Dummies Guide to Pi2AES! Throw away your PC or laptop.

Discussion in 'Digital: DACs, USB converters, decrapifiers' started by purr1n, Jan 29, 2020.

  1. atomicbob

    atomicbob dScope Yoda

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    Are you asking for spdif splitter or AES / EBU splitter.
    If AES, I use ETS PA830 regularly when sending AES to Two DACs simultaneously for DAC ABX listening.
    https://www.markertek.com/product/e...110-ohm-digital-audio-splitter-xlrf-to-2-xlrm

    ETS also makes a 75R version, which I haven't tried:
    https://www.markertek.com/product/e...hm-digital-audio-splitter-with-bnc-connectors
     
  2. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    an SPDIF splitter or switcher would be awesome if it didn’t have negative SQ effects.

    seems like a switcher would be best so it’s not splitting the signal.
     
  3. atomicbob

    atomicbob dScope Yoda

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    ETS PA820 (75R BNC version) is on backorder at Markertek. I'm in the queue, they estimate about ten days plus shipping.

    Meanwhile I measured Inferred Jitter for the PA830, comparing with loopback from dScope AES output.
    Loopback: one 2 foot and one 3 foot Canare DA202 connected in series from dScope AES output to AES input
    20201130 Inferred Jitter FFT - AES loopback 2ft+3ft Canare DA302 44KHz.png

    PA830: inserted between 2 foot and 3 foot Canare DA202 as described in loopback above:
    20201130 Inferred Jitter FFT - AES loopback 2ft + PA830 + 3ft Canare DA302 44KHz.png
    I don't see any difference between the two measurements down to -200 dBFS.

    A microscopic view of one bit transition in the time domain on the oscilloscope for spdif input and output from a transformer.
    Blue: input to transformer
    Red: output from the transformer
    20201130 spdif 44KHz XFMR input blu - output red t2.png
    Data rates for 44 KHz in spdif is 2.8 MHz. Transformer used in splitter has a passband of 10 KHz to 50 MHz. If anything, the rise and fall times appear sharper out of the transformer. I'm using an AES transformer designed for 110R impedance which isn't the best match but I didn't want to wait two weeks to have a quick look at this.

    I prefer to use AES due to balanced operation and 10Vpp as opposed to spdif unbalanced and 0.6Vpp. AES has higher immunity to EMI, RFI etc and can use longer cable lengths before attenuation becomes an issue.
     
  4. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Just a quick note of clarification, AES balanced output standard calls for is 2 to 7V p-p, nominal 4V. On the PI2AES we drive ~3.4V p-p.

    For unbalanced AES via BNC, we drive 1V, and for unbalanced spdif via RCA we drive 0.6V
     
  5. atomicbob

    atomicbob dScope Yoda

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    Yes current standard is 2 to 7 Vpp. However I was remembering AES3-1985 which was:

    The AES3-1985 specification for line driver signal amplitude was 10 V peak to peak
    maximum.

    And I still have working equipment in my lab from that era.
     
  6. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    So if I need 2 SPDIF outputs to 2 DACs I could use the SPDIF output on the pi2aes and then use a 75ohm adapter from the BNC output to get a second SPDIF out. These 75ohm adapters were recommended by @atomicbob

    Note: the adapters on amazon don’t mention if they are 75 ohms or what they are. Likely 50ohms.

    https://www.markertek.com/product/b-pf/b-pf-rca-female-to-75-ohm-bnc-male-adapter-bnc-rca

    If I need 3 SPDIF outs, assuming the BNC splitter you ordered measures well, I could use that with 2 of the above adapters and the SPDIF output on the pi2aes. Giving me 3 total.

    I just thought I’d post this so everyone knows the correct way to do it. (Assuming I’m correct)
     
  7. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    How does the Pi2AES respond to a dedicated power supply? Anyone tried it? Or @atomicbob ’s noise nuke?
     
  8. rlow

    rlow A happy woofer

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    Lots have tried (and this is mentioned in the other Pi2AES threads) and most agree the difference/improvement is minimal unless you want to power both sides with a good LPS (and even then, it may be more “different” than “better”).

    Some impressions of mine are embedded in here:
    https://www.superbestaudiofriends.o...sports-shootout-with-unison-usb-and-aes.8810/
     
  9. rlow

    rlow A happy woofer

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  10. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    Thanks. Too much written about the Pi2AES to find something specific like that.

    Atimicbob’s noise nuke isn’t too expensive if it would work with the Pi2AES.
     
  11. dllmsch

    dllmsch Friend

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    I did the same research looking for power supply upgrade and remember most member prefer a single one instead of powering them separately. Perhaps due to Pi2AES and Pi are not electrically separated anyway?
    Ended up with a 5V LPS bypassing the onboard switcher which I believe @Clemmaster and @hifiandrun also did. Marginal improvement but will have risk of frying the board and voiding warranty!
     
  12. bilboda

    bilboda Florida boomer

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    I use a noise nuke with the pi2aes. I have not a/b'd it but it would otherwise go unused, so why not? I suppose I could make another one and power the pi separately but I dunno, I am happy with what I got.
     
  13. gaspasser

    gaspasser Flatulence Maestro

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    My Pi2AES suddenly developed garbled sound out of the SPDIF Coax and the AES BNC outputs. I’ve spent the last two days sorting this out and I can get a clean signal from the USB out of the RPi so I’ve eliminated software and network issues. The Pi2AES was not dropped and I even took the whole thing apart and reassembled it. Everything seemed unchanged and undamaged. Is there anything I’m missing and is there anyway I can fix this @Michael Kelly ?
     
  14. YMO

    YMO Chief Fun Officer

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    Did you try a different OS?
     
  15. gaspasser

    gaspasser Flatulence Maestro

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    I only use Ropieee regular and XL. I reflashed and updated multiple times. Tried Ethernet and WiFi. Everything works fine out of USB on RPi as I said. The problem is when it outputs through Pi2AES.
     
  16. YMO

    YMO Chief Fun Officer

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    I recommend trying a different OS to see if it is an issue with Ropieee breaking something with their new update. I would recommend trying out Volumio and turn on Roon Bridge from the plug ins/add on menu within Volumio and see if it plays nicely with the PI HAT (PI2AES).

    Note: I use moOde but you have to install Roon Bridge via Linux Terminal to get it running. Due to this, lets do the Volumio route first.
     
  17. atomicbob

    atomicbob dScope Yoda

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    Dante does this at boot time on some of my win7 pcs. The solution here is to wait until the OS is finished with boot up procedure, then stop the digital stream service, wait a moment and then restart the digital stream service. The stream data appears to be misaligned in synchronization to the digital buffer by several bits.
     
  18. StageOne

    StageOne Friend

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    Do you have the HAT set to Pi2AES? if so, maybe try changing it to Digi Allo One. That was the default before the Pi2AES profile was added recently.
     
  19. gaspasser

    gaspasser Flatulence Maestro

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    I tried changing HAT setting from Pi2AES to Hifi Digiberry + Pro (I see that it is Allo DigiOne on Volumio) and no difference. I also tried @atomicbob suggestion and no change :(
    I will try Volumio next and report back
     
    Last edited: Dec 12, 2020
  20. YMO

    YMO Chief Fun Officer

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    If Volumio is causing any issues we can try moOde last if you want. It's a little weird getting Roon Bridge to install on that one, but I can get that part running for you in less than ten minutes via Zoom if we need to.

    I know the pain when you are locked out from your tunes.
     

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