USB cable and Sound Quality - Page 28  

R: USB cable and Sound Quality

I use sennheiser hd 800 and odac + o2amp.
I had more expensive amp and sell it now.
I don't have expensive usb cable, but I have a lot of usb cable and tested it.
The synergy concept is basilari to set up good sounding system.
Actually with odac + o2amp + hd 800 I have the best synergy with a Sony top camera usb cable with ferrite near odac input.
The sound of hd 800, anyway very good, now is magic to my ears.
But if I put a low impedance headphone in this system I have bad. bad sound.
This is my subjective experience.
Any system is different, but try different usb cable don't cost nothing. and you could be a surprise rear the corner.
I don't need abx test to know that Sony usb cable is the best. It is clearly the best in that particolar contest.


Pardon my English.



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Edited by gattari - 9/12/12 at 2:30pm

Thanks... And how are the usb cables affecting the sound: signal drop outs, hissing, better cleaner bass, more tremble detail? In other words, can you describe what aspect of the sound is being changed with the usb cables you have so far tried?

R: USB cable and Sound Quality

In my case the response on upper high frequency are changed, more rounded, and at same time detailed not anymore little harsh, but in general the music was more enjoyable to listen to.
I am very happy for result, I repeated the test and the result was the same, Sony cable was clearly the winner.


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Edited by gattari - 9/12/12 at 9:52pm

I have several USB cables, and can't say I have ever experienced a change in the high frequencies. I have experienced audio drop outs due to poor contacts, but that's about it... at least with my equipment, and it seems you have some pretty decent equipment yourself.

 

Have you done some blind tests? Also, It is possible to perceive audio different if your brain/ear has acclimated to your headphones (the HD800 has been described by some as relatively bright...)

A faulty digital cable can't create an overall coloration to the sound. There has to be some other cause.

If any USB cable is going to affect SQ a ferrite like that on a camera cable is probably a much more significant differnce than between typical construction USB cables.  How it may or may not do so, or whether it does or not is a matter of speculation, and based on the technical understanding of the technology and research in the area one would not expect any effects between perfect function and audio dropouts.

 

I have my own theories about how a USB cable *might* affect the actual sound reproduction, but as I am not an expert in the field this will probably not be all that useful to everyone.  If we were to look at what a ferrite might do to the USB signal, it would have an influence over signal propagation and risetime, the magnitude of these differences on their own would be pretty small and as previously discussed individual samples cannot possibly be sent at the requisite sampling frequency so a number of samples must be sent in a single transfer packet, which makes it even more difficult to predict that there should be an audible influence over the music playback.  The ferrite *might* also be suppressing noise on the digital signal and +5V lines - the noise *shouldn't* be an issue as the USB tranfer uses differential signalling which should effectively reject common mode noise.  My guess is the only way a USB cable could possible affect audio playback is by affecting the hardware buffer being used on the USB DAC/transport.  Whether or not one accepts this hypothesis would depend on whether or not one believes that buffer size can affect USB audio.  In my own experiments I think that I can detect a difference between massive changes in buffer size in the playback software eg. 0.05 seconds compared to 1.0 seconds, but I have not done blind tests to back this up so for the sake of scientific certainty and logical positivism this would not be considered evidence, or for some of us here not even real.

 

Personally I would not want to do blind tests rapidly switching out USB cables while the computer is switched on as device manufacturers generally do not condone this and suggest turning off the computer first.  Either way though a blind test would be no different than a sighted comparison save for the additional mental load of trying to figure out which is which and what to listen for etc.  Buffer size would be easier to do but would require an assistant.  Either way a blind test is a good way of bringing grandiose claims about "night and day differences" back to earth and showing that in reality the differences are not so night and day.  Having said this I wish I still had my $300 Audiophool USB controller card as that was clearly different to the motherboard USB ports, but also clearly colored and not in any way technically superior, but I sold that one off long ago and spend the money on something more useful.  In that case thought I observed an overall coloration of the audio, but no dropouts at all.

 

Suddenly I'm getting dirty ideas about new audiophile products, a USB cable in particular.

 

Put a USB receiver (slave I guess), a DSP, and a USB transmitter (master) inside the cable, all powered off the USB bus of course.  With those thick audiophile cables, you might be able to hide the chips along the length or more likely, inside one of the beefy plugs.  Have the USB receiver get the data from the source, pass it to the DSP, have the DSP apply an EQ to roll off the highs or apply some secret sauce filter, and pass that output to the USB transmitter.  (Maybe you need a microcontroller as well?)  Of course, this USB "cable" is directional.  

R: USB cable and Sound Quality

Well, today I have buy a ferrite and apply it to another cable, and yes, the result is the same as Sony camera cable.
At this point I strong raccomand to any odac possessor to experiment an usb cable with ferrite. This approach, for my experience, is a step up very important and clear for the overall quality reproduction of odac. Anyone have an explanation for this?
It is not a small step up it is a very clear step up.
Ciao

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R: USB cable and Sound Quality

I am curious if anyone with different dac try this little mod with ferrite to connect the usb cable with dac.
I know ferrite

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My only guess is that noise is coupling to your ODAC through the USB cable, and somehow the ferrite takes care of that. But AFAIK the ODAC uses quite a bit of filtering and split power supplies to get around this issue... It might be a faulty ODAC build...
 

 

I have... When using my HeadRoom's Total BitHead and could not tell the difference when using it out of my Dell 1505 and HP laptops FWIW.

R: USB cable and Sound Quality

Somewhere, I reading that jds lab include an usb cable with ferrite.
Perhaps this is a reason for this.
Mine is an ephipany e-DAC.
Definitely ferrite help much more than I aspect.

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What does this mean?

From usb_20.pdf found here: http://www.usb.org/developers/docs/usb_20_071012.zip

Page 142:
"Use of ferrite beads on the D+ or D- lines of full-speed devices is discouraged."

Page 143:
"The use of ferrites on high-speed data lines is strongly discouraged."

I was always under the impression that ferrite beads were used on substandard cables, but that on cables that are fully compliant with the USB 2.0 spec, they are not needed (and perhaps discouraged?)

I was also under the impression that a ferrite bead is a choke - a passive low-pass filter. They are used to eliminate EMI/RF noise. I was also under the impression this noise is well beyond the audio frequency range. How that would affect the audio encoded in a digital signal without also affecting the digital signal itself is beyond me.

Personally I don't like ferrite clamps, I tried a bunch of different applications a while ago and found in each instance the effects were damaging to SQ.  IMO ferrites are an easy way to colour the sounds and make a discernable difference to the SQ, and given how subjective musical tastes are some people will hear the difference and call it an improvement.  It is way easier to make a bad USB cable than it is to make one that makes a difference through improving signal transfer.  

 

A ferrite bead is like an inductor, except at high frequencies (also depending on model type, construction) the impedance is both high and also mostly resistive.  i.e. most of the energy in the high frequencies gets dissipated.  As you say, if it's in series with the load, you're thus lowpass filtering the signal so the load doesn't get as much of the high frequencies.  The data lines in USB are carrying high-frequency signals.  You don't want to lowpass filter them (out) if you want the other side to actually get the signal.

 

The ferrite bead is for filtering the +5V (supposed to be DC) line.  The filtering is both for keeping the crud from the source out of the destination and vice versa.  Or from other RF sources, though of course computers have plenty of high-speed clocks and switching devices already, even before you consider the actual radios.

 

The concern is with the RF noise getting into the DAC and affecting the D/A.  These devices perform better with cleaner power.  Noise at RF frequencies matters because... wait, somebody else better explain this to me too.  That said, most DACs are oversampling or otherwise performing actions at frequencies much higher than audio, prior to the output reconstruction filter.

 

To be honest, electronics and RF/EMI issues are way out of my specialty...