USB cable differences

oscroft

Well-known Member
OK, I admit it's a clickbait title ;) But I do have two USB cables that appear to behave differently - one works properly and the other doesn't, and I thought folks here might find it interesting.

I've started playing my digital music from a Mac Mini via USB into my M-DAC, and it does seem to sound better than other methods of connection. I was listening to some FLAC files, and I started to hear occasional clicks - a bit like LP surface clicks, but these files were ripped from CD. The clicks weren't in the same place twice, so they couldn't be noises in the files. And it only happened with FLAC and not MP3.

I switched on the USB buffer display on the DAC, and all looked fine most of the time. But occasionally, the buffer level would start fluctuating rapidly - and I'd get a click. And once or twice I got a "flushing buffers" message, and more clicking. It looked like some kind of data loss, so I tried a different USB cable. And it all worked just fine then. I can reproduce it too - with one cable, I get what look like these data loss errors, and with the other I don't.

The bad cable has a ferrite core at one end, at the DAC end, and the good cable doesn't. I don't know if the ferrite is the cause, or if it's just a faulty cable. But there it is - I thought an interesting observation.

(And in case anyone's wondering, in between the errors, both cables sound identical :smashin:)
 
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AmericanRodeo

Well-known Member
The wonders of Digital Signaling, just because it works doesnt mean is it always going to work or that it isnt right on the point of failing.

'When I were a lad' at uni, it was called the digital cliff or digital knee. Where the error correction circuits could be working full tilt, but you wouldnt know it, until it got to much for the system and it glitched, or in your case 'Clicked'

Same with HDMI's, no way of knowing how close to the edge you are until it fails, unless you have some expensive test equipment.

I suspect one of your USB Leads is either poorly made or has invisible damage, causing the signal to pass but with lots of errors, needing correction. The other is cleaner / better made / no damage so the digital signal is passing with less errors, so the error correction chip is having to work at a more relaxed pace.

Does that makes sense?
 

oscroft

Well-known Member
I suspect one of your USB Leads is either poorly made or has invisible damage, causing the signal to pass but with lots of errors, needing correction. The other is cleaner / better made / no damage so the digital signal is passing with less errors, so the error correction chip is having to work at a more relaxed pace.

Does that makes sense?
Yep, sounds perfect sense. It's got to be something like that.
 

dannnielll

Well-known Member
You get exactly the same effect with HDMI cables or in my case with Digital TV reception on a very sunny day and a transmitter 60 miles away. A pixelated display a screeching sounds, until the air has cooled down. There arec3 zones .. In tge near zone, tge errirs are so small that the error detection and correction has no problems. In the far zone, the error rate has built up so bad that the device just signals no signal and the grey area, where it might pick up 25 out of 30 frames and gives up on tge rest.
 

AmericanRodeo

Well-known Member
Totally agree on HDMI but the Digital TV reception could be different.

In the digital tv world, to much signal makes the picture look exactly like not enought signal. So it the case of Freeveiw if you have a BIG aerial and it is the BBC Channels crapping out, it is most likely to much rather than to little signal.

A common mistake is to see errors, think it is a low signal, add a booster (amp), signal gets worse, scratch head, add a bigger booster (amp).

Techinally, to much signal can overload the input stage of an amp and it goes into saturation, causing noise, which can't then be corrected. When setting up the large Satellite TV System our other business looks after we have to balance the inputs to the launch amps as much as we have to set up the output levels. (for reference, 12 Floors, 199 Apartments, 7 Satellite dishes, all apartments fed with all satellite signals)
 

the groundsman

Active Member
Off topic
I've posted on here ( TV forum) about this very problem. I can see the transmitter from my house and its only around 6-7 miles away but I get a terrible pixelated picture. I fitted an attenuator but still couldn't get the picture to work so something else must be causing the problem other than the over powerful signal I guess.
 

dannnielll

Well-known Member
Off topic
I've posted on here ( TV forum) about this very problem. I can see the transmitter from my house and its only around 6-7 miles away but I get a terrible pixelated picture. I fitted an attenuator but still couldn't get the picture to work so something else must be causing the problem other than the over powerful signal I guess.
Yes ,even a large barn or metallic silo at a specific distance will cause interference between the pulse train and the reflected pulse train with a slight delay. In the older analogue signal you would see the double image ,but with digital it either displays or not .. and it is the exact same problem with a digital cable, a slight kink can create a reflection
 

dannnielll

Well-known Member
Totally agree on HDMI but the Digital TV reception could be different.

In the digital tv world, to much signal makes the picture look exactly like not enought signal. So it the case of Freeveiw if you have a BIG aerial and it is the BBC Channels crapping out, it is most likely to much rather than to little signal.

A common mistake is to see errors, think it is a low signal, add a booster (amp), signal gets worse, scratch head, add a bigger booster (amp).

Techinally, to much signal can overload the input stage of an amp and it goes into saturation, causing noise, which can't then be corrected. When setting up the large Satellite TV System our other business looks after we have to balance the inputs to the launch amps as much as we have to set up the output levels. (for reference, 12 Floors, 199 Apartments, 7 Satellite dishes, all apartments fed with all satellite signals)
Fully agree, but my BBC problem is a refracted signal over a mountain top, from 60 miles so it is very much a low signal problem. Our local ..non BBC ,is about 10 miles away and overloading has occurred on occasion
 

AmericanRodeo

Well-known Member
Off topic
I've posted on here ( TV forum) about this very problem. I can see the transmitter from my house and its only around 6-7 miles away but I get a terrible pixelated picture. I fitted an attenuator but still couldn't get the picture to work so something else must be causing the problem other than the over powerful signal I guess.

Genuinely, Have you tried disconnecting the aerial completely at the aerial end or even at the wall socket end. In our London luxury tower block, if you disconnect the TV connection to the wall on the south side of the building you still get a perfect picture. The signal is that strong from Crystal Palace.

If so, it could also be the crap wet string cable that used to be installed and with thier minimal shielding you could be picking up 'extra' signals as the cable passes through the walls.

Wohaaa, massive thread drift into Digital TV!
 

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