I Just Got Flamed In The AudioAsylum!

[JimOfOakCreek]

Someone in the PC Audio forum in the Audio Asylum was bragging about how well his $550 USB cable sounded. He posted the review like a sales pitch for Synergy Cables.

While I repect other people's feelings I couldn't resist explaining that the cable conducts packets of data in the form of hi-speed pulses. I also explained that I couldn't understand how that $550 USB cable could have that kind of impact on the sound.

Holy sh*t!!! A Nuclear Word War 3 flame war errupted. Those people in that group take their cables seriously. I got to stay out of that forum!

 

[Cal Weldon]

Stick with us Jim, we try and snuff out the flame throwers here.

Besides, why do you want to hang out with a bunch of persons that think cables are that important anyway? Especially USB cables. Sheesh.

 

[paulb]

Yeah, their philosophy is that sound has nothing to do with physics.

 

[poynton]

How long is a $550 usb cable ?

Must be made of pure unobtainium at that price.

 

[rdf]

Pfft! Everyone knows LAN cable has a bigger impact on sound. Nothing but Twinax for me!

 

[7n7is]

Could digital cables have an effect on jitter or S/N that would affect the sound quality?

http://en.wikipedia.org/wiki/Jitter

 

[SY]

Only if your CD player or DAC doesn't have a clock of its own in it. Here is a list of all the outboard DACs that don't have their own clocks:

 

[bigwill]

But that's my favourite DAC!

 

[b-square]

Could digital cables have an effect on jitter or S/N that would affect the sound quality?

http://en.wikipedia.org/wiki/Jitter

If the jitter induced by the USB cable is sufficient to cause errors you have a bad cable. Replace it with another $5 jobbie and move on.

 

[andy_c]

Only if your CD player or DAC doesn't have a clock of its own in it. Here is a list of all the outboard DACs that don't have their own clocks:

It's a matter of whether the digital cable in question carries timing information or not. For an ethernet cable connecting a Squeezebox, there's no timing information and so the ethernet cable should have no effect if it's not faulty. Data transfer is asynchronous at that point.

USB is a mixed bag, though. I have the E-MU 0404 USB which uses asynchronous USB mode, so I'd expect the USB cable to have no effect. But most USB audio interfaces don't use asynchronous mode. The poster talking about the expensive USB cable was using one of Gordon's USB DACs, and I don't know what USB mode he's using. I didn't have the stomach to go through that thread to find out. That used to be a great forum, but it's been overrun by the usual audiophile suspects.

 

[SY]

Oh, that's a pity. But I suppose it's the audio version of Gresham's Law.

I wonder how those USB cables would do if a picture of them were put in the freezer...

 

[b-square]

I wrote happy thoughts on my Squeezebox with a magic red marker and the soundstage really opened up! *cough*

 

[scott wurcer]

Oh, that's a pity. But I suppose it's the audio version of Gresham's Law.

I wonder how those USB cables would do if a picture of them were put in the freezer...

Clearly you need to dip that picture into liquid N2.

 

[mako1138]

Like all Synergistic Telsa cables, the USB cable is treated with "Quantum Tunneling". I have included a link to see this process which I experienced first hand at the factory

Oooh, quantum.

By applying a two million volt extreme high frequency signal to a cable at a specific pulse modulation and frequency for an exact duration of time we alter the entire cable at molecular level through a phenomenon called "Quantum Tunneling."

I think I'll market a cable that's processed on the molecular level by an amazing new procedure that I call "Dielectric Breakdown".

 

[analog_sa]

I also explained that I couldn't understand how that $550 USB cable could have that kind of impact on the sound.

You can probably alleviate some of your ignorance with some reading and experimenting.

99% of USB audio implementations rely on an embedded clock and consequently PLL clock extraction. Cable quality is sadly an issue, as it is in spdif transfers relying on the embedded clock.

What exactly is your problem? The specific figure of $550?

 

[SY]

No, the snake oil.

 

[JimOfOakCreek]

Re: Re: I Just Got Flamed In The AudioAsylum!

You can probably alleviate some of your ignorance with some reading and experimenting.

99% of USB audio implementations rely on an embedded clock and consequently PLL clock extraction. Cable quality is sadly an issue, as it is in spdif transfers relying on the embedded clock.

What exactly is your problem? The specific figure of $550?

It's possible I may be ignorant but then it's possible I may have it right.

At the end of the USB cable we have the USB DAC with its clock and a buffer. It would seem to me any timing errors will get corrected in the end.

Even if the PPL is not 100% accurate we have a buffer at the end of the cable. Doesn't the DAC draw the data off of the buffer? Doesn't the DAC simply read the headers on the packets and adjust accordingly? Correct me if I'm wrong.

So how does the $550 cable impact these errors? I'm open minded and willing to learn.

I don't have a problem with someone buying a $550 USB cable. After all it's their money! However, I should be able to post my opinion without a hostile reaction.

 

[analog_sa]

Re: Re: Re: I Just Got Flamed In The AudioAsylum!

At the end of the USB cable we have the USB DAC with its clock and a buffer. It would seem to me any timing errors will get corrected in the end.

I am certainly not an expert in the intricacies of USB audio. One thing is certain though: there is no "own clock" - it is PLL reconstructed clock. And the buffer is not anywhere deep enough.

From what i understand an asynchronous USB implementation works a lot better but most commercial and diy dacs do not use it as the chips require involved custom programming. Not to mention writing a device driver.

I have no experience with $550 cables either. What i have tried are cheap generic cables and yes, they do sound different. As do different USB motherboard chips. What makes me think that the USB audio standard is not that sturdy.

And neither is USB data transfer. Google "USB delayed write failure" and you'll find lots of external usb hard drives do not work as advertised.

 

[JimOfOakCreek]

Re: Re: Re: Re: I Just Got Flamed In The AudioAsylum!

And the buffer is not anywhere deep enough.

That response has always puzzled me. How deep should the buffer be? At what point do errors become irrelevant because all the errors get buffered?

I understand that there is a latency issue with larger buffers. But...if the buffer was large enough to contain 3 seconds of audio that certainly should be enough to buffer ALL timing errors. After all we are talking miliseconds.

A 3 second latency isn't all that annoying is it?

So why don't manufacturers design a 3 second buffer with all USB DACs and the jitter errors would completely disappear, right?

 

[binarywhisper]

I come at this with 18 years in the computer biz.

I think $550 is a tad extreme to say the least but it is no more extreme then using a $5 dollar cable. As is usually the case with most of these issue where we have extremes the truth lies somewhere in the middle.

Data transfer has little to do with timing issues as even a modest buffer is plenty to handle that except in the most extreme cases. The problem is packet corruption and even the largest buffer will not necessarily solve that.

The error correction has improved substantially but the vast majority of USB devices still use correction routines aimed at packets of data, not audio. The difference is obvious to anyone with the training and almost impossible to explain to anyone without.

The bottom line is buy decent cables. I wouldn't use a $5 cable to sync my pda much less play audio. But $550 and quantum tunneling ..damn, thats some funny crap. I guess everyone needs a hobby

edit.........................

I just thought I should come back to this and say a decent good USB cable can be had $30 and I personally would be comfortable using that for data or audio.