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Audio/Video Hardware => Digital => Topic started by: christowp on February 20, 2017, 11:32:55 AM

Title: USB cable - not a cable thread
Post by: christowp on February 20, 2017, 11:32:55 AM
Just saw this while browsing DAC stuff. Not sure similar debates have raged here already but I just found it interesting. The rest is copied / quote 


I emailed Tom (Focusrite Technical Engineer) who had posted on another area of this site and asked him whether or not a usb lead could have an affect on the sound quality of the 2i4. He sent the following email back to me....

Hi James, (not me)

Digital cables, such as USB cables, do not suffer the same kind of 'difference in quality' that can be seen to a certain extent with analogue cables. A USB cable either works for its intended purpose or it doesn't. While cable failures may differ slightly in their nature, there is not any difference in 'sound' between USB cables as there is between some analogue cables, there can not possibly be if you take into account how these systems actually work.

Some USB cables may work in a particular situation where others fail, but this is down to different factors - and again, it will work, or it won't. For example, using particularly long USB cables with audio interfaces will sometimes cause them to loose connection with the host controller. In some cases, a longer cable will mean that the unit completely falls off the bus (i.e. it appears as though it's not plugged in).

There are some exceptions in which the data stream is intermittently corrupted by the time it is received. This will create audio dropouts (moments of complete silence) or pops and clicks etc. at best, and can not possibly be mistaken for the differences of quality seen in the analogue domain.

A 'High Quality' USB cable is merely one that is built to withstand more physical abuse and perhaps at best can handle slightly longer cable runs. They also may include a 'choke', like our cables do, which offers protection from HF interference to clean up the data stream. Do not confuse this for audible interference, it simply ensures that data is more likely to arrive at its destination intact, if it does not, then the unit will simply fail as stated above.

'The sound' comes entirely from the components used in the unit, particularly the preamps and AD / DA converters. At the point the USB cable comes into play, the signal is digital and will therefore be received correctly at either end, or not.

This same principle applies to other digital cables as well, such as S/PDIF etc. They either work, or they don't. If you would like further verification, you could run units through a dScope or similar test equipment to verify this. But that is quite unnecessary! Let me know if you have any questions or concerns and I will be happy to help.

Best regards,

Tom // Focusrite Technical Support Engineer.

Title: Re: USB cable - not a cable thread
Post by: chrisc on February 20, 2017, 12:02:00 PM
Dean would disagree and so it seems these people (maybe a vested interest?)

http://www.head-fi.org/t/765531/review-of-audioquest-usb-digital-audio-cables

Certainly the construction of a better (read more expensive) USB cable at the plug ends might make a considerable difference

You can get a variety of not so expensive USB cables from Loot, under their Lindy Cromo brand

http://www.loot.co.za/search?cat=b&terms=lindy+usb+cables.  The one selling for R187 is not outrageously priced
Title: Re: USB cable - not a cable thread
Post by: Skylark on February 20, 2017, 09:55:10 PM
This going to be fun, not.

At this early stage of the thread can those who hold differing points of view on this subject agree to disagree rather than hurl insults at each other... when it reaches that inevitable point that the molten magma starts flowing  :baseball:

That being said, some good points made in the op   ;)
Title: Re: USB cable - not a cable thread
Post by: Rotten Johnny on February 20, 2017, 09:59:46 PM
Where's Talib  :popcorn:
Title: Re: USB cable - not a cable thread
Post by: reactor_sa on February 21, 2017, 07:33:59 AM
1s and 0s are just that. They are not open to interpretation.
It's been proven with HDMI cables too, as long as the message from the source gets to the destination is all that matters.
Title: Re: USB cable - not a cable thread
Post by: chrisc on February 21, 2017, 08:15:14 AM
Snide comments aside.  You would expect a R180 cable to be better constructed than a R8 cable.  I have had cheapo USB cables, provided with a printer that cause the PC to get timing errors in the USB bus, since the crimped connector on the plug was so poorly implemented.  One I checked had a 200 ohm resistance on one of the conductors, indicating that the connection between cable and plug was corroded.

I took apart a Lindy Cromo USB cable which had become damaged by its getting sucked into an industrial carpet cleaner cleaner and the connections consisted of a folded over section 8mm long, with the metal gripping the conductor along the length.  Each conductor was individually insulated at this point.  Then there was a strain relief section 20mm long at the end, so no amount of twisting would compromise the connection
Title: Re: USB cable - not a cable thread
Post by: Crankshaft on February 21, 2017, 08:52:05 AM
It seems then that all one requires is properly constructed cable.

Title: Re: USB cable - not a cable thread
Post by: stereosane on February 21, 2017, 09:17:13 AM
Not sound related but my one USB cable almost charges my phone twice as fast as another, so there is definetly something wrong with the one cable..but sound wise I doubt it would sound different.. I hope  :O0:
Title: Re: USB cable - not a cable thread
Post by: stereoholic on April 16, 2018, 12:01:51 PM
Thread necro alert: Can someone recommend a USB cable for DAC to PC. 
Title: Re: USB cable - not a cable thread
Post by: Dubya Jay Dee on April 16, 2018, 12:43:45 PM
Thread necro alert: Can someone recommend a USB cable for DAC to PC.

As per the original post - any normal usb cable will work perfectly. If one came with the dac, use that. :thumbs:
Title: Re: USB cable - not a cable thread
Post by: stereoholic on April 16, 2018, 02:16:00 PM
As per the original post - any normal usb cable will work perfectly. If one came with the dac, use that. :thumbs:

Cool thanks, using a printer cable at the moment will stick with that then.
Title: Re: USB cable - not a cable thread
Post by: PsyCLown on April 19, 2018, 04:27:03 PM
Not sound related but my one USB cable almost charges my phone twice as fast as another, so there is definetly something wrong with the one cable..but sound wise I doubt it would sound different.. I hope  :O0:

I believe this comes down to the construction of the cable and how it is wired, some cables allow for fast charging and others do not.
Unfortunately I do not know the technicalities behind this. If the cable is constructed in a certain way it will be limited to 500ma and if the other way it can support more.

With digital cables, as mentioned, I feel a lot comes down to the construction of the cable and how long it will last - especially if you are plugging the cable in and out the whole time or it keeps moving around. Like a cable for a cell phone.
I have been through a few cheap chinese cables when using my phone to output audio via USB.