Any SPDIF coax source switch boxes available ?

Discussion in 'Digital Sources' started by BigElCat, Jan 11, 2018.

  1. BigElCat

    BigElCat AK Subscriber Subscriber

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    My DAC has only one SPDIF coax input.

    I need 4 inputs. I tried a little A/V switch box, using the RCA video input and output.

    I worked but my sound quality was slightly compromised. It may be the cable I used coming out of the box. I used an Audioquest Forest cable. The other cable in the daisy chain was a Belkin Pure AV.

    I've ordered 3 more Belkin AV 8' cables, because I like the sound I get from it.

    Psyclone made a component sized, remote switch box, I may get one of those to try.

    Any other options out there, that people have tried (and liked) ?
     
  2. mhardy6647

    mhardy6647 AK Subscriber Subscriber

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    Maybe naive on my part, but wouldn't any old-school 75 ohm video/RF cable switch box (they were legion in the analog video days) work? They'd likely have F connectors rather than BNCs or RCA jacks, but adaptors could be easily fabricated.

    I reckon they can be found cheap or free in 2018.

    I know there're some here, but probably all "A-B" (two position) switches, not more.
     
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  3. BigElCat

    BigElCat AK Subscriber Subscriber

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  4. geespot

    geespot PUT it IN MY POCKET

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    Audio Authority 1177A
     
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  5. gvl

    gvl Well-Known Member

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    I would be surprised if you needed anything more than just a quality impedance-matched mechanical switch for Coax. Optical is a different story. If using an F or BNC connector on the switch side probably best to use a RCA<->F or RCA<->BNC cable, instead of just using an adapter.
     
    Last edited: Jan 16, 2018 at 2:47 PM
  6. Bill Ferris

    Bill Ferris Well-Known Member

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    The Inday DA4X-R has been in use in my main living room`s system for around 5 years now and seems to work quite well.
    I have a OPPO UDP-203/BDP-103, Mac CD player, and Mac Laser disc player S/PDIF coax outputs switchable to my Grace Audio M920 DAC if I chose to select them now
    And it was bought from Markertek.

    I haven`t used the optical switching function though, so can`t provide any info on that performance..

    I was originally using a A/B /C mechanical "high isolation" 75 ohm coax switch with RCA to F 59 adaptors, but became concerned with the unselected inputs shorting the S/PDIF feed`s to them and what that might do to the sending device`s internal S/PDIF active devices 75 ohm driver over time..

    So I bought the Inday, and no more concerns, and the little remote control is quite handy.
     
  7. gvl

    gvl Well-Known Member

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    It would be interesting to know how jittery these selectors are as jitter numbers aren't in the specs, I guess we'll never find out.
     
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  8. Bill Ferris

    Bill Ferris Well-Known Member

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    Interesting point, but I really don`t think it`s an issue, as there is just routing of the signal going on via mechanical/reed relay switching or active (high frequency rated) FET devices being utilized, but really can`t be sure in my case, since I never opened my Inday DA4X-R up or ran 1~10 mhz. square wave, ect. tests of it on my bench..

    If I were to build one I would consider using electro magnetic reed relays since their physical layout is coax like and the low impedance actuating coil has some shielding assistance, plus with reasonable physical spacing of the selected sections during layout and construction would/should mitigate any signal cross talk/bleed over concerns, or just purchase purposely designed/constructed more expensive 75 ohm HF RF miniature coax relays from Mouser or Digi Key..

    I utilized those little 12 v DC STDP reed relays in a audio line level switching box that I built in 2000 to switch between two preamps(SS & tube & two power amps(SS & tube to a line level in/outputs Velodyn powered subwoofer and it`s been doing it`s thing quite well since..
    I don`t thinks/PDIF digital signal jitter should or would be a concern with simple signal switching/routing IMHO/E, but I could be wrong..
     
  9. gvl

    gvl Well-Known Member

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    Given they convert between optical/coax I suspect they aren't just mechanical relay switches. Also inexpensive SPDIF receivers/transmitters which are likely used in a device like that are known to have high intrinsic jitter. So who knows. If I were after the best quality and my DAC wasn't designed to reject jitter I'd probably slap an iFi SPDIF iPurifier downstream of such a switch just for a peace of mind, but it would add to the cost.
     
  10. Bill Ferris

    Bill Ferris Well-Known Member

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    Well gvl, my Inday switcher does convert/translate between the types, as it has 4 separate optical in`s & a separate optical out & 4 separate coax in`s & a separate coax out and I stay within the same signal type throughput.

    It would appear that they just switch both types at the same time with the user deciding on which type they prefer to use and if the user decides to convert/translate between the two types, well then that`s their throw of the dice as to how well/clean that inexpensive switcher/convertor/translator handles/corrupts the signal and I would think that if you stayed signal specific that there probably wouldn`t be much of a problem.
    And I suspect my Grace Audio M 920 DAC takes care of any jitter that might be present.
     
  11. gvl

    gvl Well-Known Member

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    Sure, they claim their s-Lock PLL system eats jitter for breakfast. For those with more plebeian DACs it can be more of an issue.
     
  12. Bill Ferris

    Bill Ferris Well-Known Member

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    Fair enough, I can`t speak for other`s choices in this highly charged subjective world of audio SQ, whether digital or analog, gvl..
    And if their "plebeian" DAC`s can`t handle wayward bits, then they can seek to get a better S/PDIF switch or DAC, if their ears have the resolution to chase it, or live within their means/perception and accept/tolerate "the dream" until they can, life`s priorities be damned, if/as they see fit..
     
  13. gvl

    gvl Well-Known Member

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    No argument. I was just trying to make a point that depending on the downstream DA converter a mechanical switch has some advantages apart from cost over a budget electronic equivalent that's not spec'd for low-jitter operation. I, however, would too be concerned about shorted SPDIF signal pins.
     
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  14. Bill Ferris

    Bill Ferris Well-Known Member

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    798
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    Yeah, I agree and valid point taken, I think for one of the inexpensive ways, would be to use the same DPST reed relays that I used for my subwoofer transfer box for each input, so that until energized would default switch to a 75 ohm load termination resistor, and should possibly help with any chance of undesirable signal egress/ingress, crosstalk, if that would/could be a concern or issue, after all the switched signal is digital, rich in harmonics and is operating at RF frequencies..

    It could work, and if the switch box was carefully laid out and constructed it should be a pretty pure signal relay type switching setup for coax S/PDIF while closely maintaining the coaxial 75 ohm relationship with a well filtered 12 volt external 500 ma. DC PS wired to a rotary switch selecting each reed switch in turn with selected input front panel LED indication, if desired.

    I might just build one in the future, but I do like the Inday`s remote control feature though.

    Now going to the optical switching route, is better left to trained people/company`s with that experience.
    That area of my experience is way above my pay grade, I also might think true "quality" commercial products would most likely be pricey.
     
  15. BigElCat

    BigElCat AK Subscriber Subscriber

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    I ordered a DA4X-R.

    I'm thinking about an iPurifier. I have an iFi iPower already. It powers my Paul Pang V2 card in my PC, as well as, my Singxer F-1.

    My DAC is a MusicHall 25.3 with a high spec Mullard tube. I don't think I have a jitter issue, but a galvanic divorce might do me some good.
     
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  16. Bill Ferris

    Bill Ferris Well-Known Member

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    Location:
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    Possibly BigEICat, In my setup using my DA4X-R all coax S/PDIF equipment feeding it are single point AC power/ground referenced(common ground) so I have no galvanic issues or concerns.
    Even my OPPO BDP-103 S/PDIF coax outputting which resides in my Sunroom 20 feet away, as I ran a Sine wave UPS feed to it from the living room`s master A/V rack for the ground loop avoidance and also when the power blipped, the 24/7 running OPPO would keep playing without having to reinitiate it for playing the Flash drive that it`s been relegated to do.

    I never checked for common ground between shells of the 4 RCA inputs + the output of the DA4X-R, and it being a wall wart( probably switching)power fed device, there wasn`t concerns for it directly causing any galvanic activity or issues of that nature as the connected gear if 3 prong AC powered would provide any ground reference, unless all the source equipment has ground isolated S/PDIF coax jacks, something`s most likely going to end up providing a reference ground !?!?

    I guess you`ll just have to find out in your setup, and whether that will be an issue..

    Let the folks here know your experience with it after you get settled in..

    Good luck Sir.
    Kind regards, OKB
     
  17. gvl

    gvl Well-Known Member

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    The SPDIF iPurifier comes with its own 5V iPower. MusicHall 25.3 has a defeatable upsampling rate converter that reclocks the signal and removes jitter, if any. If, however, you prefer to keep the SRC disabled the iPurifier can help to reduce jitter.
     

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