Yes, because you cannot hear "DC"....
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.
...The MDAC is connected to my Win 7 64-bit laptop via USB playing (mainly) AIFF 16/44.1 files and a limited number of 24/96 flac files utilising J.River Media Center. I've updated the firmware to V0.96 and subsequently to V0.99.
I've noticed a possible 'bug' in my MDAC which the current firmware hasn't resolved, and I haven't read anyone else bring up this issue on this forum...
When I power up the MDAC, it shows 44.1 on the bottom of the display. When I fire up J.River Media player and attempt to play a 24/96 flac file, I do not get any sound. I have to subsequently play a 16/44.1 AIFF file to obtain sound. Only then, I can proceed to play the 24/96 flac file successfully.
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
How does this MDAC compare to Naim DAC?
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
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 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
WOW 12.8 Volts is way too low, should be at least 14.5V...
I can see the there be 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 system.
John
WOW 12.8 Volts is way too low, should be at least 14.5V...
I can see the there be 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 system.
John
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
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...