Hey guys, as I'm waiting for the final tally on the MP3 test to come in, I thought I'd try my hand over the last week at running some RightMark Audio Analyzer 6.2.5 (most recent version from July 2012) tests. Around Christmas, I got my new ASUS Xonar Essence 1 as my main DAC so as a result had the old E-MU 0404USB (drivers suck and headphone amp too weak for AKG Q701) sitting around. I figured I'd try to put it to good use with some measurements and see what comes up.
What I can say so far is that RMAA is remarkably consistent with good inter-test reliability so long as one has the technique figured out with one's equipment. It's very easy to get things wrong during calibration for example. As usual, there are the caveats to keep in mind and the results I get here may not be comparable with others (good writeup here: http://nwavguy.blogspot.ca/2011/02/rightmark-audio-analyzer-rmaa.html). Here's the general setup: - Computer: Intel i7-3770K @ 4GHz, 24GB DDR3 - E-MU 0404USB --> USB2 of the computer motherboard using generic USB cables. E-MU located about 3 feet from the main computer (too close results in obvious RF interference raising noise floor). For 16/44 testing I record at 24/44, and 24/96 for 24/96. - For unbalanced testing: RCA (3ft, Radio Shack shielded cables ~$10) --> XLR adaptors (maybe $25 for the set) - For balanced testing: generic XLR cables (bought at pro music shop years back, maybe $20) First up: ASUS Essence 1 A few observations. Well made DAC. Likely much more expensive if came from some boutique audio brand. Heavier and larger thank I expected! Should be a good test of the approx limits of the E-MU as testing gear. 24/96 signal: 14302 The first 2 columns are the result between using the RCA vs. XLR cables. Clearly XLR is the way to go with 5dB improvement in noise floor, dynamic range, and stereo crosstalk. Bottom line, XLR buys you about 1-bit in digital resolution according to my setup. The last 2 columns are with the computer running full load (hence the note "NOISY i7). I was running the machine full tilt with Prime95 and the graphics card inside (nVidia GTX 570) doing the "Furry Cube" demo/bechmark from GPU Caps Viewer. Notice how the RCA unbalanced setup resulted in significantly increased noise floor by 14dB (about loss of 2 bits resolution)! XLR setup however ran stably with no evidence of the noise pollution. In theory I would have expected that a busy machine worsens "jitter" through the USB interface with all the audiophile talk about minimizing # threads and CPU load... At least no evidence from my tests to suggest this makes any difference SO LONG AS YOU MINIMIZE RF NOISE from getting into the system. Frequency response (no real issue): 14303 Noise floor: 14304 Clearly the RCA NOISY spectrum is much inferior to the others (cyan). However, the RCA quiet computer (white) has a number of spikes as well evident. CONCLUSION (assuming you believe RightMark's methodology and my competence :-): 1. My XONAR - E-Mu system is capable of measuring down to ~113dB (>18-bits) noise floor. 2. If you have a choice, XLR (balanced) beats RCA (unbalanced) hands down! 3. If you're listening with the computer, computer LOAD makes a difference but if your equipment has good noise rejection (eg. use of balanced cables), this does not seem to be an issue... If computer load correlates to jitter, I'm not seeing it showing up in these measurements. +-------------------------------------------------------------------+ |Filename: E1_Noise.jpg | |Download: http://forums.slimdevices.com/attachment.php?attachmentid=14304| +-------------------------------------------------------------------+ ------------------------------------------------------------------------ Archimago's Profile: http://forums.slimdevices.com/member.php?userid=2207 View this thread: http://forums.slimdevices.com/showthread.php?t=97950 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
