Good point about the transformers. They might already be there and if not, it isn't difficult to insert one if there should be ground loop issues after all.
Have you ever looked at SPDIF implementations of consumer equipment? Even Philips themselves had really bad designs in their CD players with horrible waveforms.
Both equipment in this case (Philco and Oppo) have RCA connectors for SPDIF. The impedance of those is probably nowhere close to 75 ohm (maybe 130ohm). Why would the cable impedance have anything to do with jitter in this case and have you measured the jitter using RCA cables vs. 75 ohm coax with these types of equipment?
That was then, this is now. Modern devices in general have decent SPDIF outputs. Maybe not the best but not as bad as some stuff from the eighties when it all began. If one only has Toslink and coax the choice is between 2 evils and one of them may be simply better than the other one.
That is why the 1 box approach works out better. If the 2 box approach means that many an imperfection (that would not occur otherwise) needs to be corrected maybe the approach was not that fruitful.
That is why the 1 box approach works out better. If the 2 box approach means that many an imperfection (that would not occur otherwise) needs to be corrected maybe the approach was not that fruitful.
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I'm not talking about eighties. E.g. anything with CS8420 in it had horribly jitter no matter how close to 75 ohm your cable was. And with SPDIF RCA connectors using 75 ohm cable vs. normal RCA cable does not really make a difference.
CS8420 was horrible itself. I think it also was one of the first sample rate converters. Their CS8412 and CS8414 also were not that good. I don' t know where the cable thing came from but when I have to use coax I use flexible 75 Ohm cable with BNC plugs/connectors. It is better than Toslink in 9 out of 10 standard cases where no tricks were done with Toslink. Also modern Toslink plugs tend to simply fall out of the receivers/transmitters as Toshiba does not make them anymore for a long time now. Being able to play high res depends on brand and type...All cheap stuff for toys.
Anyway it is loss of time to debate this simple matter. Anyone can test within a minute what performs best in his/hers setup.
Anyway it is loss of time to debate this simple matter. Anyone can test within a minute what performs best in his/hers setup.
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Every diyer should just run a simple JTEST measurement to see how well their SPDIF implementation works. Please, no listening tests. I remember early 2010s there were lots of cheap chinese CS8416/PCM1798 DACs on ebay and there are threads about those here as well. Some of those DACs were appraised for good sound even by the silver ears (nobody had golden ears back then). I bought one to test and measured the jitter. I've never seen anything so bad.
CS8416 also was bad and to be avoided. It is known that BB/TI, AKM and Wolfson make the better receivers and one should avoid Crystal stuff by selecting when buying. Simple. I think it was the cheap CS8416/CS4397 DACs then that were hyped by Lampizator. The DAC chip itself was quite enjoyable.
No we should not listen to equipment! Heavens no 🙂 We should buy test equipment more expensive than the stuff we listen to and have vast stocks of parts.
No we should not listen to equipment! Heavens no 🙂 We should buy test equipment more expensive than the stuff we listen to and have vast stocks of parts.
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I have to slightly disagree with you. CS8412 and CS8414 were quite good and there are several well-regarded DACs using them (e.g. AYA). It was after that Crystal stuff went astray.
WM8804 anytime. CS8412/14 were among the first usable SPDIF receivers (the absolutely horrible YM3623B comes to mind) and therefor they were widely used. They have typically 200 ps of jitter if I recall correctly. Maybe we should think by now that this whole interface thing is the bottleneck regardless of who designs it and what famous designs use it etc. I designed DACs and built many of them and followed the 2 box approach until I used a DAC board IN a device. Bingo. It was so simple that it was truely shocking.
I just noticed the comment below. Toslink is not to be compared with true glass fibre data cabling!
I just noticed the comment below. Toslink is not to be compared with true glass fibre data cabling!
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Going back to the OP's original question, might I suggest that there is a reason that the globe is criss-crossed by undersea optical fibres, not cables. If they are good enough to reliably transmit the planet's often critical internet data accurately then are they not good enough for humble domestic audio, with its comparatively miniscule bandwidth requirements? My only direct experience is with a TV to AV receiver connection, where the audio would often drop out when using a DVI cable. The problem was entirely cured by using a fibre connection between the two.
Yes, it was another version of the DAC hyped by Lampizator. Otherwise similar but using PCM1798. IIRC it was called Gigawork DAC.
Listening to equipment (or music rather) is different than making claims based on listening tests 😉
I only speak for myself but having measured the jitter of properly implemented DAC using Toslink vs. Coax I have not seen much difference. Both will work.
One thing to add: most Toslink connectors can't cope with 192k.
Yeah both will work (even 230V mains cable will work for SPDIF) 🙂 In tube circles some use unshielded solid silver wire with cotton insulation for SPDIF and they feed it to YM3623B receivers. It also works so the protocol can take abuse.
I am off to do some stuff. Ciao!
I am off to do some stuff. Ciao!
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I haven't measured anything, why would anyone want to measure the effect of using an inappropriate cable when it is easy to just use a correct one?
With an incorrect cable impedance, you get a superposition of the desired signal and attenuated copies delayed by multiples of twice the delay of the cable. Given the nonzero rise time of the S/PDIF signal, that will shift the zero crossings. Hence, you get a jitter increase by intersymbol interference. It could very well be that you have something else somewhere that jitters even more, but it certainly won't help to add ISI.
I've made two attempts to explain why the characteristic impedance of the connectors doesn't matter much, there is not much point in trying a third time.
I'm not arguing against what you are saying. I just think your assumption that the SPDIF implementation of the cheap Philco meets the spec is not necessarily correct.
That also might be true for the cheap unbranded Toslink transmitter and/or its circuit that is in it. I think it was Peufeu that showed an SPDIF transmitter circuit that managed to mess up the supply voltage big time. I would not trust any of the more recent cheaply produced DVD players on quality/longevity. The step to "solid state" playback can be done as those finally start to mature with few of the drawbacks as mentioned in post #1.
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There were some threads with TDR measurements of SPDIF cables in diyhifi.org. Sadly they are probably gone forever.
I am not an expert in digital technologies, I was trained in the analog field, therefore I admit that many concepts expressed here are not easy for me to understand.
Anyway, I appreciate all input and information.
And I tell you that I found among the old junk a coaxial cable of 75 Ohms of characteristic impedance and RCA connectors at its ends.
The appearance of the connectors shows their age, without chrome plating and some surface rust, which I neatly removed with fine steel shavings, the kind used/used to clean kitchen appliances, not exactly Teflon pans or pots...
Since I consider myself an audiophile but not a regular consumer of "wonder gadgets" from the "snake oil" field, I decided to give it a try. One less job is one less job. It is the ideal length, eureka!
Once installed, switching the Oppo's input - with the remote control - between optical and coaxial, and being located in the optimal listening position, I tried to perceive any difference in the sound.
I could not identify any, to my ears, which are not a few years old but are highly trained in these matters.
I reiterate that the optical cable is generic, it came with an audio equipment, but now I have doubts if it was the Pioneer DVD or the Yamaha AVR receiver. I don't think it makes a difference, surely the interior is made of glass-like plastic.
Perhaps a pure glass one would make a difference against a coaxial cable of mediocre quality? I leave the question open, but for me, the conclusion is that in the audio frequency range (20 to 20 Khz) the two cables perfectly fulfill their function, and that the optical cable should be used if there is any type of electromagnetic interference when using the coax.
I am attaching photos, sorry for the accumulated dust, they are sectors of the furniture that I do not clean very often and only I am authorized to do so.
Anyway, I appreciate all input and information.
And I tell you that I found among the old junk a coaxial cable of 75 Ohms of characteristic impedance and RCA connectors at its ends.
The appearance of the connectors shows their age, without chrome plating and some surface rust, which I neatly removed with fine steel shavings, the kind used/used to clean kitchen appliances, not exactly Teflon pans or pots...
Since I consider myself an audiophile but not a regular consumer of "wonder gadgets" from the "snake oil" field, I decided to give it a try. One less job is one less job. It is the ideal length, eureka!
Once installed, switching the Oppo's input - with the remote control - between optical and coaxial, and being located in the optimal listening position, I tried to perceive any difference in the sound.
I could not identify any, to my ears, which are not a few years old but are highly trained in these matters.
I reiterate that the optical cable is generic, it came with an audio equipment, but now I have doubts if it was the Pioneer DVD or the Yamaha AVR receiver. I don't think it makes a difference, surely the interior is made of glass-like plastic.
Perhaps a pure glass one would make a difference against a coaxial cable of mediocre quality? I leave the question open, but for me, the conclusion is that in the audio frequency range (20 to 20 Khz) the two cables perfectly fulfill their function, and that the optical cable should be used if there is any type of electromagnetic interference when using the coax.
I am attaching photos, sorry for the accumulated dust, they are sectors of the furniture that I do not clean very often and only I am authorized to do so.
Attachments
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Thanks Jean Paul !
👍
I have tried to play music stored on a pen drive with the Oppo, it did not recognize any files at all, so I gave up using that entry. I guess you think I'm too lazy, but it's not like that, only when the digital world exceeds me, I accept it and look for a good vinyl !
😊
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If you can't hear a difference between coax and optical, don't worry, be happy 🙂
