Optical vs Coaxial

[Mikekid]

Hi.

I am currently using the optical out from the DVD player to the receiver (rx-v3000). I don't have a digital coaxial cable to test drive so I was wondering what you prefer and why. The optical sounds fantastic to me but I can't compare the two....yet.

Thanks for your reply!!!!!!!!

Mike

[Malcolm]

I use both because of my mix of equipment. I cannot tell the difference between toslink and coax with my equipment. I think the pros and cons of both have been covered in other posts recently. You might want to check the archives.

[Seb]

what malcolm said.

basically, coax is often preferred because it's more sturdy and less prone to breaking than toslink.

oddly, though, toslink connections are found in greater numbers on most receivers than coax.

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[boa12]

but coax are generally more prone to pickin up noise like rf & emi. but they're also generally cheaper.

i honestly can't hear any dif between those i've tried, though i've only used those in the 30-$60 retail range.

so for me it's flip a coin.

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My Home Systems Page

[Michael Greenway]

I converted my TOSLink to a Monster Digital Coax this weekend. I listened to a few cd's and watched a few movies. It seems to me that base is tighter. My review is not complete.

[ne_surfer]

My Pioneer DVD payer has both optical & coax, I choose optical (toslink) because it electrically decouples the dvd player from my receiver (for whatever that worth). But the optical cable (AR) was more expensive than the AR coax. I did see a cheaper optical cable at Best Buy for $14, but didn't go for it, because I didn't know if my 2 year old pioneer dvd player would still pump out light, wanted to give it the best chance.

Now my point: since we're dealing with a digital signal here, either coax or optical will work the same. Furthermore, the cheapest cable will work the same as the most expensive (monster at $60, for example). Either the 1's and 0's of digital are there, or they are not. Either the signal is perfect, or its corrupt. But its not the same as an analog signal, which can be partially degraded by noise, poor interconnect cable quality, etc. So go buy the cheapest coax!

Another point: speaker wire. As long as you use a sufficient guage, say 16, and real copper, then you can't improve the signal (and sound). But the cheapest wire. Copper is copper. I would say forget about capacitive/inductive effects, which are frequency dependent (more pronounced at higher frequencies). The speaker itself will present a far more capacitive/inductive load, and any such effects in the wire will be negligible. As long as you use a sufficient guage (16 - 18), you can not do better. Forget monster, forget speaker wire as a transmission line (the frequencies are too low < 20khz).

Any use digital interconnects whenever possible.

[dougdrake2]

ne_surfer - Now you've done it. You've opened the door to a new round of debates over cable and wire.

Having a data background, I also thought at first that the digital signal was either good or it was bad, no middle ground. Totally a binary situation. But I've read a bit about it, and also some posts from some other knowledgeable folks on the board (RG, for one). I've come to believe that in fact digital is not quite so binary, so to speak.

Since there is no error detection/retransmission in this digital world, there is the possibility of lost bits that are made up for by the receiving equipment, which usually just fills in the blank with an average of what was on either side of it, I believe. There are things like jitter, etc... that can happen as well (sort of like doing video over an IP/public network).

So, I think it is possible that better cable/fiber will yield better results. The question is, can YOU hear it and is it worth the money to you to buy them. A very subjective decision, indeed.

All, of course, is JMHO.

Doug

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My System

[Prana-Bindu]

Coax is generally considered less prone to digital jitter than toslink. Really, the amount of jitter added to the signal is the only criterion by which to compare such cables; at least the only criterion so far identified.

What is jitter? Timing error. The moment in time, in relation to the rest of the signal, in which a digital unit is played affects the sound. A simple description of the jitter problem that I've seen goes a little like this: the right note played at the wrong time is the wrong note. Remember: each digital sound unit is just an approximation of the original portion of the analog waveform represented by that unit. When a digital signal is converted to analog by a cd player's or separate DAC, the audible result is not the smooth wave that the original analog signal was: it is the best approximation of that waveform that digital blocks can make. Jitter is the playback of these digital blocks at relative times not identical to the relative times established by the digital encoding process (the analog to digital conversion).

There are at least five locations in the digital playback process (when using a separate DAC) that introduce timing error (jitter). The biggest culprit is the encoding the signal goes through to be transmittable via an S/PDIF cable (such as toslink and coaxial). The only way to avoid this is to use an interface that does not burn timing error into the signal like S/PDIF does. If you have to use S/PDIF (such as in the choice you're making between toslink and coaxial), it would be best to use the interface that introduces the least amount of jitter. As I understand it (my memory is faulty here), toslink is more jittery than coaxial.

You could use a jitter filter between the transport and the DAC, but if you're gonna use S/PDIF interfaces between these units, the filter might not help at all or might add even more jitter. Also, different jitter filters have different jitter "footprints" that work well with some transports/DAC's and not so well with others. This is likely because the accumulation of jitter is similar to the accumulation of wave amplitude in the phenomenon of wave interference: there is constructive and destructive interference. In other words, timing errors from different sources may cancel themselves out or add to each other.

Isn't this fun?

You have many options to choose from if you want to get paranoid about jitter like me. You can get transport/DAC combos by the same manufacturer that has built the units to work off the same clock (DAC clock fed back to the transport for reference). You can use units that allow use of some attempts at universalizing the transmission of data and clock information separately (I2S, I2S-e, e.g.). No interface is on top right now, but it looks like second-generation I2S-e will likely win out. I say second-generation, because the units that use I2S-e at this time don't allow the feeding of the DAC clock back to the transport as a reference. The capability is in the interface, but no one takes advantage of it yet, as far as I know. So, right now the best way to avoid jitter is to use a transport and a DAC made to work off the DAC clock (same manufacturer) and using their own unique interface.

I want to use the Perpetual Technologies P-1A, so I have to deal with what it can do: I intend to run my toslink-only cd player to an Audio Alchemy DTI jitter filter, make the I2S connection from the DTI to the P-1A and another I2S connection to the P-3 DAC. Then, I promise, I'm done with this crap. Probably....

I need a nap.

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May the bridges we burn light our way....

[ne_surfer]

Hmm ... jitter is where data edges do not precisely match clock edges and move somewhat randomly relatively to the clock. The way you dela with it is to buffer and reclock to incoming data, which I presume the reciever does. (I'm not sure if the receiver extracts a clock from the coax/optical bit stream or uses its internal clock, but the frequency is exactly defined so that an internal clock would be fine.)

The A/V receiver does some digital signal processing before sending the data to the D/A. By this time the data is exactly clocked and corresponds exactly (except for the processing) with the bit stream extracted from the cd player (after error correction). Due to buffering at each stage, the data has been delayed from when it was read from the CD to when its is fed into the D/A. But the smapling rate is exactly the same, the data is clocked precisely, there is no jitter at the D/A (any jitter over the coax/optical cable has had no effect, except to delay the data stream).

Regarding the advantages of digital interconnects: digital signals have a very high noise immunity relative to analog. In fact, noise has no effect until information is completely lost. That is, up to a certain point noise has no effect. Then a one bit is misread as a zero, or vice versa, a complete corruption. But - here's the important thing - you will never see so much noise on a coax/optical cable that you with cross the noise immunity threshold. So you will not have errors that require error correction logic to insert fill into the data stream.

On the other hand analog signals are degraded to some degree by any noise, the more noise, the more distortion. And the distortion adds up as each stage of processing adds its own noise and inaccuracies (the final stage, the speaker, is the most distorting, that's why you need to use Klipsch).

The advantage of digital signals is that you use the very high noise immunity and make sure that you keep well below that threshold, and you get perfect signal processing. You don'y actually have an analog signal until the D/A stage just before the amplifier in the receiver.

(There will be some inaccuracies during the mathematical calculations/transformations of the digital data, because of the limited precision of the data. A CD is 16 bit data, my Marantz uses soemthing like 96 bit precision internally.)

[Mikekid]

Thank-you for the replies!

OK then, what does jitter sound like?? I'll be listening real close to see if it is present now, but I think everything is a-ok.

The old receiver was all analog hook-ups and now, with this toslink cable, I have definitely noticed much tighter bass response. Man it sounds good............Just re-listened to ELO Zoom dvd again last night....AWESOME!!!!

Thanks again all!!!

Mike

[Audio Flynn]

I swithed a year ago from Kimber Toslink to Audio Quest between my CD player and MSB Dac.

I was pretty sure the bass was firmer, mids fuller and highs a little less "tinny"(jitterry?).

Allot has changed since then I should go back and listen again.

Supposedly the AT&T connection is more robust than Toslink for optical signals. Toslink always seemed to be a bit of a flimsy connection; could you get more jitter if the optical signal is trnasferred to a cable that is lined up off the center line of the inside diameter of the connector on the source transport.

There has to be some error generated at the cable and component interface. Is it significant I am not sure.

I understand electronics very little; light transmission far less than that.

[Prana-Bindu]

I haven't done an A/B comparison to be able to identify the audible effects of jitter, but as soon as the next digital upgrade comes along (hopefully within the next two weeks), I'll do much critical listening and report.

Others report jitter smearing transients, degrading imaging, and compressing the soundstage. I'll let y'all know what I hear in a couple of months (hopefully).

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May the bridges we burn light our way....

[SOUNDJUNKIE]

Well...this is quite TAME.

[lynnm]

Waaaadddaahelllll!!

ne_surfer you blasphemer!! I'll be huntin' ye down like a dog and lashing you 3 gooduns with a length of coax and 3 gooduns with a length of fiber optic and you will soon discover the error of yer ways laddie!!

OW! WOW! YIPE! OOH! OY!My mistress has just demonstrated that for all practical purposes optical and coax are the same. I'll put away me 'unting fig.

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It is meet to recall that the Great Green Heron rarely flies upside down in the moonlight - (Foo Ling ca.1900)

This message has been edited by lynnm on 03-19-2002 at 10:19 PM

[PoppaPump]

Yeah, he's right, its a little more complex with digital than to just say, well its either on or off, a 0 or 1, so buy the cheapest cable possible. I do agree that cables are overpriced. I think people confuse Binary with Digital. Yes, they are similar in usage etc, but digital is much much more complex than that. If that was the cause then there would be no need for advanced systems such as Trellis Code Modulation and Convolution Coding. I suppose Signal to Noise Ratio could also be a factor, but I dont know how noticeable 100 corrupted bits out of say 10 million would be. Thats like 1/1000th of a percent or something like that.

[jacksonbart]

someone been diging through the archives/

[tommyboy]

My dvd player has both. I've always used optical, but had an extra coax laying around, so I tried it out. I couln't notice ANY difference in sound. I don't know why I've always used optical, but either way, you'll be fine.

[oldbuckster]

Most of my equipment have both....................if any of MY equipment has BOTH hooked up it will defer to COAXIAL, not sure why, both are nice....alot less wires laying around.......easy way for 5.1 hook-up...................

[Islander]

I can't comment on the theory, but when I switched a $40Cdn Monster digital coax cable for a $60Cdn Monster digital coax cable (Datalink 100) the sound was noticeably clearer.

I've got both analog and digital connections from my DVD/CD player to my receiver. The digital cable is connected to the DVD input, while the analog cable is connected to the CD input. That way, I can switch back and forth to see which sounds best. With the analog connection, the DAC in the player is working, while with the digital connection the DAC in the receiver is working (correct me if I'm wrong, anyone).

There is a slight but noticeable difference between the two connections, but neither one is best with all music, so it's good to have the choice at the push of a button. As well as the two different DACs, the player is set to upsample to 176.4 kHz (x4), but upsampling only applies to the analog output with this player, so it's apples and oranges in two ways.

As I said, if I'm being picky ("listening critically"), I just choose which input sounds better at that moment and enjoy the music.

[Guest " "]

I was surprised to learn that amoung the upper class audio crew, there is a preference for coax. They believe optical to introduce jitter as well as additional componets in the path.

So now, I need to dig out my coax, and do some auditioning.

I wonder if the original person who posted the question knows the anser.....it's been 4 years since asked.