KIMBER KABLE: Do High-end USB Cables Make A Difference?

[SIY]

Don't get me wrong, audiophile USB cables have always made no sense to me. But wouldn't it be a fair comparison when you do have a problematic case to see if this cable can help resolve that problem? Sure spending $55,- more on the DAC would be a more logical conclusion but at least that could give this cable the opportunity to show some improvement if there's any.

If your car won’t start, do you check the air in the tires?

 

[tomtoo]

If your car won’t start, do you check the air in the tires?

Uhh, watch out. Maybe some modern car's wont start without air in the tires.Ask the Bordcomputer.

 

[DualTriode]

Hello All,

I get a bit of humor out this.

It is a bit like looking into the looking glass.

The test results will never get any better than the quality of the $6.51 TRIPP-LITE USB cable that came in the box with the APx analyzer.



Thanks DT

 

[martijn86]

If your car won’t start, do you check the air in the tires?

You have no idea how on point you are. My car died monday and I've just came back from buying a new one. Other than that, I just feel like this is marketed as a cable that fixes problems that aren't there in this test to begin with. I'd put my money on this cable still making no difference (you know, like the air in your tires if your engine won't start) but the Chris Connaker's of this world may still claim that there's nothing to fix in this scenario.

 

[imagidominc]

My USB is made only of the highest quality unobtainium and angel tears. You would not BELIEVE how wide it opens the soundstage.

 

[Spocko]

If your car won’t start, do you check the air in the tires?

Nope, I open and close the glove compartment!

 

[cjfrbw]

Amir's measurements are clearly deficient. He forgets the 'magic pixie dust' suite every time.

 

[tomtoo]

The programmers in here should think about the 'subjektive' add on for @amir's meassurement equipment. Driven by a KI.
Big market!

 

[laudio]

A review that confirms common sense. Like it!

 

[HLee]

low-end USB cable might be able to make any differences

 

[Deleted member 2944]

If your car won’t start, do you check the air in the tires?

If you piss on the trunk lid it might start.
Dave.

 

[SIY]

If you piss on the trunk lid it might start.
Dave.

Electrolytes!

 

[smprather]

@amirm "It is the job of the DAC to be immune to that noise, jitter" I designed the Cypress (RIP) FX2LP USB2 receiver block. It is the phy's job (part of the DAC unit, but not part of the DAC per-se) to be immune to jitter (the "receive eye"). These serial protocols are spec'd such that if each piece of the chain meet spec (as any USB2 cable that costs more than $0.25 will), then yes, bits are bits. If jitter is bad enough to cause reception errors, then the loss in sound quality will be hugely non-linear. Ie, as you slowly increase jitter, music will go from sounding perfect, to very suddenly, pops, drops and all other manner of badness. The music won't slowly and gradually sound worse. You're a scientist Amir. Please don't (even accidentally) contribute to Audio Bullshit(tm). I love everything you do, but you missed the mark on this one a little by hedging when no hedge was necessary.

 

[amirm]

@amirm "It is the job of the DAC to be immune to that noise, jitter" I designed the Cypress (RIP) FX2LP USB2 receiver block. It is the phy's job (part of the DAC unit, but not part of the DAC per-se) to be immune to jitter (the "receive eye"). These serial protocols are spec'd such that if each piece of the chain meet spec (as any USB2 cable that costs more than $0.25 will), then yes, bits are bits. If jitter is bad enough to cause reception errors, then the loss in sound quality will be hugely non-linear. Ie, as you slowly increase jitter, music will go from sounding perfect, to very suddenly, pops, drops and all other manner of badness. The music won't slowly and gradually sound worse. You're a scientist Amir. Please don't (even accidentally) contribute to Audio Bullshit(tm). I love everything you do, but you missed the mark on this one a little by hedging when no hedge was necessary.

Glad to see other designers joining our forum.

As to your comments, what you say is only true at subsystem level, not the entire device (DAC unit). Due to shared power rails (or at least ground) and capacitive, inductive and magnetic coupling, what goes on in the USB subsystem can indeed bleed into the DAC and show up all the way on its analog output! The DAC chip clock and reference circuits can easily be polluted for example, and generate 100% correlated jitter/modulation products with the data that was fed to the DAC.

Even when eliminating the DAC, we can see this effect. Here is an example of a couple of USB to S/PDIF converters. I fed them both digital streams comprised of the j-test signal over USB. This is the results:

The J-test signal has two nested squarewaves in the form of PCM samples. The larger signal runs at 12 kHz and the smaller one at 250 Hz. We clearly see a peak at 12 kHz for both USB to S/Pdif converters. We also see an array of sidebands likely created by the 250 Hz sub squarewave.

In both of these cases the data was extracted correctly from USB interface so that jitter is not material. What is material is that the incoming digital stream has bled into the S/PDIF outbound clock. This is not good as correlated jitter is more audible than random jitter (although in above example is not material due to low amplitude).

Here is an example of a DAC telegraphing the same interference now onto its analog output:

So what looks like isolated subsystems on paper, when merged into a practical DAC (unit) implementation is anything but. Audio, despite its low speed, has incredibly dynamic range with 16 to 24 bit samples. This puts huge requirement on auxiliary circuits around the DAC chip to be quiet.

A very well designed DAC has high immunity to such cross-coupling and hence my comment.

In addition to all of the above, unless the USB bus is galvanically isolated, the shared ground with the PC happily pulls the noise on that connection and feeds it through on the ground side of the RCA connector on the output of the DAC. This is why one hears the PC activity in some systems.

In summary, as long as we are dealing with analog output of a DAC, or timing variations on a digital interconnection which by definition is analog in nature, bits are NOT bits. The system is mixed-signal and has to deal with digital+analog. Digital-only analysis does not suffice.

 

[Tks]

Amirm, I think the high end wire fanatics are on their way to pay you a visit....

.View attachment 48741

Not without an entry ticket they ain't. That being double blind test results.

 

[wwenze]

Maybe we need to do it the Mythbusters way: If a myth is busted, modify it until it becomes true.

For a start I'm pretty sure the USB2.0 wires between the header and the chassis front panel is not impedance-matched. How long can we extend it with crocodile clips before the connection breaks? Best part is anybody can do this without an APx555

 

[gfx_1]

Maybe we need to do it the Mythbusters way: If a myth is busted, modify it until it becomes true.

For a start I'm pretty sure the USB2.0 wires between the header and the chassis front panel is not impedance-matched. How long can we extend it with crocodile clips before the connection breaks? Best part is anybody can do this without an APx555

USB cables can't be too long, you'll need repeaters for the long run but at work we used them in the past to just for a keyboard and mouse (and a long VGA cable) but it didn't work reliable. High speed USB cables must be shorter. I did some testing with a real cheap USB DAC print and a longer cable from behind the computer but that introduced audible noise, short cable from the monitor hub was allright.
Some USB cables are poorly shielded when using an USB3 external disk wifi dropped during transfers on a Surface pro 4.

 

[AudioTodd]

This company also thinks unshielded RCA cables are a good idea and charges quite a high price for some of them. Lots of suckers out there that buy this crap I guess.

Yeah. I was hooking up a temporary system with some spare equipment a couple years ago and got horrible noise problems. I even contacted the manufacturer of the DAC/Preamp/Headphone Amp I was using whose staff was too busy getting ready for AXPONA to be of immediate help. That was lucky for both of us I guess, as I then realized I was using a pair of Kimber Hero interconnects. When I switched to pair of Blue Jeans Cable interconnects the noise vanished.

Those Heroes were widely recommended back when I bought them. I could never understand why, but thought I’d give them a shot even though I have never heard a deference with wire and didn’t believe in such things to begin with. I have a few vintage pairs in various lengths for sale if anyone is interested!!!

 

[phoenixdogfan]

This reminds me of 2 different friends who said they noticed the difference in sound when their audio cable was connected in the reverse direction when they moved home.
They said something about electrons aligning the cable molecule structure and.....

That cuz electrons are in a crystal structure and have a grain, when you reverse the cable, you're going against the grain, don't you know.

 

[Simer]

Dear Lord you are the Houdini of our times.