Couple of questions

Rew

Iv recently sorted out my TV/DVD/Sound set-up a bit.

I have Creative T7700 7.1 speakers and a Creative DDTS-100 decoder. At the moment I have optical cables from my DVD and PS2. Obviously the PS2 only has an optical conection but the DVD has a coaxical as well as the optical. Given that my decoder has optical and coaxical conections which is better?

The Creative speakers come with bog standard speaker wire. I could replace it all with better wire but is it worth the money?

Batbat

It is my understanding that optical is better for digital audio, but Im no expert

ShaneOC

You should not notice any difference between optical or coaxial digital outputs. Many DVD players only have a coaxial output for the digital sound.

People will blather on about the number of times that a signal is encoded and decoded using optical vs. coaxial. If you have both connections available on the decoder just try and see if one is better than the other.

Speaker wire does make a big difference to the quality of the sound so it is wort investing in some good quality speaker wire.

Rew

Cool ill check out the 2 then (only have a **** coax cable though).

The creative speakers are attached to the speake via a standard clamp on the striped cable and to the sub woofer via phono heads but I can get blank heads that I can solder the new cable to. Is there any reason other then neatness to add (or not add) solder to the striped wires entering the speakers?

Anyone know if the quality of optical cables varies?

MrPudding

Optical cables range from really cheap to "how much!!"

Co-ax is generally considered to be the best way to transfer digital sound to your amp. The cost for the cable fall into a similar range as optical. €20 would get you a slightly above entry level co-ax cable.

I tried both cables from my DVD player to my sony amp. I didn’t really notice any difference but the amp manual and most website do say you should use co-ax where possible as it reduces jitter. WTF is jitter?

MrP

robbie1876

Coax digital is better than optical, but you won't ever hear the difference unless you have some seriously expensive hardware and cables. With optical, the digital signal gets converted to a light signal and then back again. Each format conversion can have an effect on the digital signal, and the quality of conversion is determined by the quality of component that does the converting.

Overall though, I wouldnt worry about it unless you are using some reference quality audio equipment.

Rew

Originally posted by robbie1876
Coax digital is better than optical, but you won't ever hear the difference unless you have some seriously expensive hardware and cables. With optical, the digital signal gets converted to a light signal and then back again. Each format conversion can have an effect on the digital signal, and the quality of conversion is determined by the quality of component that does the converting.

Overall though, I wouldnt worry about it unless you are using some reference quality audio equipment.

Well I dont think my Creative Speakers and Goodmans DVD player are exactly top of the line. Neither are all the cables. Allthough the DVD player is proably better then ANY palyer iv seen to date for features and price. My only issue with it is that the remote in knackered and thats my fault. Basicly im just trying to make the best of the gear I have atm.

Cheers

robbie1876

Yeah, I'd stick with the optical cables, they will do you fine.

How bog standard is the speaker cable? You may not notice any difference upgrading to better speaker cable, for the same reasons as above - you need very high quality speakers to hear the difference (and good ears too!). If its the cable that came with the speakers, I'd stick with it. If the speakers could benefit from better cable they would give it to you, or recommend that you use better cable.

Rew

Speakers (and decoder):
http://ie.europe.creative.com/products/product.asp?prod=568

Iv had to extend the wire in spots to get it neat around the room (and replace a section that my Girlfriends Gunie Pigs chewed!!). Its standard .70 cent (or less) a meter stuff. Same as any home cinema kit Iv seen so far.

ZENER

With optical, the digital signal gets converted to a light signal and then back again. Each format conversion can have an effect on the digital signal, and the quality of conversion is determined by the quality of component that does the converting.

Hi robbie, most of the time we're on the same wavelength but I have to take issue with you on this one I'm afraid !

If we were discussing an analogue audio signal being "converted" to light for transmission along a cheap fiber you would get no argument from me - the double change in carrier would murder the signal to noise ratio, but we are talking about 1's and 0's! What difference does the medium make to a digital level 1 over those distances and at those bitrates ?

Strictly speaking there is no "conversion" taking place, the digital signal is not being converted to analogue prior to transmission, it's merely its carrier that changes the signal type remains the same - it's still digital!

I cringe when people exclaim "..but it's digital - it says so on the box so it must be better !!" Just because the signal IS digital also does not make it any better. I digress . . .

With regards to cable selection for the T7700 system - just make sure it's copper and that the polarity is right !! I really wouldn't waste too much time considering or money buying OFC copper cables here, you're just not going to hear it!

Muddy bass from a 24 Watt 6.5" "Woofer" (@ 10% THD) and 8 watt per channel surrounds (with the same THD figure) with no upper bass/lower mid (200 - 400 Hz) and tinny treble all make for a fine PC speaker system but not even close for Home Theatre! Just my opinion for what it's worth.

ZEN

robbie1876

Hi Zener,

Fair points raised! I'll start by repeating that you will never hear the difference unless you have some very very high end audio equipment, and even then you'll need superman's ears to hear it.

When a DVD disc is read (funnily enough by an optical laser) the signal of 1s and 0s is immediately converted to an electric signal, which is capable of transmitting through copper. When this electric signal gets fed to the optical output, it gets converted to optical by a laser diode. At the other end the laser diode converts the optical 1s and 0s back to an electric signal.

The laser diode is the critical element. It is possible that one of the diodes at either end of the optical cable may not be operating as efficiently as the other one, resulting in loss of 1s and 0s.

You'll never hear the difference though! I never heard the difference on any system I've ever installed, but I still always try to use coaxial wherever possible.

There are a couple of circumstances where Optical can be better than coaxial:

1) An optical cable will be better than a cheap, unshielded coaxial cable. Coax is subject to RF interference. If there is a lot of RF activity, it may be better to use Optical. If using coaxial, always make sure it is screened and of good quality.
2) You cant go more than 300m with coax without major signal loss, whereas you can go many miles with fibre optic. This is handy if you live in a big house....

The downside of optical is that it breaks easy and can't be bent too much. If the digital cable is in a tight space or needs to make some sharp corners, use coaxial.

I'm such a nerd!!!

Robbie

P.S. You wont hear the difference, did I say that?

robbie1876

Originally posted by ZENER
Just because the signal IS digital also does not make it any better.

Yes, I agree. I much prefered the internet back when it was analogue....:)

MrPudding

Originally posted by robbie1876

2) You cant go more than 300m with coax without major signal loss, whereas you can go many miles with fibre optic. This is handy if you live in a big house....

I agree with much of what you say. However, in the home entertainment arena range would not really be a area where optical would have a huge advantage over copper. In networking and telecoms optical can have ranges of several mile. In these cases though they use a different type of fibre and also actual lasers rather than diodes. Also, in the home it is unlike that you will have sources of RF interference strong enough to interfere with even modestly shielded cables.

Funny aside, I was doing a cabling course and we were covering fibre. The instructor was telling us that you should never look into the end of a fibre cable. It would seem that some people would to see if there was any light. Thing is, in telecoms the laser works at a frequency not visable to the human eye. This is where it get interesting. Although the light is invisible it is damaging. There are no nerves in the eye so you don’t feel any pain. The only indication that you are blinding yourself comes from the sound of the veins in your eye popping and blindspots appearing. Nice.

So anyway, back on topic. I would be concerned if there were conversions from digital to analogue conversions. But as it is digital at both ends and there is error correction that can extrapolate lost bits or correct wrong bits there isn’t really a problem.

MrP

ZENER

Yes, I agree. I much prefered the internet back when it was analogue....

It still is analogue . . thats why we need modems !!

I guess its down to personal preferences or need to be nerdy! The truth about CD's and DVD's is that they use quite a lot of error correction data to reconstruct the signal where it gets interruped due to scratches or coffee mug rings or holes drilled in them by ambitious sales men (I remember this happening ya know)?!

The quality of the circuitry/software controlling the laser alignment has a lot to do with the amount of "good" data that is passed through the DA converters (format conversion) rather that reconstructed from error correction codes, so most of the time a good quality - read more expensive - CD player will sound better.

http://www.cdrfaq.org/faq02.html#S2-17

explains it well. With all this going on, the few if any errors introduced by a cable traveling a couple of feet is hardly worth concerning yourself with.

Anyway why are we discussing the finer points of audio reproduction in a thread about a creative labs decoder and pc speaker system ? Should be ashamed of ourselves!!

ZEN

Rew

Originally posted by ZENER


Anyway why are we discussing the finer points of audio reproduction in a thread about a creative labs decoder and pc speaker system ? Should be ashamed of ourselves!!

Play nice, I have as much right to ask these questions as anyone else, we dont all have 1500 quid to spend on amp and speakers. If anything the ****ty equipment has provoked more debate then id say you normally get.

Thanks for everyones help, I got he Creative kit very cheap so it will do me for now. I think the general conclusion that the default cables etc are as good as it gets is fair enough.

On the subject of Optical and error correction, I would assume there is a simple parity check (first year CS stuff) done on the far side to check for and correct lost bits, you would need massive loss before that would break down at which point id say you would hear it. Transforming light to and from a digital circuit would be a fairly simple task as well.

Thanks again.

ZENER

Play nice, I have as much right to ask these questions as anyone else, we dont all have 1500 quid to spend on amp and speakers. If anything the ****ty equipment has provoked more debate then id say you normally get.

I'm sorry I really didn't mean that to sound as arrogant as it came out but believe me there is no way I would spend 1500 quid on something that has a couple of dBs less noise or a couple of bits more error correction. I buy amps and speakers to listen to music not to listen to the equipment.

On the subject of Optical and error correction, I would assume there is a simple parity check (first year CS stuff) done on the far side to check for and correct lost bits, you would need massive loss before that would break down at which point id say you would hear it.

Something like that, parity checking is not error correction but rather error detection, the systems in question here are simplex so parity checking and requesting data to be resent doesn't happen.

The main point here is the music or audio you are listening to - that is all you should be listening to - if you spend your time trying to justify the 20,000 quid you've just spent on a speaker cable then you've missed the point. Sure spending a couple more quid on a quality interconnect or a better brand CD player or a decent pair of speakers is worthwhile but there is a point where reason is lost and wallets/credit cards take over - thats where robbie1876 steps in !!;) G'wan ya gud ting !!!:D

ZEN

robbie1876

Originally posted by MrPudding
Funny aside, I was doing a cabling course and we were covering fibre. The instructor was telling us that you should never look into the end of a fibre cable. It would seem that some people would to see if there was any light. Thing is, in telecoms the laser works at a frequency not visable to the human eye. This is where it get interesting. Although the light is invisible it is damaging. There are no nerves in the eye so you don’t feel any pain. The only indication that you are blinding yourself comes from the sound of the veins in your eye popping and blindspots appearing. Nice.

Thats interesting, and a bit scary. There's an optical port on the keyboard I use for gigging, and it hasn't had the plug in it for the last year or so! I wonder how many people I've blinded at gigs so far. If any of you are coming to the boardstock gig on the 20th, bring good sunglasses, as I will be unleashing my weapon of optical destruction on you all...

Originally posted by ZENER
Anyway why are we discussing the finer points of audio reproduction in a thread about a creative labs decoder and pc speaker system ? Should be ashamed of ourselves!!

:ninja:

ZENER

. . . where possible as it reduces jitter. WTF is jitter?

Jitter is the deviation in or displacement of some aspect of the pulses in a high-frequency digital signal. As the name suggests, jitter can be thought of as shaky pulses. The deviation can be in terms of amplitude, phase timing, or the width of the signal pulse. Another definition is that it is "the period frequency displacement of the signal from its ideal location." Among the causes of jitter are electromagnetic interference (EMI) and crosstalk with other signals. Jitter can cause a display monitor to flicker; affect the ability of the processor in a personal computer to perform as intended; introduce clicks or other undesired effects in audio signals, and loss of transmitted data between network devices. The amount of allowable jitter depends greatly on the application.

from:

http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci213534,00.html

ZEN

ZENER

. . .bring good sunglasses, as I will be unleashing my weapon of optical destruction on you all...

Will these do ?

http://www.aerussell.co.uk/images/prod12b.jpg

Lookin' forward to the gig robbie !

ZEN

MrPudding

Originally posted by robbie1876
Thats interesting, and a bit scary. There's an optical port on the keyboard I use for gigging, and it hasn't had the plug in it for the last year or so! I wonder how many people I've blinded at gigs so far. If any of you are coming to the boardstock gig on the 20th, bring good sunglasses, as I will be unleashing my weapon of optical destruction on you all...



:ninja:

I would not be too concerned. Your keyboard will only use a diode not a laser. The Long range comms gear use actual LASERs with will blind people.

MrP