Originally Posted by rds /img/forum/go_quote.gif It seems that almost any quality modern DAC will re-clock the signal. Afaik, the data is stored in a buffer which is fed out by the DAC's own clock. Do I have that right?
Originally Posted by syllabus /img/forum/go_quote.gif So what?
Hmmmm, and here I am thinking that it is reeeeeeally obvious what I was saying.
We don't listen with oscilloscopes.
True. But the wonderful thing about oscilloscopes is that they aren't swayed psychologically by how much a cable cost or what material it is made of. They only show objective and measurable results, rather than vague waffle and emotive philosophies.
Originally Posted by Sherwood /img/forum/go_quote.gif "Designed for digital transmission" is a ridiculous statement. Cables are designed to pass electricity. Are you purporting tangible difference between analog and digital electricity?
I suspect with a scope you could reproduce my results, but yours are unique only to you.
The requirements for digital vs analog signals are VERY different, digital requires 75-ohm coax for a reason - accurate transmission of data at high speeds. I really don't feel like getting into why cables are "designed for digital transmission"
but if you want, I'll let you borrow my college data communications book has a whole chapter on digital transmission requirements in cables and equipment.
Originally Posted by FallenAngel /img/forum/go_quote.gif I have used some crappy non-75 ohm cables and they sounded quite muddy compared to the Belden 1694A.
Ah yes, but that's what you expected to hear right?
For what it's worth, I tend to agree with you. A friend of mine found some crappy looking old RCA connectors that kind of look like what grover used to use [maybe still does] for his cables minus the many layers of heat shrink and used a pair of them with a run of rugged coax cable... best digital cable I've heard. I have the same cable with bnc terminations [and adapters] as well, but none of my gear has bnc and I don't feel like hacking it apart. Besides, I only use digital cables in my home theater rig which is just for fun. I try to keep my patrick82 tenancies restricted to the standalone headphone rig.
I've also got a question... My HDPVR has a coax out that I run the aforementioned cable out of and into a rca-to-xlr adapter which then plugs in to my 'dac', a Behringer DEQ2496. Should I be worrying about the 75-to-110 ohm mumbo jumbo, or should I assume that the behringer is autoswitching that for me?
As another off topic question, any recommendations on a decent [but cheap] dac for my computer? I have a m-audio transit and a fancy looking signalcable optical cable and a single ended mosfet amp that I was thinking about hooking up for Grado duty. No dac though and the integrated sound on my system is terrible.
I forgot that I wrote some assembly code for a realtek integrated dac/headphone amp chip last year. I sent the samples stored on flash memory to the realtek using a microcontroller and told the realtek the sample rate. The chip then clocked out the samples.
The buffer held 1024 samples, which is plenty when you consider the clock speed of even of modest microcontroller. I don't think the buffer ever got below 1000 samples - and the microcontroller was doing lots of other things besides topping up the dac buffer.
All this is to say that a good modern dac (or even a crappy one in this case) should not rely on clocking externally.
As far as I can tell a good 192kHz usb or firewire receiver should make all the rest of these cables antiquated. Also, ironically, adding reclocking to a DAC (in design) will cost far less than an audiophile cable that is supposed to reduce jitter.