# does quality of optical cables have effect on SQ?



## unkle11

i'm looking for a really long optical cable and have seen 6ft long cables for 13 bucks and 4 f ones for about 40 bucks so i am wondering, does the quality of optical cables have any effect on sound quality??

 thanks


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## edwardsean

You know, I never thought so. It initially made no sense to me how a digital cable could matter that much. But, the difference in analog cables quickly became apparent to me so I started checking out whether digital cables also affected SQ. I read a lot on both sides, but in the end I just bought a whole bunch of cables. There is a definite difference in both sound signature and sound quality. It has to do with jitter introduced by the cable. But irregardless of the technical details it is worth getting a good optical cable. Many of the best ones like Van de Hul and Nordost are prohibitively expensive. Fortunately there is one that I found that is simply fantastic. It's a glass optical by Unique products. It offers a wide soundstage and fluid presentation. Here is a link.

 http://cgi.ebay.com/3'-3-ft-GLASS-TOSLINK-DIGITAL-OPTICAL-CABLE----Premium_W0QQitemZ270163963826QQcmdZViewItem


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## unkle11

thanks for your reply i will look into that link


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## infinitesymphony

Either the glass TOSlink mentioned above, or the built-to-spec Mitsubishi Eska from BJC will be great choices. It's also recommended to buy lengths of cables intended for digital use in multiples of 1.5 meters (3 feet), for various reasons relating to the wavelengths of digital signals (or at least that's my vague understanding).


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## krmathis

To me there are some audible differences between optical cables.
 I switched from a Monster iCable to a Van den Hul Optocoupler MKII in my main rig a couple of months back, and noticed some minor audible improvement.

 Unsure if its worth the 5x price tag though....


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## purk

Yes. The difference b/w my monster optical cable v.s. wirewrold optical cable was very noticable. The wireworld supernova 5+ has excellent sound quality.


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## evilking

You people aren't serious? Audible differences in an *optical* cable?

 Wow...

 You know, it is possible to test these "differences", simply by recording the output and comparing with the original. If it's not the same, then it's a broken cable. If it is the same, then you've saved money...

 My answer to the orginal question is... no!


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## Scrith

I originally used an eBay "glass" optical cable with my Benchmark DAC1. But I noticed that sometimes the error light would flash (about once or twice per hour). I did some research and found a reasonably priced (i.e. less than $100) cable, the Van den Hul Optocoupler (I posted about it here a couple of years ago). With the new cable the error light stopped flashing and the music sounded better. I posted about my experience here a couple of years ago and have noticed a few others must have read it, because now there are several Optocouplers floating around Head-Fi, it seems.

 I attribute the improvement to the idea (just my idea, mind you) that cheap (eBay) "glass" cables are more prone to fracturing or something (I hypothesize that this is particularly true if you bend them during installation). So I think a better cable (treated carefully) might be worth the investment.


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## evilking

^^^ Exactly.

 An optical cable works or doesn't work. The signal/data "gets there" properly or... it doesn't! You can't get "more signal/data" than the original to the destination, therefore the cable can't get progressively better. *If you test the output and it's 100% correct, then that's as good as it gets!*

 Honestly, those 4 previous posters should be ashamed for suggesting otherwise


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## Agent Kang

Quote:


  Originally Posted by *evilking* /img/forum/go_quote.gif 
_You people aren't serious? Audible differences in an *optical* cable?

 Wow...

 You know, it is possible to test these "differences", simply by recording the output and comparing with the original. If it's not the same, then it's a broken cable. If it is the same, then you've saved money...

 My answer to the orginal question is... no!_

 

I've tried a whole bunch purely to satisfy my curiosity regarding differences in SQ. I really couldn't hear the difference. Analog cables, I definitely can. Digital cables? Nope.


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## Andrew_WOT

This article compares some toslink and coaxial brands. Quite an interesting read.
http://www.6moons.com/audioreviews/toslink/toslink.html


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## bigshot

My Macbook has bitperfect optical output, and I use it to play back 5:1 DTS, which is resolved in my amp. If it wasn't bitperfect, it would unlock from DTS. I have NEVER seen it do that. An optical cable is an optical cable. Either it works or it doesn't. If it errors, it will error relatively big and in an instant. It won't add any sort of coloration to the sound.

 See ya
 Steve


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## bigshot

Quote:


  Originally Posted by *Andrew_WOT* /img/forum/go_quote.gif 
_This article compares some toslink and coaxial brands. Quite an interesting read.
http://www.6moons.com/audioreviews/toslink/toslink.html_

 

The same publication that gave Brilliant Pebbles a good review.

 See ya
 Steve


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## infinitesymphony

Quote:


  Originally Posted by *evilking* /img/forum/go_quote.gif 
_An optical cable works or doesn't work. The signal/data "gets there" properly or... it doesn't! You can't get "more signal/data" than the original to the destination, therefore the cable can't get progressively better. *If you test the output and it's 100% correct, then that's as good as it gets!*_

 

Here lies the point of contention. The argument is that cheap (i.e. not-to-spec) optical cables are lossy and can degrade the quality of the signal. Here's some indirect corroboration from Blue Jeans Cable:

  Quote:


 "For these applications, we build our optical cables using the finest high-performance Plastic Optical Fiber (POF), Mitsubishi's ESKA Fiber. While POF is in general rather lossy stuff compared to glass optical fiber, we prefer it for optical digital audio use because it's much more physically durable and because its aperture matches the spec for optical digital audio use, unlike glass fiber which is too small and must be used in bundles." 
 

Can better optics improve your vision? In a similar way, a better optical cable will improve the quality of light transmission. TOSlink is not regarded as the best method for digital transmission because the quality of its implementation varies from device to device. Think of it this way--a dim light may seem closer to 0 some of the time than 1, therefore it won't be properly transmitted all of the time. At least, that's my understanding; like analog cables, it's not a matter of all-or-nothing.

 Here's an article from BJC called, "Digital and Analog Cables; What's the Difference?." It mostly applies to coaxial digital cables, but one can imagine how an optical cable might have similar problems and requirements.

 Even better is this article on Audioholics called, "TOSLINK Interconnect History & Basics."


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## evilking

Quote:


  Originally Posted by *infinitesymphony* /img/forum/go_quote.gif 
_TOSlink is not regarded as the best method for digital transmission because the quality of its implementation varies from device to device. Think of it this way--a dim light may seem closer to 0 some of the time than 1, therefore it won't be properly transmitted all of the time. At least, that's my understanding; like analog cables, it's not a matter of all-or-nothing._

 


 I didn't say "all-or-nothing", I meant "100%-or-not 100%". If you have the hardware, you can "look" (save and open with an audio editor) at the data recieved with perfect accuracy (it's all digital). Then you can compare with the original *byte-for-byte.*

 It's that simple. All objective, it's either the same or not the same.

 That's the optical cable's job, to *digitally* transfer data. Just like a USB cable. When you send a file from one device, over USB, to another device, is anything lost on the way? Of course not. If the cable is faulty, the file can't be processed properly. It's not a subtle effect. Massive errors _will_ occur. The file recieved _will_ be corrupted and most likely refuse to open.

 My point is, only *broken* optical cables can make audible changes to the sound.


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## LeChuck

I consider myself to have fairly decent hearing, I have absolute pitch, and studied classical piano for 11 years. Obviously that doesn't make me any kind of special authority, but I consider myself fairly capable of discerning minute differences between components.

 That being said, despite my sincerest efforts, I have not been able to identify differences between optical, coaxial, or RCA cables.

 There have only been two times that I have been able to identify cables, and both times were with defective connectors which caused "wow what was the noise?" problems, not subtle changes in texture, colouring, or any other nuance.

 I buy and use Blue Jeans cables because they're well made, cheap, and built to order specifications, not for any special sonic reasons.


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## infinitesymphony

Quote:


  Originally Posted by *evilking* 
_I didn't say "all-or-nothing", I meant "100%-or-not 100%". If you have the hardware, you can "look" (save and open with an audio editor) at the data recieved with perfect accuracy (it's all digital). Then you can compare with the original byte-for-byte.

 It's that simple. All objective, it's either the same or not the same.

 That's the optical cable's job, to digitally transfer data. Just like a USB cable. When you send a file from one device, over USB, to another device, is anything lost on the way? Of course not. If the cable is faulty, the file can't be processed properly. It's not a subtle effect. Massive errors will occur. The file recieved will be corrupted and most likely refuse to open.

 My point is, only broken optical cables can make audible changes to the sound._

 

Good points. Inexpensive cables can do the job for well under $30 (ex. BJC's ESKA cable is $12.50 for 1 foot, $0.50-$0.75 extra per additional foot). I guess my post was intended more as a warning that it's _possible_ to lose information with an inferior cable.

 Also, USB differs from TOSlink and coaxial S/PDIF in that it has error correction, which as you mentioned is essential to maintaining file integrity. The latter two formats cannot use any form of error correction because it would further disrupt the timing information (thus causing more jitter). Some people say that unless a form of reclocking is used on the receiving end, jitter can audibly affect sound quality; this is why people invest a lot of money to eliminate jitter by using higher-end transports (or eliminating the transport via wireless transmission and buffering with a device like a Squeezebox) and reclocking DACs like the Benchmark DAC-1 and Lavry DA-10.


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## Prozakk

Quote:


  Originally Posted by *bigshot* /img/forum/go_quote.gif 
_An optical cable is an optical cable._

 

But glass opticals aren't very durable. I don't use glass opticals for this very reason.


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## sugarinthegourd

Some of the discussions around this place absolutely boggle the mind. If the transport sends:

 000101010101010111000011110000

 Then the DAC either receives

 000101010101010111000011110000

 or it doesn't. There is no in-between here. If it comes through correctly, the cable works. If it doesn't, it will sound like ABSOLUTE RUBBISH or worse. 

 Un-be-freaking-lievable. I imagine Tourmaline and Tin Ears will be here soon to cut and paste irrelevant nonsense about jitter, digital smearing and I dunno, capacitance in fiber optic cable.


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## d-cee

Quote:


  Originally Posted by *infinitesymphony* /img/forum/go_quote.gif 
_It's also recommended to buy lengths of cables intended for digital use in multiples of 1.5 meters (3 feet), for various reasons relating to the wavelengths of digital signals (or at least that's my vague understanding). 
	

	
	
		
		

		
			



_

 

if you're referring to steve nugent from empirical audio who said this. it only applies to coaxial cables, not optical.

  Quote:


  Originally Posted by *sugarinthegourd* /img/forum/go_quote.gif 
_Some of the discussions around this place absolutely boggle the mind. If the transport sends:

 000101010101010111000011110000

 Then the DAC either receives

 000101010101010111000011110000

 or it doesn't. There is no in-between here. If it comes through correctly, the cable works. If it doesn't, it will sound like ABSOLUTE RUBBISH or worse.

 Un-be-freaking-lievable. I imagine Tourmaline and Tin Ears will be here soon to cut and paste irrelevant nonsense about jitter, digital smearing and I dunno, capacitance in fiber optic cable._

 

well, there are people who believe in the effects of jitter and what not. and i think that's largely the reason people also prefer coaxial over optical

 eg. this is an illustration i stole off someone else:

 data may be sent as 

 1 0 1 1 0 0 1 but jitter will cause it to be received as

 1 01 10 0 1

 or something to similar effect


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## infinitesymphony

Quote:


  Originally Posted by *d-cee* /img/forum/go_quote.gif 
_if you're referring to steve nugent from empirical audio who said this. it only applies to coaxial cables, not optical._

 

Ah, thanks for the clarification.


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## Andrew_WOT

Good reference explaining what factors can affect toslink sound quality.
http://www.audioholics.com/education...history-basics


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## d-cee

Quote:


  Originally Posted by *Andrew_WOT* /img/forum/go_quote.gif 
_Good reference explaining what factors can affect toslink sound quality.
http://www.audioholics.com/education...history-basics_

 

heh the optical cable pictured there is the same one i use


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## edwardsean

Yes, those are the glass opticals from Unique products. They are inexpensive and sound fabulous. Extended soundstage and fluidly smooth.


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## dvw

Quote:


  Originally Posted by *d-cee* /img/forum/go_quote.gif 
_if you're referring to steve nugent from empirical audio who said this. it only applies to coaxial cables, not optical.


 well, there are people who believe in the effects of jitter and what not. and i think that's largely the reason people also prefer coaxial over optical

 eg. this is an illustration i stole off someone else:

 data may be sent as 

 1 0 1 1 0 0 1 but jitter will cause it to be received as

 1 01 10 0 1

 or something to similar effect_

 

Jitter is caused more by the transmitter than the cable. It takes a very long cable to generate any significant data (Km).
 Modern DAC has high jitter tolerance.
 jitter usually results in error data. This error is usually random. So they don't happen at any specific frequency. In another word, jitter will not make low or high frequency worse and definite will not impact soundstage.


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## c0mfortably_numb

I noticed a night and day difference between a cheap oem Toslink I got on eBay, and the premium 8.0mm Toslink from Monoprice. The Monoprice is also bargain priced at $6.42


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## shigzeo

Quote:


  Originally Posted by *Andrew_WOT* /img/forum/go_quote.gif 
_This article compares some toslink and coaxial brands. Quite an interesting read.
http://www.6moons.com/audioreviews/toslink/toslink.html_

 

while i like 6moons for website design and certainly their respect for audio in particular, they are on some great amounts of crack for most of time.


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## Chu

Quote:


  Originally Posted by *d-cee* /img/forum/go_quote.gif 
_well, there are people who believe in the effects of jitter and what not. and i think that's largely the reason people also prefer coaxial over optical

 eg. this is an illustration i stole off someone else:

 data may be sent as 

 1 0 1 1 0 0 1 but jitter will cause it to be received as

 1 01 10 0 1

 or something to similar effect_

 

People really need to think about what the definition of "jitter" is and where it comes from in relations to optics before claiming stuff like this. The speed of light is constant. EMI has no effect on photons.

 As for the second example, data is transmitted with error codes to catch things like this. Here is the specific protocol used. Note there is a checksum in each Time Slot, and a CRC for the entire Audio Block. The odds of missing this sort of error (every checksum coming out correct AND the CRC code matching) is vanishingly small.


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## Pibborando

Quote:


  Originally Posted by *edwardsean* /img/forum/go_quote.gif 
_Yes, those are the glass opticals from Unique products. They are inexpensive and sound fabulous. Extended soundstage and fluidly smooth._

 

 Quote:


  Originally Posted by *dvw* /img/forum/go_quote.gif 
_jitter usually results in error data. This error is usually random. So they don't happen at any specific frequency. In another word, jitter will not make low or high frequency worse and definite will not impact soundstage._

 

Please listen to this logic, people. There is no way different optical cables could sound different from one another.


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## LawnGnome

Quote:


  Originally Posted by *d-cee* /img/forum/go_quote.gif 
_if you're referring to steve nugent from empirical audio who said this. it only applies to coaxial cables, not optical.


 well, there are people who believe in the effects of jitter and what not. and i think that's largely the reason people also prefer coaxial over optical

 eg. this is an illustration i stole off someone else:

 data may be sent as 

 1 0 1 1 0 0 1 but jitter will cause it to be received as

 1 01 10 0 1

 or something to similar effect_

 

This is incorrect. If it doesn't receive a signal during the time period, it is evaluated as a 0 or off.

 So a signal with severe timing issues would be more like this:

 101010 ideal signal

 1 0 1 0 1 0 Your idea of jitter

 10001000100 More proper representation. 

 The periods where signal aren't received are a an 0. Because the receiver is either getting a light pulse = 1 = ON, or no light pulse = 0 = OFF. 

 There is either 0 or 1, no grey, no in between, no blanks.


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## Chu

Quote:


  Originally Posted by *LawnGnome* /img/forum/go_quote.gif 
_This is incorrect. If it doesn't receive a signal during the time period, it is evaluated as a 0 or off.

 So a signal with severe timing issues would be more like this:

 101010 ideal signal

 1 0 1 0 1 0 Your idea of jitter

 10001000100 More proper representation. 

 The periods where signal aren't received are a an 0. Because the receiver is either getting a light pulse = 1 = ON, or no light pulse = 0 = OFF. 

 There is either 0 or 1, no grey, no in between, no blanks._

 

This is not quite true, for pretty much the exact reason you list 
	

	
	
		
		

		
			





 Most digital encoding schemes are set up so that the voltage (or in this case, stream of light) is forced to swing every once in a while no matter what data is being sent. 

 There is a _lot_ of literature out there on the best ways to do this, but they took the easy way out for digital audio over toslink. 01=1, 10=0. 00 or 11 is an error. It might be the other way around 
	

	
	
		
		

		
		
	


	




 Back to the op. This means, at a bare minimum, 50% of the bits you are sending over that cable are dedicated to finding flaws in the signal. There are more bits being sent that are dedicated to evaluating the link (and thus the cable) then there are to actually play back your music. As long as your cable is good enough s.t. the link is good, your cable is fine.


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## d-cee

don't hurt me! i'm just borrowing someone else's illustration

 i don't claim to be able to hear jitter (as i've never been able to remove/add it in my system)

 but i won't rule it out completely either, stranger things affect SQ in this hobby of ours =)


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## dvw

Quote:


  Originally Posted by *Chu* /img/forum/go_quote.gif 
_This is not quite true, for pretty much the exact reason you list 
	

	
	
		
		

		
		
	


	




 Most digital encoding schemes are set up so that the voltage (or in this case, stream of light) is forced to swing every once in a while no matter what data is being sent. 

 There is a lot of literature out there on the best ways to do this, but they took the easy way out for digital audio over toslink. 01=1, 10=0. 00 or 11 is an error. It might be the other way around 
	

	
	
		
		

		
		
	


	




 Back to the op. This means, at a bare minimum, 50% of the bits you are sending over that cable are dedicated to finding flaws in the signal. There are more bits being sent that are dedicated to evaluating the link (and thus the cable) then there are to actually play back your music. As long as your cable is good enough s.t. the link is good, your cable is fine._

 

The coding scheme is called Manchester bi-phase. The idea is actually to have a transition every bit. 00 and 11 have no transition, therefore they will never happen. This is used to make clock recovery easier. This is also used in 10 Mbit interface. So there is always two symbols in every bit and is not bandwidth efficient but it is adequate for audio application.

 For error correction they used an interleaving method. I don't remember from the top of my head. But any way this system is pretty robust from an error perspective.


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## unkle11

hi thanks for all the replies, i assume the above arguments about toslink applies to digital coaxial also?


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## Chu

Quote:


  Originally Posted by *unkle11* /img/forum/go_quote.gif 
_hi thanks for all the replies, i assume the above arguments about toslink applies to digital coaxial also?_

 

Some arguments do, some don't. Digital Coax is subject to all the same problems that normal cables are when it comes to interference, transmission loss, etc.

 However, they are still transmitting a digital signal, so the all-or-nothing arguments still apply.

 The protocols used are incredibly robust. To give you an idea of the quality of cable needed to ensure a good link, when TI were designing their chipsets for encoding/decoding digital audio, in their labs they were able to recover a bit-perfect signal from a six foot run of coat hangers.


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## unkle11

that.. boggles.. my mind.. i have no idea what to do now.. especially since the only coat hangers i have are plastic... should i just head out to radioshack? lol


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## rb67

Haha it'd be a much more pain in the butt to try to hook up some stiff wire without terminations!

 Follow the facts. Just get a well made cable that won't break with quality connections that will last. If a claim sounds like rubbish, it most likely is.


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## bdshort

Just for reference, I find that the metal coathangers from Wal-Mart give me a much wider soundstage and tighter bass than hangers from Target or K-Mart.


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## rb67

Hm... I've always found the ones from target to be more accurate.


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## peelax

I agree, the ones from target give much more transparency to the music, with a deeper bass. Possibly because the mid range is slightly rolled off? Although I heard someone wrapped ESR paper around the Wal-Mart and the sound stage was greatly improved!


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## Chri5peed

I don't really believe, but what the hey!
	

	
	
		
		

		
		
	


	




 My Optical cable is my cheapest interconnect. I'd rather not use an adaptor, is there anywhere that does a decent Toslink to Mini lead, under $50.

 Its just that I wouldn't want it sticking out or is it like 1/8 to 1/4 adaptors, i.e. not very obtrusive?


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## Dept_of_Alchemy

Quote:


  Originally Posted by *peelax* /img/forum/go_quote.gif 
_I agree, the ones from target give much more transparency to the music, with a deeper bass. Possibly because the mid range is slightly rolled off? Although I heard someone wrapped ESR paper around the Wal-Mart and the sound stage was greatly improved!_

 

I have heard that too, it must be true. Although it's been reported that the k-mart ones scale much better with brilliant pebbles than the other brands.


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## evilking

I'm glad people are starting to see sense.


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## Chri5peed

Glass does let bigger '1's through.


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## peelax

It is important to make sure your optical is plugged in the right way round too, contrary to popular belief glass does have a direction, preferring to let photons flow one way more than another. As manufacturers generally don't label the correct direction of photon flow it is important to conduct listening tests to determine it. If you have the cable plugged in the wrong way it will sound more fatiguing with more digital harshness, if it is right you get a more analogue sound with a blacker background. This is due to the way in which micro fractures in the glass reflect photons causing photonic standing waves in the cable. These micro fractures are directional, as they tend to form at the same sort of angle. The resulting standing waves interfere with the digital signal making the rising and falling of the ones and zeros more difficult to detect, in effect adding jitter and timing issues to the signal.

 If you cannot detect which direction you should be plugging in your optical cable I can test it for you with my equipment for a nominal fee. I will also cryo treat it to align the silicon molecules properly, something that (amazingly) most cable manufacturers do not do.


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## jp11801

Quote:


  Originally Posted by *purk* /img/forum/go_quote.gif 
_Yes. The difference b/w my monster optical cable v.s. wirewrold optical cable was very noticable. The wireworld supernova 5+ has excellent sound quality._

 

X2!!!


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## krmathis

Quote:


  Originally Posted by *Chri5peed* /img/forum/go_quote.gif 
_My Optical cable is my cheapest interconnect. I'd rather not use an adaptor, is there anywhere that does a decent Toslink to Mini lead, under $50._

 

The Monster iCable is decent, and probably priced around $35.
 I noticed improvement when going from the Monster to my current Optocoupler MKII (paid $130 shipped). But that said, I lived happily with the Monster for one year...

  Quote:


  Originally Posted by *evilking* /img/forum/go_quote.gif 
_I'm glad people are starting to see sense._

 

So am I...


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## Chu

Quote:


  Originally Posted by *peelax* /img/forum/go_quote.gif 
_If you have the cable plugged in the wrong way it will sound more fatiguing with more digital harshness, if it is right you get a more analogue sound with a blacker background. This is due to the way in which micro fractures in the glass reflect photons causing photonic standing waves in the cable. These micro fractures are directional, as they tend to form at the same sort of angle. The resulting standing waves interfere with the digital signal making the rising and falling of the ones and zeros more difficult to detect, in effect adding jitter and timing issues to the signal._

 

The thing about digital is that past a certain threshold, it just doesn't matter anymore. Once you're bit-perfect you are good.

 Also, and it's been said before, digital signals do not degrade nicely. If there truly is a problem with your cable you're not going to get problems like "the noise floor isn't as black." You're going to get errors that resemble what a CD sounds like when C2 error correction fails, i.e. unlistenable.

 edit : hook, line, and sinker


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## Chri5peed

Quote:


  Originally Posted by *krmathis* /img/forum/go_quote.gif 
_The Monster iCable is decent, and probably priced around $35._

 

I notice you're in Norway[Rock on!], where did you get your cable? Their USA site won't ship internationally.


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## fwojciec

Quote:


  Originally Posted by *peelax* /img/forum/go_quote.gif 
_It is important to make sure your optical is plugged in the right way round too, contrary to popular belief glass does have a direction, preferring to let photons flow one way more than another. As manufacturers generally don't label the correct direction of photon flow it is important to conduct listening tests to determine it. If you have the cable plugged in the wrong way it will sound more fatiguing with more digital harshness, if it is right you get a more analogue sound with a blacker background. This is due to the way in which micro fractures in the glass reflect photons causing photonic standing waves in the cable. These micro fractures are directional, as they tend to form at the same sort of angle. The resulting standing waves interfere with the digital signal making the rising and falling of the ones and zeros more difficult to detect, in effect adding jitter and timing issues to the signal._

 

QFT. Thanks for the lucid explanation. It's good to hear an informed opinion every once in a while. There is so much misinformation floating around... I can't help but laugh at all those "audiophiles" who have their optical cables plugged in the wrong way around.


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## krmathis

Quote:


  Originally Posted by *Chri5peed* /img/forum/go_quote.gif 
_I notice you're in Norway[Rock on!], where did you get your cable? Their USA site won't ship internationally._

 

I placed my order at the Norwegian distributor, Audio Media. Which themselves had to special order the cable, to my specifications (1.5 meter, TOSLINK to miniplug) from the factory in the Netherlands. I paid a total of $150, shipped to my door.

 You might get lucky here: http://www.vandenhul.com/distrib/distrib.htm


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## Chri5peed

Lol, Optocoupler MKII looks like it!

 Is it glass?


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## krmathis

Quote:


  Originally Posted by *Chri5peed* /img/forum/go_quote.gif 
_Lol, Optocoupler MKII looks like it!

 Is it glass?_

 

I have found no official information from Van del Hul about which material used. But I have the impression that its glass and not plastic.

 This is all there is on the official website:
http://www.vandenhul.com/cable/optocplr.htm#specs


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## n4k33n

Wow, this thread has informed me exactly who has some sense and whos advice to follow, and whos deluding themselves. Thank you, I don't have that much money to throw away =D


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## Chu

Quote:


  Originally Posted by *dvw* /img/forum/go_quote.gif 
_For error correction they used an interleaving method. I don't remember from the top of my head. But any way this system is pretty robust from an error perspective._

 

I'm having a lot of trouble tracking down exactly what error correction methods are being used. Is this part of the EAS3 spec somewhere I am not seeing, or is it at a higher level?


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## peelax

Quote:


 2. Errors

 This usually causes very significant changes in the sound, often loud popping noises but occasionally less offensive effects. Any data loss or errors in either are a sign of a very broken link which is probably intermittently dropping out altogether. 
 

http://www.epanorama.net/documents/audio/spdif.html

 I hate sceptics like this, they don't know how to use their ears. Obviously they have little holistic knowledge. Light is not a naturally binary phenomenon, therefore a whole spectrum of errors and deviations can take place. I know what I hear and there is massive differences after cyro/proper alignment of the optical cable. As different frequencies of modulation interact differently with the glass medium (due to micro-fracture) different bit patterns get effected differently. This translates into less than idea frequency response and noise. That is why proper alignment means better sound, and the more money you spend of a optical cable the more balanced it is across the whole audio spectrum, especially in the 3rd harmonics.


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## Chu

Quote:


  Originally Posted by *peelax* /img/forum/go_quote.gif 
_http://www.epanorama.net/documents/audio/spdif.html

 I hate sceptics like this, they don't know how to use their ears . . ._

 

Here is the problem with this argument. This is what your signal path looks like:

  Code:


```
[left](output&misc)----DAC----DEMODLATOR============MODULATOR----TRANSPORT ^ ^ a b The "====" is the cable.[/left]
```


 Here is the thing. Usling lab equipment, we can show that with absolutely dirt cheap cables, the bitstream at 'a' and 'b' is the same. So using premium cables, i.e. the portion represented by "====," what can we possibly gain?


----------



## Chu

Quote:


  Originally Posted by *peelax* /img/forum/go_quote.gif 
_http://www.epanorama.net/documents/audio/spdif.html

 I hate sceptics like this, they don't know how to use their ears . . ._

 

Here is the problem with this argument. This is what your signal path looks like:

  Code:


```
[left](output&misc)----DAC----DEMODLATOR============MODULATOR----TRANSPORT ^ ^ a b The "====" is the cable.[/left]
```


 Here is the thing. Usling lab equipment, we can show that with absolutely dirt cheap cables, the bitstream at 'a' and 'b' is the same. So using premium cables, i.e. the portion represented by "====," what can we possibly gain?


----------



## fwojciec

Quote:


  Originally Posted by *Chu* /img/forum/go_quote.gif 
_Here is the problem with this argument. This is what your signal path looks like:

  Code:



		Code:
	

[left](output&misc)----DAC----DEMODLATOR============MODULATOR----TRANSPORT ^ ^ a b The "====" is the cable.[/left]



 Here is the thing. Usling lab equipment, we can show that with absolutely dirt cheap cables, the bitstream at 'a' and 'b' is the same. So using premium cables, i.e. the portion represented by "====," what can we possibly gain?_

 

I've just seen a Sense of Humor (the special edition model with the much hyped "Irony" decoder) at a good price in the for sale forums - you should check it out


----------



## Chu

Quote:


  Originally Posted by *fwojciec* /img/forum/go_quote.gif 
_I've just seen a Sense of Humor (the special edition model with the much hyped "Irony" decoder) at a good price in the for sale forums - you should check it out 
	

	
	
		
		

		
		
	


	


_

 

See what this forum has done to me!


----------



## tourmaline

For digital cables , quality isn't as important as for analogue cables. They are more prone to interference then digital cables. Any fair priced cable will get you a good sound. There is a difference when you go up the ladder, but not as noticable as with analogue cables. As said earlier, if you have enough quality there, you're set. All you wanna avoid with digital cables is that the error correction kicks in, that is audible! Jitter etc, has probably more influence on the sound.


----------



## Chri5peed

Just ordered the Optocoupler. Damn you head-fi!


----------



## krmathis

Quote:


  Originally Posted by *Chri5peed* /img/forum/go_quote.gif 
_Just ordered the Optocoupler. Damn you head-fi!_

 

Great choice!
 I am sure you will be pleased with it...


----------



## Chri5peed

Quote:


  Originally Posted by *krmathis* /img/forum/go_quote.gif 
_Great choice!
 I am sure you will be pleased with it... 
	

	
	
		
		

		
		
	


	


_

 

I should change it to 'damn you Krmathis'
	

	
	
		
		

		
		
	


	





 I asked for a link to buy the $45 Monster iCable, instead I get the $120 Optocoupler!


----------



## krmathis

^ LOL


----------



## Xenafor

Sorry, bit of a noob question, but you would never plug an optical cable into a non-DAC amp, would you? When, then, does one use an optical connect?


----------



## infinitesymphony

Quote:


  Originally Posted by *Xenafor* /img/forum/go_quote.gif 
_Sorry, bit of a noob question, but you would never plug an optical cable into a non-DAC amp, would you? When, then, does one use an optical connect?_

 

Between the transport and the DAC, for example from a CD player's TOSlink output to a DAC's TOSlink input. Amplifiers only accept analog input, except for DAC/amp headphone combos and home theater receivers / preamplifiers, which tend to have built-in DACs.


----------



## Kaluminati

I think conclusion should be that, if you bought an expensive optical cable already, then indeed it does make a big difference. If not, then no there would be no difference in sound quality if you bought a $200 toslink to replace your $30 one.

 ;P

 my 2 sense (yes, sense)


----------



## krmathis

Quote:


  Originally Posted by *Xenafor* /img/forum/go_quote.gif 
_Sorry, bit of a noob question, but you would never plug an optical cable into a non-DAC amp, would you? When, then, does one use an optical connect?_

 

Correct! 
 Its used between the transport (ex. CD transport or computer) and the external DAC.


----------



## Pibborando

Quote:


  Originally Posted by *Xenafor* /img/forum/go_quote.gif 
_Sorry, bit of a noob question, but you would never plug an optical cable into a non-DAC amp, would you? When, then, does one use an optical connect?_

 

If you can find a place to plug an optical cable into an amp with no optical in... then you might have more problems than you realize.


----------



## GANESHA

Quote:


  Originally Posted by *c0mfortably_numb* /img/forum/go_quote.gif 
_I noticed a night and day difference between a cheap oem Toslink I got on eBay, and the premium 8.0mm Toslink from Monoprice. The Monopriceis also bargain priced at $6.42
	

	
	
		
		

		
		
	


	


_

 

Which one was better?


----------



## infinitesymphony

Quote:


  Originally Posted by *GANESHA* /img/forum/go_quote.gif 
_Which one was better?_

 

Judging by his wording, I think he meant to imply that the Monoprice cable was better.


----------



## Pars

Quote:


  Originally Posted by *Chu* /img/forum/go_quote.gif 
_The thing about digital is that past a certain threshold, it just doesn't matter anymore. Once you're bit-perfect you are good.
 <snip>_

 

The only problem with this is this isn't really digital... it is a digital signal transported across an RF medium (i.e., analog 
	

	
	
		
		

		
		
	


	




), irregardless of whether it is optical or coax (electrical).

 Yes, there is correction for the data (AFAIK). What about the biggest problem with SPDIF... the clock? This is multiplexed onto the bitstream and is supposed to be extracted at the end. There isn't any error correction on the clock signal. 

 Bit-perfect simply means the bit pattern of the data at the end matches the transmitted data. In other words, all the music data arrived at the DAC. 

 The other part of the puzzle is to make sure that it arrives at the DAC and is clocked into the DAC chip at the right time (jitter), which involves recovering the clock in real-time, and is where things go awry in SPDIF (or TOSLINK). Even if you fix all the impedence mismatches (reflections), etc., the format itself is compromised... which is why you see some recommend that the DAC contains the master clock, and the clock is slaved (via I2S or whatever) back to the transport.


----------



## Chu

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_Bit-perfect simply means the bit pattern of the data at the end matches the transmitted data. In other words, all the music data arrived at the DAC. _

 

No, it doesn't.

 When I say bit perfect I'm referring not only to the actual sequence of bits, but also reproduction within certain temporal thresholds. This is the generally accepted definition, because if a certain temporal specifications is not met, at some point either you're going to overflow your buffer or discard late packets, which means your stream is no longer bit perfect.

 These specifications are very well defined, and even coat hangers have proven to be good enough to meet it in lab tests with copper digital cables. I'm having trouble thinking of an equivalent for optical, but I'm sure I could find something interesting with some work.

 Also, note that the manchester-esque encodings being used are self clocked. You seem to be describing a system where there is a "clock signal" and an "audio system" where if the two get skewed (i.e. jitter) things start going wrong. This is not true, the data itself _is_ the clock.


----------



## Pars

Quote:


  Originally Posted by *Chu* /img/forum/go_quote.gif 
_No, it doesn't.

 When I say bit perfect I'm referring not only to the actual sequence of bits, but also reproduction within certain temporal thresholds. This is the generally accepted definition, because if a certain temporal specifications is not met, at some point either you're going to overflow your buffer or discard late packets, which means your stream is no longer bit perfect._

 

The definition I see on sites such as audioasylum, etc. seems to be more along the lines of what I described. 

  Quote:


  Originally Posted by *Chu* 
_These specifications are very well defined, and even coat hangers have proven to be good enough to meet it in lab tests with copper digital cables. I'm having trouble thinking of an equivalent for optical, but I'm sure I could find something interesting with some work.

 Also, note that the manchester-esque encodings being used are self clocked. You seem to be describing a system where there is a "clock signal" and an "audio system" where if the two get skewed (i.e. jitter) things start going wrong. This is not true, the data itself is the clock._

 

Yes, I probably did not describe it well. The clock (wordclock) is actually used to mux the data, and it is this timing that is hopefully recovered by the receiver, thru PLLs, etc. One would note that many of the more popular hi-end DACs spend alot of effort in reclocking the incoming SPDIF signal to attempt to eliminate the inherent clock jitter (Benchmark DAC1, Lavry DA10 to name a couple). Professional solutions slave the transport to the DAC clock via a separate link. A couple of links to note:

http://www.audiocraftersguild.com/Aa...on.jitter2.htm

 and

http://audio.peufeu.com/node/7

 including the linked AES paper by Dunn and Hawksford.


----------



## Chu

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_The definition I see on sites such as audioasylum, etc. seems to be more along the lines of what I described. _

 

This is going to take a little research to say with complete confidence, but I'm 90% sure that while the SPDIF signal's clock is usually slaved, the DACs is not. I'm trying to find a specification document that spells this out without paying the AES, but so far the only cursory evidence that I can offer is most of the DACs I've found on digikey have either a clock input pin or a integrated crystal isolator (BB/TI,AD, most of their audio DACs have a similar pin configuration). In the diagram in the peufeu.com article you'd have a bit perfect signal at the Transforum/SPDIF under your definition, but not after the DAC stage. This really is starting to split hairs though.

  Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_Yes, I probably did not describe it well. The clock (wordclock) is actually used to mux the data, and it is this timing that is hopefully recovered by the receiver, thru PLLs, etc. One would note that many of the more popular hi-end DACs spend alot of effort in reclocking the incoming SPDIF signal to attempt to eliminate the inherent clock jitter (Benchmark DAC1, Lavry DA10 to name a couple). Professional solutions slave the transport to the DAC clock via a separate link. A couple of links to note:

http://www.audiocraftersguild.com/Aa...on.jitter2.htm

 and

http://audio.peufeu.com/node/7

 including the linked AES paper by Dunn and Hawksford._

 

There's a lot of interesting stuff in here. I'm having trouble swallowing the line of reasoning in the peufeu.com article because they state "Moreover, SPDIF chose a coding system that renders it impossible to recover a clock without random data noise in it. Incredible indeed !" which I assume is a reference to naieve manchester encoding, which SPDIF does not use. I really wish I saw the full line of reasoning of this statement because a lot hinges on it. I really need more time to digest Dunn but given formula (1) what exactly is considered the audible threshold (in dB) for sidebands generated?


----------



## hciman77

Quote:


  Originally Posted by *Chu* /img/forum/go_quote.gif 
_I really need more time to digest Dunn but given formula (1) what exactly is considered the audible threshold (in dB) for sidebands generated?_

 

As far as I am aware no controlled test has shown jitter sidebands to be audible below -80db. The Dunn model is mathematical and not supported by listening tests. You could read Ashihara's papers(1,2) or the Gannon and Benjamin (Dolby labs) paper. In these tests random jitter is impossible to detect in music until you hit several 100s of nanoseconds, with deterministic jitter and a single high freq tone the threshold is 10ns in music it is 20ns i.e a lot. Certainly no empirical evidence exists to suggest that jitter in the ps level is audible.

 The very worst jitter measured on any modern CD playing device is 4ns (random) on the Oppo 971 (Stereophile's figures)

 1. Detection threshold for distortions due to jitter on digital audio
 Kaoru Ashihara1), Shogo Kiryu1), Nobuo Koizumi2), Akira Nishimura2), Juro Ohga3), Masaki Sawaguchi4) and Shokichiro Yoshikawa5) 

 2. A Jitter Simulator on Digital Data 
 Authors: Ashihara, Kaoru; Kiryu, Shogo


----------



## Pars

Yes, I've read those papers. While the Dunn model is mathematical, it is based upon accepted hearing thresholds. Granted, no empirical evidence as you note exists for hearing thresholds in the single digit picosecond range, although Jocko on diyhifi seems to claim he can hear 2ps jitter.

 You note the 4ns figure for jitter measurments in a CD player as being worst case. I might question those measurements, but that misses the point.

 Firstly, that irregardless of what your personal belief is regarding the audibility of jitter, less is better (barring insane levels of contortions required to get you there). After all, we were promised perfect sound forever 
	

	
	
		
		

		
			





. Granted, elimination of jitter entirely is probably not possible (like many things in the physical world), but minimizing it within sane boundaries is certainly a worthwhile goal. And I don't view nanoseconds as being an acceptable level. Many people still do not like the sound of digital... at least this is something that can be measured and hopefully improved.

 Secondly, the thread is regarding transport/DAC connection via optical SPDIF... I would bet that jitter levels here are at a minimum an order of magnitude higher that within a single-box player using !2S, and probably more like 2+ levels, even for high end (i.e. expensive equipment). 

 My point was that bit perfect (from my understanding of the term) is only the start, and says nothing about maintaining the clock integrity over a flawed connection medium (SPDIF). This is where I would agree with peufeu and others that jitter is one of the main culprits (via improper interface standards and implementation of those standards) to the "sound" of digital cables. Even though this is a sub 10MHz application, it is still an RF application, and few if any implementations seem to recognise that. 

 Looking at the digital out in my Rotel RCD855, there is a crappy transformer (probably there more to meet FCC requirements than anything), which then feeds a piece of 2 conductor ribbon cable which is ~10 inches or more in length (Molex-type plug-in connector on the PCB even!), feeding an RCA jack. Sure, it probably works (never tried it), and probably manages to get the music data itself across to the DAC with no show-stopping errors. Clocking? Dont think so. Seems like that might be a nice 75 ohm transmission line, eh?


----------



## Chu

Before I type another wall of text response (and quite honestly I'm too tired to do the research I would need to try to back up some of my claims at 2:00am on a Sunday morning), I'm wondering if it's possible to work backwards.

 Do these cable companies publish their measured specs for these cables? Jitter is pretty easy to measure in the ranges we are talking about.

 Actually, with all the members of college-fi running around, getting the measurements ourselves shouldn't be that hard if people are willing to loan cables.


----------



## bigshot

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_Firstly, that irregardless of what your personal belief is regarding the audibility of jitter, less is better_

 

That's absurd. If you can't hear it, it doesn't matter. What's the point of cutting a microscopic, inaudible problem in half? It's still a microscopic inaudible problem! EVERYTHING in audio costs money and time to set up properly. NOONE has an infinite supply of either. There are LOTS of other things that *are* audible that deserve consideration. The way to get a great sounding system is to focus your energy on getting better sound- sound you can hear.

 My theory on jitter is that it was created by high end audio manufacturers and complicit advertorial writers to answer the threat of high quality mid priced equipment. If you are selling a $5000+ CD player, how do you compete with a company that sells one that sounds just the same for $300? You invent a fictional McGuffin that only exists on paper and point to that.

 See ya
 Steve


----------



## mojo

I decided to test my 99p 1.8m eBay optical cable vs. a much more expensive 1m glass cable (Onkyo branded, I was told it original cost around £50). I connected two soundcards together and played a perfect sine wave on loop for six hours with each cable. Recorded the input and wrote a little program to check for errors (easy because it's a sine wave produced by rounded LUT). With both cases, the recordings were perfect sine waves all the way through, in other words identical to the output.

 This suggests that there is no difference between cables. Both perfectly transported the digital data. As for jitter, clearly there was never enough to cause an error. IAUI most DACs use some kind of re-clocking anyway to deal with jitter issues.


----------



## infinitesymphony

Quote:


  Originally Posted by *mojo* /img/forum/go_quote.gif 
_As for jitter, clearly there was never enough to cause an error._

 

Jitter has nothing to do with errors. A bit-perfect signal can have high amounts of jitter.

  Quote:


  Originally Posted by *bigshot* 
_My theory on jitter is that it was created by high end audio manufacturers and complicit advertorial writers to answer the threat of high quality mid priced equipment._

 

Jitter is real and measurable, and it's present to some extent in every cycle-based piece of electronics, not just audio equipment.


----------



## Chu

Quote:


  Originally Posted by *infinitesymphony* /img/forum/go_quote.gif 
_Jitter has nothing to do with errors._

 

Are you saying jitter cannot cause errors? That's easily demonstratively false. It's a question of thresholds.

  Quote:


  Originally Posted by *infinitesymphony* /img/forum/go_quote.gif 
_Jitter is real and measurable, and it's present to some extent in every cycle-based piece of electronics, not just audio equipment._

 

True, but we're really talking about at what threshold jitter because audible. And if cables cause enough jitter to even approach this.

 The discussion just feels a little strange at points. A lot of laymen papers (and some posts here) seem to treat jitter as some sort of temporal multiplier, as in if the jitter is measured as 4ns (a number completely off the top of my head) every packet essentially is being pushed back by 4ns. This definition being arrived at by walking back from the definition of "time smearing" as the audio signal being slowed by some function of the jitter. This simply can't happen.


----------



## infinitesymphony

Quote:


  Originally Posted by *Chu* /img/forum/go_quote.gif 
_Are you saying jitter cannot cause errors? That's easily demonstratively false. It's a question of thresholds._

 

No, I just meant that errors are not inherently caused by jitter. In other words, you can't measure jitter just by the number of errors that occur. I think that the misunderstanding is about the use of the word "error," specifically the difference between bitstream errors and timing errors.

  Quote:


  Originally Posted by *Chu* 
_The discussion just feels a little strange at points. A lot of laymen papers (and some posts here) seem to treat jitter as some sort of temporal multiplier, as in if the jitter is measured as 4ns (a number completely off the top of my head) every packet essentially is being pushed back by 4ns. This definition being arrived at by walking back from the definition of "time smearing" as the audio signal being slowed by some function of the jitter. This simply can't happen._

 

I don't know for sure (it's beyond my understanding), but I figured that when a manufacturer specified something like "4 ns" jitter, they meant +/- 4 ns variation. Sort of like, "I'll be there by 8:00 p.m. with 5 minutes of potential time error (7:55-8:05 p.m.)."


----------



## The Pieman

I purchase some audio odds and ends from an Audiophile shop in Melbourne where they recommend and sell expensive analog interconnects. When it comes to optical, they sell and recommend nothing that costs more than $20. They have a firm belief that you are wasting your money if you are spending more than that on an optical cable.

 cheers
 Simon


----------



## mojo

Quote:


  Originally Posted by *infinitesymphony* /img/forum/go_quote.gif 
_No, I just meant that errors are not inherently caused by jitter. In other words, you can't measure jitter just by the number of errors that occur. I think that the misunderstanding is about the use of the word "error," specifically the difference between bitstream errors and timing errors._

 

I think you completely missed my point there.

 Most DACs re-clock data in some way. They do not usually rely on the source clock solely. Thus, the jitter you hear is not from the source clock, it's from the DAC's clock.

 The only way cable jitter could be an issue is if it were large enough to cause errors in decoding the bitstream, or large enough to significantly mess up the DAC's re-clocking.

 I would also point out that light should travel down an optical cable in exactly the same way every time, unless the cable is moved. Granted, the cable might move a bit due to sound vibration etc. However, even so at 70% the speed of light it seems unlikely that the time taken for light to travel down the cable (~6ns for a 1.8m cable) would vary enough to produce jitter beyond the ps range. Even if you think a human being can hear that, it was re-clocked by the DAC anyway.


----------



## Pars

Quote:


  Originally Posted by *bigshot* /img/forum/go_quote.gif 
_ Quote:


  Originally Posted by *Pars* 
Firstly, that irregardless of what your personal belief is regarding the audibility of jitter, less is better

 

That's absurd. If you can't hear it, it doesn't matter. What's the point of cutting a microscopic, inaudible problem in half? It's still a microscopic inaudible problem! EVERYTHING in audio costs money and time to set up properly. NOONE has an infinite supply of either. There are LOTS of other things that *are* audible that deserve consideration. The way to get a great sounding system is to focus your energy on getting better sound- sound you can hear._

 

That is an absurd response. It hasn't been proven how much of it you can hear, nor what real-world performance of typical players is. If it doesn't concern you, then so be it... you can vote with your wallet. I have done reclocking of a player, at a cost of ~$100 or less, so I know what the effects on my ears are... I would venture you have not done this, and are talking from a hypothetical perspective.

  Quote:


  Originally Posted by *bigshot* /img/forum/go_quote.gif 
_My theory on jitter is that it was created by high end audio manufacturers and complicit advertorial writers to answer the threat of high quality mid priced equipment. If you are selling a $5000+ CD player, how do you compete with a company that sells one that sounds just the same for $300? You invent a fictional McGuffin that only exists on paper and point to that.

 See ya
 Steve_

 

Yeah, the earth used to be flat also 
	

	
	
		
		

		
		
	


	




. It sounds like a conspiracy! I haven't noticed any manufacturer of CD players, etc. advertising lower jitter, but then again, I don't pay alot of attention to most manufacturers.


----------



## bigshot

Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_That is an absurd response. It hasn't been proven how much of it you can hear, nor what real-world performance of typical players is._

 

Right/Wrong

 It hasn't been proven. (Why spend thousands of dollars on unproven theories?)

 Real world performance of typical players *has* been measured. The jitter on them falls under the range of audibility.

 Jitter is a hoodoo.

 See ya
 Steve


----------



## OverlordXenu

I find it hilarious that someone still bought a $120 optical cable after reading this thread.


----------



## JohnerH

So bottom line is?

 Cheap or expensive?

 This thread should probably be converted to a poll 
	

	
	
		
		

		
		
	


	




 J


----------



## infinitesymphony

Quote:


  Originally Posted by *JohnerH* /img/forum/go_quote.gif 
_So bottom line is?

 Cheap or expensive?

 This thread should probably be converted to a poll 
	

	
	
		
		

		
			





 J_

 

There was no consensus. 
	

	
	
		
		

		
		
	


	




 It wasn't a discussion of cheap vs. expensive, it was asking if there was any difference at all between cables. I think that most people would find the answer to be "yes," though there are different reasons for making the claim.

 Does the cable need to be expensive? No, but it may help to buy a quality cable. If you want to follow the TOSlink specification, try Blue Jeans Cables's optical cable built from Mitsubishi ESKA plastic.

 The other variation is the Unique Glass TOSlink (also available on Audiogon and eBay), which substitutes stranded glass for plastic; be aware that these are more brittle than plastic, which makes them easier to damage.


----------



## BigEat

One question. I generally agree that the fiber optic is fiber optic, but I have heard that the quality of the insulation can make a difference and frankly that the insulation on the cable is the only difference. But for longer runs, I've heard that without greater insulation, some jitter can be introduced into the signal that might not otherwise exist.

 Is that total BS?


----------



## infinitesymphony

The insulation is not the only difference (and I'm not sure how much of a difference it makes in an optical cable); optical cables themselves can be constructed out of different materials, for example plastic and glass.

 The further I've looked into "what causes jitter," the more I'm lead to believe that almost every step of the transmission process can either cause or introduce jitter, including cables. I don't know if there have been adequate studies about cable-induced jitter to prove or disprove it, and I'm not even sure that there's an accurate enough testing methodology to make that determination.

 Either way, if jitter introduced by cables exists, we're talking about very small amounts of jitter, probably a great deal smaller than the jitter introduced by the transport or DAC (which itself is often claimed to be inaudible). So, I think it's unlikely that the improvements caused by upgrading an optical interconnect involve jitter reduction.


----------



## TMM

Quote:


  Originally Posted by *BigEat* /img/forum/go_quote.gif 
_One question. I generally agree that the fiber optic is fiber optic, but I have heard that the quality of the insulation can make a difference and frankly that the insulation on the cable is the only difference. But for longer runs, I've heard that without greater insulation, some jitter can be introduced into the signal that might not otherwise exist.

 Is that total BS?_

 

Sounds like bs to me.


----------



## BigEat

That's interesting on the insulation. My view is that it is for the most part a marketing scheme although in some contexts, you can detect differences in build quality. Better build quality obviously translates into durability, but not sonic improvement.

 What about the interconnect itself? Same answer? In other words, if the cables are cables in the optical context, is the same true of interconnects? Sonically speaking I mean.


----------



## infinitesymphony

Quote:


  Originally Posted by *BigEat* /img/forum/go_quote.gif 
_What about the interconnect itself? Same answer? In other words, if the cables are cables in the optical context, is the same true of interconnects? Sonically speaking I mean._

 

I don't necessarily believe that optical cables are all the same. Which type of interconnect do you mean? "Interconnect" is basically another word for "cable."

 Also, are you sure that the marketing claims about insulation were referring to optical cables? As far as I can tell, optical cables don't have insulation (unless you count the external PVC covering), since there's really nothing external that would interfere with the signal.


----------



## BigEat

True, sorry too generic. I meant quite literally the termination point on each end whether toslink or mini adapter etc. I have seen varying quality on that. For example, the mini adapters (used to adapt Toslink to Apple Macbook for example) are all over the place in terms of build quality. Headroom themselves sells one for next to nothing. You can also see subtle differences in the Toslink adapters otherwise. 

 This is of course all pretty theoretical perhaps, but I've noticed a much bigger difference in quality at the actual termination or "interconnection" point.


----------



## infinitesymphony

Quote:


  Originally Posted by *BigEat* /img/forum/go_quote.gif 
_True, sorry too generic. I meant quite literally the termination point on each end whether toslink or mini adapter etc. I have seen varying quality on that. For example, the mini adapters (used to adapt Toslink to Apple Macbook for example) are all over the place in terms of build quality. Headroom themselves sells one for next to nothing. You can also see subtle differences in the Toslink adapters otherwise. 

 This is of course all pretty theoretical perhaps, but I've noticed a much bigger difference in quality at the actual termination or "interconnection" point._

 

Ah, you mean the connectors. With an optical cable, a snug fit is all that's required, since the end isn't making an electrical connection as it would in a coaxial cable. So, the connector quality isn't especially important for transmission quality, unless it's badly-attached to the cable itself, or doesn't fit deeply enough into a device, etc. In other words, not built-to-spec.


----------



## BigEat

That makes sense. 

 So, what could account for differences among one cable to the next?

 Not to get off topic, but would the same be true for USB cables?


----------



## infinitesymphony

Quote:


  Originally Posted by *BigEat* /img/forum/go_quote.gif 
_So, what could account for differences among one cable to the next?_

 

Here's a link to a current thread with optical cable discussion that includes information from some people who know much more about the subject than me (feel free to ignore the "cables-are-all-the-same" guys). 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *BigEat* 
_Not to get off topic, but would the same be true for USB cables?_

 

In most cases, no, because the implementation is different. In a perfect world, digital cable quality shouldn't matter, but it does, and it's due in part to the synchronous nature of the S/PDIF standard that complications can arise. The majority of USB devices don't require 100% perfect real-time synchronization for ideal operation (unlike S/PDIF), so that potential errors should theoretically become less of an issue.

 Some audio devices like the E-MU 0404 USB use a non-standard (isochronous) method of communicating over USB that is similar to S/PDIF, and it's been argued that it might be possible to improve that cable. Or, at least it would be, had E-MU not supplied a very good USB cable with ferrite chokes on the ends.


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