Optical vs coaxial

petergabriel

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Oct 30, 2019
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I have read a lot about optical vs coaxial connections, when attaching a digital product to a DAC, so I decided to try it out, connecting both types to my Rega DAC (1. Gen).

My setup
Airport Express connected with Audioquest optical using Airplay 2.
Squeezebox Touch connected with Wireworld coaxial.
Test music using exact same albums via Deezer Hifi.

Switching input on Rega DAC made A/B test possible while playing the same song in close to sync from my iPhone and on my Squeezebox Touch.

I know Airplay 2 transcodes Deezers flac files to Alac, but theoretically the transcode should be lossless. I also know from tests found online that the jitter performance of the Squeezebox Touch is much better than what the Airport Express is capable of.

So, with that in mind, I started my listening test using headphones. Here is what I heard:

I really had to listen, with a capital L to hear any difference. I am not sure there is any. If anything, I convinced myself, I found vocals a little more focused on the Touch, the overall sound a little less harsh, with slightly(!) more body, and surprisingly, the stereo perspective a wee bit wider on the Express. But, with that being said, I am not sure if I wanted to hear a difference that really isn’t there, because I don’t think I will be able to hear the difference on my Dynaudio speakers, not even with an a/b test.

My conclusion. I will feel totally satisfied using either coaxial or optical to connect my equipment, as long as the cable is of good quality. I don’t think there is any difference worth hightlighting one connection as better than the other soundwise, besides the technical ones where coaxial handles hires, and optical does not, and where optical is immune to electric interference and coaxial is not.
 

petergabriel

Well-known member
Oct 30, 2019
31
8
545
www.petergabriel.dk
I suspect that when most of us conclude that we can't be sure we hear a difference that there isn't one worth bothering with, if it's actually there. My ear will concentrate more on one thing than another, so it takes several switches back and forth to try to assess any differences.
Exactly. I switched back and forth numerous times, and I believe what I heard was more some sort of placebo effect than real differences. Now I can simply relax and listen to the music, and not worry whether listening via Airplay 2 is not as good as my beloved Squeezebox. In other words, streaming via Airplay 2 from my phone, with all its conveniences, does not degrade the sound. Great!
 
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12th Monkey

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I'm always struck by a parallel in reviews of cars. Most glaringly where a facelifted model is described as being a touch better than the preceding one - the latter of which will usually be recalled from memory. It's a rare thing that such a test includes any back-to-back. The temperature/weather and the state (and especially make/model) of tyre are likely to make more of an appreciable difference.
 

nopiano

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Feb 15, 2009
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I'm always struck by a parallel in reviews of cars. Most glaringly where a facelifted model is described as being a touch better than the preceding one - the latter of which will usually be recalled from memory. It's a rare thing that such a test includes any back-to-back. The temperature/weather and the state (and especially make/model) of tyre are likely to make more of an appreciable difference.
An interesting analogy with cars. I often wonder what prompts facelifts and redesigns, apart from the marketing department wanting new, improved etc. I’m sure that manufacturing hiccups, owner feedback, and the bit we don’t hear much about - changing suppliers - has a big bearing on things.

With Hifi, I’ve read that the big speaker firms commission an entire production run in one go. So when that slug of 10,000 units, or whatever, is sold, they redesign and release the V2, s2, i model, or whatever label they contrive. That’s also why you get one or two models hugely discounted to clear stocks. In contrast, the bespoke or made to order types are made for many years, perhaps with minor tweaks in production but no model change.
 

Adam W.

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Aug 19, 2020
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I put all of my interconnects in the freezer an hour before listening to a song.

The freezing process works some kind of magic on the copper crystals. I don’t have time to go into the complicated scientific explanation.

Needless to say, the sound quality improves drastically. I can hear details that aren’t even in the song, the dynamic range is limitless and the soundstage extends into my neighbors house it’s so wide!

Of course, this only lasts for roughly one five minute song as the interconnects tend to defrost quickly.

It’s literally unbelievable.
 

Roger_A

Well-known member
Mar 31, 2010
25
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18,545
I put all of my interconnects in the freezer an hour before listening to a song.

The freezing process works some kind of magic on the copper crystals. I don’t have time to go into the complicated scientific explanation.

Needless to say, the sound quality improves drastically. I can hear details that aren’t even in the song, the dynamic range is limitless and the soundstage extends into my neighbors house it’s so wide!

Of course, this only lasts for roughly one five minute song as the interconnects tend to defrost quickly.

It’s literally unbelievable.
Well, at least we can all agree with your last sentence!
 

idc

Well-known member
Jan 2, 2008
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I am no electronics expert, but there is no reason why one cable should sound any different to another. All they need to do is transmit a stream of 1 and 0s from the source to the DAC.

If you found no certain audible difference with an A/B test, then an A/B/X blind test would likely show there is no difference. The other test is to measure the sound in the headphones, which would need a test rig such as this used by Rtings


 
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insider9

Well-known member
Sep 20, 2016
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I put all of my interconnects in the freezer an hour before listening to a song.

The freezing process works some kind of magic on the copper crystals. I don’t have time to go into the complicated scientific explanation.

Needless to say, the sound quality improves drastically. I can hear details that aren’t even in the song, the dynamic range is limitless and the soundstage extends into my neighbors house it’s so wide!

Of course, this only lasts for roughly one five minute song as the interconnects tend to defrost quickly.

It’s literally unbelievable.
And I thought I had an amazing imagination 🤣 Have you considered liquid nitrogen cooling for your cables? I'm sure there could be a market should you develop this.

Range of possibilities with cable lifters, unicorn aura isolation and psychosomatic room treatment. I know what you're thinking I've not mentioned magic marbles. It's because the market is saturated with this. It's all about exploiting the right niche.
 

insider9

Well-known member
Sep 20, 2016
1,182
633
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I have read a lot about optical vs coaxial connections, when attaching a digital product to a DAC, so I decided to try it out, connecting both types to my Rega DAC (1. Gen).

My setup
Airport Express connected with Audioquest optical using Airplay 2.
Squeezebox Touch connected with Wireworld coaxial.
Test music using exact same albums via Deezer Hifi.

Switching input on Rega DAC made A/B test possible while playing the same song in close to sync from my iPhone and on my Squeezebox Touch.

I know Airplay 2 transcodes Deezers flac files to Alac, but theoretically the transcode should be lossless. I also know from tests found online that the jitter performance of the Squeezebox Touch is much better than what the Airport Express is capable of.

So, with that in mind, I started my listening test using headphones. Here is what I heard:

I really had to listen, with a capital L to hear any difference. I am not sure there is any. If anything, I convinced myself, I found vocals a little more focused on the Touch, the overall sound a little less harsh, with slightly(!) more body, and surprisingly, the stereo perspective a wee bit wider on the Express. But, with that being said, I am not sure if I wanted to hear a difference that really isn’t there, because I don’t think I will be able to hear the difference on my Dynaudio speakers, not even with an a/b test.

My conclusion. I will feel totally satisfied using either coaxial or optical to connect my equipment, as long as the cable is of good quality. I don’t think there is any difference worth hightlighting one connection as better than the other soundwise, besides the technical ones where coaxial handles hires, and optical does not, and where optical is immune to electric interference and coaxial is not.
Peter, first of all what a pleasure having you here. "So" in one of my favourite albums of all time 😉

Secondly, what did you use to perform that test? MP3, FLAC, wav?
 

Tinman1952

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May 19, 2021
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I am no electronics expert, but there is no reason why one cable should sound any different to another. All they need to do is transmit a stream of 1 and 0s from the source to the DAC.

If you found no certain audible difference with an A/B test, then an A/B/X blind test would likely show there is no difference. The other test is to measure the sound in the headphones, which would need a test rig such as this used by Rtings


I have read this so many times….🙄
how do you think those 1s and 0s are transmitted….?
Answer’ its analogue square wave! Voltage switching between two levels.
So an analogue signal is certainly affected by cable construction….
 

MUSICRAFT

Well-known member
I am no electronics expert, but there is no reason why one cable should sound any different to another. All they need to do is transmit a stream of 1 and 0s from the source to the DAC.

If you found no certain audible difference with an A/B test, then an A/B/X blind test would likely show there is no difference. The other test is to measure the sound in the headphones, which would need a test rig such as this used by Rtings


Funnily enough a few days ago we took on/in T+A's HA 200 amplifier and Solitaire P Planar-magnetostatic headphones and Solitaire P-SE magnetostatic headphones. I don't think there's going to be any place to hide for recordings, external components and cables to be used with these T+A bad boys
:cool:
:)

t+a ha 200 silver front.jpg

t+a solitaire p.jpg
 

idc

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Jan 2, 2008
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I have read this so many times….🙄
how do you think those 1s and 0s are transmitted….?
Answer’ its analogue square wave! Voltage switching between two levels.
So an analogue signal is certainly affected by cable construction….
So long the cable is constructed to a reasonable level and is not overly long, it will transmit that square wave. If it fails, then the sound will cut out. The cable cannot affect sound quality.
 

Tinman1952

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May 19, 2021
559
284
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So long the cable is constructed to a reasonable level and is not overly long, it will transmit that square wave. If it fails, then the sound will cut out. The cable cannot affect sound quality.
But it can affect the timing of the signal…..
which affects the reconstruction of the wave form. The ‘rise time’ of these square waves matters.
So yes it does affect sound quality….
 

Tinman1952

Well-known member
May 19, 2021
559
284
770
How? Show me the scientific evidence you have that proves the "rise time" affects SQ and exactly how it affects SQ and that effect will be audible.
It’s not about whether or not the 1s and 0s arrive …. or not. It’s about the timing of these 1s and 0s. That’s what a DAC uses to reconstruct the analogue wave form correctly…
If you want ‘scientific evidence’ then just do some research on digital audio transmission…
 

aversaurus

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Jan 11, 2016
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As long as the cable is good enough to transmit a complete digital signal that's all you need .but if it makes you happy buy the most expensive cables out there and experience the no difference happy knowing you have the best .
 
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idc

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Jan 2, 2008
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Those who say that its just 1s and 0s and so it can’t affect sound quality should watch this (at least once) and inwardly digest……🙄
View: https://youtu.be/grzoqEb2KMk
What I get from that is, so long as the source sending the signal and whatever is receiving the signal are working fine and were properly designed, there is no affect on SQ. Problems may be encountered due to jitter and various forms of interference. At 8.17 in the video, various problems that can affect the signal are mentioned and suggestions as to how that can affect SQ, but no examples are given. By that I mean, if the jitter is measured at such and such, then that means "reduced deep lows" or a "loss in resolution".

Why does he not show a specific cable against another cable and play or measure the difference? I want to hear the "reduced deep lows".

It seems to me that something has to be seriously wrong with the design or equipment for there to be an audible effect, and no maker is going to sell a product that just does not work. The video also states the likely problems will be with the digital/analogue conversion and is not specifically about cables causing those problems.

An Amazon basics optical cable at £4.99 is going to be well enough made that it is not going to have an audible effect on SQ, compared to another at £70.
 
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abacus

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Sep 24, 2008
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Timing is irrelevant with a good DAC as it has its own clock built in and that re-clocks the incoming 1s & 0s so that the timing is always as good as it can be.

So long as the DAC can identify when the signal is either on or off then it will work perfectly, if it can’t then it stops working. (If its borderline you may just get drop-outs)

There is nothing magical about digital transmission, and if somebody does then they should get their old school science books out and have a good read. (If for some reason it was not taught in their school there are plenty of scientific papers out there that explain it, as well as many easy guides done by professionals)

Bill
 
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Tinman1952

Well-known member
May 19, 2021
559
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770
As long as the cable is good enough to transmit a complete digital signal that's all you need .but if it makes you happy buy the most expensive cables out there and experience the no difference happy knowing you have the best .
You need to understand the difference between ‘ a complete digital signal’ and a complete but ‘corrupted signal’…….corrupted by timing errors!
 

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