M2tech listening test
Last weekend I had an opportunity to do some listening tests with M2tech USB/spdif converter in a system consisting of Quad ESL989 speakers, McIntosh MC501 monoblocks, diy hybrid preamp, Berkeley Audio Alpha DAC and Chord QBD76 DAC. There were two PC based music sources - small Asus EEE and expensive music server PC .
We listened to hi-res (up to 24/192) and standard 16/44 files. Berkely DAC locked at 192kHz with single wire spdif, but Chord needed 2-wire connection (only 96kHz with single wire). Chord also has USB input, but it doesn't go over 48kHz.
To make long story short: I'm sure I wouldn't be able to tell the difference between Asus EEE+M2tech and Music server PC if somebody else switched between sources. I thought I can hear some minute difference in favour of M2Tech - as if the instruments had somewhat more presence and body.
Probably the main reason for perceived difference was the fact that I modded that M2tech (stabilized linear outboard power supply instead USB supply and linear stabilizer instead of switcher for clock).😀
Anyway congratulations to the M2tech!!! I think it's a great achievement to make such affordable product that can turn cheap laptop PC into music server that can compete with multi k$ dedicated music server PC.
Last weekend I had an opportunity to do some listening tests with M2tech USB/spdif converter in a system consisting of Quad ESL989 speakers, McIntosh MC501 monoblocks, diy hybrid preamp, Berkeley Audio Alpha DAC and Chord QBD76 DAC. There were two PC based music sources - small Asus EEE and expensive music server PC .
We listened to hi-res (up to 24/192) and standard 16/44 files. Berkely DAC locked at 192kHz with single wire spdif, but Chord needed 2-wire connection (only 96kHz with single wire). Chord also has USB input, but it doesn't go over 48kHz.
To make long story short: I'm sure I wouldn't be able to tell the difference between Asus EEE+M2tech and Music server PC if somebody else switched between sources. I thought I can hear some minute difference in favour of M2Tech - as if the instruments had somewhat more presence and body.
Probably the main reason for perceived difference was the fact that I modded that M2tech (stabilized linear outboard power supply instead USB supply and linear stabilizer instead of switcher for clock).😀
Anyway congratulations to the M2tech!!! I think it's a great achievement to make such affordable product that can turn cheap laptop PC into music server that can compete with multi k$ dedicated music server PC.
I found some device claimed for galvanic iso, but they "cover"
the chip markings...
http://www.pcinstruments.dk/PDF/DT9... sampling og 500 volt galvanisk isolation.pdf
the chip markings...
http://www.pcinstruments.dk/PDF/DT9... sampling og 500 volt galvanisk isolation.pdf
You may want to try this one:
ADUM4160
ADUM4160 | Full/Low Speed USB Digital Isolator | Digital Isolators | Interface | Analog Devices
Charles 🙂
ADUM4160
ADUM4160 | Full/Low Speed USB Digital Isolator | Digital Isolators | Interface | Analog Devices
Charles 🙂
And for isolation in BD design Crazy-T USB dac
you can find ADuM2400 + ADuM2402 (between XC3S200 and XC3S50 chips...maybe for I2S bus...)
🙂
you can find ADuM2400 + ADuM2402 (between XC3S200 and XC3S50 chips...maybe for I2S bus...)
🙂Well, I tried to duplicate your "problem" already, that is the problem. Connected it with external DAC and plugged that Toslink mini adapter in: nothing happened and it played music like seconds before.
Well, I tried to duplicate your "problem" already, that is the problem. Connected it with external DAC and plugged that Toslink mini adapter in: nothing happened and it played music like seconds before.
My USB-transit stops playing on its digital output when I push the Toslink mini into it's optical input (with no signal). Maybe they changed that, because they got too many calls of non-working transits.
There was a Toslink mini adapter included with my transit, so in order to not lose it, I plugged it into the optical input, which muted my transit, LOL 🙂
However for the transit to be clock master you have to give it a signal:
1) CD-player (switched on) -> Toslink -> digital input of m-audio USB-transit
2) digital output of USB-transit -> Toslink -> DAC
3) PC -> USB -> transit (or course)
control panel of USB-transit set to 44100 .. 48000 input & output
This must work on any transit because it is a recording device and has to sync out to in when given an input signal.
Please report back,
Charles 🙂
I used that same mini adapter. Could you open your Transit and take a pic? There are only 3 screws in the bottom.. I don't have a CD player & toslink cable to test with, but how I could test if it really takes the clock from the input?
Btw. I'm using Windows 7 and the drivers sucks, hard.. Only 16-bit 44.1kHz works, and there isn't any input/output options. Maybe that is the problem.. Would be nice to get it working before I start to mod it. USB isolation & new power circuit & mic preamp & BNC connectors is in the planning stage. 🙂
Hm, perhaps you could select a 48kHz file for playback, while feeding the transit's input with 44.1 from a CD-player. That should give you slow-motion sound 🙂
Have made a pic, but have problems with the upload, sorry ...
Yep, drivers seems to be the Thing. I would still like to see the pic, I sent a PM for you Charles. Sorry if you felt like I doubted you, but it really isn't working with W7. 🙂
I connected it with PC with XP and plugged that Toslink adapter and the result was silence! So I hope they will get this driver issue sorted. Last driver update is 14.11. and they know it isn't a working solution. You lose sound after boot etc. But since I already have the card, I think I will mod it before trying something else. But sorry for offtopic.
I connected it with PC with XP and plugged that Toslink adapter and the result was silence! So I hope they will get this driver issue sorted. Last driver update is 14.11. and they know it isn't a working solution. You lose sound after boot etc. But since I already have the card, I think I will mod it before trying something else. But sorry for offtopic.
That's it 🙂
Now you just feed it an S/PDIF from any external source and you have asynchronous USB with your transit.
Upload still does not work, have emailed you the pic.
Charles 🙂
Very interesting USB Hub
I found it very interesting, to use with USB devices like the HiFace.
It is an USB hub with high quality power supply which can be used for connecting USB audio devices. Here is the info I got from Mr Alan Olsen, Chief Technology Officer of Vaunix Technology Corporation regarding the isolation and the power supply of the LabBrick USB hub.
"...We cannot say that the LPH-204B is an isolated hub product, nor can we say that its ground connection is truly isolated from the host PC. This would be a misrepresentation of the facts. We can say that the +5V (VBUS) and the data lines (D+ and D-) are isolated from the host PC. We may also say that the hub is reactively decoupled from the host PC. Alternatively, we can say that the hub (including ground) is well filtered. The question ... regarding the isolated ground stems from the user's concern that ground loops and ground noise can effect the performance of his USB peripherals. This is a valid concern. Here is some more background information on isolated USB hubs. There are some isolated USB hubs available on the market. Their data transmission speed is limited to 12 Mbps (full-speed). This is because the isolation circuitry restricts transmission bandwidth and introduces significant propagation delay. This precludes operation at high speed (480 Mbps) and renders the hub useless for many applications, including video. There are no USB hubs on the market that have just the ground connection isolated. To isolate the ground connection without isolating the data lines puts the equipment at great risk to damage. A very slight ESD or transient event (power-up or power-down) can cause this damage when the ground is floating....
... The LPH-204B uses a switch mode power supply.
From a customer's perspective, this may be a bad thing as they may be concerned about switching noise. Switching noise should not be a concern. We use a proprietary design that yields a very clean output voltage. This design was originally developed for our signal generator product line. These signal generators have a specification that requires the spurious energy to be below -80 dBc! ..."
I found it very interesting, to use with USB devices like the HiFace.
An externally hosted image should be here but it was not working when we last tested it.
It is an USB hub with high quality power supply which can be used for connecting USB audio devices. Here is the info I got from Mr Alan Olsen, Chief Technology Officer of Vaunix Technology Corporation regarding the isolation and the power supply of the LabBrick USB hub.
"...We cannot say that the LPH-204B is an isolated hub product, nor can we say that its ground connection is truly isolated from the host PC. This would be a misrepresentation of the facts. We can say that the +5V (VBUS) and the data lines (D+ and D-) are isolated from the host PC. We may also say that the hub is reactively decoupled from the host PC. Alternatively, we can say that the hub (including ground) is well filtered. The question ... regarding the isolated ground stems from the user's concern that ground loops and ground noise can effect the performance of his USB peripherals. This is a valid concern. Here is some more background information on isolated USB hubs. There are some isolated USB hubs available on the market. Their data transmission speed is limited to 12 Mbps (full-speed). This is because the isolation circuitry restricts transmission bandwidth and introduces significant propagation delay. This precludes operation at high speed (480 Mbps) and renders the hub useless for many applications, including video. There are no USB hubs on the market that have just the ground connection isolated. To isolate the ground connection without isolating the data lines puts the equipment at great risk to damage. A very slight ESD or transient event (power-up or power-down) can cause this damage when the ground is floating....
... The LPH-204B uses a switch mode power supply.
From a customer's perspective, this may be a bad thing as they may be concerned about switching noise. Switching noise should not be a concern. We use a proprietary design that yields a very clean output voltage. This design was originally developed for our signal generator product line. These signal generators have a specification that requires the spurious energy to be below -80 dBc! ..."
Hello! I'd like buy an USB/SPDIF converter for my AD1865N non oversampling DAC with tube output. (only SPDIF input have, I2S haven't). which is the best for me? Need M2Tech Hiface or enough a Musiland (which?)? I'd like use my Win XP base notebokk as transport. No need 24bit/192kHz, but i would like good quality sound without high cost. Thanks for help and sorry for my bad english...
For this PCM2707 (16/44.1 non-os) can be used. Also, I2S output can be connected directly (over the shifter) to AD1865 EIAJ lines.
Has anyone tried this? I don't have access to any 48khz files now, but it'd be great to be able to use my Transit more effectively rather than spend more money on the M2Tech. Great idea, Charles. - Pat
I have noticed a sharp edge to the sound of my modded HiFace set-up when using I2S as compared to SPDIF. I've been thinking that one explanation for this might be the SPDIF transformer providing galvanic isolation from the DAC. So I'm back to this old chestnut again of galvanic isolation. Here's my summary of the info about this in the thread so far:
- high-speed USB 2.0(480Mbps) cannot be so isolated with currently available technology.
- isolating I2S will introduce jitter (using ADUM, etc)
- this could be an acceptable trade-off Jitter Vs ground Noise
- if MCLK is rec-clocked after the I2S isolation it might be more acceptable.
One further thought occurred to me - what about splitting the I2S signal & going differential to two DACs i.e one DAC process R+/- & the other processing L+/-. I don't suppose the simpler version of one DAC processing R+/L+ & the other processing R-/L- would remove common noise (as effectively or at all?).
Would this achieve the same result as galvanic isolation in that it would remove common noise?
Can it be done effectively at 24/192 speeds?
I'll start a new thread on this as it applies more generally than just the HiFace
- high-speed USB 2.0(480Mbps) cannot be so isolated with currently available technology.
- isolating I2S will introduce jitter (using ADUM, etc)
- this could be an acceptable trade-off Jitter Vs ground Noise
- if MCLK is rec-clocked after the I2S isolation it might be more acceptable.
One further thought occurred to me - what about splitting the I2S signal & going differential to two DACs i.e one DAC process R+/- & the other processing L+/-. I don't suppose the simpler version of one DAC processing R+/L+ & the other processing R-/L- would remove common noise (as effectively or at all?).
Would this achieve the same result as galvanic isolation in that it would remove common noise?
Can it be done effectively at 24/192 speeds?
I'll start a new thread on this as it applies more generally than just the HiFace
I'm using Foobar V1.0 as my playback software with WAv files which have been EAC copied to disk.
Your findings are interesting.
Reclocking the Master after isolated I2S transmission IMO is a good idea, but at the same time this is what people normally want to avoid first place by going I2S instead of S/PDIF.
However being connected to the computer's power noise in any way is a pain, and it will always limit playback quality.
In the end ... reclocking the I2S master clock - or - reclocking the master clock after optical S/PDIF transmission and clock extraction is not so different an approach.
The quality you get in the end is that of the reclocking solution.
What do you think ?
Charles 🙂
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