Originally Posted by myinitialsaredac
That is an interesting view point. However you still have to assume that usb cables are using swings of voltage to transfer data. Any cable that uses electricity is going to be affected by dielectric dispersion and absorption, or the dielectric being unable to fully drain so instead of a 101 you get a 111 because the voltage is not dropping instantaneously and you have almost a half voltage before the next swing which can be misread.
ALL the usb errors I have gotton have been due to windows software or bad hardware or even a faulty controller (design). almost never is the actual *implementation* flakey. it works or it does not. it delivers bits there, somehow the receiver can pick the bits out and then save them to something (camera, flash card, disk, sound device, or even keyboard/mouse!).
usb is very very asynch (not isoch like firewire is). with all the slop that is designed into the protocol, you'd think that 'bit timing' would not be one of the things that would affect data delivery.
the ideal thing would be to have 'timestamps' labeled with each single data sample. duh! you'd think that would be obvious, right?
they do that in a LOT of datacomms (my field of work) but they don't do that in audio. you have to extract clock from the data, in consumer spdif.
but even with noise and such on the cable, usb is differential (for one thing) so its already pretty immune to a lot of 'cable things' that make one cable better than another.
once the frames or packets are pulled off the wire, they have to be assembled into data samples and assigned their own timestamps (so to speak) in timing. note WHO is doing this! this is AT the usb receiver side of things. he receives a datagram, he opens (time goes by), he strips off headers and checksums and other protocol stuff (time still going by) and then he gets enough data for send THAT to the 'internal dac' and THIS is where timing really matters.
and the waveform on the usb cable matters about..... 0%. its digital, guys, and a LOT of trash can be on a digital signal and the bits STILL seem to get thru.
again, I've personally seen something close to this 100-digital-deck chain (grin) and the bits really do get there. that says a lot about how GOOD spdif really is. people need to give more credit to those that designed this since it has been doing a pretty OK job of things all these years.
I would care more about long long cable length, but this is for ALL usb (even more important is my remote usb disk!)
as long as the cable is within spec and the receivers are doing their jobs, the bit delivery works Just Fine(tm).
blame the dac or its stages. stop blaming cables in the digital world.