Length of digital cable?

Update: I bought the 4-ft digital cable with RCA adaptors from Empirical Audio that Steve recommended. Break-in is typical with a rough patch after about 24 hrs. It emerges hrs later with a very broad soundstage and becomes light and airy, sounding more like live music. It's probably 75% broken in now, and the highs are quite controlled; guitars sound steely; sound in general sounds cleansed--really not what I expected. Transients are delightful.

I don't have another high end cable with which to compare; it costs less than the Cardas Lightning 15 and the better Audioquest. No question that it is extremely cost effective in the SQ it produces and strikingly illustrates that cable should be treated equally with other components.
Steve has recommended other products that will get me world class sound, but I probably can't handle world class sound at the moment. I'm too overwhelmed by the SQ I have now.

Thanks to Al and Steve for catching me up. Audiogon is a valuable source thanks to these gentlemen and many more members.

Steve, I understand one can't make a true 75 ohm digital cables with RCA connectors. That's the advantage of using BNC connectors, right - that is the BNC connectors allow for a true 75 ohm cable? So if you need to use RCA adaptors on the BNC cable, doesn't that negate the benefits of a true 75 ohm BNC to BNC cable?

Camb - Its true that RCA connectors are more like 45 ohms, but if you use good 75 ohm BNC adapters like I do, the effect is negligible. If you have BNC on either the output or input device, you can use the native BNC which is better.

The benefit is really the cable itself and how it is terminated to the BNC and shielded. It cannot be just any 75 ohm BNC. The BNC must be designed specifically for that particular cable to avoid an impedance change at the cable termination.

If you terminate to an RCA, it is very difficult to avoid a big impedance discontinuity because it is never a good match for the cable.

Steve N.
Empirical Audio

Thanks Steve,

I wish more manufacturers offered a BNC option. RCA still seems to be the norm, unfortunately.

Cam

Although BNC would theoretically be preferable to RCA connection, there is actually next to no audible difference between an spdif using either. Steve mentions that the BNC must be designed for a particular cable, which frankly is a dubious statement. The connectors 'are what they are', and the cable that exists to connect them together should offer as close to the 75ohm Zo as is possible, which is not difficult. If using RCA connectors, the shorter the better, i.e. Furutech FP126, and designing the cable to terminate at 75ohms exactly can make a perfect match. Using adaptors also makes little difference, both on a scope and audibly. Saying that, I do agree that more equipment manufacturers could do with offering them.
Cable length should not be an issue if the said cable is an exact impedance match for the output and input, as refections should not occur. Cable length is an issue in mismatched impedances though. As I mentioned earlier, I use 40cm of my own design, which offers one of the cleanest, detailed and most spacious and unfatiguing sounds we have heard from many digital cables, which are in fact just high speed analog signals really anyway. It is most likely that there may be system limitations that would mask the subtleties of the true sonic differences between connection options.

Best Rgds,
Paul.