digital optical or coax

Is one better than the other for playing CDs or DVDs?

I've heard two answers: no, and coaxial. There is some extra signal conversion involved in optical from what I understand; whether that conversion is enough to affect the digital signal is a little less clear. There was some discussion of the two formats in this thread that you may find interesting.

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gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review

If there are differences, I don't think they would matter in the real world listening of DVDs or CDs.

Myself, I use whatever is convenient. I have a lot of studio equipment that uses S/PDIF coax and that fills up the coax jacks on my 950 in a hurry. I use optical then for the other components. No worry, no problem.....

I don't know why, but Stereophile has a decided bias against optical. I have seen references to "digital fog" and bandwidth issues of optical vs coax. I have seen in more than one place it mentioned that even though coax, because it is electrical and can have more susceptibility to EMI/RFI, does in fact do much better in terms of jitter than optical. Maybe due to the extra electrical-to-optical and back conversion that's necessary for Toslink. FWIW.

Thanks for your help!

In principle, coaxial has higher bandwidth and theoretically can give you better sound. However, in practice, the difference is probably undetectable to the human ear.

There are two main advantages to coaxial: it's cheaper, and you can bend this way and that without it breaking.

There is one main advantage to optical: not being an electrical signal, it will not contribute to a ground loop problem in your system. If you're getting a ground loop hum, you could always try switching from coax to optical and see if it clears it up. It might, or it might not, depending on the actual path the group loop is taking.

Jeff

I use digital coax and it works fine for me. I have never had any problems with it.

I was just going to echo Jeff's obversation regarding the Toslink interface. Some of the earlier Toslink interfaces had a somewhat limited bandwidth, and I think that bad rap stuck with them.

Yeah, I should add that I have used both, and not really heard any differences. But I do "default" to coax just because the cables are more robust.

(Nothing like a good Belden 1694A! )

Also, assuming sane logic at the recieving end, bandwidth (for a DIGITAL signal) isn't a more is better deal - either there's enough or not. If the bits can fit, GREAT! If not it's just broken.

If the equipment at the receiving is getting the signal and not dealing with it according to the best practices for the applicable protocol that's an equipment issue. Just a software engineers $0.02!

Don't forget jitter. Wider bandwidth is better. Safety margin on top.

I have been using coax for digital connections. I was informed that glass Toslink could provide a better connection than coax, and that the limitation of most Toslink connections was the plastic used. I elected to try this. The difference is audible and not subtle. The coax simply couldn't compete (I tried three different ones, at varying price levels). There's a lot more information being passed through the glass Toslink. The glass Toslink I used is available for $29.99/ one meter on Ebay.

http://www.smr-home-theatre.org/Schneider/Schneider.html

Jeff

"More information?" What additional data is being passed through the glass Toslink that isn't being passed by the coax cable? I'm especially curious with Dolby Digital and DTS streams, which are packeted data. Any further information or examples would really be helpful.

Thanx,
Sanjay

You know, Sanjay, it's all that Easter Egg secret data that the producers put into digital audio content targeting only those people who are using the right cable. I read about it somewhere on the Internet (www.audiotic_concepts.com, I think). It makes normal CD's sound as good as DVD-A or SACD.

I'm surprised an audio expert like yourself isn't aware of this.



Bob "My drugs are peaking" L.

[This message has been edited by boblinds (edited August 04, 2003).]

Suffice it to say, a glass Toslink at that price is a steal to say the least.
A 'good buy' requires very little justification, but to say how it's better than plastic does open up a totally new discussion!

I notice a more focused soundstage and greater "pace" and "rhythm" when using glass optical cables instead of plastic. I also hear the missing sounds when I use glass, and much more than when I use regular coax. The background is more "black" with glass. Even my wife noticed the night and day differences which blew her away.

Bob, OK, that makes sense. I guess my skepticism comes from a bad personal experience I had with glass cable (shattered into little shards when I tried to bend it). BTW, I'm with the others: I use whatever digital connection is available on the back of my pre-pro, coax or Toslink.

Best,
Sanjay

Ummm ... SoundHound? Do you claim to hear this difference even when listening to Dolby Digital sources?

Jeff

Jeff:

Yes, especially Dolby Digital sources - it's a night and day difference. Is sounds as if a "vail had been lifted" from the soundstage, especially from my Onkyo transistor amplifiers.

All righty, then how do you explain this alleged improvement in sound with digital packets? Where does this improvement come from?

Jeff

I'm impressed. You not only nailed every standard audiophile cliche but you've also got Jeff taking you seriously. All that's left is to use "ruthlessly revealing" in a sentence.

Best,
Sanjay

In spite of the ruthlessly revealing nature of glass Toslink cable, and the packeted nature of the Dolby Digital bitstream, the improvements were nonetheless overwhelming. The fact that the packets of data arrive unaltered in form contribute to the massive superiority of glass Toslink.



[This message has been edited by soundhound (edited August 05, 2003).]

Wow! You really had me worried, there, SoundHound!!

Jeff

Yea, now I have to find out if I can return all these cables...

-Joe

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Remember the Intellivision?
http://www.gotmaille.com/nostalgia/

Is SH serious or joking? I *can* believe that glass is better than plastic, just due to transmissivity, but I personally would default to coax over any kind of Toslink anyway.


[This message has been edited by Kevin C Brown (edited August 05, 2003).]

Kevin:

Glass absolutely blows away plastic. It's like several veils had been lifted - I'm hearing more sound than I ever had. I'm replacing all the coax digital lines in my studio with glass optical ones. I bought a bunch of boxes that translate the coax signal to optical so that I can use the glass. Unbelieveable difference!



[This message has been edited by soundhound (edited August 06, 2003).]

You're killing me.

Jeff

OK. Now I see what's happening here.

The movie that Soundhound is currently working on is causing actual brain degeneration.

Soundhound -- in the tradition of that great film, "Last House on the Left" -- keep repeating to yourself:

It's only a movie...
It's only a movie...
It's only a movie...

Glass optical reveals much sweeter highs, and the midrange has a palatable presence that beguiles the listener.



[This message has been edited by soundhound (edited August 06, 2003).]

Personally I think that the reason for the difference in sound is the difference in the speed of light through glass rather than plastic. The digital "packets" maintain their "punch" and "zest" and "zing" and "pow" much better in glass and this translates into much cleaner, clearer, dynamic and punchy sound. It's for this reason that I use only glass fibre in my cold fusion-based perpetual motion machines!

Jeff Mackwood

Ouch!...sorry, just bit my tongue while it was pressed against my cheek.

But from a maintenance stand point, is glass fiber good for audiophiles who don't do windows?

Good to see the senses of humour alive and well There was a semi serious debate of glass vs plastic awhile back:

http://ubb.outlawaudio.com/ubb/Forum14/HTML/000064.html

Personally, plastic is the way to go...glass keeps the laser too strong and harms the equipment

I find I have to keep the glass shuttered away from the window near the AV system.
It makes soundtracks entirely too 'hot'.
I found a tinting lacquer for 230 a bottle, but can't decide which density of tint. I hear there's a blackmarket version, which goes a shade darker than legal.

Seriously, I find that the best optical cables are glass cables with green-tinted glass.

Just like drawing the green line around the outside of CD's, the green-tinting limits the amount of internal reflection in the cable and, therefore, transmits the signal with less ambient interference and greater data integrity.

I believe that the glass is made from reprocessed Coca-Cola bottles.

I am taking a break! This is information overload!

Of course I forgot to address the other side of the thread: namely coax.

We all know that electrical signals travel relatively much slower in copper than the speed of light. So to properly configure and "balance" a system that is comprised of both optical and copper digital streams one most choose the proper matching length of copper to go along with the fibre.

The method of doing so is to first pick a set length of fibre for all of those connections. Let's assume that it's 1 metre. (Americans in the crowd can pick 1 yard instead - just to spite the French - and I don't mean my Quebec confreres!)

Take that one metre length and multiply it by the ratio of the speed of the electrical signal in copper to the speed of light in glass (or plastic for all of the non-Soundhound converts out there.) Next, shorten your coax cables to that new length.

In this manner your coax signals will arrive at the right time and you will avoid corresponding problems with clearly audible sound effects / delays. Your intimate "club" recording would otherwise sound like you are sitting at second base in Toronto's Skydome - with the lid closed.

Trust me, it makes an amazing difference.

Jeff Mackwood
National Research Council of Canada
(thought I'd throw that in to clearly establish my bona fides)

Jeff,
I thought that if your "cutting the cables to the relative wavelength" would work for coax it must make a difference for plastic optical as well. So I figured out that I needed to cut precisely 6.2mm from my optical cable conecting my CD player and my newly purchased 950. It was a bitch getting the end back on but after a little bit of time with some super-glue (not the generic stuff but the stuff actually made for glass) and some duct tape I finally got it to transmit the signal again. And what a signal it was. I popped in my favorite Michael Jackson CD (listened to Thriller as I do when I audition all my equiptment) and it sounded simply amazing. The soundstage openned up so incredibly I thought that I was in the recording studio. I heard things on this CD that I never new existed. It sounded like it wasn't just Michael singing but Michael, LaToya and Janet all singing in harmony. Thank you so much for giving me this tip.
Aaron

About that adjusting the lengths of the electrical coax lenghts to the optical cable lenghts so that the signal travel time in the respceitve media are equal: nice start.

(To find out speed of light in an optical media, divide the speed of light in a vacuum by the index of refraction of the optical medium.)

Matching the signal travel times in the cables is only a partial solution. Whatever video and audio circuits are involved will have their own "travel" times: delay in the respective circuits for signal propagation and processing.

Whether optical or electrical, the travel times for the signals is on the order of a few tens of nanoseconds or so, which may be a LOT less than the delay introduced by audio or video processing.

Paul

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the 1derful1

Paul:

There you go again, trying to inject logic into the argument

I have found that coating the outside of the optical cable with green, not black, magic marker (Sharpies, specifically) can drastically cut down on the amount of signal loss in a long cable. Black won't work because it's too absorptive. Green has just the right amount of absorption and reflectance characteristics, perfectly balanced to the wavelengths of light involved, and the n of the cable itself.

I'm dying here!

Using logic: me bad! No spanking for me.

I wonder if the green marker trick will work for the edge of a CD. Compact Disc, not Certificate of Deposit.

Paul

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the 1derful1

Is anyone being serious or is all this a joke...I really can't tell at this point. Soundhound, you do sound serious regarding the glass thing for Toslink, are you?

I'm dead serious

It's a good thing I wore my galoshes to work today. My tall galoshes.



-Joe

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Remember the Intellivision?
http://www.gotmaille.com/nostalgia/

this is really too funny...

SH: You should think about doing reviews after that first post.

[This message has been edited by Jason J (edited August 07, 2003).]

Ooooohhhhmmyyyygggaaawwwddddd.....I'm turning audiophile!

I think it gets really scary when you can do something like the following:

Upon insertion of the Micromagic vibrapods underneath my Esoteric A-247 CD player, it was like a wash of surf over my system. The high frequencies were much more focussed and clear in detail and presentation. The midrange showed the most benefit, becoming almost transluscent to the hardware in terms of the reproduction of the elements of the original recording. The low frequencies, while not exhbiting the improvement that I realized with the rest of the audio spectrum, certainly contained a better amount of pace and rhythm, almost revealing spacial discreteness in terms of the ultra low frequencies split between the left and right channels.

And not believe a word of it...

I believe you, Kevin.

Not to worry; you can now get over-the-counter medication to take care of that swelling!

Sanjay

Who's reality is scarier? Kevin's or Bob's?

See you on the dark side of the Moon. The psychoacoustic replication of the ultra low frequency range in the left and right hemispheres (predominantly focused in the frontal lobe) is far better on the dark side.

This is why space travel is so important. Just ask Sid and Timothy when you get here... and bring some of that smok'in glass fiber, a box of waterproof matches, and a bottle of oxygen.

I'd be really interested in some spatial time travel...

“Time travel horizons are rather like black hole horizons. While a black hole horizon is formed by light rays that just miss falling into the black hole, a time travel horizon is formed by light rays that all emerge from a bounded region. In other words, they don’t come in from infinity or from a singularity, but originate from a finite region containing time loops…..ordinary matter with positive energy density has an attractive gravitational effect and warps space-time to bend light rays toward each other.”

Per Stephen Hawking

Kevin I think its clear if you intend to time shift, - dump those digital coaxial cables and move away from those jittery plastic conducting toslinks. Future proof your current system with superconducting glass toslink fibers. Spatial time travel will come at a speed at or beyond ‘light’.


[This message has been edited by Smart Little Lena (edited August 09, 2003).]

The 950 will not do spatial time travel. It's one of the features that they omitted in order to keep the price down.

It may be a feature in the next generation pre/pro that Outlaw is rumored to be working on.

Stephen Hawking's concept of an Event Horizon refers to the gravitational boundary limit of a Black Hole as it relates to photon (light) behavior. The characteristics of matter/energy at the Event Horizon can actually allow matter/energy to escape from a Black Hole.

The bigger the Black Hole, the greater the surface area, and therefore the greater the radiation emitted. It is surmised by Hawking that there are practical limits to the size (mass) of a Black Hole, and this has led to further conjecture about Worm Hole's, and their role in this space-time interplay. One might consider that Worm Holes are the Glass Optical cable God uses.

Light energy, while having measurable mass, is still going straight; it is space that is curved, but we just don't conceive of space that way. Therefore... the next time you use photons to send your musical signal through a glass fiber, rest assured that they are neither analog or digital in character when they are in transit through space time. At any one finite moment in time, it is impossible to predict where the photon is, or it's physical properties at that instant.

Space is a state of mind over matter. Sid... Please pass the fiber over to Timothy...

spatial time travel...may be a feature in the next generation pre/pro that Outlaw is rumored to be working on.
Hawkin’s will want one of those pre/pros.