[leeperry]

And you should know that "what I hear is truth" doesn't fly in this section of the forum. You know, I can tell the difference between USB hubs too. The ones I use on my computer now all seem to have a warrior drum playing faintly in the background, while the other ones didn't have it. Don't tell me its not there, cause I can hear it. 

I believe you, yo!
 
The science side has been thorougly discussed in the previous pages, those threads feel like an endlessly broken record. If you've compared a lot of cables -IRL, and preferably on an adaptive transport- and if they all sounded the same to you, then life is good. Go out and have fun, life's too short.

 

[Yoga Flame]

 
Quote:

There is no way you can hear the difference between usb ports.
Also unless a usb source is broken all dacs will work perfectly with them.
 
I don't understand why people seem to think that usb cables/ports would effect the bass or soundstage.
It is undeniable that usb sends 1's and 0's, so it is ridiculous to assume the signal is being distorted in a way that only effects certain elements, it's just impossible.
 

 
I can attest to USB ports making an audible difference in some situations. Many computers have USB ports located in the front of the case for convenience. When I listened to a mini USB sound card plugged into this, the noise floor was much higher compared with the rear USB port.
 
Often, these front ports are wired to the motherboard or internal add-on USB card with plain hookup wire. These unshielded wires pick up a lot of noise and pass it on to whatever gets plugged into the USB port. The noise may not be bad enough to distort the 1s and 0s, but it can still get into the analog circuitry of the DAC. That's why galvanic isolation is desirable, amirite leeperry 

?
 
Another situation is when one USB port has power filtering and regulation and another just uses the onboard rails directly. This can make a difference with DACs that draw their power from USB. But well designed DACs with ferrite beads and built-in regulators should be affected less by this.
 

 

[endless402]

Quote:

There is no way you can hear the difference between usb ports.
Also unless a usb source is broken all dacs will work perfectly with them.
 
I don't understand why people seem to think that usb cables/ports would effect the bass or soundstage.
It is undeniable that usb sends 1's and 0's, so it is ridiculous to assume the signal is being distorted in a way that only effects certain elements, it's just impossible.
 

you're not accounting for the quality and stability of the power coming out of the port (especially if the device is powered by the port)

 

[tmars78]

Quote:

you're not accounting for the quality and stability of the power coming out of the port (especially if the device is powered by the port)

Yeah, but what they are saying, is that that would not affect treble or bass. It would be pops and clicks, or drop outs. 

 

[chinesekiwi]

All said and done, the quality of the power supply, whether it be from mains or a power supply like in PC setups with soundcards, is far more important and has more of an impact than than 'audiophile usb cables'. Not to mention operating systems with the KMixer in Windows XP and before.

 

[drez]

Quote:

There is no way you can hear the difference between usb ports.
Also unless a usb source is broken all dacs will work perfectly with them.
 
I don't understand why people seem to think that usb cables/ports would effect the bass or soundstage.
It is undeniable that usb sends 1's and 0's, so it is ridiculous to assume the signal is being distorted in a way that only effects certain elements, it's just impossible.
 

I think a common tendency is to presume that these systems are much less complex than they are in reality.  Sure glitches are the most immediately obvious form of audible artifact from a digital signal transport system, but USB audio is (generally) not bulk mode transfer.  Digital audio is typically 44.1khz, correct me if I'm wrong but as far as I understand this is 44100 samples per second.  Jitter comes in a range of magnitures and types, so the distortion (jitter has different possible effects on different parts of the system) might be as low as 1/44100 of a second second or much larger depending on the effect of the jitter and is not necessarily manifest as a dropout.  Think of mp3 compression - a bad (high jitter) digital signal can effectively reduce the resolution of a digital signal (best analogy i can think of).  A lower resolution mp3 doesn't dropout or glitch consistently, the audible result is subjectively much more varied and inconsistent, even with large differences in resolution.  Having good dac and transport goes some way toward reducing the the audibility of these effects.
 
There are a few interesting, if not entirely unbiased  discussions of the effects of jitter on DAC systems such as here, here, or here.  Note that none of these should be considered reliable sources as they are likely influenced by trade sponsors.  I also should not be considered a reliable source as I am an architect and not an electrical/sound engineer.
 

 

[leeperry]

I think a common tendency is to presume that these systems are much less complex than they are in reality.
 

It's all a bunch of zeros and ones

 
Anyway, a friend of mine just ordered a top of the range async transport, I'll put it through the cables test...hopefully, they'll all sound the same this time.
 

 

[Prog Rock Man]

Quote:

There is no way you can hear the difference between usb ports.
Also unless a usb source is broken all dacs will work perfectly with them.
 
I don't understand why people seem to think that usb cables/ports would effect the bass or soundstage.
It is undeniable that usb sends 1's and 0's, so it is ridiculous to assume the signal is being distorted in a way that only effects certain elements, it's just impossible.
 

There is a way people can hear a difference between USB ports, there are too many credible reports of sound quality differences to say that is not the case. The real question is why are there sound quality differences.
 
I too do not understand how a USB cable can affect bass or sound stage. I don't think those who hear differences do either. I am also in the it either works or it does not camp. So are this lot and they should know........
 
http://www.usb.org/home
 
I would love to see an audiophile USB cable maker submit a cable for testing and peer reviews of their claims of enhanced sound qaulity. Even an endorsement by USB.org of such would be a start.

 

[maverickronin]

Quote:

There is a way people can hear a difference between USB ports, there are too many credible reports of sound quality differences to say that is not the case. The real question is why are there sound quality differences.

USB power is pretty noisy and I can easily see it being different from port to port even on the same computer which could effect the sound if the isolation, smoothing, or PSRR on the DAC side isn't up to snuff or that USB port just happens to suffer from an unholy amount of noise which is enough to even overwhelm a good design.
 
Unless a boutique USB cable has power smoothing caps or some other fancier power smoother built in it won't do jack about that either though.

 

[uelover]

I have an USB isolator coming its way and I will see if that will nullify the need for a 'good' USB cable/port.

 

[Talos]

 
Quote:

USB power is pretty noisy and I can easily see it being different from port to port even on the same computer

 
And not just the power...  The data signal transmitted from a USB port consists of a waveform that the circuitry on the other end is going to try and interpret as a series of ones and zeroes.  If the signal is "clean" then that process should be quite unambiguous.  But if the data signal itself is "dirty" or "noisy", then you can imagine how that introduces complications into the process.  Ignoring for the moment what the the sonic consequences of any such "noise" might be, or just how much "noise" in the data signal is necessary for its consequences to be audible, there exists sophisticated equipment that electrical engineers can use to observe and quantify this "noise".
 
Although I have not seen it myself, a friend with substantial credentials in the industry (he designs DACs, not cables!), who has done such measurements, has confirmed to me that there are some very significant differences between computers, and even in some cases between individual USB ports on one computer.  FWIW, he mentioned to me the Macs generally have very good, clean, USB ports.  I happen to use a MacBook Pro, which he tells me is very good, so I'm happy.  Also, FWIW, he tells me that most "Audiophile" USB cables do not appear to offer any measurable differences over standard cheap data cable,although there are a small number that do.
 
My own experience - which was very much contrary to my expectations - was that a Nordost USB cable totally blew away a (relatively) high quality data cable, to the extent that I questioned whether the demonstrator was pulling the wool over my eyes.  But I bought the cable, and can easily replicate the results on my system at home.  Make of that what you will...

 

[skeptic]

Quote:

 I bought the cable, and can easily replicate the results on my system at home.  Make of that what you will...

Any chance you'd be willing to run diffmaker and post the results?  It is freeware: http://www.libinst.com/Audio%20DiffMaker.htm
 

 

[Rdr. Seraphim]

So, what power is being supplied between a computer and an externally powered DAC--e.g. a MacPro and a Wyred 4 Sound DAC--via the USB cable? I can understand a USB port providing power to and external USB HD. However, it doesn't makes sense for an AC powered DAC to need power from the USB port. In that case, is the DC from the USB port unused? 

 

[kr0gg]

as i've read DC line is needed for PC in order to recognize any device.
so even though it might not be actually used while working it is necessary to have it connected.

 

[Talos]

 
Quote:

Any chance you'd be willing to run diffmaker and post the results?

 
I'm not sure that would help here.  You are talking about the cable that connects my PC to my DAC.  I have no way to get the DAC's output back into the computer to digitize and compare.  I suppose I could run a cable with RCA's on one end and and a Mic jack on the other, from my DAC to the Mic input on my PC and digitize that.  The problem with that approach is that the sound quality would be seriously degraded by the analog input and D/A stages of the computer.  Those degradations would be (and say this in expectation, not, to be honest, having actually done it!) significantly greater than the differences induced by changing the USB cable.
 
Or am I missing something?....