Paul McGowan:
In yesterday’s post I brought up the subject of the lowly TOSLINK cable, sometimes known as an optical cable. For most of us, this is the worst sounding digital audio interconnect made. Depending on the unit you are connecting to, sample rates are limited to 96kHz and below. Toshiba, the inventor and manufacturer of the TOSLINK cable has announced it will be phasing the product out over the next few years. So one might conclude than an optical cable isn’t a great way to go, given TOSLINK’s poor performance. Yet most of the modern world is moving much of the data we consume over optical cables. What’s the disconnect?
We discussed the idea that nothing could be better for isolation between two units than connecting them optically. In fact, in the very first Digital Lens product we built in the mid 1990′s, we optically coupled the RAM board to the final output board, each with its own isolated power supply, and that helped the Lens (a RAM based digital in/out regenerative reclocking device) perform its best. During that same era a very forward thinking company (at the time) Wadia Digital pushed hard to get high-end audio manufacturers to adopt what was know as the ATT ST fiber optic glass cable as a standard for connecting two pieces of digital audio equipment together. It was a great idea. It was expensive. But in the end, not many transport manufacturers went along with it and the concept faded into the darkness. PS Audio was one of the few who placed this expensive connector on our transports and DACS all to no one’s advantage (ultimately) but we believed in the format and wanted to lend our support.
Most Audiophiles have grown up with the only reference to optical coupling the lowly TOSLINK cable and thus, most opinions are based on this product. Toshiba wanted to make a dirt cheap optical interface. And they did. One of the reasons they went with an optical cable is it allowed them to control the entire interface between equipment without worry of noise or signal levels. Imagine that in the early days of digital audio you want to make sure your device connects with every other device flawlessly. If you can control the transmitter (in the source equipment), the connecting cable and the receiver, plus keep them electrically isolated from each other, you have a good chance of achieving your goal of compatibility between machines even if those machines weren’t made by you. Making a high performance connection was never part of their goal. Consistently meeting the minimum requirements for connection between two pieces of kit seems to be the main focus and to that end, TOSLINK succeeds beautifully. A tribute to any engineering effort to say the least.
What’s interesting about this thread of thought is understanding the limiting factor in the cable is primarily the sending and receiving units, also primarily made by TOSHIBA. Powered by internal LED’s, these connectors are designed with one goal in mind: cheap. And cheap they are, ranging between $1 and $2 depending on quantity. Another factor is the cable itself and the connectors. They have the same goal: cheap.
But if we disassociate ourselves from this low quality cheap implementation of optical cables and understand that a properly built cable and sending/receiving unit is employed, there’s perhaps nothing better for connecting digital audio equipment.
Optical is growing throughout the world and diminishing in audio. Optical passed the high-end by.
It didn’t even wave on the way out.
