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Optical VS. Coax??

Old 04-05-03, 10:28 AM
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Optical VS. Coax??

OK, need some help here. After buying a Coax wire last night (and opening the package!) I realized my DVD player only has an Optical output. Is there really a big difference between the two? Also, is it really neccessary that I spend $100 on an Optical cable if I dont have a $5000 set-up? Any help would be greatly appreciated. Thanks!
Old 04-05-03, 12:08 PM
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There shouldn't be any difference that you or I would notice. And no... no need to buy a $100 optical cable. Check out www.buy.com and search for AR-080, 081, or 082. They are 3', 6', and 12', respectively.

The 3' and 6' lengths are right around $13-14 shipped. I have found Acoustic Research cables to have the same quality as Monster Cables. I'm sure someone with some digital testing equipment could find a difference.. but come on. Over half of us could probably benefit from a new contact lens prescription or hearing aid before we'd notice a difference in $100 cables.
Old 04-05-03, 01:15 PM
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Inexpensive optical cables can be found at almost any store that sells DVD player accessories, even at Wal-mart Supercenters.

One nice thing about digital outputs, whether coax or optical, is that the quality of the cable is less important than it is with analog outputs, such as component video cables or speaker wires. With digital signals either the ones and zeros get through or they don't. They are not subject to the same sort of degradation as analog signals.
Old 04-05-03, 01:16 PM
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When your DVD player sends a digital signal to your receiver, only two things can happen. The signal gets there, or it doesn't. That being said, optical cables are fairly fragile as cables go. A higher end cable may be better constructed and last longer.

www.partsexpress.com has some optical cables starting at about $3.
Old 04-05-03, 05:52 PM
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It's sort of a moot point if your player only has optical, isn't it?
Old 04-05-03, 06:48 PM
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Coax has a theoretical advantage over optical since the optical signal must be converted twice. Optical is also more prone to jitter. That said, most people canít tell the difference and as noted above, the issue in your case is essentially moot.
Old 04-05-03, 07:48 PM
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Originally posted by Mr. Salty
It's sort of a moot point if your player only has optical, isn't it?
Good point. But, it's not like we all have anything better to do.
Old 04-06-03, 11:53 AM
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The reason I was asking was because if I found out there was a huge difference, I might consider switching players. From what I have seen here, I think I will stick with what I have for now.
Old 04-07-03, 01:45 PM
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Originally posted by audrey
Coax has a theoretical advantage over optical since the optical signal must be converted twice. Optical is also more prone to jitter...
I was wondering what jitter was (not the sort of thing one finds in the FAQ at the top of this forum) and found this paper on the subject. But I am left wondering why optical HT links are more prone to jitter than coax. (I suppose that it has to do with the conversion of the signal to light pulses and then back again to electical pulses.) Care to elaborate? And what would jitter be like in its effects on audio?
Old 04-07-03, 03:11 PM
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I think jitter is introduced by light reflections from the walls of the fiber optic cable.

The paper referenced above also says this:
Jitter generation can be defined as the quantity of jitter
added to a signal. This parameter is primarily used
with transmitting components, such as laser drivers,
serializers, line drivers, regenerator clock/data recovery
circuits (CDRs), and limiting amplifiers.
Old 04-07-03, 04:10 PM
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Originally posted by lizard
I was wondering what jitter was (not the sort of thing one finds in the FAQ at the top of this forum) and found this paper on the subject. But I am left wondering why optical HT links are more prone to jitter than coax. (I suppose that it has to do with the conversion of the signal to light pulses and then back again to electical pulses.) Care to elaborate? And what would jitter be like in its effects on audio?
Iím not sure how technical you are or how much depth you want, so I will keep this simple. Perhaps others will chime in. Although there are different types of jitter, they can all be thought of as a form of timing error in the digital signal. The actual data (the 1s and 0s) are correct, but are delivered at the wrong time. Robert Harley (Stereophile) summarizes jitter as: the right amplitude at the wrong time, is the wrong amplitude. Jitter tends to add a harshness to digital audio that is most noticeable in the high frequencies.

In the 2 channel world, anti-jitter devices, sometimes called jitter bugs are fairly common. I use an external clock w/ my CD transport to reduce jitter. Although subtle, I find re-clocking the signal lessens listening fatigue somewhat.

As to why opticial is more susceptible to jitter than coax, one reason is the slower response time of the optical transmitter and receiver. There are also some anomalies that can be introduced by the cable material and construction.

If you would like to hear what jitter sounds like, the Stereophile Test Disc 2 contains a track with deliberately induced jitter. BTW: this is also a great all purpose disc with lots of useful tests like Treble, Mid, and Bass decades for graphing frequency responseóand itís fairly inexpensive.
Old 04-07-03, 11:16 PM
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I've always said that you will only hear a difference between the two if you can hear grass grow and paint dry.
Old 04-08-03, 01:48 AM
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I am a painter and can verify that one cannot hear paint dry. I can hear 80-mph Wyoming wind gusts thowing sand and dirt on a freshly painted side of a building though.
Old 04-08-03, 02:17 AM
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Originally posted by Wolf Husky
I am a painter and can verify that one cannot hear paint dry. I can hear 80-mph Wyoming wind gusts thowing sand and dirt on a freshly painted side of a building though.
Hmm...bitter? heheh...
Old 04-08-03, 10:25 AM
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Thank you for the information audrey.

[For those interested, the Test CD 2 can be purchased for $9.95 + $4.95 S/H here (near the bottom of the page).]

Last edited by lizard; 04-08-03 at 10:47 AM.
Old 04-09-03, 12:10 AM
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One difference is that the coax can be bent more than the toslink.
Old 04-10-03, 11:24 AM
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Here's the difference:

Optical costs more than Coax
Coax is more flexible than optical

That's it. Also, there is no difference in output quality between expensive or audiophile coax and any old RCA cable. Get the cheapest optical cable you can buy because again, there is no difference in output quality. I got one at Radio Shack for $3 because they're getting into the snakeoil audiophile cabling business, and that particular model was discontinued.

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