Raspberry Pi I2S to SPDIF Hat

Discussion in 'Digital: DACs, USB converters, decrapifiers' started by Michael Kelly, Apr 30, 2016.

  1. Raicorl

    Raicorl Rando

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    Not quite 100% sure but from my lazy experiment, powering only hat via my 19V LPS(got it dirt cheap locallly) yield the best result. Better than 5v Allo's switching + 19V LPS (big no no for me) / 5V alliexpress LPS + 19V LPS. I dont like 5V Allo + Meanwell supply either. Too lazy testing single Meanwell config.
     
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  2. NDonchev

    NDonchev Rando

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    Hi guys, I have the PI2AES for some time now and I'm very happy with it.

    The main thing I want to say is that it really makes a big difference depending on how the device is powered. It was suggested by a guy around here to try powering the unit with a lead acid battery. Although was very sceptical that it will make a difference I decided to get the cheapest battery I could get just to try.

    The lead acid battery is a definite improvement over the normal Meanwell power supply. The biggest improvement that is instantly noticed is that the sound is calmer, smoother, more natural and it just sounds more connected and flowing. On top of that I can say there is improvement all over the place - details, soundstage, imaging, timbre, cleanness.

    I see discussions are mostly about LPSs, but I haven't tried one, maybe it is also great. However, I would definitely encourage you to try a lead acid battery on the PI2AES. I guess it will cost you no more then 20 dollars or euro to get one for the experiment. If you need more info on that, let me know. Basically, you need a battery, a suitable a power supply for it and a small cable to connect the battery to the PI2AES. I measured the device's power consumption and it is an almost constant 510mA with RPi4 and a 2.5" HDD. This means that if you have a 4.5mAh battery it should work for about 6-8 hours in one charge.

    For me the change from Meanwell power supply to lead acid battery makes the PI2AES sound really, really good and it is easily audiable. Highly recommended.
     
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  3. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    In the midst of these discussions regarding powering, I would like to put some information out there that might impact your decisions. We are working on a couple of DAC add on boards to the PI2AES. These would plug on top and into the I2S header. The impact on powering, is that in order to generate the +12V/-12V analog supplies, we need a minimum of 14V input. This is why we have changed our standard switching supply from 12V to 24V.

    I apologize in advance if this screws up anybody’s plans! Obviously the board will continue to operate as is, and if you do not use these add on boards, then there is no impact.

    Regards,
    Michael
     
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  4. Clemmaster

    Clemmaster Friend

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    Can you please consider a cheap RJ-45 I2S add-on board, too? :D
     
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  5. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    I have given this some thought. But the question is, what pinout?

    Michael
     
  6. MisterRogers

    MisterRogers Ethernet Nervosa

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    I haven't checked the variance with pinouts, but are pinouts consistent with connector type (Ethernet, HDMI, etc.)? Metrum using Ethernet, are there others using same with different pinouts?

    Course, it's couldn't possibly be that simple.
     
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  7. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    I realize I should not overthink this. If you guys have a device with an I2S interface, tell me what it is. it is not a problem to make a couple of the these and keep them in stock. You folks have been my main inspiration, so if you need it, I'll do it!

    Cheers,
    Michael
     
  8. MisterRogers

    MisterRogers Ethernet Nervosa

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    That'd be awesome Michael! An Ethernet adaptor compatible with Metrum's I2S would work with all of their DAC's and streamers, plus it'll be compatible with Sonnet Audio's upcoming DAC's and streamers.
     
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  9. Clemmaster

    Clemmaster Friend

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    Here's Metrum's pinout:

    [​IMG]

    It'd be great if it were half heigth, so it wouldn't make the enclosure any taller :)

    And maybe a pass-through for the header's 5V and GND pins, for those who'd like to feed it 5V directly ;)
     
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  10. MisterRogers

    MisterRogers Ethernet Nervosa

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    Michael, with how well your HAT works serving up I2S, I would definitely think it'd be worth you supporting it better as a turnkey configuration. I have an Ambre that isn't getting much play right now because of how well your HAT's working serving I2S to my Pavane.
     
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  11. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    What does that mean to you? The PI plus the PI2AES in the case? What software to run, power supply included, etc.?

    I have another company (MJK Audio) that is going to be focusing strictly on audio. The genesis of Pi2 Design was from the embedded space where my previous company developed interfaces for various IoT applications. But when I shut the company down (after 23 years) I didn’t want to keep the staff needed to support the software that was necessary for that market. I still do a lot of custom designs for other companies but I leave all the Linux and junk to them!

    My preference at this point is to take everything I am learning with the pi and apply it to standalone products under the other company name. Selling individual boards is not a great moneymaker. But it is damn fun, and the interaction with you audiophools has been great! And I don’t lose money, so it will make sense for me to keep doing this even when we roll out more consumer oriented, less DIY products.

    Cheers,
    Michael
     
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  12. MisterRogers

    MisterRogers Ethernet Nervosa

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    Hmmm, well - honestly wasn't thinking THAT turnkey (Pi / PI2AES, power, etc.), but I suspect they're be a market for it; the same blokes who buy up Ambre, etc. I was mainly thinking, that if users could buy PI2AES as they do now and specify an option for an attached I2S port module (still DIY, but not solder-slinging, crimping, etc.), it'd be a fairly turnkey way to get solid I2S performance.
     
    Last edited: Nov 14, 2019
  13. Clemmaster

    Clemmaster Friend

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    Essentially a board with a female header to connect to the I2S header of the Pi2AES, a RJ-45 connector and 4 standoffs. Could maybe work with just 2 standoffs, too, so the board doesn't have much wasted space.

    Optional would be a header for clean 5V feed, or a DC jack.
     
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  14. msommers

    msommers High on Epipens

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    Adding a HAT to the current device that is plug n plug (like all HATs) that has the Ethernet port to connect to I2S input compatible with Metrum would be an instant buy for me.

    I just can't bring myself to get an Ambre at their new price when I know deep down the device isn't THAT complicated.
     
    Last edited: Nov 14, 2019
  15. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    I will put something together using the pinout from @Clemmaster and post it for your approval!

    Please note however, the way the PI2AES power circuitry is designed does not allow external 5V to be fed into it. Simply not possible.

    Cheers,
    Michael
     
  16. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    See below. Pinout is as per @Clemmaster. We will make a new back plate for the case to accommodate this. I figure we'll charge around $25 plus shipping for the board and plate.

    [​IMG]
     
  17. msommers

    msommers High on Epipens

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    Done and done. Wow!
     
  18. MisterRogers

    MisterRogers Ethernet Nervosa

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    I like it - nice and clean.
     
  19. msommers

    msommers High on Epipens

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    @Michael Kelly you mentioned earlier other HATs as well. More out of curiosity, are you able to expand on what those would be?
     
  20. lehmanhill

    lehmanhill Almost "Made"

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    Very nice. I'm the guy that likes to DIY everything, but I would have gone this way because its so nice and clean.

    On the subject of an MJK Audio version, its not me, obviously, but I'm guessing a lot will depend on the user interface software bundled with it and how friendly and reliable that software is for the non-DIY consumer.

    Assuming there is a Pi inside, you should consider some sort of SLC memory storage for the OS and interface. With most MLC SD consumer SD cards, I get roughly a year before something crashes on the SD card. Sometimes, the crash needs reloading of a fresh disc image, but sometimes the SD card is bricked. As a caveat, some don't have the same level of this issue as I do, so it may be something I am doing wrong.

    Of course, this depends on what OS/software I am using. PiCorePlayer lasts longer because of fewer writes to the card, but the fancier the system, the more writes to the card. My guess is that Squeezebox Lite isn't possible in a commercial product, so you will likely end up with one of the commercial alternatives like Roone.

    Anyway, as a digital out device, the product will still end up in the somewhat high end market. You will need good reviews from Darko or the like to get the word out. Good luck with that project and thanks to catering to us crazies.
     
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