USB cables size matters

[Kimo]

I have had a variety of USB cables in the "lab" over the last couple of years ranging in price from zero to over a thousand bucks.  There have been differences, which I highlighted in a previous thread, but no real consistency.  

 

So, I thought I would concentrate on length, rather than model.  Well, there you go.  I listened to a lot of mediocrity and basically all the 1 meter cables were a bit brighter than the 1.5 to 2.0 cables.  

 

Not satisfied with my own hearing, I reached out to a couple of digital gurus, who will remain nameless, and they informed me that what I heard was absolutely the case.  I also learned that HDMI cables should be 6' in length optimally and that a little longer was better than shorter.  

 

So, I must conclude that size matters, and, at least up to a point, longer was better.  I know this controversy has been discussed for awhile.  Just sharing my observations.  Shouldn't cost much for others to give it a try.  I was literally comparing freebies, a Belkin Gold, and a Supra Excalibur.  

[Kimo]

3 minutes ago, Archimago said:

 

You mean Taiko Audio? Sure... Give it a try.

 

I guess I should also consider that the shorter cable is working better and that the slightly lighter and whiter sound is more accurate, but it is hard for me to believe that an extra half a meter leads to degradation.  

 

I wonder what sort of review I would receive if I took a 10.00 Phillips USB and hid it in a fancy jacket.  I could add an empty little box as well.

[Kimo]

50 minutes ago, fas42 said:

 

The engineering of how digital signals are handled in the audio world is not good enough. Period. Which is why all this nonsense about, say, getting the "right lengths" becomes relevant - it's equivalent to trying to stabilise how two physical things are joined using a whole lot of rubber bands; changing a single rubber band will alter how strong the connection is, .

 

In the world of physical objects, you get rid of the rubber bands, and weld the objects together. Job done. But in the world of audio reproduction this is rarely done - so much of it is juggling a huge variety of rubber bands, and the content of forums like this makes it obvious this is still part and parcel of "how things are done!".

 

Indeed.  Check out all these silly pictures.  I guess certification means squat.

 

 

[Kimo]

5 hours ago, semente said:

ASR have measured USB cables of different lengths recently.

There's evidence of shorter being better (into a DAC with a medicore input implementation).

I looked at that.  In the video I linked, one of the short ones was pretty bad.

 

So far, I am to conclude that length doesn't matter, or 1.5 meters is best, or shorter is always better, or increments of .6m are best.  I guess the truth has a good chance of being one of these.

[Kimo]

10 hours ago, Currawong said:

A problem that can occur is, some "high end" USB cables don't meet the USB spec of a 90 Ohm impedance. As a result, you get signal reflections along the cable, which will interfere with the signal, and possibly be worse than your regular Belkin Gold.

 

 

The Belkin and Supra Excalibur are both certified, so they should both meet the spec pretty well.  They simply don't sound the same.  The Supra is a little lighter and brighter, but not harder.  So are the brand unknown shorter cables that I tried.

[Kimo]

1 hour ago, sphinxsix said:

It's pretty logical - if a cable matters, its quantity, in this case length matters too. 

I didn't do comparative tests but it seems pretty logical again - the shorter the cable, the slighter its influence on sound (unless a cable designer uses some devil's tricks to deliver the most neutral sound at a given cable length but I've never heard about something like that).

 

I have seen optimal lengths called out for coaxial digital 1.5m, USB 1.2 or 1.5m, speaker cables 8-10 feet, hdmi 2m, power cords at least 6 feet, turntable cable 1.25m.  Speaker cables would seem to fall into a shorter is better take, but digital appears to have more satanic influence.

[Kimo]

So, now I am left with a shorter cable sounds worse, because it is letting through more noise, and a shorter cable sounds better, because USB cables perform worse as length increases.  Oh, and there may be a need for a USB exorcism at some point, as well.

 

Actually, this all kind of makes sense.

 

 

[Kimo]

13 minutes ago, sphinxsix said:

 

Welcome to the audio world! 

Don't forget to have fun!

 

 

Frankly, I somehow tend to think these are not extremely serious sources..

 

 

In audiophile terms you got some big guns here!

 

https://www.nordost.com/faqs.php

 

https://static1.squarespace.com/static/53f2ba7ce4b0e9d91b048708/t/60a5a4b8ba05500910893c5c/1621468344871/Alpha+USB+User+Guide+v1.3.pdf

 

https://www.mapleshadestore.com/freeupgrades.php

 

https://bobpariseau.com/blog/2018/4/23/hdmi-premium-certified-cables-these-are-what-you-want

 

[Kimo]

5 minutes ago, bogi said:

My previous post was about using an adapter instead of a cable on computer side of Topping HS02 isolator. Of course, on device side I need a cable. This thread inspired me to search for more information about optimal digital cable lengths including some explanations and best also some calculation.

 

Minimal cable length is calculated for a given rise time of digital signal. Rise time is transition time from digital level 0 to 1. The first reflection should not arrive sooner as the rise time value. Given that condition, John Siau* calculated maximum rise time for a cable length of 1.5m: "If the rise time of the original signal is less than 11.9 ns the reflections will arrive after the transition has completed and the reflections will have no impact on the timing of the data transition". Given that information, max. rise time for 0.75m cable when would be about 6ns.

 

I did not find more exact information what is rise time value for high speed USB transfer (480MBit/s), which is used for audio.

 

* Thread title on ASR is "Technical Article: Digital Audio Cable Reflections and DACs". Actually it is the last post of the thread.

 

John Siau also did some computing of maximum cable lengths: "If 2 transits through the cable is equal to the period of data transitions, the third transit will arrive in sync with the next data transition.". It means he points to a situation when the 1st reflection arrives just at the time when next data transition starts at computer side. He calculated that for 44.1k clocked source side (SPDIF) this corresponds to a max. cable length of 9.5m: "Using RG59, this unfortunate alignment happens when the cable length is 9.5 m long. Using the fastest coax, this problem would occur at a length of 14.9 meters. Divide these lengths by two for 88.2 kHz audio, and divide by two again for 176.4 kHz audio."

 

It is now easy to recalculate this for 8kHz high speed USB audio:

max_length1 = 9.5 * 44.1 / 8 = 52m

max_length2 = 82m

Since USB cable length is restricted to 3m it means the first reflection arrives always much much sooner then the next data transmit. So longer USB cables should not cause any issue from reflections point of view. These calculations show that longer USB cable is safer than shorter - but again only from reflections point of view.

Given these calculations, I decided to compare my 0.75m Supra cable with 1.5m Belkin Gold Series. I repeated the comparison more times and I'm sure my decision is not result of bias after reading the above calculations. I prefer the longer Belkin cable so I will continue to use it instead of Supra cable. Without HS02 USB isolator I did not find Belkin as better cable. Supra has separately shielded power and data wires. With HS02 isolator it seems to bring no benefit anymore.

 

Always do a listening test and trust your ears more than my opinion!

 

Thanks for all that.

 

Would you say that the Supra sounds a little whiter/brighter than the Belkin Gold?  I think the Excalibur and the Belkin both sound fine, just slightly different in their tonality.  All the longer cables I have around here, and I have some real crap, have worked fine, but all sounded a little darker than the 1m counterparts.

[Kimo]

5 minutes ago, bogi said:

Yes, a bit brighter and low level details like percussion are a bit cleaner with Belkin. But as I mentioned above, my Supra is 0.75m and Belkin is 1.5m long. My opinion is not related to Supra 1.5m which I don't own.

 

If you have a plain old 1m USB cable around I would be interested in knowing if it tonally sounds closer to the Supra or the Belkin.  I just can't get myself to spend another 150.00 for a 2m of the Excalibur to compare directly to the 1m that I have now.

[Kimo]

6 minutes ago, bogi said:

I have such a cable around but who knows what's the level of impedance match (90 Ohm) of connectors - it influences level and polarity of reflections. Then, Supra has separately isolated data and power lines so it should be less influenced by computer noise. So I couldn't attribute sonic difference only to cable length. Therefore I don't wish to influence you so much by an opinion based on an unknown noname cable.

 

I have identified one of the no names as a Philips from Staples.  I will pick up a 1m and compare with the longer Philips and shorter sundry cables.  Won't be the same as comparing 2 certified cables, but I can't seem to find a 1m of Belkin Gold either.

[Kimo]

Struck up discussions with a few high end dac designers, who shall remain nameless.  Didn't seem like make, model, or length concerned them much with their designs, provided the cable wasn't too long.  2m seemed to be around the max.

 

In line filters weren't dismissed, but deemed generally unnecessary, provided the source was of good quality.  Especially the power supply.

 

Outboard convertors were generally dismissed as lower quality than what was already on tap, with one exception.

 

So I guess that size does matter, but only if it gets too long.