Cable recommendation for long distance between PC and DAC

Discussion in 'DACs' started by cloneofkane, Jan 2, 2018.

  1. gvl

    gvl Well-Known Member

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    882
    Digital audio has no error correction, only detection. I believe for the stated purpose it makes little difference whether to run digital or analog. For digital I'd say optical is a safer bet than USB for long runs.
     
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  2. willyrover

    willyrover Super Member

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    I use one of these 25ft active USB cables with no problems.


    MacMini/Server in the closet, through floor, across basement, back up through floor near the stereo, and into a DacMagic 100 via a regular 3ft USB cable.

    581824F9-180C-4437-A3B0-7BA800164F5C.jpeg
     
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  3. E-Stat

    E-Stat Super Member

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    The only bummer is inherently higher levels of jitter due to band limiting. Neither of my current renderers support Toslink.
     
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  4. cloneofkane

    cloneofkane AK Subscriber Subscriber

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    I pulled the trigger on short USB/long RCA, but will keep this solution in my back pocket -- thank you!
     
  5. gvl

    gvl Well-Known Member

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    882
    Unclear which DacMagic it is, but the original DacMagic has a ASRC, so jitter should not be an issue.
     
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  6. nyhifihead

    nyhifihead Well-Known Member

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    Location:
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    Those USB active repeaters are not great, they still still have loss and dropouts at that distance.

    rca (analog) should be kept as short as possible. extending the range while still in digital domain is optimal

    a great solution would be to use a USB over cat5. cat5 patch cables are cheap and your good for over 200ft.

    TCP/IP gives you perfect packets & galvanic isolation from PC.

    startech & icron make enterprise grade converters that people love for audio, they are ultra low noise. PS Audio even makes something called lanrover that's a similar solution, expensive though

    ultimately I think this is your best bet. cheap ebough and you may find an increase in fidelity. I found a darker background with my icron USB over cat5.

    https://www.ebay.com/itm/Active-4-P...o-50M-with-power-supply/272736023759?NAV=HOME
     
    Last edited: Jan 3, 2018
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  7. whoaru99

    whoaru99 Epic Member

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    Looks like water under the bridge at this point.

    I presumed since you linked in an optical cable that was the type of S/PDIF output you had. If the S/PDIF output and input connections are not optical/Toslink then an optical/Toslink cable won't work.

    Just FWIW, S/PDIF actually refers to the protocol and specifications. For consumer goods, the interconnection type for S/PDIF is normally either electrical/coaxial or optical/Toslink, sometimes both are present.

    If you actually have the phono-type (RCA) coaxial connectors I'd probably have used that. A component video cable (or any 75-ohm type coax with phono/RCA connectors/adapters) generally works well.
     
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  8. botrytis

    botrytis Trying not to be a Small Speaker Hoarder Subscriber

    Based on other forums I have read TOSLINK has inherently MORE jitter than USB. Also higher noise floor. In general it is worse to use TOSLINK than USB (it is a way older system and has not been updated at all - unlike USB).
     
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  9. rwartner

    rwartner Super Member

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    [I'm curious, why would you think its better to run a long analog cable which is susceptible to all kinds of interference and degradation which never get corrected instead of a long digital run which isn't susceptible to interference, has error correction, is simply moving data, and can't color the sound in transmission until it gets converted to analog?]

    I thought about that later, I have no technical basis. Just thought it would be better. And the RCA cable already there. All you are doing is replacing computer DAC with external one. So the hookup is known to work.

    I don't like either solution. To me it depends on the investment. How much do you want to spend - how important is it?
     
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  10. northpaw

    northpaw Active Member

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    As to the long analog cable runs, I have no expertise but I do have experience using some (as is mentioned by others here too). If a quality double-shielded cable is used, such as for component video or a digital-grade cable, the shielding is great and the capacitance of the cable is low. The cables linked in post #18 should be perfectly fine. I use 12-foot shielded cables to connect a preamp to an amp (so I can keep the speaker cables short), with no deterioration in sound that I can detect. Botrytis appears to have the same experience (post #9). Moreover, the line-level output from the DAC will be even higher signal levels than the preamp outputs the Botrytis and I are using, rendering any noise that does get through to a lower S/N ratio.

    I also suspect (no engineer here) that any errors that don't get corrected properly in the digital domain have the possibility of causing big affects on decoding to analog, depending where the error is (nearer the least significant bit (LSB), or nearer the most significant bit (MSB)). In contrast, noise in analog circuits, if the S/N is high, is quite low.
     
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  11. cloneofkane

    cloneofkane AK Subscriber Subscriber

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    Location:
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    I've got the original Cambridge Audio DacMagic (2009) and think I've got it set up correctly, but I'm not getting any sound. I found the manual online and followed the set up instructions pretty closely.

    1) I connected the RCA cables and ran them to the open connectors on my receiver, Tape 2
    2) Before powering on the DAC, I connected the USB cable between the the DAC in and PC out.
    3) I powered on and saw that the sound card recognized the DAC as "C-Media USB Headphone Set", which is what the manual said it would name it. I then disabled the other sound outputs, as directed by the manual.
    4) I opened up YouTube and started Ted Nugent - Stranglehold... well, because.
    5) I set the Selector on the front to USB and the incoming sample rate is illuminated at 48. (see picture)
    6) After getting no sound, I swapped input connectors from DAC into Tape 2, cassette player into Tape 1 (worked fine) to DAC into Tape 1, cassette player into Tape 2 (again worked fine). So I think I have disqualified anything wrong with the receiver.

    I know the PC is playing because when I open the sound window and C-Media USB Headphone Set is has a moving meter showing music playing (see picture). I was also able to change the output from 48000 Hz to 44100 Hz and back in the sound settings, and the DAC showed the level move from 48 to 44 and back.

    Anything obvious that I've done incorrectly? Or is something wrong with the DAC? Should I try using DeOxit with swab to clean the DAC RCA connectors?

    Thanks in advance for any thoughts/advice.
     

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    Last edited: Jan 3, 2018
  12. gvl

    gvl Well-Known Member

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    882
    Sounds like it. Do you know its history? Also, did you check if by some chance volume is muted on the PC? I've just tried and the green level meter is moving while the volume is muted.
     
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  13. cloneofkane

    cloneofkane AK Subscriber Subscriber

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    I don't know any history -- my brother received it as part of a trade and didn't need it, so he shipped it off to me without setting up himself. I did check the muting and it was not muted.

    I forgot to mention one other thing:

    I did download the latest driver update 4.12 to add compatibility with Windows 10 which I am using. I have the CA Control Panel that I can open from my notification bar, but when I open, it shows "no devices connected". I am going to dig a little more into this to see why it won't recognize the DAC.
     
  14. northpaw

    northpaw Active Member

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    Location:
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    To check the functionality of the DAC, can you hook up a reliable digital source to one of the non-USB inputs? Either optical or coax from a CDP, or if lacking other digital sources, the optical or coax outputs from the back of a HDTV.

    If they work, then the problem is either in the PC or the USB part of the DAC, or in PC set up issues, and you won't be spinning your wheels on the latter, without a better narrowing down if the problem likely lies there.
     
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  15. cloneofkane

    cloneofkane AK Subscriber Subscriber

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    Location:
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    I don't have a CD player, and the 25 ft RCA cables won't reach the nearest HDTV in my house. In a pinch I could bring in my garage receiver and speakers (more portable) and set up.

    I did find a Dynex digital optical cable and hooked up from the S/PDIF output to the DAC, and got the same results: the DAC showed an incoming sample rate of 48 and, when playing a YouTube video, could see that the RealTek HD Audio Manager was playing music. Feeling my way through this, but wouldn't this indicate that it's not an issue with the USB part of the DAC, but maybe the sound card/RCA connectors?
     
  16. cloneofkane

    cloneofkane AK Subscriber Subscriber

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    I can also bring in the garage receiver and speakers and use different RCA cables to eliminate the possibility that there might be something wrong with the new cables I purchased yesterday (or that they might be too long?).
     
  17. whoaru99

    whoaru99 Epic Member

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    I can say with 100% certainty the length itself is NOT why you have no sound.
     

     

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  18. botrytis

    botrytis Trying not to be a Small Speaker Hoarder Subscriber

    I would say it is your internal soundcard having issues. Can you listen to it with headphones to make sure it is working?

    I agree with whoaru99....
     
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  19. whoaru99

    whoaru99 Epic Member

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    You could also test the cables by temporarily using them in place of those between the tape deck and receiver, without hauling in all that other stuff.
     
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  20. whoaru99

    whoaru99 Epic Member

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    And, if round about you do end up connecting to the TV digital output, you must ensure the digital output of the TV is set to send PCM, not Bitstream. Your stereo DAC will not work with a Bitstream output from the TV. That could give a misleading assessment/diagnosis.
     
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