Spdif terminations>True 75Ohm, Hey Jocko!

  1. music_man
    Well I am sure many will be interested but I am interested in what Jocko thinks, among others.

    I found something out by "accident" today.
    First everyone should know you can have a $10 or $25,000 Spdif coaxial cable terminated in RCA and it is not 75Ohm. That is old news. It may or may not be hampering your sound. Most likely it is. Some DAC's do not care if you use a coat hanger however, but few.

    So Many will use a BNC if they have it, most don't. Then ala Nordost 2018 you can lock a cheap RCA adapter into a BNC terminated cable. I found that this is much lower than 75Ohms. Closer to 50. Not good.

    So what I discovered is that if you terminate the cable 'only' with a Delrin Butt compression "F" connector. Absolutely not crimp or metal Butt compression. That will make the impedance vary in either direction almost always. So, once the "F" connector is on screw in a cheap F>RCA adapter. Tighten it with pliers and no complaints why BNC is better then. Do not overtighten and crush it. Now you have a cable which must be true coaxial to be 75Ohm with the "F" connecter on it and a RCA screwed into that. I recommend Silver over Copper if you can source it. It was easier to find long ago. Or just gold is fine. Now measure this end to end with the RCA at both ends. Use a MM and sweeping scope. Guess what? Now the RCA's, The whole cable is 75Ohm! I tried several to make sure. Maybe not exactly 75 but nothing is repeatedly. Especially once you have applied it. I mean like to a decimal point, at the most 2 Ohms up/down. So you now have a true 75Ohm coaxial cable terminated in RCA.

    Granted as I said some DAC's do not care. If people are using things like Jplay, Fidelizer, Audiophile optimizer then I will say having a 75Ohm cable is going to make at least as much difference for you. Or anyone, it is just a good idea which is why high end equipment has AES3 and BNC. The proper impedance is important but no RCA cable matches it. Skip the $25,000 Nordost Odin 2 I have right here and use the cable I just mentioned with Belden RG6B/U Quad shield. You, like myself may find it sounds better than the Nordost costing 25 grand or any other RCA cable. The Nordost is RCA into a BNC, not close to 75Ohm. The "F" connector somehow allows the RCA to maintain very close to 75Ohms. If not spot on. Even if you do not think you hear it for the standard by Sony/Phillips this is of importance. I have used it on an MSB Select with Burmester 69. On the other end of the spectrum I used a $150 Samsung DVD player and Oppo DAC. So I checked it out both ways. I heard it, you may not but it is still of importance. Albeit less on the MSB obviously as it deals with jitter better. Make sure the cable is 6 feet long and you are good to go. Now I am saying, skip any cheap or expensive factory terminated coax cables that end in an RCA. Unless they are terminated with a Delrin Butt compression F connector and RCA screws on. No factory cables do Afaik.

    You can actually get the cable at Walmart(Black Web), I do not know if they have the RCA's. The cable is less than $7 and online two F>RCA are less than $2. $10 cable I personally feel is beating all comers including the Odin 2.

    Unless I am in the dark and this is well known please excuse my stupidity then. I am thinking not only did I just realize this but it is not well known if at all. I could just be a complete idiot if this is common knowledge in which case my apologies.
     
    tansand likes this.
  2. tansand
    I appreciate this, thank you! Do you have a picture or a link to the delrin butt connector?
     
  3. music_man
    Thank you. I am glad for once someone found something I did useful. I do not have a pic but it is on the cable at Walmart from the brand "Black Web". Just search "rg6" at Walmart. They have from 6'(What you want) to 100' if you were installing sat/cable or something. Odd it is at Walmart, cheap of course and just happens to be the highest quality available. The cable they use is Belden which is the best and it is Quad shield which is the best. some people say Quad compresses the sound but I feel it provides emi/rfi interference protection by other cables which is a big deal with spdif. I swear it sounds slightly better than the cable that costs as much as a nice car. Just so you can see the connector, than you know what you are looking for. See at the bottom of the connector it is plastic,black color? That is Delrin. The ones with metal at the bottom, the part that pushes in with the tool are not good for this. You might as well buy at Walmart for less than $7 because the tool is at least $40 online. Plus the connectors are $5+ each. The cable is $1.40 a foot. So that is a very good deal there. If you are in a country that does not have Walmart I guess just look online.

    BTW, I did not pay for that cable. Being in the Audio industry they send me stuff for evaluation and I have to send it back. I do have high end stuff but that is overboard imo. My best sddif cable is like $800. I use AES3 and for that also odd Mogami is the best cable I have heard like $25. It is also one guy at TAS reference cable too.
     
    tansand likes this.
  4. tansand
    Definitely on my to do list, thank you very much, I have been annoyed by this problem for ages! :)
     
  5. music_man
    Make it easy just go to Wallyworld lol. I am not sure why it bothered you. To me it was no matter the price of the cable it was 50Ohms causes most jitter. I just stumbled upon this. It is weird because the Fconnect RCA is over 60Ohm where any other RCA is 50-ish. Put it on the true 75 Ohm cable and it goes up just enough! Freaking amazing. 45 years I don't know this! Beware though, the RCAP's are not, must have the F connector to pull this off.
     
    tansand likes this.
  6. tansand
    It was Jocko! The idea that my dac came with this optical thing I did not want, but then gave me an RCA connection which would never be proper instead of a BNC connection just bugged me! :)
     
    Last edited: Apr 16, 2018
  7. music_man
    LOL. I hope he shows up and comments on this. Come on I am going to take a $10 cable that sounds better than one the price of a new sedan. A lot of these cables are not even coaxial. However the Nordosts all are. they are nice but maybe one for like $500 or something.
     
    tansand likes this.
  8. tansand
    Well this helps a lot, I have these beautiful Trompeter jacks but I never got around to modding anything..Thanks again, I hope he sees it too, and other people here get the idea. Cheers, man!
     
  9. music_man
    I know you are done talking here that is okay. I just wanted to add that the Walmart one is a Chinese cable, "Fousine". It actually specs better in every category than belden 1694A. It is 100% Quad shield foamed FEP dielectric, Solid 99.999 copper center conducter, Mylar tape with 2 Copper braids(better than aluminum). The jacket is fire resistant PE. The loss,impedance,capacitance etc. at just 6' are very good. In fact better than the Odin 2 lol. The Odin 2 also uses foamed FEP, as does Audioquest since PTFE is very rare now. I compared the specs to a top quality US made Veratex cable and they are also considerably better. Unfortunately I disposed of the PDF and it is very difficult to find. I just spent 15 minutes looking again to no avail. However you can search on the "GE pro) version as it is the same exact thing. As much as I love rebranding of Chinese products this is actually top notch. It will at the least beat any $1,500 cable I am sure. Since what is special about it and the most important thing is you are getting true 75Ohm. Straying from that too much is the downfall of Spdif. RCA for sure is going to spoil the party. Even the RCA on the DAC but no worries because good DAC's can deal with internal jitter. Meaning the fault of the DAC itself due to having an RCA. I have seen some 20 grand DACS with RCA,Toslink and AES3 but no BNC. BNC is actually better than AES3 but most DAC's are lacking it.

    You can not just solder on the Trompeter. Things will be worse then. You have to rework the entire PCB traces. Unless $$$ DAC not even worth bothering.

    Anyways how this sounds to anyone is subjective but it is bit perfect. Which you cannot achieve with an ordinary implementation of an RCA cable. For $10 this setup is incredibly good. I have much more expensive cables here but I was shocked by this. AS it was an accidental discovery to begin with. I just picked it up and decided to measure for no reason. To my amazement it is exceptionally close to 75Ohm. The most important thing. Any cable differs +/-3Ohm. it is well within that. I was dumbfounded. Again, it is subjective but that alone is going to go a long way towards the right sound. If you want to color it, look for something else. I do not tune systems with cables anyways. However there was a noticeable difference to almost anything else I have tried thus far.
     
    tansand likes this.
  10. music_man
    This is why you do not use Toslink. AES3 is even lower. These are all less than $25 cables. I measured the cable we are discussing here at a stereo crosstalk of -99.2 db. Lower than the Odin 2. Granted what we hear is not specifications, but you want leakage? Yes, that may be inaudible. Nonetheless, but I stick with science. I understand my other buddy here does not want to use optical either.

    These charts are courtesy of Archimago.

    Spdif RCA Coax
    Summary spdif.png

    Toslink. Glass has best but barely.
    Summary toslink.png
    Under -60 db is nitpicking but as I just said I prefer science. You may hate this cable and love/hate any other. This is pretty much the most highly subjective side of audio. For $10 I would suggest to try this before any more expensive cables. Heck, you may even prefer Toslink.
     
  11. tansand
    Just temporarily. :) Now that I think back on it, the plan with the Trompeters was to get some transformers etc to terminate the line, this was a long time ago..I guess I should ask, is a 75ohm cable all thats needed? I seem to remember Jocko saying the RCA jacks were a 'problem' too.
     
    Last edited: Apr 17, 2018
  12. music_man
    The problem is RCA is not 75Ohm usually but this worked. If you terminate a 75Ohm cable in RCA it is not 75Ohm. However this Walmart cable is copper clad steel which is not good. I would get some RG6 with FEP dielectric and solid copper center core. Any Hardware store has it. Probably not QS but DS 100% is fine. Best is DS with copper braid. The cable is 75Ohm which is important only if all components of it are. Here odd enough it works.

    Don't bother switching out to BNC unless your DAC is over 10 grand. Otherwise it is just not worth your time for the gain you will notice.

    Some people argue with Jocko but he is correct and guess what? An Engineer like myself. We tend to eschew bs and go for science.
    Hey, bs works too. Sort of lol.
     
  13. music_man
    I wanted to point out, this is where Spdif over 1.5 meters comes from. Doing stuff like this. It is indeed needed here. Get into very good seriously expensive cables and you can get from .5 meter to 5 meter and anything in between. Companies that make $75,000 cables would not offer .5-1M if it was not a good idea lol. That is part myth and part true. In this regard, what we are speaking of doing here it is most certainly true. The idea behind this was people that don't want to spend the price of a new Mercedes on their cable :)
     

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