Usb 24 192khz M2tech Hiface - Page 4

Mine shipped wed also. i don't think I will get it until at the end of next week though.

Spdif cables and media players

While my unit is still on its way (the italian post does not seem to be the fastest one), I asked Marco at m2tech about spdif cables and media players.

Spdif Cables :
After reading this article about spdif and cable length, I asked if Marco had any recommendations about a specific brand or length of cables to use.
I copied his answer below :
theoretically, with a perfect matching cable length doesn't matter. With a partial mismatch, you can have a benefit by a longer cable when the length is such that the reflected wave is either in phase with the direct wave or the length is an exact multiple of the wavelength. But you can't control this, so it's absolutely random. On the other hand, every cable shows an attenuation which is proportional to length, so a long cable would have reflections with a slightly lower magnitude because of the extra path they run with respect to the direct wave (which travels the shortest path).
Summarizing: with a good match, short cables are better because attenuation is reduced and EMI sensitivity is low too; with a poor match, we're in the hands of God.


Media Players :
Apparently, with the new drivers, the m2tech can work with Foobar, Media Monkey and WinAmp.

I should get it ether today or tomorrow. As for the cable length and such, it makes sense, and I doubt it's audible. If you got the default hiface, then it's rca -> bnc. The rca cannot truly output 75ohm, so there is impedance mismatch already.

i have ordered the custom one, so I get true 75 ohm, so the shorter length would be better for me.

very excited about the news!

Do they have discussion/interpretation of the results and how the measurements were done?

If "JIT=0.970ns" means 970ps of jitter, it doesn't look too well against some of the gear Stereophile measured for jitter.

yea I just wanna see musiland vs m2tech vs say offrampturbo

This seems worse than musiland if true. I thought musiland is talking about sub 100ps here.. And this thing is 970ps??? What the....

From what I understand jitter measurements should be handled and interpreted with great care.

First, Stereophile usually measures jitter at the DAC output, which means that the signal coming from the transport has already gone through many steps before being measured. The only time I saw stereophile measure jitter at the digital level, it gave very high level : The bel canto usb link was measured at 2 ns and the emu 0404 usb at around 8ns of jitter.
Anyway, those numbers should not been compared directly to other measurements if the other tests are not using the same parameters : test protocol, measured frequency, test equipment, ...

Second, I have seen a lot of jitter numbers thrown about the Musiland but not all of them are comparable in my opinion to those that are measured at videohifi. Some people suggested that the total jitter of the Musiland depends on the jitter of the FPGA used in it. However, in the specs of the Xilinx, there isn't a direct reference to which jitter is actually being measured. Also, the Musiland use some very cheap clocks that hold back its potential (bad phase clock noise performance). This might explain why a simple unit such as the Teralink-x (which however uses high quality clock and power filtration) can outperform the Musiland.

As an owner of the Musiland Monitor 01, I am a little bit disappointed of its performance consedering that it uses asynch usb that is in theory way superior to the usual adaptive mode.

In my opinion, if the m2tech Hiface converter has comparable performance to the Lynx PCI cards, it is great news.

Anyway, all of this is pure speculation from me. I am still awaiting for the m2tech hiface so that I can directly compare it to the other converters I own (musiland monitor 01 usd, Teralink-x and Emu 0404 usb)


Edit --- I found here a different measurement of the LynxTwo which shows its jitter (at the analog outputs at around 20ps)

Of course, this is why I asked about discussion/interpretation of the results. Google Translate is pretty cool.

Interesting. Do you have a link for this?

Looking forward to your comparisons!

Well, I am all for more update on this matter.

The jitter numbers are here : Stereophile: Bel Canto USB Link 24/96 USB-S/PDIF converter

I copied below the text discussing jitter at the digital output of the converters.
Also, the bel canto has around 6ns of jitter (instead of 2ns as I typed yesterday).

Fig.1, for example, shows the eye pattern of the Boulder 1021 disc player's data output, plotted over one "unit cycle" as, for 60 seconds, it fed the Audio Precision a 16-bit AES/EBU datastream comprising the Miller/Dunn J-Test Signal. The calculated jitter level was the lowest I have so far measured with the SYS2722, at 1.75ns, and you can see that, other than a slight thickening of the horizontal sections of the traces, the eye is indeed wide open.

Fig.1 Boulder 1021, eye pattern of AES/EBU data output carrying 16-bit J-Test signal (±3V vertical scale, 175ns horizontal scale).

For comparison, fig.2 shows the eye pattern of the Bel Canto USB Link's output feeding the same data to the Audio Precision, sourced from a WAV file on the Mac mini. You can see that while the eye is still wide open, there is greater timing uncertainty at the start and finish of the unit cycle than there was with the Boulder. The measured jitter level was 5.85ns; ie, three times greater than the Boulder. To put this in perspective, the jitter from the E-Mu 0404 fed the 16-bit Miller/Dunn data was 7.9ns, and that of the M-Audio Transit USB was 2ns.

By the way, the Boulder CD player that is mentioned by Stereophile costs $24,000!

if you match the stereophile of the transit at 2ns and the m2tech at 0.97ns that is significant. However there are no real standards of testing between any tests talked about.