MDAC first listen (part VII)
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Krisposs12
Active Member
Ah yes I see. Thanks for the explanation. I will just stick with USB until I can sort out the issue with the STX.
Many thanks
Krisposs
Help - my MDAC has recently taking to spontaneously restarting, i.e. clicking off and rebooting. I've unplugged everything from it and it still sometimes happens. Running original firmware. Mains quality here can be pretty odd, given the way some power amps have periodically hummed.
What can this be? Apart from another manifestation of my current jinx: garden water pump just stopped, can't restart it, and the Yaris I've borrowed (wife away with family car) does not always start for me, for no obvious reason.
What can this be? Apart from another manifestation of my current jinx: garden water pump just stopped, can't restart it, and the Yaris I've borrowed (wife away with family car) does not always start for me, for no obvious reason.
JohnW
pfm member
Is it possible your mains supply is so poor that the MDAC drops out and restarts?
Press the knob on power-up and watch what the PSU voltage indicates (How it varies)...
John
I too use JRiver via USB and do not get this problem, although Win 7 on the computer in question is 32 bit. MDAC status shows "ready" right up to the point where you press play on JRiver and it then toggles correctly to show the nature of the incoming data. It looks, for all the world, as though your computer is issuing digital silence at 44.1kHz which the MDAC is (correctly) locking onto.
Are you sure that USB (i.e. the MDAC) is not set as the default audio device?
Krisposs12
Active Member
Just one more thing John (sorry!) - if as you say there is nothing to protect the headphones (though the M-DAC), I presume this means that the M-DAC headphone amp does not have a AC coupling or DC offset feature? In this case, is there also a risk of degradation or damage to the M-DAC's headphone amp itself if one of the digital inputs is presenting a DC signal?
Thanks once again (by the way, I think more than a pint of beer you two deserve a crate of champagne or something)
Krisposs
Thanks once again (by the way, I think more than a pint of beer you two deserve a crate of champagne or something)
Krisposs
It wanders up and down between 12.8 and 13.3, can go from lowest to highest or vice versa in about 15 seconds. Didn't restart yet. What's a critical value?
Thanks,
Jon
Krisposs12
Active Member
Hi John,
Just FYI, after doing some research I found that the issue with the STX is known (sticks to the last observed bitpattern as you surmised) and has been observed before (found on http://www.stereophile.com/content/asus-xonar-essence-ststx-soundcards-follow-september-2010):
"I was at first alarmed by this behavior—if you happen to pause playback just when a waveform peaked at its maximum possible level, the resultant DC offset will be equivalent to a full-scale signal. But this offset is in the digital domain; it would present a problem only if it translated to an equivalent DC offset in the analog domain, where it might be amplified by the power amplifier, with possible damage to the loudspeakers' woofers if the entire playback chain was DC-coupled. I tried the Xonar soundcard's digital output with every D/A processor I had in the house, ranging from the budget-priced Benchmark DAC1 to the super-expensive dCS Puccini. In every case, when I paused playback on the PC, the resultant digital offset did not give rise to an analog offset. Even when I deliberately arranged for the latched data in the Xonar's digital output to be equivalent to a full-scale signal, I couldn't measure any related DC offset in any of the processor's analog outputs. So while this behavior is curious, it isn't pathological."
Does this mean that other DACs have some sort of built in protection to prevent conversion of a digital offset whereas the M-DAC does not at this stage? Otherwise, how else could the digital offset consistently not induce an analogue offset in a range of DACs?
Cheers,
Krisposs
Just FYI, after doing some research I found that the issue with the STX is known (sticks to the last observed bitpattern as you surmised) and has been observed before (found on http://www.stereophile.com/content/asus-xonar-essence-ststx-soundcards-follow-september-2010):
"I was at first alarmed by this behavior—if you happen to pause playback just when a waveform peaked at its maximum possible level, the resultant DC offset will be equivalent to a full-scale signal. But this offset is in the digital domain; it would present a problem only if it translated to an equivalent DC offset in the analog domain, where it might be amplified by the power amplifier, with possible damage to the loudspeakers' woofers if the entire playback chain was DC-coupled. I tried the Xonar soundcard's digital output with every D/A processor I had in the house, ranging from the budget-priced Benchmark DAC1 to the super-expensive dCS Puccini. In every case, when I paused playback on the PC, the resultant digital offset did not give rise to an analog offset. Even when I deliberately arranged for the latched data in the Xonar's digital output to be equivalent to a full-scale signal, I couldn't measure any related DC offset in any of the processor's analog outputs. So while this behavior is curious, it isn't pathological."
Does this mean that other DACs have some sort of built in protection to prevent conversion of a digital offset whereas the M-DAC does not at this stage? Otherwise, how else could the digital offset consistently not induce an analogue offset in a range of DACs?
Cheers,
Krisposs
Hi Asimo,
Here are a few points of comparison (I have both DACs):
Resolution : very little difference between the two ; the M-DAC is perhaps slightly more refined in the treble. Midrange and bass are very well defined in both. The M-DAC is quite articulate in the bass.
Tonality : the M-DAC has a lighter, airier presentation. The Naim DAC has more heft, more bass weight.
PRaT : This is where the Naim DAC shines, really giving a sense of flow and forward momentum to the music. The M-DAC is more subtle here. Perhaps John W can comment on whether the M-PAX power supply upgrade will improve this aspect ?
Ease of presentation : Both DACs provide a wonderful sense of ease to the presentation, which I attribute to their very high resolution and dead-quiet backgrounds. Instruments, voices and sounds are simply credible . No mental effort is required to decipher anything. You can almost feel the brain relax. There is also a sense that you are listening as far back in to the recording as is possible.
I'm not a soundstage freak, but the M-DAC is very good in this regard.
Pace, rhythm and timing are top on my list of priorities, so I'm not selling my Naim DAC… (unless John has something else up his sleeve that can tempt me away
)The M-DAC is about a quarter of the price of the Naim DAC.
Hope this helps,
Jan
JohnW
pfm member
WOW 12.8 Volts is way too low, should be at least 14.5V...
I can foresee the there being instances where your mains drops even lower (and this will be when the MDAC is forced to reset).
Where do you live - 12.8 Volts is the lowest I've heard of...
You MDAC SQ will be effected by the lower input voltage - not to mention the rest of your audio system - POOR power amps... don't count on "Full Power" from them!
John
JohnW
pfm member
For the highest SQ, the MDAC has no high pass filter... High pass filters are detrimental to Bass performance. The MDAC will recreate what ever the input Data - that's what its designed to do.
I want to be quite clear about this, the issue is not with the MDAC, but your source - you cannot blame the Car for a bad driver...
This "xonar" is just a pile of CxxP to have such a serous issue - it should have been corrected after the review when the issue was discovered and made public - way back in September 2010 at the very least...
JohnW
pfm member
No the MDAC does not care about the input signal - it will "100%" faithfully reproduce the digital input signal (whatever it is) and cannot be damaged...
I live in SW Germany a small village in the Blackforest, about 30km from Basel. Until this restart issue, my main gripe with the mains was what I take to be hefty DC offset, almost anything with a toroid in it hums periodically, power amps the worst. Now it sounds like I've got DC and low voltage...pity we went to the trouble of building a house here
Jon
- put me down for an MPAX with "enhanced" output voltage
JohnW
pfm member
I live in SW Germany a small village in the Blackforest, about 30km from Basel. Until this restart issue, my main gripe with the mains was what I take to be hefty DC offset, almost anything with a toroid in it hums periodically, power amps the worst. Now it sounds like I've got DC and low voltage...pity we went to the trouble of building a house here
Jon
Hi Jon,
We are talking about Germany here - Germans who live by the book and reams of paper to support every action!!
The AC Voltage would appear lower then is allowed - so you should be able to get the electricity board to correct at at there expense... there will be regulations specifying the lower and upper voltage limits. They should come around and plugin a "Data Logger" and monitor your AC voltage over a couple days... Week...
MPAX is not going to help much, way too low input voltage... It would stop the MDAC tripping out, but you might not gain the full benefit of the improved SQ...
Hey, but your place in the forest sounds OK
beats China We could make a custom software build for you to reduce the dropout voltage trigger level... But with such low input voltage, your not going to be getting the best from your MDAC.
John
Hi Jon,
We are talking about Germany here - Germans who live by the book and reams of paper to support every action!!
The AC Voltage would appear lower then is allowed - so you should be able to get the electricity board to correct at at there expense... there will be regulations specifying the lower and upper voltage limits. They should come around and plugin a "Data Logger" and monitor your AC voltage over a couple days... Week...
MPAX is not going to help much, way too low input voltage... It would stop the MDAC tripping out, but you might not gain the full benefit of the improved SQ...
Hey, but your place in the forest sounds OK
We could make a custom software build for you to reduce the dropout voltage trigger level... But with such low input voltage, your not going to be getting the best from your MDAC.
John
Now I just need to learn how to ask for that in German...! once completely and humiliating failed to convey my limited understanding of DC offset to an electrician who was doing some work for us.
Apart from the mains quality, it is great here, and just as with sq, if you ever need a stop-over when travelling you are welcome. We met once at some london airport when I handed you my dead dacapo - first case of leaking caps I think. That was a while ago.
And on a good day the mdac sounds great here too. It's only today I've had this shutting down behaviour.
Jon
Krisposs12
Active Member
Thanks John. Wasn't implying the M-DAC was at fault for anything - just wanted to understand the situation of why other DACs wouldn't show a DC output. Now I understand the M-DAC deliberately avoids such things for SQ reasons which is a perfectly good reason.
And yes it is pretty bad show for a supposedly high-quality component like the STX to have such an issue. Fortunately I always listen to headphones around -20dB anyway (if the input is 100%, or around -10dB when the input is digitally lowered in volume, but either way at a modest volume anyway) so no harm done and I could keep doing this for listening to 192kHz content through the STX coax output. Unfortunately Asus have poor customer support and there's almost zero chance of anything happening about it so I guess I'll just have to avoid using the STX when not necessary and stick mainly to USB.
Many thanks again for your advice. If you do end up integrating a safety mechanism into a future firmware release to counteract a DC offset input which would allow me to safely use the input from the STX then thanks in advance for your effort. If not, then there's plenty else to thank you for!
Best regards,
Krisposs
gh0st
pfm Member
talking of power
if anyone is of a DIY disposition and likes looking at boring metal boxes with transformers in them, I've put up a quick thread where I'll log my crack at a DIY PSU build for MDAC
http://www.pinkfishmedia.net/forum/showthread.php?t=120306
/dom
if anyone is of a DIY disposition and likes looking at boring metal boxes with transformers in them, I've put up a quick thread where I'll log my crack at a DIY PSU build for MDAC
http://www.pinkfishmedia.net/forum/showthread.php?t=120306
/dom
JohnW
pfm member
Hi Krisposs,
Dom will looking into the possibility of adding an option to protect against high level DC inputs by working within the MDAC's "Level meter routine" - but we are really short of DSP horse power - especially at 192kHz (ironically).
We will soon have an ASync 192kHz USB adapter for the MDAC which will resolve your issue.
John
Dom will looking into the possibility of adding an option to protect against high level DC inputs by working within the MDAC's "Level meter routine" - but we are really short of DSP horse power - especially at 192kHz (ironically).
We will soon have an ASync 192kHz USB adapter for the MDAC which will resolve your issue.
John
misterdog
Not the canine kind
Hi John, I've reconnected my turntable and Pre-Amp the balance is normal.
Even without a glass of wine !
So I assume the 3db balance shift required on the MDAC indicates a problem?.
It stills sounds great, so it is not a problem for me.
It was good of you to offer to fix it, but as it was not your problem should I not send it back to the dealer?.
Tho. Checz. is nearer than China !
Regards Paul
Even without a glass of wine !
So I assume the 3db balance shift required on the MDAC indicates a problem?.
It stills sounds great, so it is not a problem for me.
It was good of you to offer to fix it, but as it was not your problem should I not send it back to the dealer?.
Tho. Checz. is nearer than China !
Regards Paul
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