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MDAC First Listen (part 00100001)

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Julf -

I agree that a simple ABX test would resolve the first issue and, with the assistance of she who must be obeyed, I shall do this!

Thanks for confirming my views re the difference between bit perfect players, and the truth about snake oil salesmen.

As regards the noise getting past the MDAC, noise without doubt can get past the similar CDQ and can be blocked by a USB isolator board from Olimex, so I would not be surprised if the same could happen with the MDAC. However, I would agree that it would appear more likely to be a hardware related rather than software related issue, especialy bearing in mind what I have read about electrical noise on the USB bus on the Pi.

Sq225917 -

If you mean that I should use a USB isolator, I will try this, but I'm not sure whether the Pi can power the Olimex board that I have. I could try it powered, but I don't have an appropriate power supply at the moment. I'll revert after I try the Olimex board powered by the USB connection from the Pi.

Jirij -

I'm not sure that I fully understand your post. I have read most of it, verbatim, somewhere else and I did not fully understand it then. No disrespect meant, but I'm not sure how much is serious and how much is tongue in cheek.
 
tim, it's just noise on the 5v line or an earthing issue, either way the Olimex will deal with it.
 
I have been playing around using different music players and computers with my MDAC.

I have used an Intel atom based PC running Vortexbox (uses Logitec Media Server and Linux ALSA), a Windows 8.1 PC running JRiver and Foobar 2000 (both WASAPI) and a Raspberry Pi running Runeaudio (Arch Linux based). All pass the bit perfect test at 44.1kHz, 16 bit and 96kHz, 24 bit, with the original wav files and Flac encoded versions.

The Vortexbox and PC (both players) seem to sound the same to me, or at least, each time I think I've heard a difference, when I try again, it's gone! However, the Pi seems sound a little courser and less detailed. Given that all the set ups have passed the bit perfect test, this seems a little odd. It could of course be “audiophile nervosa” (the little £25 computer cannot be as good as the £200 atom or £400 PC and this prejudice manifests itself in a perceived difference in performance that is not actually there!), but I don't think so.

I understood that all bit perfect players should sound the same with an asynchronous DAC like the MDAC, but is this really correct?

Depends what you mean by 'player'. Software - shouldn't be a difference. Hardware - wouldn't be surprised if there was a difference

Some companies allege that bit perfect players can sound different (e.g. JPlay: http://www.jplay.eu), but are they just snake oil salesmen, like those who tell us that £100 USB cables are better than normal Maplin ones?

As above, depends what you mean by 'player'.

Could it be that there is some electrical noise (analogue) getting into the M-DAC from the Pi along the USB cable? I had this problem with a CDQ and solved it with a USB isolator board from Olimex.

Yes

Anyone any thoughts?

As you've spotted by now, there are lots of thoughts. Doesn't mean any of them are 'right'

Listen. Decide for yourself. Don't worry if your observations or conclusions differ from others or if you can't justify to others what your observations are. Simply listen to what you prefer.
 
My new record cleaning machine removes so much noise.

Maybe I should try my laptop through it ??

Is it possible to get get static transferred from a PC ??
 
OK ABX test completed! I put the Olimex USB isolator in between the computers and the MDAC (the Pi was able to power it). I swapped the cables and computers, and she listened (unbiased and good ears!). As per usual, when there is no difference between pieces of equipment, no computer or software application was consistently preferred and any difference between them was called as minimal at best. So, the conclusion is that there is no real difference between the Pi, PC and Atom, running the software I mentioned in my first post and in my system.

Incidentally, by “player” I meant music player application, such as Foobar or JRiver.

So why do all this? I just like messing with computers and HiFi and was intrigued to see if a really cheap and small computer (such as the Raspberry Pi that I used) could be used as a source for the MDAC without compromising sound quality. Looks like it can be!
 
OK ABX test completed!

Thanks for going through the effort - and posting the results.

So why do all this? I just like messing with computers and HiFi and was intrigued to see if a really cheap and small computer (such as the Raspberry Pi that I used) could be used as a source for the MDAC without compromising sound quality. Looks like it can be!

And that is good news for most of us (not that it really is news, but...).
 
So why do all this? I just like messing with computers and HiFi and was intrigued to see if a really cheap and small computer (such as the Raspberry Pi that I used) could be used as a source for the MDAC without compromising sound quality. Looks like it can be!

Tim
I have a suggestion for you if are interested in extending your test. You can trial JPLAY for a period ( a week IIRC) and with 2 computers you are in a position to try their extreme Ultrastream set up. JPLAY shuts down all but essential computer activity as they reckon it introduces noise. Nothing to lose . .
 
JPLAY shuts down all but essential computer activity as they reckon it introduces noise. Nothing to lose . .

What I always find strange is that someone would use windows as the operating system on a computer purely dedicated to playing music. If it is a dedicated system, use an operating system that can be optimized for dedicated/embedded operation, not one optimized for general desktop computing.

And no, this is not about being pro-windows or anti-windows - I can totally see using windows if you also use your computer for other stuff besides playing music. But taking a windows PC, and shutting down "all but essential activities" renders it useless for general use, so why not go for a dedicated solution in the first place?
 
Well obviously you are not able to use the computer whilst music is playing, that is self evident. And yes if you have the luxury of having a dedicated computer for music . . . But many people don't, hence JPLAY's success.
 
Well obviously you are not able to use the computer whilst music is playing, that is self evident. And yes if you have the luxury of having a dedicated computer for music . . . But many people don't, hence JPLAY's success.

People that don't have a second computer could get a RPI.
 
Well obviously you are not able to use the computer whilst music is playing, that is self evident. And yes if you have the luxury of having a dedicated computer for music . . . But many people don't, hence JPLAY's success.

Not sure what you mean but while playing music I can use my computer for various tasks (including heavy computations) and rarely get stuttering or any other issues.
 
Not sure what you mean but while playing music I can use my computer for various tasks (including heavy computations) and rarely get stuttering or any other issues.
I believe that was with relation to JPlay, which essentially cripples to OS in certain ways (disabling printing, some network services, ...) while actually making it use more CPU time on context switching (marketed as "Reduce OS latency by making Windows switch tasks faster.").
A double-edged sword, in my opinion. It's more of an OS modification tool, not a "player".
 
Re. DSD-capability.

Since the MDAC2 is able to handle DSD, I would be interested in knowing how much cpu/ram power is needed for a computer player to replay DSD.

1) Will the Raspberry Pi be enough?
2) An Atom DN2800mt pc with 8gb ram + Win Server 2012?
3) Or do you need an i3 /i5 /i7 processor with 8gb ram or more?

The pc / rpi will be used as a dedicated audio computer.

Edit: I already own option 2.
 
Re. DSD-capability.

Since the MDAC2 is able to handle DSD, I would be interested in knowing how much cpu/ram power is needed for a computer player to replay DSD.

1) Will the Raspberry Pi be enough?
2) An Atom DN2800mt pc with 8gb ram + Win Server 2012?
3) Or do you need an i3 /i5 /i7 processor with 8gb ram or more?

The pc / rpi will be used as a dedicated audio computer.

Edit: I already own option 2.
MDAC will support DoP, which is DSD encoded in PCM, meaning the computer will simply replay a "simple" PCM file, which shouldn't be very expensive.
Similarly with DFF/DSF, which (to my knowledge) don't use any compression.

edit: I'd personally store/archive any DSD data as DoP since DFF/DSF are not supported by anything except a few 'audiophile' players. The conversion is fortunately easy, thanks to http://www.rendu.sonore.us/apps.html. Plus you save space by using the flac lossless compression.
 
Re. DSD-capability.

Since the MDAC2 is able to handle DSD, I would be interested in knowing how much cpu/ram power is needed for a computer player to replay DSD.

1) Will the Raspberry Pi be enough?
2) An Atom DN2800mt pc with 8gb ram + Win Server 2012?
3) Or do you need an i3 /i5 /i7 processor with 8gb ram or more?

The pc / rpi will be used as a dedicated audio computer.

Edit: I already own option 2.

Not much, so any system should be OK.
 
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