Optical Vs Electrical digital

[Quietschbox]

Headphones are _very_ revealing, I doubt I'd be able to hear the same differences through speakers.

Place both speakers left n right to your ears and you will hear way more detail.
Don't forget to keep the kids away from the amp.

[Quietschbox]

Empirical Audio Pace-Car Reclocker
http://forums.slimdevices.com/showthread.php?t=37557

Quotes, in order of pages:

"The point of this reclocker [pace car] is the same as everything else sold by Empirical Audio:
to part credulous audiophiles from their money (in large chunks preferably)."

"One man posted in a tread in another forum. He worked in a studio. Dont remember where or when. His statement of claim was that jitter dos not exsist.
It is something the pro audio hardware industry has invented to earn more money on hardware sales."

"Once you have heard the SB3 with the Pace-Car at 16/44.1, you wont care about 48kHz. Its that good.
Steve N.
Empirical Audio"

"I've been modding DAC's for many years, and I've probably modded 15 different ones.
I found that none of them are immune to jitter, even though most have some claims of such.
Steve N.
Empirical Audio"

Internet threads about usefulness or uselessness of expensive equipment can be entertaining.

[Chippy_boy]

Or rather lookup "s/pdif" "jitter" "optical" .

Did that, found
"Even modern DACs have typically a small buffer and reclocking circuitry, so the jitter is not so big problem nowadays that it used to be."

So it totally depends on your devices and cables used.

How true. A decent modern dac is much more tolerant of a jittery signal than earlier ones. That being the case, optical should be able to sound just as good as coax. There's only bits and jitter in the signal - nothing else. Get the bits right and remove the jitter and there's nothing else left to make them sound any different... apart from the snake oil.

[Tom472]

Some manufacturers are now offering the at&t standard optical interface (much better than TOSLINK, designed to take the kind of banwidth required by digital audio).

This has received some good write up on the DIYaudio forum as a DIY option too. This would presumably be the best option for a long cable run between source and DAC.

The internal reflection issue with short co-ax cables stems from the whole 75 ohm issue. There shouldn't be any reflections if the cable, connectors, transmitter and receiver circuitry are all proper 75 ohm items. As some have noted, phono plugs rarely are.

I bought some BNC sockets a while ago which seem to fit perfectly into the hole left by commonly used phono sockets - its an easy DIY switch.

Regards
Tom

[StanleyB]

Some manufacturers are now offering the at&t standard optical interface (much better than TOSLINK, designed to take the kind of banwidth required by digital audio).

What's the bandwidth of digital audio, and what's the bandwidth of TOSLINK?

[DSJR]

In decades past, the Toslink connection was judged inferior due to the loose mechanics of the system I believe. the AT&T connectors were judged far superior back then.

Never having carried out measurements or any research on this, I'm just repeating "feelings" by those who were supposed to know.

[Barry]

Some manufacturers are now offering the at&t standard optical interface (much better than TOSLINK, designed to take the kind of banwidth required by digital audio).

This has received some good write up on the DIYaudio forum as a DIY option too. This would presumably be the best option for a long cable run between source and DAC.

The internal reflection issue with short co-ax cables stems from the whole 75 ohm issue. There shouldn't be any reflections if the cable, connectors, transmitter and receiver circuitry are all proper 75 ohm items. As some have noted, phono plugs rarely are.

I bought some BNC sockets a while ago which seem to fit perfectly into the hole left by commonly used phono sockets - its an easy DIY switch.

Regards
Tom

Given the dimensions of an RCA phono connector, it can never have a 75 ohm impedance.

BNCs are obtainable in two versions: 50 ohm and 75 ohm. Make sure yours are 75 ohm and remember that a 50 ohm BNC plug has a centre pin of larger diameter, so will physically damage a 75 ohm socket if it is mated with one.

Regards

[Tom472]

What's the bandwidth of digital audio, and what's the bandwidth of TOSLINK?

It's a bit difficult to say as its not a constant signal in the normal analogue sense and also varies depending on the data being sent. Most people specify standard 16 bit stereo to be around 6MHz, some would say its technically much higher than that.

As for the bandwidth of TOSLINK, well it depends on what it's made of, how good the interconnects are etc. Poor cables (the plain clear plastic ones) will do about 5MHz, better cable should get to more like 10MHz. The interface between the light source and cable is also pretty critical, and this is generally where a lot of TOSLINK interfaces cause problems. Optical connections obviously have the potential for very high bandwith, as demonstrated by high speed phone lines etc.

Having said all that though, as noted earlier, as long as the signal is effectively re-clocked at the other end, the bandwith limitations shouldn't technically contribute to "jitter".

Regards
Tom

[StanleyB]

Most people specify standard 16 bit stereo to be around 6MHz, some would say its technically much higher than that.

As for the bandwidth of TOSLINK, well it depends on what it's made of, how good the interconnects are etc. Poor cables (the plain clear plastic ones) will do about 5MHz, better cable should get to more like 10MHz.

For Gigabyte transmission, fiber optic cable require a far wider bandwidth. In the case of 5.1 and 7.1 audio, the bandwidth is also far higher than for 2 channel stereo.

The reason I asked the question is because there are TOTX and TORX sockets designed for high frequency applications that are in excess of the 2 channel stereo spec., as well as fiber optic cables to support high bandwidth applications.

I am not sure what type of fiber optic cabling AT&T uses, but I have been using high bandwidth optical cable in the design of my own TOSLINK cables, and high bandwidth TORX sockets on my DACs for years without any hoohaa being made about it.

The following is a pic of a standard audio TOSLINK cable, next to one of my high bandwidth fiber optic cable terminated into TOSLINK connectors.