NEW SNAKE OIL PART THREE: R-09HR MOD-4 Vs. LINE+EXT. PREAMPA fellow TS member posted a question in another thread (Edirol R09HR Part Two) a few months ago asking if a comparison using the same mic/subject recorded MIC input verses external preamplifier was available (like the ticking clock in a quiet room tests) so differences (if any) might be auditioned. At the time no such test recording existed but I suggested sometime doing a comparison recording using chromatic windchimes might be a possibility.
A few nights ago took time to setup such a test using my own DSM mics HRTF baffled mounted in front of two windchimes being excited by a fairly quiet fan. The test setup was done just inside my garage door with the fan just outside as shown in the photo below.
THE TEST SETUPAs evident in the photo, two chimes are used with DSM-6S/H (GUY-baffled) mic placed a close distance away nearly centered between the two. In the recording the ‘medium’ chimes are mostly heard on the left, with the ‘large’ chimes in the right channel.
For having identical recording gain, the first (~30 min 24bit/88.2K) recording was made using the R-09HR’s LINE input at full up #80 REC LEVEL setting and a PA-3SX preamp set at highest #3 gain. After the LINE+ EXT PRE recording, the mic was disconnected and a signal from a 1k Hz electrical signal from a variable level generator was inputted and adjusted so the deck displayed 0 dB VU.
Then the PA-3SX preamplifier was disconnected and the same signal level was applied to R-09HR’s MOD-4 mic input set on ‘HIGH’ sensitivity and #80 REC LEVEL full up setting showing nearly same 0 dB VU full scale reading ~1 dB below max VU (more about this later).
Then another (~30 min 24bit/88.2K) test recording was made inputting baffled mic directly into R-09HR MOD-4 deck.
THE AUDITION SAMPLE CLIPBoth test recordings were then compared and, as much as possible, two ~11 second nearly identical clips were selected. Below are the statistics for the two 11-second comparison clips.
The two 11 second (joined with 0.1 sec. silent space) audition clip is as follows: LINE+PRE – SILENCE – MIC+MOD-4 as shown in the waveform image below.Download the 24bit/88.2K 22 second/~11 MEG audition file at: www.sonicstudios.com/LINE_MOD4.wavSuggest auditioning with sample being continuously looped for easier comparison.THE AUDITION SETUPI loaded the sample clip into my audio editor set for looped playback, used an M-Audio AudiophileUSB soundcard set for full (non-dithered-bit) playback, and connected a set of Sony MDR-SA3000 open-type headphones with 8-100,000 cycle bandwidth to the phones output jack.
I have to admit initially preferring the MIC MOD-4 sample clip for the clearly richer, more exciting (left-channel) sounding medium-size chimes clapper strikes of over the (in comparison) more damped sound of the LINE+PRE sample.
However, after listening in loop mode playback for a minute or two, started remembering past audition experiences of metal/chrome tape formulations, and experiences with ‘hyped’ directional/omni mics also initially sounding better to my ears, but after a short period of use revealed to having an unnatural hyped coloring characteristic not desirable for using when a natural recorded sound is intentioned.
Also, thinking of past (hyped) gear experiences is applicable in this case with the knowledge the PA-3SX preamp used has extensively tested performance. The preamp, when set at maximum #3 gain, has flat 7 - 55,000 cycles –3dB bandwidth, is a well-damped voltage feedback design (very fast settling type) not ringing with pulse-type fast transient signals, and has an output capable of driving very heavy capacitive/resistive long cables/headphones loads.
In other words, there’s good reason to believe the external test preamp was following the mic signal faithfully providing a low coloration LINE input to the test deck. So we move on to consider any differences (variables) of test mic powering/loading effects.
Identical current in both tests powered the test mic. MOD-4 deck (open circuit) supply voltage is ~1.3 volts higher, and also applying a lighter ~4.1K ohm load as compared to the external preamp’s mic loading of ~1.8K ohm. This does load the mic output more, and be ~1dB lower with ext. preamp connected. This makes up for the ~1dB lower applied (max’d out ‘High@#80) MOD-4 deck gain making for identical recorded test signal levels.
Extensive past experience with various powering/loading variations with DSM mics gives me reason to highly doubt audible differences were caused by mic input variations, and most likely the effect of the R-09HR’s internal preamplifier, and maybe the additional high-frequency spike noise being at cause.
SUMMARYThere’s good chance R-09HR’s internal preamplifier does not settle quickly when presented fast audio transients like those produced by the medium chime’s clapper sound, and also possible low-level spike noise is adding additional ‘flavoring’ to spice up such sounds to be audibly ‘more interesting/complex’ than with less ‘colorful’ more accurate signal processing like possible with a well designed external preamplifier.
Regardless of the cause, at least to my ears there’s a definite audible difference. This simple comparison test gives good evidence for some recordists to consider an external preamplifier with the R-09HR deck for achieving the most natural sounding recordings.
BONUS 1 MIN 24 SEC CHIMES RECORDINGFor those desiring a larger 44 MEG (24bit/88.2K LINE input mode) file for a more satisfying chimes experience the file is here:www.sonicstudios.com/09HR-LINE_CHIMES.wav