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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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In Reply to: RE: Elizabeth is right posted by audioengr on August 14, 2012 at 09:25:34:
I agree that the first reflection is the most important one, as it is the largest one.
I disagree that the "average transport" (whatever the heck that is) has an average rise time of 25 nsec. In fact I remember about 10 years ago when Hi-Fi News measured a Theta DVD player and measured a risetime on the the S/PDIF output of around 3 nsec. This is about what I measure on our digital audio products also. So we are already off by around an order of magnitude.
Light in a vacuum travels about 1 foot per nanosecond. In a copper cable it is about 75% to 80% that speed (typically). So if a cable is 3 feet long long, each trip will take roughly 4 nanoseconds. Then three trips means the first reflection will arrive around 12 nanoseconds after the original signal. Depending on the circuitry in the transport and the DAC, this could be in exactly the right time range to screw up the original signal. It will all depend on the circuitry of the transport (mainly) and the DAC (partly).
On the other hand, using a longer cable of say 8 meters (25 feet) will change the time of the first reflection to around 70 nanoseconds and there is no possibility of a problem with CD. Even cutting it in half to 4 meters would give a much better chance of good sound with a broader range of equipment. But going to 1 or 1.5 meters is almost like asking for trouble.
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Follow Ups
- Mostly disagree - Charles Hansen 21:00:17 08/15/12 (12)
- Correction and ddendum - Charles Hansen 01:19:35 08/17/12 (11)
- Wow just tested this ims - theob 09:01:12 08/18/12 (7)
- excessive length - unclestu 13:44:36 08/20/12 (3)
- RE: excessive length - Bromo33333 08:33:41 08/26/12 (0)
- RE: excessive length I have a 25 ft cable not coiled, run back past TV and return on floor at baseboard. nt - Elizabeth 20:13:35 08/21/12 (0)
- Just try it w/o a prejudice that this cant be right...nt - theob 06:45:33 08/21/12 (0)
- I love it! - Charles Hansen 05:33:14 08/19/12 (2)
- RE: I love it! - theob 11:10:45 08/19/12 (1)
- Cool! - Charles Hansen 10:24:51 08/20/12 (0)
- RE: Correction and ddendum - Sunya 05:52:19 08/17/12 (2)
- RE: Correction and ddendum - Bromo33333 08:46:43 08/26/12 (0)
- RE: Correction and ddendum - Charles Hansen 05:29:53 08/19/12 (0)
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