Optical Cable Question

[mixadude]

Here's somethin else to look at

I really can't buy that there is any appreciable difference between plastic and glass in a properly designed five foot piece of either. I do think that how well the ends are made and maintained matters more.

Have a nice day Mr. always polite to everyone

[royphil345]

Are you really that lost? ...There's everyone and then there's you. You dished out PLENTY of disrespect and trash for no reason at all before I returned the favor. What did you expect? Don't expect much respect from me in the future either.

"Here's somethin else to look at"

Oh... very interesting again... not

More random information you got from the internet about the very basics of a FO system that has little to do with the discussion. You want to point out what part of that supports your argument?... Didn't think so. Your only argument so far in all these posts is "I just don't think..." WEAK But, actually would have been a very acceptable post and opinion without all the disrespect, garbage, random information, and arguments that had nothing to do with the issue.

[mixadude]

OK then. I'm sorry if I was disrespectful. I'm clearly outclassed here when comparing rudeness and audio abilities.

I also think everybody should buy cheap gear and really expensive cables, just as long as they're happy with their hifi experience.

Have a nice day.

[jneutron]

Holy crap...what a garbage thread.

TDR is Time Domain Reflectometry. It is used to find a discontinuity in a line. Send a pulse down the line, look for the reflection..a break or kink in the line will send signal back to the source.. measure how long it took, divide by two, and with the prop speed of the pulse known, calculate how many feet down the line the problem is. This is the exact same method used by the telephone company decades ago to locate breaks in the twisted pair that goes to your phone..

Two types of fiber optic lines I am familiar with...stepped index, and graded index. Both keep the signal towards the center of the line by different designs.. Both have dispersion characteristics..

A five, ten, 20 foot run of any fiber, glass or plastic, will not suffer from "multipath" ghosting, the path length or prop speed vs radial distance from the core is not sufficient to do anything like that.

Jitter is NOT introduced by the light bouncing inside the cable...different "path lengths" can affect the risetime of the pulse at the receiver..if the cable is too long, it may cause the pulses to be outside the receiver's capabilities. If it is too long, the fiber's frequency dependent dielectric coefficient could cause pulse spreading..that article mixa pointed to states jitter per length of cable, but that simple specification is incorrect...however, for the guys in the field, it is very very good for general understandings of how the fo cables and systems will work. Pulse spread equations are too esoteric to have the field guys use them...it's actually receiver specs jitter w/r to pulse spreading.. not fiber per se...

Mixadude is correct..the vast (and I mean vast) bulk of FO problems are due to the termination surfaces (cleaving and polishing), and integrity of the cable length, kinks breaks, etc.

If you swap 1 meter cables and hear a diff, you have problems with the setup and interfaces, not the fact of plastic or glass..

Cheers, John

[Resident Loser]

...why always facts?...jneutron, don't you know it always upsets the applecart?

We make up custom length fiber-optic cables in the field...like soldering(but not really)care in prepping the fiber, adhesive and connectors is a good start...then the ends are fixed in a jig and polished until they pass light from a calibrated source to a reciever unit...it ain't rocket science...pretty straightforward if you have the patience...sloppy mechanical skills usually produce poor results.

jimHJJ(...I know you know...)

[jneutron]

...why always facts?...jneutron, don't you know it always upsets the applecart?..

Just call me "Don"...where's that windmill?

...sloppy mechanical skills usually produce poor results.

In all aspects of life. (don't go there)

One word.....plastics..

Cheers, John

[Resident Loser]

...English teacher Mr. DeAngelis would say "Droll sir, quite droll"...

jimHJJ(...long ago and far away...)

[Monstrous Mike]

Holy crap...what a garbage thread.

John, you should know by now that there are only three main ways to change somebodys mind about something: force, emotion or logic. Obviously force is not an issue here so we are dealing with emotion and logic (logic includes science, facts, laws, reason, the truth, etc.).

When somebody says they heard (or saw) something you are dealing with emotion and sometimes all the facts in the world are not going to convince them that they didn't actually hear or see what they did or that there is some other explanation for it.

As a matter of fact, I think this sort of thinking is an impediment to the advancement of society. I really stuck around here a while ago because I found audiophiles to be a prime example of someone who has determined a belief based on emotion. The only science they would accept is something that supported their belief while rejecting anything to the contrary (this is a classic case of confirmation bias).

Perhaps we should consider teaching children in school how to think critically and avoid being swayed in their beliefs by a bombardment of emotional arguements which can easily suppess factual and logical points of view.

Addendum:

I have been thinking about this some more and I believe global warming is an issue which has an emotion/logic/science conflict in its arguements. Granted, it was all started by scientists, specifically University of Massachusetts geoscientist Michael Mann and colleagues who came up with the poster child of global warming, the hockey stick graph. When politicos got hold of this, the emotion machine went into work and now we are faced with global flooding, super hurricanes, no icecaps, etc. unless we all stop driving, close coal plants and ride bikes. There are a growing number of scientists who now admit we really know less than we think we know and the "hockey stick" graph is due to mathematical artifacts. On top of that, nobody can correctly link increased carbon dioxide in the atmosphere to rising global temperatures. And actually, CO2 is not a pollutant but rather a necessary gas which is needed for plant life and vegetation.

However, in the minds of the average joes, the thoughts of ice caps melting and flooding New York will be indeed very hard to reverse. It's much easier to create a monster than to convince people that it was a possible fabrication.

Obviously, this issue is infinitely more important than audio cables but I think the principles of why and how people believe in what they believe in are the same. And in the end, emotion will win out over logic, reason and science most of the time.

This has got to change, IMHO. Scientists love to be wrong. That's progress. Emotional people hate to be wrong.

[EdwardGein]

Hershon stated that he got better sound on his HK 31 DVD player by using an optical cable. You complained that the optical cable on your HK 22 DVD player did not produce the same results and blame Hershon. What's wrong with this picture? You are comparing apples to oranges or 2 different models and blaming Hershon because you didn't get the same result on your model that he got on a different one.

[Beckman]

Don't know if there is an audible difference but:

http://electronics.howstuffworks.com/fiber-optic1.htm

http://electronics.howstuffworks.com.../tm/106-10.htm

[Ihatehershon]

This board is almost worthless now and my brother & I are almost tempted to leave it for good. It use to be helpful to get a straight answer or recommendation to a simple question. Instead all it consists of nowadays are bizarre questions to minuteae or stupid answers to valid questions. Let me spell this out again, as apparently your high IQ's fail to comprehend this.

Anytime you feel like going and not coming back......by all means,GO!!!!!!!!!
Why are we wasting our time with this loser, who pretends he knows about Home Theater. Every post of Hershons starts an Argument. You all know me under LEAFS264 and Hershon got me so mad, I gave him a what for, and was banned by Eric for it. Fine that was my falt. But it just dawned on me that if we stop responding to the RETARDED,FEEBLE,CHILD LIKE cries for attention that Hershon has, This board would be so much better for it!! He really is a Home Theater virgin. But to pass himself off to others as a Audiophile is just low and cowardly.
So, Hershon you and "your brother" (ya right) can rub salt for I'll i care. Just please stop wasting our time.

Jay

[EdwardGein]

Let's see you obviously have no life and need to resort to using my brother's screen name as part of yours and yet, you call Hershon and I losers. Personally I call that pathetic.

[Ihatehershon]

Let's see you obviously have no life and need to resort to using my brother's screen name as part of yours and yet, you call Hershon and I losers. Personally I call that pathetic.

Lets recap. When you first started posting under Edwardgein, everybody called you Hershon anyway because we knew who it was. But you retorted by saying and I quote
"I'm not Hershon and I have never heard of this person Hershon you speak of "
OOOOOOHHHHHHH so now he is your "Brother"
Stop with the lies.....
HERE ENDITH THE LESSION...GRASSHOPPER.

[FLZapped]

Cables don't produce sound...that should tell you something.
.

Oh sure they do, just take one and tie it to the end of a stick and whip it around....it'll make lots of sound.....

-Bruce

[hermanv]

Holy crap...what a garbage thread.

Jitter is NOT introduced by the light bouncing inside the cable...different "path lengths" can affect the risetime of the pulse at the receiver..Cheers, John

Lets see John, slow rise time equals uncertain slicer levels at the input buffer and add some everpresent noise and the inevitable result: edge to edge jitter. Or non-cumulative time sampling uncertainty if one wants to pontificate.

So even thought the plastic fiber doesn't make jitter, the different path lengths cause time smear or slow rise times if you preffer that term and (what was that?) results in (Oh god what have I done) jitter. Therefore, plastic fiber cables cause jitter (but you are right by god, they only do it when they're in use). Glass fiber has better rise time, less time smear.

Whether or not jitter affects the sound of a given system is highly dependant on the design of the data recovery stages. So the effect varies from one system to another, but to claim that plastic cables can not cause jitter is focusing the microscope so close that the end result (jitter) experienced by the user is lost. It would seem all of us contribiute some garbage to the world.

Coax is cheaper, doesn't have the mechanical interface problems, has better rise times, so it outperforms plastic fiber over short distances, what was the question?

[bjornb17]

Hershon stated that he got better sound on his HK 31 DVD player by using an optical cable. You complained that the optical cable on your HK 22 DVD player did not produce the same results and blame Hershon. What's wrong with this picture? You are comparing apples to oranges or 2 different models and blaming Hershon because you didn't get the same result on your model that he got on a different one.

You're closed minded, and not worth my time.

[jneutron]

Lets see John, slow rise time equals uncertain slicer levels at the input buffer and add some everpresent noise and the inevitable result: edge to edge jitter. Or non-cumulative time sampling uncertainty if one wants to pontificate.

So even thought the plastic fiber doesn't make jitter, the different path lengths cause time smear or slow rise times if you preffer that term and (what was that?) results in (Oh god what have I done) jitter. Therefore, plastic fiber cables cause jitter (but you are right by god, they only do it when they're in use). Glass fiber has better rise time, less time smear.

Whether or not jitter affects the sound of a given system is highly dependant on the design of the data recovery stages. So the effect varies from one system to another, but to claim that plastic cables can not cause jitter is focusing the microscope so close that the end result (jitter) experienced by the user is lost. It would seem all of us contribiute some garbage to the world.

Coax is cheaper, doesn't have the mechanical interface problems, has better rise times, so it outperforms plastic fiber over short distances, what was the question?

Good...one who understands..I make the assumption that since you are a communication engineer, you fall into that category...your verbage certainly shows that.

Simplistic explanations are necessary for those in the field.. You certainly see that the players here arguing do not have the level of understanding you possess..your explanations are above them. The distinction between the cable "creating" jitter, which it doesn't exactly do, and the receiver input's inability to distinguish the signal clearly as a result of pulse spreading and noise, is lost here..so I glossed over the topic..

The question posed here was that a one meter length of plastic is sufficient to introduce jitter at at a level which corrupts a simple audio rate bitstream. The response from at least two, me included, is that the end interfaces will be far more significant for a one meter run, than any possible dispersion effect.

Agreed?, or, have you more info to share?

Cheers, John

[hermanv]

My first outboard D to A showed a distinct improvement in sound quality between a coax connection and a plastic Toslink cable. I reasoned that it was possibly jitter.

About a month later I was offered a super deal on a Monarchy jitter reduction box, so I bought one. After adding the box, the difference between the Toslink and Coax cables dissapeared. The Toslink cable was 1 meter long, my system was mid priced Conrad Johnson (not allways known for superb impulse response or resolution) So even in a moderate system the effect of jitter was noticable. Longer cables and better systems would probably be more sensitive.

Now once the whole jitter issue was raised, many manufacturers took pains to fix it, so it may be less an issue than ever before. If anyone asks, I just recommend coax. I usually say buy a composite video cable, adding the words "digital cable" to the packaging appears to substantially increase the manufacturing cost.

One other point, I think Toslink is an LED driver not a laser and the receiver is a photo transistor not a PIN diode so the issues of fiber cleaving, matching, polishing, etc. seem to have far less impact than they do in the laser driven ultra high bandwidth communications cables. I have never tried glass fiber cables, but the majority of reviewers have said that they sound much better. Enough so, that I suspect the issues of fiber terminations are not the predominant cause of system degradation when using optical connections.

[jneutron]

My first outboard D to A showed a distinct improvement in sound quality between a coax connection and a plastic Toslink cable. I reasoned that it was possibly jitter.

About a month later I was offered a super deal on a Monarchy jitter reduction box, so I bought one. After adding the box, the difference between the Toslink and Coax cables dissapeared. The Toslink cable was 1 meter long, my system was mid priced Conrad Johnson (not allways known for superb impulse response or resolution) So even in a moderate system the effect of jitter was noticable. Longer cables and better systems would probably be more sensitive.

Now once the whole jitter issue was raised, many manufacturers took pains to fix it, so it may be less an issue than ever before. If anyone asks, I just recommend coax. I usually say buy a composite video cable, adding the words "digital cable" to the packaging appears to substantially increase the manufacturing cost.

One other point, I think Toslink is an LED driver not a laser and the receiver is a photo transistor not a PIN diode so the issues of fiber cleaving, matching, polishing, etc. seem to have far less impact than they do in the laser driven ultra high bandwidth communications cables. I have never tried glass fiber cables, but the majority of reviewers have said that they sound much better. Enough so, that I suspect the issues of fiber terminations are not the predominant cause of system degradation when using optical connections.

Thanks.

From your description, you did not compare glass vs plastic. As I recall, this was part of the initial thread topic...instead, you found that plastic was a problem..

Since you substituted a "presumably" better receiver, then found plastic worked as well as coax, you accepted the statement that it was jitter, and that the box was designed to reduce it..but, you didn't consider that the box may just have a better front end..maybe they used a PIN? Who knows.

From your short text here (after all, this isn't the "AUDIO LAB" ), you didn't eliminate reflections from the receiver terminus, pulse spreading, losses..but just subbed a receiver.. It would be nice to know what the actual solution was, but I'm sure most don't have the equipment at home to make that determination.

Cheers, John

[hermanv]

It is quite hard to speak in absolutes, but a couple of reasonable assumtions follow:

The Monarchy jitter box retails for about $200. Probably the build cost is $100 "out the door". This usually equates to a parts cost of $50 or less. So almost certainly they used a comercially available Toslink female reciever jack with built-in optical detector - maybe 18 cents, not a $10 and up exotic diode and amplifier. If you are going to regenerate a digital signal using phase lock loops and an expensive low jitter, voltage controlled oscillator you would most likely not pay to fix the problem twice by also using expensive receivers on all three inputs. But you are right, I can not guarantee this.

The reviews I mentioned compared glass to plastic on a large number of different manufacturer's receivers with the glass fiber never underperforming the plastic (although some heard no difference, none ever said plastic was better) So here a number of optic to electrical junctions were tested and if it was the junction, it was likely that at some point one would have noticed plastic was occasionally superior to glass. Again there is no absolute guarantee that every possible combination was tested and probably none were instrumented.

Jitter ends up as the most probable common denominator.

Sometimes anyone of us can be wrong, but most birds that waddle and quack are in fact ducks.

[jneutron]

It is quite hard to speak in absolutes, but a couple of reasonable assumtions follow:

The Monarchy jitter box retails for about $200. Probably the build cost is $100 "out the door". This usually equates to a parts cost of $50 or less. So almost certainly they used a comercially available Toslink female reciever jack with built-in optical detector - maybe 18 cents, not a $10 and up exotic diode and amplifier. If you are going to regenerate a digital signal using phase lock loops and an expensive low jitter, voltage controlled oscillator you would most likely not pay to fix the problem twice by also using expensive receivers on all three inputs. But you are right, I can not guarantee this.

The reviews I mentioned compared glass to plastic on a large number of different manufacturer's receivers with the glass fiber never underperforming the plastic (although some heard no difference, none ever said plastic was better) So here a number of optic to electrical junctions were tested and if it was the junction, it was likely that at some point one would have noticed plastic was occasionally superior to glass. Again there is no absolute guarantee that every possible combination was tested and probably none were instrumented.

Jitter ends up as the most probable common denominator.

Sometimes anyone of us can be wrong, but most birds that waddle and quack are in fact ducks.

All of us are wrong at one time or another...that is indeed, my work environment...50-50 shot, I have, of being correct..

I would have considered other factors such as signal strength, bw, terminus reflections, and such, before just arbitrarily accepting jitter as the most likely culprit..as you say, probably none were instrumented, so the assumption that jitter was "most likely"... could be right, or could be wrong..

The use of "ice cream science" is not very scientific by it's nature, as causality is not demonstrated by correlation..

Oh, btw..ice cream science: Sharks attack at the beach...ice cream is sold at the beach...if you get rid of the ice cream, the sharks will stop attacking..

Correlation, not causation.

So, the statement that jitter is the cause is a guess..not supported by actual testing, to the best of your knowledge...but a guess nonetheless...

Perhaps a good guess, perhaps not..neither of us can shed light on the true reason, without a more rigorous measurement scenario.

Cheers, John

[mixadude]

This is a very old thread, but I've actually been employed as a fiber tech on most of the Monday Night Football this year, as well as other major events since this rageous thread came to be. I guess they couldn't find anyone that knows what they're doing or had more than my 30 years of experience in audio and video.

I can't really find much difference in using 1500 feet of (single mode) fiber or 50 feet regarding jitter as long as the fiber is good. I definately see light loss, but the electronics seem to adequately take care of the jitter if the fiber (including termination) is in reasonably good shape.

When it goes bad what we get in the audio are crackles and clicks and pops almost like a sample rate mismatch, or a total link loss. When it's marginal there is plenty of jitter and you can see it on the eye scope even with a 100 Hz or sometimes even a 1000 Hz high pass, but by then it's almost a total loss. A clean signal will ofter show some jitter, but there is a threshold where it becomes audible, and when it does it's very noticeable.

Now these Evertz racks and cards we use are very pricey, pushing $250,000 for each system. Each system runs about 60 channels of audio; some analog, some digital, HD video, SD video and serial data. Many of the glasses have several systems MUXed on each one. I've been managing 3 of those systems in different locations. I can't really say how this stuff equates to the prosumer stuff, but that's my current experience on fiber.

Given all of that, I wouldn't consider running fiber a good alternative to copper for short distances, it's just too physically problematic. Cat 5 is much easier and even more reliable.

But to answer the original question, as long as the fiber is rated for the appropriate wavelength and type involved, and the terminations are good, i think the pricing is a sucker's game.

[royphil345]

I absolutely agree on not paying ridiculous sums of money for an optical cable.

Which terminations would be more likely to remain perfectly shaped and perfectly clear for the life of the cable? Plastic or a modestly-priced glass cable? Would seem like a good selling point for those that don't have your test equipment or knowledge to repair a cable. Maybe why glass cables often sound better in a home environment... dude...

[mixadude]

Yeah, I can see spending a little extra for a better termination housing. As far as plastic or glass, I can't really say, all we use is glass for our stuff, but for a short s/pdif ehh... whatever works. My take on it is that if there is detrimental jitter you will definately and obviously hear it, no problem, no guessing necessary. If it's within compensatable limits of the system, you will not. There is always jitter! It's just a matter of how much can be tolerated by the system before it becomes untenable, but when there are errors beyond the limits, it's obvious. It also happens at different frequencies. Low frequency jitter is generally more easily handled by the system but there is usually more of it.

I don't know how everybody might use this stuff in their home systems, but my hifi sits in one place. I might turn it around and make a change a few times a year, so there is almost no wear and no opportunity for dust or other goo to get in the connections.

On the stuff I use in broadcast, we might change it around and relocate it several times a week, often across country. It's all portable including the glass. I spend more time cleaning fiber ends than anything else at work. I don't actually move the cables or equipment, the "utilities" do it. I just make it work. Every time I plug in, I clean and inspect the ends. I don't re-butt ends in the field, I have spares. Out of a TAC-12 line we design our systems to use 9 online max. When there's a dead one I just re-patch and replace the whole TAC-12 before the next show. I send the faulty stuff back to the shop, where they can put it on the TDR and cleave and butt it in a controlled environment, and determine the billing.

My biggest headaches are interfacing to house fiber lines where it's impractical to run our own. I clean them and run a laser meter on them at various wavelengths and use what works, but there's always loss through the connections. It's just balancing acceptable limits on various lines sometimes.

I have had a few problems with cards going bad. That's more interesting actually. One of them actually blew a chip right off the circuit board! In a mobile situation like this it could have been caused from just about anything, probably a bad patch on a data line on that one.

[PaDave]

Fiber Optic cables do not need any RF shielding because it is immune to any RF frequency interference, sheilding is only so the Glass or Plastic cable does not break if bent, and no their is no difference in sound quality unless you are running low grade equip. between the three,