[uofmtiger]

Is having a dejitter DAC that important?

Currently, I have a Sony computer with a sigmatel soundcard and a Turtle Beach Audio Advantage Roadie USB for DTS on movies. However, I am looking to get better sound from my computer for music and I have read a lot about jitter and USB cards.

I have run across a few ways to reduce jitter, but there is very little information on the products I have run across. The products that I have seen are Behringer SRC2496, DIYEDEN's Great March, and Emu 0404 USB (which is supposed to come out this month). Of the three I am leaning toward getting the Emu.

However, after reading over several threads on this site, I see that very few people are all that worried about jitter. If I decide that jitter is not that important, it opens up a lot of avenues like the Zhaolu D2.

Should I stick to getting the E-mu or I am I too worried about jitter?

BTW I do not want to spend much over $250 for the DAC/sound card.

 

[Ferbose]

Every DAC has jitter rejection capability to various degrees.
Some do it so well that hardly any jitter artifact can be measured, and some do it quite badly.
And it's more about circuit design than the chip being used.

 

[tschanrm]

Quote:

Originally Posted by uofmtiger However, after reading over several threads on this site, I see that very few people are all that worried about jitter. If I decide that jitter is not that important, it opens up a lot of avenues like the Zhaolu D2. Should I stick to getting the E-mu or I am I too worried about jitter? BTW I do not want to spend much over $250 for the DAC/sound card.

Most usb implementations have measured higher jitter than s/pdif. Having said that, I wouldn't really worry about jitter. Is the Sony computer you refer to a desktop or laptop?

 

[uofmtiger]

Quote:

Is the Sony computer you refer to a desktop or laptop?

It is a Sony VAIO VGX-XL1 Digital Living System Desktop. I had to add a Turtle Beach Roadie USB in the short-term for DTS because the Sony card combined with WMC did not have DTS capabilities. It is easy to switch between the two, but I am not sure it just does not make more sense to get the EMU USB to use all the time.

Here are the info for the E-mu:

E-MU® Systems has announced its new EMU 0404 USB 2.0 Audio/MIDI Interface that delivers an unparalleled level of USB audio quality to the Mac or PC with premium 24-bit/192kHz A/D and D/A converters, pristine XTC™ mic/line/hi-Z preamps, and ultra-low jitter clock.

From its plug-and-play functionality and hands-on ergonomic design to professional features like independent ground lift switches and signal-to-noise specs that are simply unmatched by any other USB interface on the market, the EMU 0404 USB will forever change your expectations of USB audio. The EMU 0404 USB also comes with E-MU's powerful Production Tools Software Bundle

The E-MU 0404 USB 2.0 Audio/MIDI Interface features:

Premium 24-bit/192kHz A/D and D/A converters offer unmatched USB audio fidelity (A/D: 112dB, D/A: 117dB measured SNR performance)
E-MU XTC Class-A ultra-low noise mic/line/hi-Z preamps with soft limiter and 48V phantom power (-127dB EIN) with 60dB of gain
Independent ground lift switches for optimal audio fidelity/flexibility
Hardware zero-latency direct monitoring (mono or stereo)
Plug-and-play operation with hands-on control of all major functions
Cross-platform support (Mac OS X and Windows XP/x64) and compatibility with most popular audio/sequencer applications (ASIO2, WDM, MME, Apple Core Audio and Core MIDI, AC3 and DTS Passthru protocols supported)
Includes Production Tools software bundle with E-MU's Proteus VX Software Sound Module, as well as software by Cakewalk, Steinberg, Ableton, IK Multimedia, and many more - everything needed to create, record, edit, master and burn your music is in the box
EMU 0404 USB I/O Configuration:

Two E-MU XTC mic/line/hi-Z preamps (w/soft limiter and 48V phantom power)
Two 1/4" balanced outputs
1/8" stereo speaker output
24-bit/96kHz optical S/PDIF in/out (switchable to AES/EBU)
24-bit/96kHz coaxial S/PDIF in/out (switchable to AES/EBU)
One set of MIDI in/out
Stereo headphone output

They specifically mention low-jitter in the description. If most DACs have de-jitter capablities as Ferbose mentions, why do only a few actually mention it in the specs?

The Behringer is only $129, so it would be the cheapest route to go, but with E-mu's reputation, I am thinking it makes the most sense. The again, if jitter is not the issue, I may want a different DAC.

 

[replytoken]

Quote:

Originally Posted by uofmtiger However, I am looking to get better sound from my computer for music and I have read a lot about jitter and USB cards.

What are specifically looking to improve over your existing sound?

 

[uofmtiger]

Quote:

Originally Posted by replytoken What are specifically looking to improve over your existing sound?

I am not saying that I find the sound quality objectionable at all with the current setup. However, as many audio/musicphiles know, it is not possible to know if I am getting the best sound possible (within my budget) without hearing it with a different setup. When I read that USB/spdif causes jitter and it would help to have a better sound card, DAC, etc... I can't help but wonder if I am missing detail or music sound quality.

As an example, I have an iPod that sounded perfectly fine, but I decided to also listen to it using a pocket amp 2 that I bought for my car. The sound was better with the ipod/PA2V2, so I use it for the iPod when I am away from the car. It gives a better sound stage, detail to the instruments, and bass punch. However, I would have never known that without buying the PAV2V.

This may be how audiophiles get into trouble because there is always something coming out that is supposed to be better. Personally, I try to keep my audio expenditures to a level that works for me and if I can get better sound from my computer system for $200 or so, that is the way I want to go.

I was just curious why I rarely read about jitter issues on this site when it seems to be a common problem with computer sources. Of course, I have also read that it is difficult to hear jitter, so that is why I was asking the question.

 

[granodemostasa]

it depends on your computer. I'm having no noticable "jitter" related issues right now... mine has 2gb of ram (which apparently is very important towards getting rid of jitter).
i'm using my laptop, an M-Audio Audiophile usb spdif to the zhaolu dac.

empirical audio's website has a list of things to do in order to improve the performance of usb audio...most of the things are simple click this X thing to do X that can be done in a few minutes.

 

[regal]

You probably won't know how much jitter is affecting your sound without an A/B comparison to a known low jitter source. Effects of jitter can be surprising.

 

[uofmtiger]

Quote:

empirical audio's website has a list of things to do in order to improve the performance of usb audio...

Very interesting site, thank you for the suggestion. I also liked their info related to the setup of Foobar2000. I have 1GB of RAM, so I guess it would not hurt to put in more. My computer maxes out at 2GBs, but I am guessing that is enough from your post.

Quote:

i'm using my laptop, an M-Audio Audiophile usb spdif to the zhaolu dac.

Does the Zhaolu DAC have any de-jitter properties? The Zhaolu seems to be the most popular DAC around here, so I would love to go that route if and when they get the $270 unit back in stock. However, the jitter issue worries me enough that I will probably get the E-mu USB instead if the Zhalou does not have one of the de-jitter clocks.

 

[replytoken]

Quote:

Originally Posted by uofmtiger This may be how audiophiles get into trouble because there is always something coming out that is supposed to be better. Personally, I try to keep my audio expenditures to a level that works for me and if I can get better sound from my computer system for $200 or so, that is the way I want to go. I was just curious why I rarely read about jitter issues on this site when it seems to be a common problem with computer sources. Of course, I have also read that it is difficult to hear jitter, so that is why I was asking the question.

Given the budget you have chosen, and your desire to generally improve your overall sound, I would be aware of jitter issues, but I would not let them drive your decision. Jitter seems to be a somewhat elusive topic, with many suggesed cures. Regardless of what you do, I suggest that you try and let your own ears be the deciding factor.

 

[Mikenet]

I'd advise you to be VERY careful with this stuff. Jitter is a kind of voodoo in the audiophile world. Early studies showed that except for ultra-high levels(that even consumer electronics didn't reach), it was inaudible. Unfortunately they tested random jitter, not the data-correlated jitter introduced in SPDIF. Much smaller amounts of data-correlated jitter should be audible. How much it takes to be audible and what it sounds like are hotly debated. There hasn't been very much study in that area.

The "scientific" tests on different CD-players, DACs, etc have been heavily flawed. The jitter test signals that most people used didn't test specifically for jitter, but for all kinds of distortion. Most of the "jitter" the jitter graphs show is actually amplitude modulation sidebands due to weak power supplies or [in the case of CD players] power noise leaking from the transport into the DAC and amplifier sections. Of course, people started to associate a certain sound with these high "jitter" devices, and jitter became a boogey man.

Since the jitter problem is such a voodoo topic, most solutions also fall into the voodoo category. For example, the ram that was previously mentioned. I'm not going to say that increasing ram doesn't decrease jitter. But it really shouldn't. Assuming correctly written drivers and decent hardware, the computer only has to keep a buffer on the sound card full, and as long as it stays full, the data will be clocked out from an independent clock. Lower machine performance would simply cause the buffer to be filled in larger "chunks", yet the local clock of the sound card knows nothing of this. It's completely isolated. What's a lot more likely to occur is dropouts in the sound. But these aren't jitter, and are very obvious. In reality, I'm sure some bad sound card and driver implementations exist. It's possible that sometime, somewhere, higher system performance increased jitter performance. But it's very likely that it was not measured properly, if it all. When I see it on a proper jitter testing device(I believe Tektronics and others make devices that will measure data and clock correlation as wells as overall jitter) and not on some vague jitter test graph.

Many USB sound devices(do to broken in a popular OS) are designed improperly. In these, the clock is not independent of data. In fact it's derived from the incoming USB datastream. These will highly dependent on system performance and timing. Adding ram may make a difference. If it's for the better, or worse, I can't say.

Just be careful will all this, and understand that well meaning people have been misinformed and will likely try to mislead you. Keep your wits about you, and if at all possible, listen first.

Personally, if I were you, I'd keep it in the back of my head, but not make it the huge issue most make it. If you have the opportunity to get a jitter reducing DAC, or a better USB audio device, go for it. But I personally wouldn't expect a night and day difference.

 

[uofmtiger]

Quote:

Personally, if I were you, I'd keep it in the back of my head, but not make it the huge issue most make it. If you have the opportunity to get a jitter reducing DAC, or a better USB audio device, go for it. But I personally wouldn't expect a night and day difference.

Thank you for the very informative post. The main reason I like the E-mu (which is not out yet) is because they seem to have a great reputation in computer audio. I am guessing that they will implement the "USB ultra low clock" with the same expertise that they put into their sound cards.

At first, I was considering an internal Emu 1212 or 0404 and an external DAC like the Zhaolu. However, when I saw the new USB E-mu coming out, I thought it might be the best choice. I am still leaning that way because it costs the same as the Emu1212 and I can still add an external DAC if I feel something is missing.

I doubt I will have the ability to test it without buying it first. I guess I can buy it, test it and return it if it does not prove to improve the sound I am getting now.

 

[Mikenet]

The E-mu USB device looks like a good all-arounder. Probably a good choice. Plus E-mu has the resources to write custom drivers(as they always do with all their other cards) that would bypass the normal USB jitter issues. And if you want to play with upgrading later, it should make a good basis for comparison.

 

[tschanrm]

Quote:

Originally Posted by uofmtiger At first, I was considering an internal Emu 1212 or 0404 and an external DAC like the Zhaolu. However, when I saw the new USB E-mu coming out, I thought it might be the best choice. I am still leaning that way because it costs the same as the Emu1212 and I can still add an external DAC if I feel something is missing.

You can use an external DAC with the 1212 if you wanted to as well. The main advantage to the 0404 USB is the integrated headphone amp, line/mic pre-amp, external power supply, and what appears to be a main output analog volume control. While you may not get as good of a DAC as the 1212m, I think you get a lot of other useful features.

 

[slwiser]

One of the better threads about jitter:

http://www6.head-fi.org/forums/showthread.php?t=20998

Another more recent one here, very good:

http://db.audioasylum.com/cgi/t.mpl?f=critics&m=24976