ert
100+ Head-Fier
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- Jun 23, 2004
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Quote:
A valid point, but one I was trying to avoid because it drags a contentious issue into the argument. I'm really just curious what design criteria are used in "audiophile" usb cables. My suspicion is, as with most of the high-end cables, the "design" revolves around the use of "exotic" materials, absurd amounts of wire (garden hose), magic geometries, and decorative braids, boxes, and connectors with no attention given to the field of digital transmission.
Quote:
It is a problem sometimes, although as Currawong pointed out, this is a non-issue for USB devices. I have built analytical instruments with USB interfaces, and in many cases there is actually a sophisticated microcontroller or even a full blown PC inside the instrument that interfaces to the serial bus (USB, SCADA, etc). Data I/O on the bus is packetized bulk data transfer or control I/O. For a USB device, lets say a spectrometer, typically the PC sends a command, and receives some data back (the measurement). Since it's all bulk or time-insensitive command data, jitter is a non-issue. However in digital "fly-by-wire" control, jitter can be important, although generally we are concerned about jitter on the order of micro-seconds at most, whereas audio jitter is relevant at less than 100 ns. Proper design (and active research area) can accommodate most issues.
| Originally Posted by AdamWysokinski /img/forum/go_quote.gif I am aware that DBT/ABX are not welcomed in this forum, but let me say that there is no point in buying expensive equipment to test jitter level until it is proven that people are able to distinguish normal and voodoo cables (later, if they could, we would test which they prefer). |
A valid point, but one I was trying to avoid because it drags a contentious issue into the argument. I'm really just curious what design criteria are used in "audiophile" usb cables. My suspicion is, as with most of the high-end cables, the "design" revolves around the use of "exotic" materials, absurd amounts of wire (garden hose), magic geometries, and decorative braids, boxes, and connectors with no attention given to the field of digital transmission.
Quote:
| Originally Posted by AdamWysokinski /img/forum/go_quote.gif BTW in every science lab that I've been working in or visiting, very expensive, precise and sensitive equipment is attached to computers using normal cables and jitter is never a problem. Pretty strange, huh? |
It is a problem sometimes, although as Currawong pointed out, this is a non-issue for USB devices. I have built analytical instruments with USB interfaces, and in many cases there is actually a sophisticated microcontroller or even a full blown PC inside the instrument that interfaces to the serial bus (USB, SCADA, etc). Data I/O on the bus is packetized bulk data transfer or control I/O. For a USB device, lets say a spectrometer, typically the PC sends a command, and receives some data back (the measurement). Since it's all bulk or time-insensitive command data, jitter is a non-issue. However in digital "fly-by-wire" control, jitter can be important, although generally we are concerned about jitter on the order of micro-seconds at most, whereas audio jitter is relevant at less than 100 ns. Proper design (and active research area) can accommodate most issues.
