USB cables, is there a length I should not go beyond?

RE: USB cables, is there a length I should not go beyond?, posted on October 30, 2009 at 12:46:03
audioengr Manufacturer Posts: 4088 Location: Oregon Joined: April 12, 2001	5m is the maximum length to maintain the protocol integrity. If it's async USB, the cable quality and length should not matter.

Not true, length matters in all protocols, posted on October 30, 2009 at 13:45:23

Gordon Rankin
Manufacturer

Posts: 2247
Joined: June 9, 2000

Steve,

Isosynchronous is not error correcting. Longer lengths will cause data errors.

Several companies said they were coming out with 30, 40, 50 foot cables at RMAF... I'm like what..

It's easy to see that the longer runs effect all devices. I have about 20 USB DACs and ADC's here the THD will go up on 24/96 and the Class 2 24(32)/192 stuff I have here when you go over 3M.

It's easy to test run an Oscillator on the Computer to the DAC in question measure the THD at 1M, 2M, 3M and 5M and you will see a change. Above 5M it just get's crazy.

There also that and the ground looping problem but if you float the computer your all set.

Thanks
Gordon
J. Gordon Rankin

What????, posted on October 30, 2009 at 17:08:02
audioengr Manufacturer Posts: 4088 Location: Oregon Joined: April 12, 2001	Are you trying to tell me that Async will not work with the standard maximum 5m length in the USB spec without errors? That's strange. I have an async USB interface from Tascam working over a 5m cable. Sounds identical to the 3-foot cable.

Steve read the post again, posted on November 2, 2009 at 07:03:40

Gordon Rankin
Manufacturer

Posts: 2247
Joined: June 9, 2000

Steve,

Anything will work up to 5M. If you read what I said you will have ISO errors with cables that exceed a certain range.

Why don't you buy a USB Analyzer and take a look at what you are talking about.

All cables sound different for various reasons. One of them is data rate, one noise interference from VBUS/GND, EMI/RFI radiated noise... etc...

If you have errors the THD goes up... if you have noise then you have other issues.

Most of this has nothing to do with Async or Adaptive.

Thanks
Gordon
J. Gordon Rankin

2-3M MAX from my testing, posted on October 30, 2009 at 08:12:48

Gordon Rankin
Manufacturer

Posts: 2247
Joined: June 9, 2000

Gang,

Unless you are stuck with 44.1/16 any 24 bit dac is going to be better off with as short of a cable as possible.

Wireworld did some testing with 3" (yes inch) compared to 2M and found some staggering results. Guys don't do this... 3" is too close to the computer. Wireworld did this for testing.

I can see THD rise on longer cables. So it's not a good thing to try anything more than 3M.

Especially the companies who say they have 10M and higher. But when asked about testing... well they never really did any. Believe me 10M will have significant errors and that will result in poor sound.

High end cable makers need to wake up and get with the program.

Thanks
Gordon
J. Gordon Rankin

RE: USB cables, is there a length I should not go beyond?, posted on October 29, 2009 at 11:55:04

ForgotPassword
Audiophile

Posts: 58
Joined: September 21, 2009

A connector-to-connector "cable" would be ideal. Personally, I never use USB cables that exceed one foot.

"We should no more let numbers define audio quality than we would let chemical analysis be the arbiter of fine wines." N.P.

RE: USB cables, is there a length I should not go beyond?, posted on October 29, 2009 at 12:16:23
AudioDoctor Audiophile Posts: 678 Location: Minnesota Joined: March 25, 2008	you are going to have to explain what you mean by a "connector to connector cable." Happiness is a clean record, and warm tubes!

Simple., posted on October 29, 2009 at 12:23:26
ForgotPassword Audiophile Posts: 58 Joined: September 21, 2009	Imagine two USB connectors back-to-back. That's the idea. "We should no more let numbers define audio quality than we would let chemical analysis be the arbiter of fine wines." N.P.

That's what Gordon mentions in the post below, too (about Wireworld) - ..., posted on October 29, 2009 at 12:04:13
carcass93 Audiophile Posts: 2634 Location: NJ Joined: September 20, 2006	- 3" being audibly superior to 2m. Intuitively, it makes sense, but definitely can be impractical in real-world setups.

RE: That's what Gordon mentions in the post below, too (about Wireworld) - ..., posted on October 29, 2009 at 22:54:25
fmak Audiophile Posts: 4115 Joined: June 1, 2002	Why, if async is the 'ideal' handshake for the interface? There is a defined impedance (I think 100 R) for usb cables. I suspect the cable effect is related to this and to shielding and dielectric.

RE: That's what Gordon mentions in the post below, too (about Wireworld) - ..., posted on October 29, 2009 at 12:29:17
Mercman Audiophile Posts: 2005 Joined: October 20, 2002	The cables I'm testing are all 2 meters.

True. The only USB DAC I own.., posted on October 29, 2009 at 12:09:50

ForgotPassword
Audiophile

Posts: 58
Joined: September 21, 2009

is the little 01US that sits on top of the cMP^2 in my bedroom system, so cable length was never an issue. But yea, a foot-long cable would be very inconvenient if I were to use a USB DAC in my main system.

"We should no more let numbers define audio quality than we would let chemical analysis be the arbiter of fine wines." N.P.

RE: USB cables, is there a length I should not go beyond?, posted on October 29, 2009 at 11:28:20
Roseval Audiophile Posts: 506 Joined: March 31, 2008	The standard says 5m max but in general these standard are at the conservative side. The Well Tempered Computer

RE: USB cables, is there a length I should not go beyond?, posted on October 29, 2009 at 11:12:59

Mercman
Audiophile

Posts: 2005
Joined: October 20, 2002

I would use the shortest possible. I am presently using a 2 meter cable in my setup. It works very well.

I just was given a bunch of USB cables to evaluate. WireWorld Starlight 5, Transparent Audio, and Nirvana Audio.

I got Windows 7 Pro running. I like it!

Let us know . . ., posted on October 31, 2009 at 15:34:13
LarryK2 Industry Professional Posts: 54 Location: New Hampshire Joined: December 25, 2006	. . . the results of your tests - I'm in the market for a 1M USB for my office system. Running a generic cable now. Best, Larry

RE: USB cables, is there a length I should not go beyond?, posted on October 29, 2009 at 12:17:47
AudioDoctor Audiophile Posts: 678 Location: Minnesota Joined: March 25, 2008	I am curious to know how these cables compare to the Belkins etc... Happiness is a clean record, and warm tubes!

RE: USB cables, is there a length I should not go beyond?, posted on October 29, 2009 at 13:00:14
Mercman Audiophile Posts: 2005 Joined: October 20, 2002	I think I remember Gordon saying to not go beyond 3 meters. I'll E-mail you the results. I have tried many cables and I have a Belkin Gold here and a bunch of other stuff.

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USB cables, is there a length I should not go beyond?

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