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fiber optic vs coax vs USB cable from computer/source to DAC .... which is better ?

tomchr

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I recommend an optical link as well as it eliminates any ground loop and noise associated with the source. Ground issues seem to pop up pretty consistently, especially with low-cost PCs. If you don't like optical links, a transformer isolated coaxial link will work just as well.

Tom
 

Willem

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New here, and best wishes for the new year for you all. I have a related question. I just bought a Pioneer U-05 DAC/preamplifier to replace my old Quad 33 pre amplifier and the various DACs built into my digital sources (Chromecast audio, old BluRay player and Panasonic plasma TV - I no longer have analogue sources). I thought it was about time to integrate the lot with a modern pre amp with digital inputs. The Pioneer has two optical and two coaxial inputs, plus usb and AES/EBU. I had checked the various manuals for the type of digital connections on the sources (I could not easily get to the back of the units), but when I tried to connect the BD player I discovered that it did not have the coaxial output that the manual said that it has (just optical). So I a now have three sources with optical outputs and two inputs. I know there are converters to convert optical to coaxial, but wondered if they degrade the signal, and if so, how badly. The TV has the least quality audio signal (it is quite heavily compressed cable TV) so I could use the conversion on that source. Are there any data?
The rest of the system is quite revealing, with a Quad 606-2 power amplifer, Quad 2805 electrostats and a B&W PV1d subwoofer tamed by an Antimode 8033 dsp room eq unit.
 

RayDunzl

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I know there are converters to convert optical to coaxial, but wondered if they degrade the signal, and if so, how badly

Likely, imperceptibly.

All my stuff goes through a 4 input (optical and coaxial on each) to one output switch (again, optical and coaxial). Mix and match as needed.

1546936946158.png


It's really more of an 8 in - 2 out.

https://www.audioauthority.com/product_details/1177A
 
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Willem

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Thanks, even if the one you have is rather more complex (and expensive) than what I need. All I see here in the Netherlands are pretty generic simple boxes.
 

RayDunzl

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Thanks, even if the one you have is rather more complex (and expensive) than what I need. All I see here in the Netherlands are pretty generic simple boxes.

I would expect it to be fine for your TV...
 

Panelhead

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Yes, the conversion is very simple. Benchmark had a guide for DIY conversion. They took it down.
I used John’s directions to convert a couple HD radio players outputs from optical to coax.
It involved removing the transmitter chip. Then a simple circuit with resistors and small value caps. My dac never had an issue locking into the 44.1/16 feed. Replaced the toslink with a BNC connector too.
The six dollar units on Amazon do it with a receiver chip and output to RCA. But should be higher quality than the signal from the TV.
 

Blumlein 88

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Yes, the conversion is very simple. Benchmark had a guide for DIY conversion. They took it down.
I used John’s directions to convert a couple HD radio players outputs from optical to coax.
It involved removing the transmitter chip. Then a simple circuit with resistors and small value caps. My dac never had an issue locking into the 44.1/16 feed. Replaced the toslink with a BNC connector too.
The six dollar units on Amazon do it with a receiver chip and output to RCA. But should be higher quality than the signal from the TV.
I'd be leary of some of the cheapest options. Those sometimes have clocking that compromised the sound. even from the TV. I'm not saying you need to spend hundreds only that some cheap items are substandard even if they work.
 

RayDunzl

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Is there such a device that has a remote control?

Never shopped for that feature.

This one switches to the "highest priority" active input on its own (takes care of most cases here).
 

rudy

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i just hooked up a $3 usb a/b cable between my streamer and my DAC. it sounds amazing!! was going to buy a $100 equivalent
 

Sal1950

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restorer-john

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It's interesting nobody mentioned or asked about cable length. USB hits limits pretty quickly if the cable is too long. I've run 30ft+ Toslinks with no problem and I'm sure coax (RCA) would be fine too over that length.
 

sgent

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It's interesting nobody mentioned or asked about cable length. USB hits limits pretty quickly if the cable is too long. I've run 30ft+ Toslinks with no problem and I'm sure coax (RCA) would be fine too over that length.

Good point, any USB cable longer than 16ft (by spec) needs either a hub or an active extender which is available up to 50 meters for USB 2.0 speeds (what you need for sound).
 

carlmart

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Optical SPDIF with rates not higher than 24/96. The reason - no electrical coupling, no humm, no buzz, no interference - just pure bits. :)
But as other ppl said, and if don't have optical - use what u have, USB, coaxial etc
The problem with optical interface has always been its problem, not the electrical isolation. The reconversion makes it sound inferior to a coaxial one. That much I could listen in the CD players days. There used to be an optical system, designed by ITT I think, that was comparable to coaxial in audio quality, but very rare and available on very expensive CD players/DACs.
 

antcollinet

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That is some serious thread necromancy you've got going on here. :p

The problem with optical interface has always been its problem, not the electrical isolation. The reconversion makes it sound inferior to a coaxial one. That much I could listen in the CD players days. There used to be an optical system, designed by ITT I think, that was comparable to coaxial in audio quality, but very rare and available on very expensive CD players/DACs.

That is not how it works. If the bits are detected correctly (and you will hear it as clicks/crackles/pops/dropouts if they are not) and the DAC is even vaguely competent at recovering the clock (nearly all from the last 20 years or so are) - then there can be no audible difference between Toslink and Coax. It is the same data.

(Unless - in the case of Coax - there is a groundloop causing audible noise. In which case you can hear that with Coax - optical Toslink will break the ground loop and prevent the problem.
 
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