This test was encouraged by William Haven of the NatureRecordist list to compare high-gain, low-noise performance of portable stereo field recorders costing under $1000. We were able to build upon recent tests done by Raimund Specht by adding the Nargra Ares-M and the Core Sound Mic2496 preamp coupled with the digital input of a Tascam HD-P2. My thanks to Sweetwater, Robert Williams, William Haven, Dan Dugan, Greg Weddig & Anthony Capaner for their roles in making this test possible.

The test was conducted in of a lead-walled and acoustically treated narration booth that was located in a windowless interior room of a masonary building. I could not hear traffic in the interior room. The loudest, audible sound that penetrated the booth was a 75Hz mechanical rumble with harmonic overtones that has more presence on the right channel. This rumble was steady enough for me to use as a RMS reference level for matching the playback volumes of the test samples with some adjustments due to differing Hz response of the recorders.

Above test movie: SD744T; Tascam HD-P2; HHb MDP 500; Core Mic2496->Tascam HD-P2; Art Phantom II -> NH900 Hi-MD; Art PhantomII-> Nagra ARES-M recorders compared. Additional comparisons between Hi-MD and MT2496, H4 and MT-90 recorders.

sound: uncompressed 16bit/48K; video: H.264 QT movie <10mb>

Test QT movie with compressed IMA:4 soundtrack <3mb> Test movie in Windows 7 format <3mb>

background and comments below

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Here are a few observations that might assist with assessing this test:
     
<>   Recorder pre-amp noise starting as low 400Hz that is audible above the self-noise of the NT1-A microphones is the primary element that can be heard and compared in this test. The self noise of te Rode NT1-A mics is among the lowest available, about 6 dB(A).
     
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  The Right channel NT1-A mic has noticeably louder self-noise than the NT1-A on the Left channel. The more pronounced hiss from this mic is consistent throughout the tests.
   
<>   The Sony MZ- NH900 Hi-MD recorder used in the test cannot support phantom powered mics directly, thus, an Art Phantom II is inserted to provide 48 volts for the mics and an unbalanced mic level output. More information about this combination.
     
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The low-end frequency response of the reference Sound Devices 744T recorder extends much lower than the other recorders to well under 10Hz. The Hi-MD & Nagra Recorders have steady drop-off in low-end response starting at about 100Hz. I inserted a 6dB/octaave high-pass filter starting at 50Hz when matching RMS/volume to help account for this discrepancy. The high-pass filter was not inserted when making the file with the final comparisons. Thus, the differences in the amplitudes that can be seen in the waveform-- though much of it inaudible in the QuickTime movie test due to concentrations below 40Hz.

 

   
 

 

 

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  The frequency response of the HHb MDP 500, the Sony NH900 Hi-MD and the Nagra Ares M recorders drops-off quickly at 16K Hz.
   
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The test is not useful at comparing spatial imagining or differences in tonal emphasis the recorders may have because the booth greatly minimizes reflections that would nomally create reverberation.

   
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  I included versions with compressed soundtracks including a Windows 7 format movie because some recordists have no means to download a 10mb file. For those folks who can only hear the movies with the compressed soundtrack, I would point out that it is very difficult for one to hear the noise performance differences between the first four recorders in this test-- even when listening to the uncompressed soundtrack in the 10mb movie.
   
<>   The mic pre in the Nagra Ares M recorder has a tremendous amount of gain. We estimated the high gain "sweet spot" to be 11 downward clicks from maximum setting which is around about 87dB. At this impressive level, however, we noticed that the case of the mic is microphonic. Its possible that the "chirping" sound that can be heard in the Nagra sample is a minute mechanical sound within the case that is being transmitted directly.
   
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  The high-gain noise performance of the M-Audio Microtrack 24/96 recorder is compared to Hi-MD in another test < 1mb>
   
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  The high-gain noise performance of the Samson "Zoom" H4 recorder is compared to Hi-MD in another test < 1mb>
   
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  The high-gain noise performance of a Sharp MT-90 MD recorder is compared to Hi-MD in another test < 1mb>
     
     
   
Summary
   

For recording ambience with high pre gain in quiet locations, the HD-P2, HHb MDP 500 and the Mic2496->HD-P2 combination* performed almost as well as the $4000 744T reference recorder. The noise bed of the mic pres in these systems is masked almost entirely by the self-noise of the very low-noise test mics.

The noise bed from the Art Phantom II-> Hi-MD combination is much more audible but one can still detect the self-noise of the NT1-A mics similtaneously. This system should perform very respectably with all, available low-noise mics. Its 75dB gain is second only to that of the Nagra Ares-M.

I agree with Dan Dugan's recent assessment that the noise bed of the Nagra Ares-M seems comparable to that of portable MD recorders. The chirping sound we encountered needs further exploration.

* The digital output of the Mic2496 can be used with a digital recorder like the M-Audio Microtrack 24/96 or Hi-MD to create a system under $1000. Here's a 16/48K aiff test comparing a 24 bit digital recording made with the HD-P2 and 16 bit recordings made with the MT 24/96 and NH900. (The difference in clock tone between the MT 2496 and the NH900 is due to different means of attachment). As expected, there is no, noticeable increase in noise between the well-saturated 16 and 24 bit digitally transferred files.

For more discussion, see "$1000 recorder challenge" string on NatureRecordist list.

 

   
Rob Danielson Mar 2007