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

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

  1. kris2014

    kris2014 Acquaintance

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    Hi Michael,

    Thanks for the reply. I bought that board to see if I can use Pi2AES via USB :) That's just a USB to I2S converter board and GPIO pin compatible with Pi HATs.

    It's not like I don't like Pi. USB is just more versatile.
     
    Last edited: Feb 20, 2020
  2. Pescatore

    Pescatore New

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    I've got a Pi2AES inbound and looking forward to playing with it. I'm a little confused about the outputs though, and I'm probably about to learn something.

    My understanding is that the output of the BNC connector on the Pi2AES is AES, and the RCA connector outputs S/PDIF. But I've seen mention in this thread of using an RCA adapter on the BNC connector because some RCA connectors don't make good contact. Are AES and S/PDIF compatible standards? I've read that RCA coax has about 50 ohms impedance vs BNC at 75 ohms. Does this create problems connecting the BNC output to an RCA input? I've read elsewhere that a BNC to BNC cable connected to a BNC female to RCA male adapter will maintain it's 75 ohm impedance, but is this combination a mismatch with the RCA S/PDIF connector on a DAC?

    My use case will be (for now) Pi2AES RCA or BNC output to a Modi MB S/PDIF RCA input. I'm wondering if there are sonic advantages to the BNC to BNC cable with the adapter vs just going with RCA to RCA coax.

    Or have I entered the world of cable nervosa...
     
  3. fastfwd

    fastfwd Friend

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    Both SPDIF and unbalanced AES specify 75-ohm cable assemblies. FWIW, the BNC-RCA adapter linked earlier is a 50-ohm BNC (at least visually; for $3, who knows whether it's actually built to that standard).

    Don't freak out. In your application, cable impedance will not affect what you hear.
     
  4. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    The best advice I can give is to buy a high-quality cable, RCA to RCA without adapters. It does need to be expensive. Look for a video cable that is specified to be 75 ohm. Something like this will work very well:

    https://smile.amazon.com/Cmple-1-RCA-Composite-Subwoofer-Digital/dp/B003UW91BE/ref=mp_s_a_1_6?keywords=rca+video+cable+75&qid=1582332517&sr=8-6&th=1&psc=1

    Michael

    ps - you always want to use a direct cable from the PI2AES to your DAC without adapters if you can. That’s why we have all the different outputs!
     
  5. FlySweep

    FlySweep Friend

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    Was it the one I linked on the prev page? Product description states it transfers at 75 ohms. Here's another one I found.
     
  6. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Oops - does NOT need to be expensive!!!
     
  7. Pescatore

    Pescatore New

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    I've already got a high bucks RCA cable I can reuse :)

    Thanks all for the responses!
     
  8. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Ideally you still want it to be 75 ohm. But in reality, the link is pretty forgiving of impedance mismatch if the cable is just a few feet long or shorter.

    Michael
     
  9. joch

    joch Friend

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    I thought the AES/EBU standard is 110 ohm?
     
  10. fastfwd

    fastfwd Friend

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    Yeah, that's the one. The product description says "rated to smoothly transfer 75ohm signals", which sounds like the right thing but is basically nonsense:
    • Rated by whom?
    • What does 'smoothly' mean? It isn't a term of art in this context.
    • And there's no such thing as a '75 ohm signal'; that's like saying, "This faucet is rated to smoothly transfer 1/2-inch PVC water."
    What you want, ideally, is a connector that "presents a 75 ohm characteristic impedance". It's more-or-less physically impossible for an RCA to do that, but at least the BNC side can. Here's an adapter made by Canare, who have a reputation for making high-quality connectors, especially RCAs for digital audio: https://www.markertek.com/product/bcp-rcaj/canare-bcp-rcaj-bnc-male-plug-to-rca-female-jack-adapter. If you look closely at the 75 ohm BNC side of that adapter, you'll see the difference between it and a 50 ohm BNC.

    But @Michael Kelly is right: Although adapters might not actually hurt in an application like the one we're discussing (because the cable will only be a few feet long), they certainly won't help. So if you really need to connect a BNC female output to an RCA female input, the pedantically best option would be a 75 ohm cable terminated with a 75 ohm BNC on one end and a Canare "RCAP" RCA plug on the other. You can buy a very nice cable like that for around $20: https://www.bluejeanscable.com/store/digital-audio/index.htm
     
  11. fastfwd

    fastfwd Friend

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    That's balanced AES3, with XLR connectors. Unbalanced with BNCs is 75 ohms.
     
  12. joch

    joch Friend

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    Makes sense for the 75R BNC
     
  13. raif

    raif Man made lobster/plankton

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    Got my PI2AES setup using @purr1n ’s guide. This has to be one of the most fun little quasi diy audio projects I have done in recent memory. A huge thanks to Marv for putting together this guide and of course Michael Kelly for dropping advice all over the thread.

    Some noisy equipment / machinery stopped me from being able to do any decent listening so I will have to do my comparisons once I am back in the office on Monday.
     
  14. kris2014

    kris2014 Acquaintance

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    I sometimes got confused there. Coaxial cables are single core 75 ohm, while AES/EBU cable appranelty has 2 cores per cable. So I don't know how the impedance was determined for AES cables.

    For now I just stick with offerings from canare, which are available from a bunch of pro gear resellers Redco, etc.
     
  15. YMO

    YMO Chief Fun Officer

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    Thank you @Michael Kelly for dealing with my crazyness during my apartment move. Tell Greg thanks for putting up with me.

    So I got everything today and took me 30 minutes to built the thing and just five minutes to set up moOde Player as my OS.

    Heads up everyone, all future Cases that you order from PI2AES will have the updated printouts for their RJ45 adapter and also as a bonus, a bigger MicroSD card slot. This will be slightly different from the photos that @purr1n has on the first page.

    Long story short: If a dummy like me can put this thing together, anyone can. The OS flexibility is nuts. Within five minutes of using moOde I set up my Wi-Fi, make sure DSD to PCM > Bifrost 2 via coax is output max at 24/192, and everything running bit-perfect. Glad I took a leap of faith and order a set.

    When I move to my apartment next week I might use an Ethernet cable due to a lot of Wi-Fi connections in my new apartment complex.

    After using it for ten minutes, only one minor drop-out from playing DSD > PCM, but not even close to a big deal. I just think it's my Wi-Fi.

    Other than that, damn this sounds better than USB already to my Thinkpad. Bye bye USB for serious listening......? Order another one for a bedroom setup....?
     
  16. TheloniuSnoop

    TheloniuSnoop Friend

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    I got mine together, and the thing lights up, but in (trying to) setting it up, I discovered that I will have to subscribe to some sort of Volumnio plan to stream. This whole process seems over my head anyway, so I'll probably just sell it. Too bad. It really seems like a nice system.
     
  17. dasman66

    dasman66 Self proclaimed lazy ass - friend

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    MoOde will stream Tidal & Qobuz with no subscription. You do have install bubbleupnp on your android (not sure of equivalent for iOS). Select MoOde as the renderer in Bubble, then enter your Tidal/Qobuz user/password into Bubble. Then stream away.

    Bubble is here: https://play.google.com/store/apps/details?id=com.bubblesoft.android.bubbleupnp&hl=en_US
     
  18. raif

    raif Man made lobster/plankton

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    I am in the middle of the 15 day "free" period. I have been sticking to qobuz and this thing has been rock solid. Also, I have a laptop / external monitor setup and can't count the number of times prior that I opened my macbook up in a meeting to have some retrosynthwave blaring through the speakers because I just yanked the usb cord when leaving my office.

    PI2AES + Volumio has been a stress-free, always-on solution that, regardless of usb nervousa, has been well worth the price of entry for simplicity alone.
     
  19. neogeosnk

    neogeosnk Friend

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    It's $32 a year to stream tidal/qobuz using Volumio, but was running spotify for free. There's instructions on the interwebs how to do that.
     
  20. YMO

    YMO Chief Fun Officer

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    If you want to stream you can use Volumino as a UPnP/DNLA render and use your phone as the controller. Not hard, only took me 30 minutes from setting it up and to run Qobuz.
     

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