So as part of my little journey to understand the mechanics of the how and what do measurements mean, I'm testing a bunch of DACs to help to this end, encountering a bunch of problems but the Herus is one of the first of a few to come. Some 'traditional' measurements like stepped sine sweeps are not done due to severe equipment limitations.
The Setup:
Acer Aspire V5 122P Win8 laptop->printer cable -> Ressonessence Labs Herus-> 1/4 to RCA adapter-> shielded RCA cables-> SB1240 line in-> usb cable with a ferrite choke on the device side-> Fujitsu Lifebook
Software:
ARTA
Jriver Media Centre running ASIO driver for Herus
Other Equipment:
Fluke 8060A May 2013 cal for levels calibration
Test conditions:
Batteries only for laptops
Herus cal. to 2.126V as the 0 dbFS to avoid clipping the ADC(95 in windows volume control)
24 bit 48khz sampling rate unless stated otherwise, all test run@48khz
For the Herus, no special filters, just yer olde linear phase filters. Gets better at higher sample rates of course
Noise with Full Scale 0dbFS at +8.6dbu. That gives us about -100dbFS of signal to noise and that is not the real full scale output. The noise floor of the SB1240 sits around -94.4dbu ref +8.4dbu. Extra noise sources may be the use of adapters or the fact that the Herus is meant to be an amp as well?
Here I used a -90dbFS signal as per JA's test at stereophile, This test actually sits pretty close to the SB1240's resolving limits and it might be a little wrong but generally I think the test shows the Herus as noisier compared to mine done with the SB1240(will have to update the ADC thread with more baseline measurements).
Same test with 24 bit data, a little noisier than what I see with the SB1240. Okay, I admit, I just like looking at the squiggly lines.
DIN or SMPTE IMD test, I'm not really sure what is reported but this test exceeds the SB1240's limits by 0.02%.
CCIF HF twin tone test, the Herus suffers some performance dip in the 19khz 20khz twin tone test. For the 13/14khz test, the Herus gets close to the resolution of the SB1240.
THD at 1khz, measures properly as expected in the product spec sheet. Predominantly 2nd harmonic distortion device.
Jitter, sidebands are slightly higher than the SB1240's ones by 1 or 2 db by eyeballin it but otherwise demonstrates proper implementation of today's aysnc stuff. Oh yes, this graph is not comparable to the previous SB1240 ones as they use the dbFS scale to match Stereophiles stuff and give a better presentation of data, will update the 1240 thread later on that as well.
Impression:
Since this is a loaner unit that has been burnt in a while, I just let it sit on my laptop area as my sole DAC for listening since the last night before measuring it today afternoon. Coming straight of from my SB1240, it felt more relaxed and less aggressive sounding than my own. I'm not gonna go crazy for the internal amp but I rather have an amp in front of it like burns does with his Herus+Vali last time. Then again its not like I own IEMs either. I think I can conclude that the Herus is a fine sounding unit for now, nothing to compare with though so I may
Associated Equipment:
NAD AV716(judge me), HD800 Anax 2.0, E12, K240DF(slight mods)
