Optical vs. coaxial DAC connection

[Marco]

[Question addressed to Mark Bartlett of Audiocom International]

Mark,

Ian and me were discussing last night (as you do!) the merits of optical and coaxial connections between a transport and DAC.

Ian reported that he obtained better sound from the optical connection via a Toslink lead (with his admittedly temporary cheap DAC) than he did with the coaxial connection in conjunction with a (fairly) high quality Kimber coaxial digital interconnect.

As you know, the consensus of opinion is that the coaxial connection is the way to go for best performance, but is that actually always the case and if so why?

Basically, what we'd like to know is if the optical route has any advantages over the coaxial one, and vice versa - and why!

What process is involved in both instances when the signal is being transferred?

Can you help?

Cheers.

Regards,
Marco.

[Filterlab]

...Basically, what we'd like to know is if the optical route has any advantages over the coaxial one, and vice versa - and why! ..

I use optical over anything else, and I can give you one massive reason why optical is preferable; light is not affected by electrical interference whatsoever.

[Marco]

Interesting.

And yet whenever I've compared (umpteen times) the optical and coaxial connections on a hi-end DAC, with the requisite cables, the coaxial option wins hands down on sound quality every time...

Perhaps Mark can enlighten us?

Marco.

[Filterlab]

It shouldn't (theoretically) make any difference which input is used as long as the 1s and 0s are received. The resulting sound quality comes from the DAC after the transfer of data and not before, which of course doesn't apply to an analogue source.

However, I can understand why there may be differences.

[Marco]

Maybe it's a cable thing?

Marco.

[Filterlab]

Could be, there is a stark difference even with optical cables. I've tried a dozen or so and the best ones are the mid-price jobs from Maplin, £22.00 for a five metre cable that sounds better than a 0.75 metre for £175.00 from a higher end company. Maplin stuff is seriously underrated, although having said that there's not much choice in optical cables.

[Audiocom AV]

Hello Marco

Optical connections are not susceptible to line noise or other electromagnetic interference. With a cheap DAC the line noise would be predictably higher and the performance of the coaxial input is being reduced.
With a high performance DAC such as the Sony DAS-R1, line noise is very low; the coaxial input is also electromagnetically screened.

Both the coaxial and optical inputs use SP/DIF (Sony/Philips Digital Interconnect Format), the standard for carrying digital data between devices. There is no difference in the signal being transferred for optical or coaxial, both carry the same information. The selection or choice depends on the equipment, cables and personal preference.

Regards,
Mark

[Marco]

Optical connections are not susceptible to line noise or other electromagnetic interference. With a cheap DAC the line noise would be predictably higher and the performance of the coaxial input is being reduced. With a high performance DAC such as the Sony DAS-R1, line noise is very low; the coaxial input is also electromagnetically screened.

Thanks for that, Mark. It is indeed what I suspected, backs up my subjective listening tests (and what I mentioned to Ian last
night)

In my set-up I will continue to use a high quality (Transparent) digital coaxial lead.

Marco.

[Mike]

Maybe it's a cable thing?

Marco.

Don't forget there could be an issue with the quality of the optical conversion at either/both ends of the link! There can also be problems caused by the cleanliness, or rather, lack of, with the optical connections themselves. Notably, 'noise'.

Cheers,
Mike.

P.S. I have 'views' on the subject of digital transmission which I'll go into sometime. Like when I'm REALLY bored!

[WikiBoy]

[Question addressed to Mark Bartlett of Audiocom International]

Mark,

Ian and me were discussing last night (as you do!) the merits of optical and coaxial connections between a transport and DAC.

Ian reported that he obtained better sound from the optical connection via a Toslink lead (with his admittedly temporary cheap DAC) than he did with the coaxial connection in conjunction with a (fairly) high quality Kimber coaxial digital interconnect.

As you know, the consensus of opinion is that the coaxial connection is the way to go for best performance, but is that actually always the case and if so why?

Basically, what we'd like to know is if the optical route has any advantages over the coaxial one, and vice versa - and why!

What process is involved in both instances when the signal is being transferred?

Can you help?

Cheers.

Regards,
Marco.

For coaxial then cable is critical. Everyone thinks that CD is frequency limited and in the anologue mode it is. BUT in the digital mode it behaves more like radar in some of its propogation characteristics. Much **** is talked about transmission in digital mode and how it cannot be corrupted. For a simple digital stream OK but for digitised music that is something else. You need minimum stop start corruption and as a digital pulse is like square wave it has extreme high frequency components. SO the best cable is one that acts almost like a wave guide as opposed to a transmission line.

That is why I use a pipe. Get the cable right and coaxial is far better than optical. Optical has far higher pulse corruption due to the speed capability of switching light on and off and the start and decay properties of that light source.