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USB cable and Sound Quality - Page 5  

post #61 of 134
Thread Starter 
I went to order a right angle adapter and optical cable last night. Turns out I had put two of the optical cables in my cart instead of one. So now I have one adapter and 2 cables comming.
post #62 of 134
possibly with a DAC that runs from the USB bus's power, I can see the merit of a better cable.
post #63 of 134
Reason is not automatic. Those who deny it cannot be conquered by it. Do not count on them. Leave them alone. - Ayn Rand

(Yes, I admit, I got that quote from the last episode of Criminal Minds )
post #64 of 134
I think there is an different between using a better USB cable, but you might not notice the different or the different is too small for you.
post #65 of 134
just compare the amount of connections in HDMI vs USB (more bits mean more possible bit loss) and at the end, I don't think few lost bits over HDMI would be that bad in a 52" tv or one bit lost once in a while over your USB connection will be audible. It's not like a hiss or something like that.
post #66 of 134
There is a thread on this topic every 3 months or so, it seems.

Summing up previous posts: I did not believe that USB cables made a difference, and voiced considerable skepticism about them on numerous occasions here. I finally broke down and got one (a Monster cable of some sort) just to prove everyone wrong. I subjected it to blind tests on both myself and my wife. Guess what? We could both tell the difference. I then went nuts and spent around $50 on a Cryoparts cable, which in blind tests also proved to be slightly better.

Believe what you want. That is my experience. Blind tests (the only tests I trust in matters such as cables) have proven it for me after a tremendous amount of skepticism on my part.
post #67 of 134
gold tip = prevents/slows oxidation

personally, i'd get something that has just enough length (from my computer tower USB port to the top of my desk, about > 1 meter/4 feet), and perhaps a choke core (EMI/RFI filter). Definitely something that can be gotten for cheap!
post #68 of 134
From this thread: http://www.head-fi.org/forums/f46/us...atters-371033/

Quote:
Originally Posted by audioengr View Post
Since I am an industry expert on the subject of USB audio and electrical engineer with 30 years of digital interface design experience, I though I would set the record straight.

All of you that believe that no errors take place on a USB cable that is proper length (< 5m), are absolutely correct.

On the other hand, all of you that believe that USB cables cannot color the sound of streaming playback are dead wrong, in fact they do. The effect that the cable has is called dielectric absorption and dispersion. This adds jitter to the signal as it is detected at the receiver. Cables with ferrites will actually add more jitter due to limiting bandwidth of the cable, so this is not advised. Longer cables and cables with larger than normal conductor gauge will also add jitter because of skin-effect and losses. The very best sounding USB cables will be short, use Teflon/air for dielectric and use very thin conductors for the signals, properly annealed Silver being the best.

If you dont understand jitter, then you know very little about quality digital audio. Do some searches on the forums and you will learn a lot. Getting quality results from digital audio is primarily about reducing and maintaining low jitter. Second order effects are D/A quality and preamp/analog stage noise and distortion.

Those that claim jitter is a non-issue have never heard a decent digital source IMO. We are all at different levels in our audio quest, but it is good to understand the fundamentals. This way, you know what kinds of things will actually make significant improvements.

Steve N.
Empirical Audio
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Quote:
Originally Posted by audioengr View Post
Dielectric absorption is when the dielectric (insulation) in the cable charges due to the changing signal, but it resists discharging completely. It "holds onto" some residual charge. This can easily be measured with the right instrumentation. This absorption of charge is a kind of electrical "sponginess" of the insulator, like a sponge soaking up water, but does not release all of it when it is squeezed. The effect is that the transient signals encounter a sort of "inertial resistance" and tend to "spread" in time as a result, adding signal distortion and ergo jitter.

This also happens in capacitors. This is why a ceramic capacitor in the analog signal path sounds much worse than a polystyrene cap in the signal path.

As for the USB interface and it's rejection of incoming jitter, this depends entirely on the implementation. Even Asynch interfaces can be affected by incoming jitter. Even reclockers can be affected to some extent, although less so than typical interfaces.

Most of the digital designers, including me, that are convinced that they have finally tackled the jitter imuunity problem end up eating our hats because the problem is still there to some extent. It is one of the hardest nuts to crack IMO.

Steve N.
Empirical Audio
post #69 of 134
Quote:
Originally Posted by myinitialsaredac View Post
Yes I am in agreement that if cables worked properly (perfectly) then a 1 will sound the same through any cable as will a 0. But this is unfortunately not so.
But if the USB cable can't work properly, how can a USB harddisk work without fault ? Because if a single bit of data(0/1) error, then all the rest of the following data should be wrong ?
post #70 of 134
Looks like the exactly same arguments bouncing back and forth.

Yes, a cable can make a difference, digital or analog. Yes, it does send 1 and 0 (actually, it send waves of existing or non existing signal, voltage). That wave is interpreted into 1 and 0. Since almost all USB audio is streamed, it must arrive at a perfect time (quite fast and very precise). When it does not, it is called jitter - a timing irregularly that forces the receiver to work outside of perfect conditions which obviously degrades its performance. Simple enough?

As all of the ways to ignore/prevent/fix, whatever, I'll leave that up to you to figure out.
post #71 of 134
Quote:
Originally Posted by FallenAngel View Post
Yes, a cable can make a difference, digital or analog. Yes, it does send 1 and 0 (actually, it send waves of existing or non existing signal, voltage). That wave is interpreted into 1 and 0. Since almost all USB audio is streamed, it must arrive at a perfect time (quite fast and very precise). When it does not, it is called jitter - a timing irregularly that forces the receiver to work outside of perfect conditions which obviously degrades its performance. Simple enough?
great summary
post #72 of 134
The only way it could be true is if USB hard disks (etc) have error correction while USB DACs don't (due to latency?). I still don't believe colouration of the types suggested in this thread is possible.
post #73 of 134
Quote:
Originally Posted by FallenAngel View Post
Looks like the exactly same arguments bouncing back and forth.

Yes, a cable can make a difference, digital or analog. Yes, it does send 1 and 0 (actually, it send waves of existing or non existing signal, voltage). That wave is interpreted into 1 and 0. Since almost all USB audio is streamed, it must arrive at a perfect time (quite fast and very precise). When it does not, it is called jitter - a timing irregularly that forces the receiver to work outside of perfect conditions which obviously degrades its performance. Simple enough?

As all of the ways to ignore/prevent/fix, whatever, I'll leave that up to you to figure out.
Thanks for the summary.

So, in a hypothetical situation. If the DAC has a large enough buffer, then it can store up (maybe 1-2 second) of audio, so if the jitter occurs, it can use the buffer and fix the problem. Considering USB 2.0 has a bandwidth of 480Mpbs, it shouldn't be a problem in terms of bandwidth.
So anyone know if any of the higher end DACs has this function? If so, then we can use a less than perfect cable?
post #74 of 134
Quote:
Originally Posted by brandnewgame View Post
The only way it could be true is if USB hard disks (etc) have error correction while USB DACs don't (due to latency?). I still don't believe colouration of the types suggested in this thread is possible.
I think USB hard disks do have error detection and correction (at least it's not hard to implement one, while it is extremely valuable). All you need to do is to have a CRC or some checkpoint, and if it fails, then you can resend the data. But DAC can't really do that because you need the data in real-time. That's the main difference between the two.

The jitter part makes sense to me, but I believe that's the only reason for colouration.

If I'm wrong, feel free to correct me =)
post #75 of 134
Yes, there are buffers on the DACs except they are never 1-2 seconds long, they are usually tiny, storing milliseconds.

Properly implemented buffering (and better yet, having a dedicated receiver which will store data, check for errors and correct them before sending anything to the DAC) would eliminate jitter from that transmission; but that still leaves the data being sent from the digital receiver to the DAC. This shoud be done in I2S and which runs off both the word clock and the serial clock and makes it a lot better for data transmission.

Yes icebird144, if you use a buffer or simply sent data faster than needed (to make up for error correction overhead) with the DAC buffer understanding this, you've found a good way to solve the problem and you not only don't need a good cable, you barely need a good transport, in comes the $30 ChainTech AV-710 which with a good DAC will sound just as good as a $1000 CD player.
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