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Coax vs optical...

Mitko 55

Mitko 55

Active Member
I have Wiim pro plus connect to Smsl su1 dac and I can hear differences between coax and optical outputs. Coax sound richer, fuller, warmer, optical sound, flatter, colder thiner. I don't have golden ear nothing like that but I can hear the differences almost from the first notes. I tried Tidal streaming both ways, also my CD player has both outputs. Same results. My friend have same stremer connected to Topping D30.Same results,coax fuller, richer, optical thiner colder. I Didn't expect that much differences between digital outputs. Any other opinions?
 
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I've read many times coax connection sounds better than optical. One exception might be if the digital source is electrically noisy for some reason and optical connection might deal with that to a degree.
 
My initial reaction: This seems like a case of perception bias.

Both transmit digital signals. Optical can in rare occasions have bad jitter but it sounds like this:

what does jitter ACTUALLY sound like?

In a previous post we had an encounter with jitter in audio. The talk about jitter is hard to miss these days. There are plenty of products on the mar...
www.sereneaudio.com www.sereneaudio.com

It does not change the tonality or frequency response.
If there's a fault with a digital connection you will experience pops, clicks and pauses in the music. It does not matter if the cable is glass or plastic.

The Wiim Pro Plus has some settings for each output. Check if these are the same for coax and optical. They are in the app under "Audio Settings".
 
Retro_Pete said:
My initial reaction: This seems like a case of perception bias.

Both transmit digital signals. Optical can in rare occasions have bad jitter but it sounds like this:

what does jitter ACTUALLY sound like?

In a previous post we had an encounter with jitter in audio. The talk about jitter is hard to miss these days. There are plenty of products on the mar...
www.sereneaudio.com www.sereneaudio.com

It does not change the tonality or frequency response.
If there's a fault with a digital connection you will experience pops, clicks and pauses in the music. It does not matter if the cable is glass or plastic.

The Wiim Pro Plus has some settings for each output. Check if these are the same for coax and optical. They are in the app under "Audio Settings".
Click to expand...
No pops no clips, settings in wiim app correct, both 24/192 sound is not bad just noticeably different
 
On some units coax will have higher bandwidth over fiber. Have also found that usually coax sounds better, but it has been limited to a couple cd players, and my Xbox. But with the Xbox it was fiber vs HDMI.
 
Well, the coax is a direct electrical connection. It doesn't have to be switched then reversed. My experience has been coax is typically better. As someone else stated, the advantage of optical is electrical isolation.
 
Mitko 55 said:
No pops no clips, settings in wiim app correct, both 24/192 sound is not bad just noticeably different
Click to expand...
Alright, then the connection itself is ruled out as it seems to work alright.
Unless there is something different in the setup of inputs in the SMSL dac, It seems then we’re back to perception bias.

If you haven’t already, it’s worth doing these tests blind and ensuring the sound levels are matched. That’s really the only way to minimize the perception biases we all have and can’t avoid.

In addition to expectation bias, several factors can influence perceived sound, including:
  • Mood
  • Health
  • Alcohol
  • Nicotine
  • Energy levels
  • Stress levels
Each of these elements can affect our sensory perception, especially when it comes to sound.
 
Mitko 55 said:
I have Wiim pro plus connect to Smsl su1 DAC and I can hear differences between coax and optical outputs. Coax sound richer, fuller, warmer, optical sound, flatter, colder thinner. I don't have golden ear nothing like that but I can hear the differences almost from the first notes. I tried Tidal streaming both ways, also my CD player has both outputs. Same results. My friend have same streamer connected to Topping D30.Same results, coax fuller, richer, optical thinner colder. I Didn't expect that much differences between digital outputs. Any other opinions?
Click to expand...
That`s also the similar results of my SQ comparison almost 10 yrs. ago between the 2 types of digital outputs, whether feeding my Mc. CD player`s S/PDIF coax output to my Pro Ject S2 DAC, or lossless WAV. ripped copies sent from my HQ OPPO Universal player using a 1 Terabyte flash drive using the OPPO player`s S/PDIF coax output.

I don`t internet stream all my digital music/video is sourced inhouse and HQ hard wired distributed to 6 room`s of my house`s stereos.
 
Back in the 80s there was a lot of hand wringing over toslink vs coax, with the concern being about jitter. I remember seeing some tests in which optical cable jitter varied a lot simply by bending or coiling the cable. I believe the problem is that multiple plastic fibers are used and the signal bounces more times through some of the fibers than others resulting in the increased jitter. There is an alternative optical fiber that uses single mode glass fiber with an AT&T connector that doesn't suffer from this problem but is much more expensive (?) and found on very few pieces of audio equipment (my VRDS-20 CD player has both toslink and AT&T fiber outputs).

I don't know if the argument about the audibility of jitter was ever settled, but I don't see it mentioned in this forum much at all, so I assume it was. I tried comparing my 35 year old CD player's unbalanced analog out to the output of an SMSL SU-1 DAC, fed by coax and toslink outputs from the CD player, and could hear no differences between any of them using either speakers or electrostatic headphones. I don't know if that says more about the DACs in the CD player and the SMSL or my ears, probably the latter.
 
mrehorst said:
Back in the 80s there was a lot of hand wringing over toslink vs coax, with the concern being about jitter. I remember seeing some tests in which optical cable jitter varied a lot simply by bending or coiling the cable. I believe the problem is that multiple plastic fibers are used and the signal bounces more times through some of the fibers than others resulting in the increased jitter. There is an alternative optical fiber that uses single mode glass fiber with an AT&T connector that doesn't suffer from this problem but is much more expensive (?) and found on very few pieces of audio equipment (my VRDS-20 CD player has both toslink and AT&T fiber outputs).

I don't know if the argument about the audibility of jitter was ever settled, but I don't see it mentioned in this forum much at all, so I assume it was. I tried comparing my 35 year old CD player's unbalanced analog out to the output of an SMSL SU-1 DAC, fed by coax and toslink outputs from the CD player, and could hear no differences between any of them using either speakers or electrostatic headphones. I don't know if that says more about the DACs in the CD player and the SMSL or my ears, probably the latter.
Click to expand...
I've never noticed jitter and have always chosen Toslink when it's available to avoid ground loops, which can actually be a significant issue in some systems.
 
Retro_Pete said:
I've never noticed jitter and have always chosen Toslink when it's available to avoid ground loops, which can actually be a significant issue in some systems.
Click to expand...
I've never had a noise problem so I tend to use coax, mostly because cables are easy to make or buy in shorter lengths. Optical cables are probably available in short lengths these days, too, but they didn't used to be.
 
Retro_Pete said:
My initial reaction: This seems like a case of perception bias.
Click to expand...
Didn`t happen in my case, as I had "zero prior digital signal connection experience", nor were any of my audio friends into digital audio connection music delivery experience, nor was I swayed by prior reading someone else`s opinion(s) on the web, so I had Markertek.com (broadcast supply Co.) build me 2 high quality coax and 2 high quality TosLink optical certified polished end jumpers 3 ft. ea. (interconnects), so I could A/B decide for myself. No ground loop noise interfered with the S/PDIF coax connection, as the Sony player or DAC`s S/PDIF coax connection was galvanically isolated (can`t remember which)

The in use Sony 400 CD/SACD/DVD carousel player (my older Mc. MCD-7007 CD player only provided a S/PDIF coax output beyond its analog outputs) in use at the time of my experiment ~10 yrs. ago ( being a late computer digital music external DAC based adopter)
The Sony by chance had both its S/PDIF coax and TosLink optical outputs active at the same time, so I could feed both to my recently purchased HQ $,$$$.$$ studio grade DAC that supported both types and easily switch the DAC`s inputs between the 2 back and forth on the fly while playing well known select HQ DDD CDs, and after spending a period of ~wk. comparing the 2 types, to my ears, S/PDIF coax sounded better to my ears and first time visitors often compliment me on the sound quality of my house`s 4 rooms of varying SQ 24/7/365 operating stereos.
 
The debate over optical versus coax has resolved itself over time. Here's why:

Conventional wisdom item 1: Optical cables typically are less robustly built than coax and more likely subject to damage.
Well, this may be possible, but damaged optical cable is readily apparent: either it passes the digital signal or it doesn't. Otherwise undamaged, it delivers the same digital signal that the coax cable would.

Conventional wisdom item 2: Optical cables introduce jitter in the digital signal.
Really? Does that mean that the fiber optic cables that deliver the internet signal from my cable internet provider to the local digital hub are full of jitter? Likely not. Again, if the signal originating from your digital source arrives at your DAC, whether its optical or coax, then you're fine. Most DAC's - whether built into a CD player or standalone DAC - are able to internally correct for jitter anyway.

Conventional wisdom item 3: Optical cables have limited bandwidth, and can only pass digital streams up to 96khz.
Please don't tell my DAC this. I'm listening to a digital stream at 192khz at the moment. Besides, how did those digital streams at 192khz from Amazon or Qubuz arrive at your home? They most certainly passed through fiber optic cable at some point on their journey.

Anyway, my 2 cents is to plug in the cable, relax and enjoy the music. Doesn't much matter if the cable is coax or fiber optic.
 
whell said:
The debate over optical versus coax has resolved itself over time. Here's why:

Conventional wisdom item 2: Optical cables introduce jitter in the digital signal.
Really? Does that mean that the fiber optic cables that deliver the internet signal from my cable internet provider to the local digital hub are full of jitter? Likely not. Again, if the signal originating from your digital source arrives at your DAC, whether its optical or coax, then you're fine. Most DAC's - whether built into a CD player or standalone DAC - are able to internally correct for jitter anyway.
Click to expand...
You're comparing apples and oranges. Those connections are carrying Gbps signals that would not make it through a toslink cable. The fibers and hardware are completely different from consumer audio junk (relatively speaking).

Modern DACs, even cheap ones, may be better at correcting or ignoring jitter than old ones were.
 
Interesting question/subject. Other factors not mentioned are the quality of the connectors. I did see the question of Glass vs Plastic was asked but not answered. Glass is usually better but more expensive and more prone to cracking under too tight of a bend. The shop I worked at when Fiber was introduced built the first machines to polish the elliptical ends of glass fiber cables for AMP. That said I personally have never compared because I never had a need to. I use one older XLO digital cable in my systems.
 
Most Toslink cables are plastic. Yeah, they can vary widely in quality. Also be broken, or damaged by bending. You can bend light, but it usually takes a lot of power to do so. The fiber cables used in datacenter are always glass fiber, or solid glass, with very heavy sheathings that keeps it from being bent too far.

The positive of fiber over coax is that fiber will not absorb any radio interference, or other interference that can affect coax. Think if you have a good glass fiber cable that isn't being bent or coiled it will have far less of a jitter issue. Fiber will always be better over longer runs, on my home network, fiber would always win over twisted pair.

Back to the base conversation, on the units I have used with Toslink, there are different bandwidth specs between fiber/coax. Coax usually having higher bandwidth.
 
mrehorst said:
I've never had a noise problem so I tend to use coax, mostly because cables are easy to make or buy in shorter lengths. Optical cables are probably available in short lengths these days, too, but they didn't used to be.
Click to expand...
They are. Think the one that connects my Wiim to my miniDSP is 20 cm or so. Neat.

Bill Ferris said:
Didn`t happen in my case, as I had "zero prior digital signal connection experience", nor were any of my audio friends into digital audio connection music delivery experience, nor was I swayed by prior reading someone else`s opinion(s) on the web, so I had Markertek.com (broadcast supply Co.) build me 2 high quality coax and 2 high quality TosLink optical certified polished end jumpers 3 ft. ea. (interconnects), so I could A/B decide for myself. No ground loop noise interfered with the S/PDIF coax connection, as the Sony player or DAC`s S/PDIF coax connection was galvanically isolated (can`t remember which)

The in use Sony 400 CD/SACD/DVD carousel player (my older Mc. MCD-7007 CD player only provided a S/PDIF coax output beyond its analog outputs) in use at the time of my experiment ~10 yrs. ago ( being a late computer digital music external DAC based adopter)
The Sony by chance had both its S/PDIF coax and TosLink optical outputs active at the same time, so I could feed both to my recently purchased HQ $,$$$.$$ studio grade DAC that supported both types and easily switch the DAC`s inputs between the 2 back and forth on the fly while playing well known select HQ DDD CDs, and after spending a period of ~wk. comparing the 2 types, to my ears, S/PDIF coax sounded better to my ears and first time visitors often compliment me on the sound quality of my house`s 4 rooms of varying SQ 24/7/365 operating stereos.
Click to expand...
Bill, what do you think could be the root cause of this issue?

Both technologies transfer data as 1s and 0s, reconstructed at the receiving end. Any deviation from the original signal would likely stem from noise or jitter, but these effects would typically be inaudible with high-quality equipment. It’s worth considering that the signals might be processed differently, perhaps using distinct filters or roll-off characteristics, which could lead to subtle variations but that would be indicative by a frequency response for each output in the manual.

To whom it may concern; let’s keep the discussion focused on the technical aspects and approach it constructively. I encourage everyone to engage thoughtfully and address the topic directly. This isn’t an attempt to derail the conversation or provoke reactions; it’s an effort to explore the issue thoroughly and in good faith.
 
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