Optical VS Coax the showdown!

[Malakei]

OK, this is obviously a silly question but what should I be looking for. Im running 14ga speaker wire if that changes anything. From what i do understand, optical is better for computer related interconnects where as you get the truest sound from your digi coax. Is this true or have i been falsely informed. I tried a digital coax cable last night and the speakers didnt work. Wasnt sure if it was the reciever on the wrong settings or what. It was set to prologic II so i wasnt sure if i needed it to be on DTS or dolby digital for it to work instead. Im pretty positive i had it in the right jacks but i have a feeling my reciever only had a coax out which doesnt make sense to me but who knows. Even on the simple red white jacks the speakers are clear as day with no interference which is why i wanted to try digi coax cuz i heard its the best sound as long as you dont have any interference. If you do i was told to go with optical which eliminates the background inerference that you sometimes get. Someone Help Also I dont wanna spend more then 30 bux on a 3 foot audio cable, heh. If that changes anything.

 

[MDS]

There is no difference between optical and coax digital connections in terms of sound quality. They both carry digital bitstreams (DD, DTS) data in s/pdif format. Each can carry PCM data (CDs).

Optical may be better if there is significant rfi/emi interference but that is rarely a problem anyway and coax cables are well shielded to avoid the problem. The Toslink connectors on optical cables are more fragile than the RCA connectors on coax but that is another non-issue unless you yank on the cables. Use whichever one you have connections for. I use coax digital for the set-top box because it only has coax digital outs and the receiver only has one coax input. All other components have both optical and coax outputs and I use the optical because that is what is free on the receiver.

What are you trying to hook up? If you are connecting your computer's soundcard to a receiver, you have to enable digital output in the soundcard's mixer applet. On the receiver, you have to 'assign' the coax or optical input to a front panel input so it knows which digital input to read from when you select a particular input; ie assign 'optical 1 input' to 'DVD' if you hook the dvd player to the DVD input of the receiver and the dvd's optical out to the optical 1 input.

 

[BMXTRIX]

I think the above was an excellent explanation. Toslink (digital optical) is not subject to interference the way S/PDIF (digital coax) is, but it is more fragile and typically is not run as long of a distance. A short run to your receiver and you don't mess with the optical cables, then go Toslink. A longer run or you have a feeling the cables may get abused, go S/PDIF.

A quick note that digital optical is Toslink (Toshiba) and digital coax is S/PDIF (Sony/Phillips Digital InterFace), the ones and zeroes are all the same.

 

[MDS]

A quick note that digital optical is Toslink (Toshiba) and digital coax is S/PDIF (Sony/Phillips Digital InterFace), the ones and zeroes are all the same.

True and False.

S/PDIF defines both the electrical characteristics (signalling) of the hardware interface for connecting coax cables terminated with RCA connectors as well as the format of the data.

Toslink is the name of the connector on digital optical cables. The data format is S/PDIF.

http://www.andrewkilpatrick.org/mind/spdif/

 

[BMXTRIX]

I think that we are both right actually... Doing a little more research shows that coax & optical digital can use either toslink or S/PDIF connectivity. The communications protocol is what determines the actual connection.

This is almost esoteric though as almost every digital optical output that I have seen uses the toslink standard and almost every coax output I have seen uses S/PDIF.

Definitions from Audioholics which match others I have seen on the net (I learned something new for sure, thanks!):
"SPDIF
SPDIF is an acronym for Sony Philips Digital Interface and is a CD “Red Book” standard digital audio transfer file format. A SPDIF interface can transport either stereo left-and-right channel information or multi-channel sound. It is typically found on audio and a/v equipment such as CD transports, Laser Disc players, DVD players, some digital satellite products and computer sound cards where it is implemented using an RCA connector. A SPDIF interface is a 75-ohm connection, identical to composite video in specification. Years ago many audiophiles felt that SPDIF offered better sound than the TOSLINK interface discussed below. Improvements in TOSLINK conductors have closed this performance gap and made concern over the interface a moot point.

TOSLINK
Short for Toshiba Link, TOSLINK is also a CD “Red Book” standard that allows for digital audio (both left and right channels or multi-channel sound) to be transported between components using an optical conductor and light as the carrier. Contrary to popular belief, TOSLINK does not use laser light but instead relies on the output of a simple LED. The Achilles heel of TOSLINK is the optical quality of the interface. The plastic conductors used in cheap cables can damage data and compromise performance.

TOSLINK connection performance is somewhat limited by the bend radius (bending a light conductor causes internal reflections and signal loss) of the conductor design. Additionally, the TOSLINK interface is length sensitive with maximum performance available only with runs of less than 20 feet."

 

[MDS]

The communications protocol is what determines the actual connection.

Exactly. An analogy would be tcp/ip over cat5 cables (802.3) vs tcp/ip over wireless (802.11 a/b/g). The communications protocol is tcp/ip and is the same for either interface - only the physical layer is different.

You are right that it is an esoteric distinction and it doesn't really matter because we know what people mean when they say Toslink cable vs s/pdif cable.

 

[Malakei]

learning

im learning something new from you guys everyday i come to the forums. however.. like i said i did try the digital coax as spdif and i didnt get any sound coming out of my speakers ... im running a yamaha htr5750 does anyone know if theres special settings that have to be set for digi coax or im thinking because where the coax in is on the receiver i think says CD and maybe because CD is typically lower bandwidth the receiver doesnt have capabilities for digi coax DVD.. however the reciever does have the toslink for the optical for dvd but my run of cable would only be a foot or two... is having it so close going to ruin the performance because of the tight bend?

 

[BMXTRIX]

A few inches of bend usually is fine for Toslink... But, you shouldn't have an issue as long as the DVD player and the receiver are setup correctly. You may need to go into your DVD player menu and actually turn on the digital output and set it to DTS.

Then within your A/V receiver you can assign the digital input to any of your sources. That is, if you plug it into the input marked "CD" but it is your DVD player, you can reassign it so that when your receiver is on DVD, it uses the CD digital audio feed.

You also want to be sure that your receiver is looking for digital audio. The Yamahas, at least the Z1 that I have, can be set to only look for analog audio. If I don't tell it to 'auto-detect' or to specifically look for 'digital' it will specifically look for 'analog'. This should be covered in your manual.

There are lots of reasons why you wouldn't hear digital audio in your home theater surround system, but the connection is not the likely culprit. Always a possible culprit, but not likely.

 

[Malakei]

hmm

well ill try checking my dvd player menu if i can switch the ound output to digital... that sounds like it would make the most sense. when it comes to reassigning the dvd player to read the cd audio...thats a cat of a different color... im not familiar enough with my reciever yet on what it can and cant do, but i will definately try and research how to assign different components to different inputs, unless you know how

 

[BMXTRIX]

It's a Yamaha so from Yamaha's website:
http://www.yamaha.com/yec/customer/manuals/PDFs/HTR_5750_5740.PDF

It discusses reassigning digital inputs on page 48 and seems fairly straightforward. Should take only a few minutes.

It looks like you have 3 optical input connections and 1 coax input connection on the back of your receiver. You also have 1 optical output if you are going to a CD recorder or something similar.