Is the "ST" AT T optical digital connection dead?

lotusm50: there are a number of highend dacs and transports that still offer at&t optical connections, though these are sometimes options. i perceive a movement towards aes/ebu, however, as the upper-end standard for transport>dac digital connection. why? 'cause many think it's sonically superior to at&t and coax (toslink hasn't been in the equation for years). -kelly

Lotus- I agree with you. I prefer the ST interface when properly implimented. It can certainly help reduce noise caused by ground currents between the transport and DAC and RFI. Regrettably, not all ST interfaces are created equal. Poor attention to power requirements and ground return paths can dramatically reduce the benefits of this type of interface. Of course, poor cable fiber termination, end polishing, alignment and fiber type (SM vs MM)can also pose problems. With Goldmund digital, I definitely prefer the ST interface. Just my .02

Although I have not had experience with ST, the general consensus in the past few years is that AES/EBU and coaxial sound better than ST, with better cables. ST has been criticized for the diameter being too large, thus allowing the data to 'bounce' and reflect inside the cable, causing timing errors and smearing the finest details and cues. That is why Theta made "Laser Linque", their own form of glass fiber connection. Unfortunately, that was short-lived and there are those who say it did not live up to its claims. I believe ST also rolls off the highs, which helps some systems sound better, even though this is inaccurate and a loss of information.

I found ST, when using a good ST-type cable - not the standard Siecor stuff, outperformed every coaxial or balanced cable I have ever heard, and the balanced cables had a consistent unmusical midband. The ST was faster and less dirty sounding with better extension top and bottom. Of course it all depends on how well the interfaces are implemented, and the ST worked just brilliantly on my Theta gear (now sold to another).

I work for a telco and the ST standard is quite old and has been superceded by different connectors and different standards (such as single mode where a narrower colour range is used). I suspect it is just too expensive to bring telco fibre standards down to the retail audio market when telco developments keep moving forward. For example all the action now is in DWDM where even higher bandwidth is obtained by using multiple colour ranges at the same time - bandwidths way beyond the requirements of audio.

Redkiwi: if you like sound of better optical interconnects you may be shocked when hear sound with NO digital optical (or other) interconnect at all. Stan Warren, invented couple years ago, "OpticDirect Interface" which he applied with Toslink. There is no loss of signal in such arrangment at all !!!. Sound quality obviously depends in great degree on "modem" and Toslink is not the best. Better optical modems such as as ATT ST type will sound even better.