Length of digital cable?

We found that the shorter the better if the cable is well designed. I use 40cm, it is astoundingly detailed and tonally very accurate..

Ps, you use 40cm of what cable?

Hi Lynne,

I agree with Steve's comments about length, and I don't doubt that his cable is an excellent one. As he indicated above and in his Positive Feedback paper, the optimal length is dependent on signal risetimes and falltimes, which will vary from transport to transport and are usually unspecified. But as indicated in his paper, what probably stands the best chance of being optimal in any given setup is a length of around 1.5 meters (about 5 feet), assuming that a very short length is not practicable.

In addition to signal risetimes and falltimes (the amount of time it takes for the signal to change from its low voltage state to its high voltage state, and vice versa), what length is optimal in any given setup can also be affected by the propagation velocity of the particular cable, by the accuracy of the impedances of the cable and the components it is connecting, and by the amount of electrical noise that may be riding on the signal that is provided by the source, or that may occur as a result of ground loop effects or RFI pickup. So it's all somewhat unpredictable.

Regarding your second question, most likely the length of the ethernet cable is unrelated to the poor sound. The timing of D/A conversion in the AVR (which is where jitter matters) and the timing of data transmission via ethernet are inherently unrelated. It's conceivable that the cable type and/or its length could have a slight effect on sonics by affecting the amount of digital noise that could radiate or couple from the cable to circuit points within the AVR, but I'd expect that kind of effect to be subtle at most.

Best,
-- Al

Hi Al,

I need to order a second cable for a second system, so I will try a 1.5m length. With this 18 ft Beldon, I'm getting a smooth high end like analogue. I can live without stonishing detail if I have to but not the "digital-sounding" high end.

Further, I will work on RFI with tweeks--noise caps etc. Al, I have the strangest phenomenon. My hk990 was upstairs. When I would change sources, the middle LED's on the read-out would go out. When I powered off and on again, the lights were on again. I tried a different circuit but the issue was the same. My contact at hk said he thought it was really strange and had never heard of it but sent me a new amp. De javu all over again. I recently moved that system to the basement. Issue is gone.I haven't tried computer source in the basement yet. Might be improved.

I exagerate a little in regard to the sound quality of the computer source. It's not horrible. My sister doesn't notice the difference. A friend who is somewhat an audiophile does. But I take note of your comments.

Thanks.

Best,

Lynne

Hi Lynne,

I have no thoughts about the HK990 issue.

Regarding the ethernet cable, I can recall a couple of members here whom I consider to be particularly credible reporting that upgrading their ethernet cables to SHIELDED CAT6 resulted in significant improvements. It wouldn't cost much to give it a try. Newegg.com is a good source.

The likelihood of that providing a benefit may depend, though, on the shielding (if any) and other characteristics of the mating jacks.

Best,
-- Al