on both recorders:
-12dBFS
- gain setting on the PMD 671 : 5
- gain setting on the SD722 : 68
- no high-pass filtering selected on the mic pre-amps
Except of some cutting, I did not change the original sound files:
http://www.avisoft-saslab.com/SD722.WAV
http://www.avisoft-saslab.com/PMD671.WAV
To me, the differences are very small. The dummy resistor test section
reveals the lower inherent noise floor of the 722 preamps. However, as Klas
already mentioned, when using such high-output microphones, these
differences should become nearly irrelevant.
The most important difference is perhaps the higher (hard-wired) cutoff
frequency of the PMD 671 preamp, which might reject a portion of the bass
components that might be useful for a "spacy" sound. I don't know how the
new PMD 671 exactly compares to the PMD 670 (the MIC Signal-to-Noise Ratio
specification on the Marantz website is 65 dB for both models).
Nevertheless, it makes much more fun to use the more professional
SoundDevices recorder (high-quality metal housing, very nice battery
powering concept, large internal harddisk, ...).
Regards,
Raimund Specht
Avisoft Bioacouctics
http://www.avisoft.de
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