Replacing my ancient Hifi – er……helllp!

… and is being revived to be done to death again, it seems…

it’s safe to assume that the “USB” cable mentioned was being compared against another “type” of “USB” cable

No it isn’t. USB is a standard. there are iterations of it to increase the data throughput but USB 2.0 is perfectly capable of transmitting far larger amounts of data than any current conventional codec would require.

Bear in mind that USB transmission speed are measured in MB/s (about 35 MB/s for 2.0). A flac conversion of a CD rarely exceeds 1200kb/s. Quick back of a fag packet calculations make me think that you have about 30x redundancy in USB 2.0. You could effectively stream 30 separate CD’s across a USB cable before it started bottle necking and affecting the sound quality.

They are comparing like with like and are making a complete hash of it. They sound like ******* idiots to anyone who has even a minimal knowledge of data transmission protocols.

I was particularly fond of this comment from the user comments section:

The missing detail is also a concern, is it possible that the data missing was absorbed by the metal artifacts in the internal construction of the cable?

Oh my sides, it is too good.

I’m going to bite 🙂 I’m not for one minute saying that What Hi-Fi are good at reviewing, or that they really heard those differences, or that a posh USB cable is a good investment. I agree that it was probably total rubbish but…

Even though bits are bits, error checking, etc, etc… DACs are incredibly sensitive devices. Any interference from a nearby cable, computer, etc is probably going to have some effect. You’ve basically plugged in an aerial to the device.
I think that the manufacturers of ‘audiophile’ DAC cables aren’t going to suggest that it communicates better data*, etc. Just that it’s going to do less harm in terms of EM and RF interference.

Of course, there are a lot bigger problems to eliminate first, for just about everybody, but that wasn’t the point I was trying to make.

* of course, some probably do and they should be laughed at.

Haha those what hifi reviews read like the bike radar C456 reviews……….. What is this piece of shite I’m riding…

I’m a bit confused – was there only one cable being used? If the reviewer heard a degradation in performance using the cable, what was he comparing it to?

Torminalis 1:

If you use a cable that is below the standard then it is not USB. It is a bit of wire with USB connectors.

Torminalis 2:

No it isn’t. USB is a standard.

So – can you get USB and “USB” cabling, or not?

PS: The review isn’t available, but as the product is called “Silver Line USB”, I guess it’s one of Torminalis’s “It is a bit of wire with USB connectors.”, yes?

Bump. You there, T?

Dunno why that review isn’t loading directly from the URL but it’s still there if you browse from the home page.

Home > Reviews > Audio Interconnects (digital).

Fourth one down.

You could stick a USB connector on either end of a gibbon but it would not be a USB cable was my point. I would be very surprised if anyone manufactures things that have USB connectors that are not USB standards compliant.

As for RF interference and shielding, this is where I start to get hazy because I am a programmer and not a physicist or an electronic engineer. I believe that the majority of RF interference would come from the power supply and most DACs have a separate (usually external) power supply with varying degrees of shielding. The bus at the DAC end will only pick up interference if there is a design problem I thought? It should be sufficiently isolated that interference would not make it as far as the actual DAC components. If anyone here can give a definitive answer I would be very interested to hear but for now, I am still happy to say that a USB cable is possibly the least consequential component in any system assuming it meets the requirements of the standard.

Not hugely detailed, is it.

It seems that there are various types of “USB” cable available, then…

I would guess that the cable was being used in comparison with their favoured model (although they don’t say what it is).

Doing so, they obviously think that the review type offered a degradation of sound, in a AB comparison.

So – I don’t see (apart from the claim that you can’t hear differences between cables) why this is risible?

Even Torminalis seems to agree that there is a difference between “proper” USB and “a bit of wire with USB connectors”.

You could stick a USB connector on either end of a gibbon but it would not be a USB cable was my point.

And a comparison between your “proper” USB cable and a double-ended gibbon would show up as a difference in audio performance, was mine.

eh Woppit – what’s your argument? He’s agreeing with you. But that isn’t what What Hi-Fi are saying, they’re saying that they can tell the difference between every USB cable they’ve tested!

At least this one tells us what DAC they’re using and which cable they’re comparing it to.
http://www.whathifi.com/review/wireworld-ultraviolet-5-usb

Well, I guess if you fancy trying it, most hi-fi shops will lend you one to try for yourself in your system.

USB is a standard. A cable will either meet it or it will not. If it doesn’t meet it then it will not be manufactured. The double ended gibbon is a construct of this debate and does not actually exist in the real world.

Even if your hardware exceeds the minimum resistance/capacitance/impedance the transmission software that governs encoding and decoding of the data will not allow you to exceed the performance. The only way you are going to significantly degrade the quality of a USB connection is to run cables that are too long.

I am pretty confident that there is no one in the world that would be able to tell the difference between a £2 cable and a £2000 cable, assuming they both met the USB standard.

Then I must have misunderstood:

You kill me Woppit, you really do. A triumph of marketing over actual tech. Have you ever heard of a bit parity algorithm?

I have heard the difference between cables, so I’ve no problem with the concept (please let’s not start that argument all over again).

So from that POV, I see no problem in that aspect of the review.

It’s the lack of information about the test itself that I find poor. Just a sort of “take it or leave it that’s all your getting”. But at least it wasn’t a page and a half of gibberish from Alvin Gold… 😉

http://www.usb.org/developers/compliance/ if you’re interested Woppit.

So – I don’t see (apart from the claim that you can’t hear differences between cables) why this is risible?

Because USB cables carry bits (encoded as voltage transitions) and the relationship between those bits and the actual audio waveform that they represent is very indirect. If the cable connection is rubbish enough to cause bit errors then it’s going to have very different and much more obvious effects on the output sound than the subtle tonal and rhythmic ones they’re claiming.

The only vaguely plausible idea that’s been offered is Alex’s – analog signals off the cable (either the actual intended USB signal, or RF interference, power supply noise etc picked up uinintentionally) leaking into parts of the DAC circuitry where it’s not supposed to go. Parasitics in analog and mixed signal systems can have insidious effects. But that’s an issue in the DAC design and its what you pay hardware engineers to get right – after all the USB signal itself is far stronger than anything that’s going to piggyback along on it.

USB is a standard. A cable will either meet it or it will not.

Oh, I think I see what you’re saying. All the cables reviewed as “USB” are USB because they have to meet performance standards, whatever materials or construction methods are used, is that it?

Yes, that’s what he’s saying, see the link I posted above for the actual compliance schedules.

Not that it’s a particularly difficult thing to make a USB cable that works – the tests are mostly about interoperability of the devices you’re connecting.

Gotcha.

(As in – I understand, not – You’re a sunk ‘Argie’ submarine and I write for a scuzzy rag owned by an improbable Aussie Pensioner).

Back to non USB chat… old mate of mine has some nice cheap tannoy kit in just now
http://www.facebook.com/thehomecinemacentre
Sub and some bookshelfs http://www.thehomecinemacentre.co.uk/index.php/special_offers/promotion/i.us_i700_light_oak/

I’m being very entertained by this USB ‘audio quality’ nonsense. I wonder if anyone has done back-to-back audio comparisons of fibre-optic connectors, and deduced that a really expensive one is better than a cheap one because the glass is from Stuben or Swarovski?
Hmmmmm, someone seems to think price makes a difference to sound quality:
http://www.bestcovery.com/best-digital-optical-audio-cable-toslink