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A revolution in audio communications. The surround sound card (for the Raspberry Pi) which seemed impossible, but now it is done !
A revolution in audio communications. The surround sound card (for the Raspberry Pi) which seemed impossible, but now it is done !
A revolution in audio communications. The surround sound card (for the Raspberry Pi) which seemed impossible, but now it is done !
150 backers pledged AU$ 14,404 to help bring this project to life.

Use this space to cheer the creator along, ask questions, and talk to your fellow backers. Please remember to be respectful and considerate. Thanks!

    1. Flatmax Studios 2-time creator about 3 hours ago


      The Octo doesn't have amplifiers on board, only preamps. You will need to amplify the audio to use them with passive speakers. Alternatively you could purchase active speakers, rather then purchasing an amplifier.

    2. Missing avatar

      Danijel about 3 hours ago


      I am planning to couple passive low cost speaker directly to octo. Is that possible or driver is mandatory? In case if this is possible what characteristic should speaker have?

    3. Flatmax Studios 2-time creator about 3 hours ago

      Hey Danijel,

      If you want to use the Octo for an active crossover, then you can also choose nice drivers which will work well together.
      Whether you're building an active speaker or buying one off the shelf, make sure the amp can driver the impedance of the speaker (normally 4 or 8 Ohms).


    4. Missing avatar

      Danijel about 5 hours ago

      What would be the optimal loudspeaker (characteristic) for use with octo?

    5. Missing avatar

      Paul on March 4

      Thanks Sergey, Matt.
      I've been after the same thing, an update on fulfillment I guess.
      Thanks Matt. Looking forward to getting my hands on a unit!

    6. Flatmax Studios 2-time creator on March 2

      Hey Sergey,

      Thanks for your support.

      We have already gone into manufacture for the boards and RCA breakout boards. The TRS boards are in the final stages of design.

      I will send out surveys over the next few days. These surveys will be requesting your delivery address.


    7. Missing avatar

      Sergey Shupilo on March 2

      Greetings. I'm newbie on kickstarter, so i know nothing regarding how it goes after the campaign is over, how much to wait, so... Can you please share information regarding the status and/or when the product is gonna be shipped to backers? Thank u very much.

    8. Flatmax Studios 2-time creator on February 17

      Hey everyone,
      I have setup a forum to support this community and this product.
      We can talk more easily and freely there, feel free to send messages and have discussions there :…

      Feel free to comment here as well if you like.

    9. Missing avatar

      James Mansion on February 12

      Commenting to myself again, I always press Return too early!
      From a software point of view,its pretty easy to load raw bits from a CD, transform for crossover or room correction, upsample. Then you get the question of volume control, because it seems that you can't rely on AV receivers to do the volume in analogue after DAC, and also few of them support the optional time resynch feature. HDMI seems to have a reputation for jitter that is even worse than SPDIF but the optional feature is there to improve things and there are lots of clock recovery systems like you get for SPDIF. It seems untapped to me - everyone has HDMI output now. Something that can take HDMI PCM, make a stab at recovering a reasonable clock, isolate from the computer's grungy ground, and emit lovely analgue would be just great. I'm everyone who appreciates such things would be pleased. Both of us, even!

    10. Missing avatar

      James Mansion on February 12

      You can do 8 channel PCM over HDMI, uncompressed, at least 24/96 from memory. But yes, it would be a different thing entirely. ALSA should give access in most cases. I've found it can be picky if it thinks there is no display, but there is an audio channel sink.
      Sure I think the voltage controlled gain could go there, ideally for unbalanced as well. I would think control over USB would be handy. I'm suspicious of the software gain on some of the DAC systems, it might be in the digital domain.

    11. Flatmax Studios 2-time creator on February 12

      Hey James,

      Thanks for the suggestions.

      Regarding analogue volume control - it is a really nice idea. Perhaps these types of analogue volume controls can be injected between the custom breakout headers and the final balanced or RCA breakouts ?

      I have checked out the HDMI options. Unfortunately to do HDMI with multichannel, they all use compressed formats such as DTS and others. The chips are very expensive and require licensing of some form or another. For that reason, using HDMI audio extractors is expensive and probably suitable for a different project.

      Those amps look sweet !

    12. Missing avatar

      James Mansion on February 10

      Actually, there is a product I really want. Currently I take a stereo DAC into a miniDSP 2x4HD and then I use an Audiolab 8200AQ in bypass to do passthrough volume control before my power amps and DIY active speakers. Its a faff.
      What I'd really like is an add-on that does this:
      with one of the new buffered reclocking HDMI chips in front of it and a decent buffer amp stage.
      If the volume management can be done with USB or serial (I'm thinking Arduino Leonardo here) then we have a way to use many many PCs etc to generate 8 channel audio in software having done frequency shaping and crossover, and a way to run the gain without nasty digital effects. And the DIY active community will be Very Happy - and possibly the surround PC crowd too.

    13. Missing avatar

      James Mansion on February 10

      Hi, the amps are:……
      There are others but these are reasonably well-known, especially the Hypex.
      The bottom line is that a complete active preamp/player/crossover system looks rather tempting. A 4-out board for RPi would probably sell, its annoying to have to consider HDMI.
      Maybe that's the trick - for RPi and other PCs and videa/SBC cards: take HDMI audio in and reclock it to RCA or balanced. MiniDSP do something like that, but its a bit spendy and they have a reputation for poor PSU design (at least in snotty hifi circles) if I remember. The 2x4HD I have is fine, to be honest..

    14. Flatmax Studios 2-time creator on February 6

      Hey James,

      External DC power is a possibility. I could add DC barrels to the balanced boards, which would allow you to plug in your own supply.
      Not sure exactly which amps and what type of connectivity you are referring to.

    15. Flatmax Studios 2-time creator on February 6

      Hey Michael,

      Glad you are happy with TRS, yes they are balanced. I was also thinking that TRS to XLR cables would do nicely !

    16. Missing avatar

      James Mansion on February 6

      If there was anything I'd want, it would be a way to provide top notch DC power.
      I'm using a miniDSP 2x3HD at the moment and it sounds OK, but you'll find plenty of people who are sniffy about the power line filtering etc.
      And the other thing I would like, would be an internal breakout to hook up the outputs directly to amps from Hypex, LCAudio and the like. Maybe even Aksa (pricey though).

    17. Missing avatar

      Michael Pirker on February 6

      Hi, sorry for responding so late. Thanks for your question from Jan16th. TRS terminated connectors should be good. You will deliver balanced outputs? I did use such already in the past, often customized cables for specific purpose. Usually I will add TRS to XLR converter cables with balanced output and plug the XLR cable/microphones.

    18. Flatmax Studios 2-time creator on February 4

      As we approach streatch goal #1, we are getting ready to announce the next set of stretch goals. Thinking along the lines of 3D printable face plates to cover the connectors and make it easy to attach to your boxes/projects.
      Wondering whether anyone has other ideas concepts which are appealing to most people here ?

    19. Flatmax Studios 2-time creator on February 4

      Hey Paul,

      Thanks for the lead, I have registered with them and begun the process for starting a topic there. Incidentally we have had users of our other Pi sound card work out how to build Volumio with Audio Injector support built in !…

    20. Missing avatar

      Paul on February 4



      Keep up the hard work Flatmax, you're doing very well!

    21. Flatmax Studios 2-time creator on February 1

      Hey stewartjm,
      Thanks for the leads. I have now posted in and begun the moderation process for
      If anyone else has good leads please post or let me know !

      thanks again

    22. Missing avatar

      stewartjm on February 1

      Two audio/music forum communities that might appreciate being aware of this kickstarter:

      I searched both and didn't see a specific mention of the octo yet. There are good search results for raspberry pi and kickstarter campaigns on both. So a tasteful post would probably be appreciated.

    23. Flatmax Studios 2-time creator on February 1

      Hey Paul, sorry about that !
      I haven't mentioned it but I am doing everything to promote this campaign as much as possible. It is difficult for me to remember exactly where I have been putting the word out.
      I have found forums to be great for attracting interest ! Thanks again for your help. Marketing is very relentless work !

    24. Flatmax Studios 2-time creator on February 1

      Hey Kyle,
      The cs42448 datasheet states that power consumption is around 600 mW. That is roughly 80 mA from the 5V supply and 61mA from the 3.3V supply. This represents a total of around 120 mA from the 5 V supply.

      The RCA breakouts add no extra power requirements.

      The TRS 1/4" balanced breakouts use NE552 opamps.Their current draw is around 10 mA from a 5V supply per dual package. If you use the output balanced breakout, then it will consume around 80 mA . If you use the input balanced breakout, then it will consume around 60 mA.

    25. Missing avatar

      Paul on February 1

      Haha @Flatmax ... I just joined up at diyaudio and was about to post there about this Octo when the 'similar subjects' forum check scanned for posts and found you'd already posted there! I guess you overlooked that from your list of promotion? :) LOL. No problems.

      +1 for Kyle's question BTW. Does the card have much of a power requirement given it doesn't include an amp?

    26. Missing avatar

      Kyle on February 1

      Is there any information about the power requirements/consumption of the card? It would be useful information to have when considering power supply/UPS options for portable/automotive power.

    27. Flatmax Studios 2-time creator on January 30

      Thanks for pledging James.
      The chip is the cs42448 codec, here is a link to the manufacturer data sheet :
      Here is a link to the manufacturer's page :

    28. Missing avatar

      James McCanna on January 30


      I pledged today and I have looked for the underlying chip used here? Can you tell me or show me where to look? James

    29. Flatmax Studios 2-time creator on January 29

      Hey Paul, sorry for the late reply, just got back from a week in China.

      Thanks for posting to Max2Play. I have posted a link on the raspberry pi forum [1] below. I have also posted a few times on the pi reddit group, sent a tweet or two as well as facebook posts !
      Another forum I have hit is

      To help us get to this first stretch goal and possibly a few more, it would be great to have people sharing the project on social media.


    30. Missing avatar

      Paul on January 25

      Hey flatmax can you list the marketing you've already done to avoid us duplicating?
      I posted to a forum for the Max2Play software.
      Has anyone posted to other obvious places like Volumnio?

    31. Flatmax Studios 2-time creator on January 24

      Hey hwanin21,

      Nice idea ! Actually I have looked into OTG using the Pi in device mode. It has been reported possible to set the Pi into device mode.

      We plan to put the VHDL on the chips to make it simpler to install and ensure it works reliably.

      Later we will do a latency test. At this point I expect sub 2ms with an unloaded CPU... stay tuned !

    32. Missing avatar

      hwanin21 on January 23

      Great work!

      Have you investigated the use of the USB OTG as an audio gadget device for the raspberry pi? This could be the cheapest usb multichannel sound card out there.

      Do you have any plans for releasing the schematics and FPGA VHDL code? This board is something I have been looking for for a very long time.

      This doesn't matter that much, but do you have any latency numbers? I'm planning on using for a hexaphonic pickup for a guitar, and passing the audio over the network.

    33. Flatmax Studios 2-time creator on January 23

      Hey Jeremy,

      Thanks for backing !
      Yes, each channel have have its own volume control so you can set the volumes as you like.
      You can potentially do anything you want, there are plenty of free GPIO lines for buttons or switches or whatever you fancy.

      We need more traffic to our campaign, can you suggest where we could promote this campaign ? Please share with your acquaintances.


    34. Missing avatar

      Jeremy wylie on January 22

      Hello and thanks for this amazing board. I will be using this most likely with a different board then a ra!spberry but it also has the rasp pin out mount. I will most likely used in a vehicle scenario.

      In other answered questions. You said it can be faded forward/back by pinouts. And in a another area you said various channels could possibly controlled in volume. Making a full side to side front back control possible.if so this makes the board potential unstoppable.

      In your level control cross over diagram do I have this correct that there is four high channel and four low channels. Or are they all just free channels to be leveled to were user wants.

      Any chance for a screw down input output version in the future. I like the rca version i backed it. the break out version is not to my needs as it would have to be five pin not three and the plug version is not so vibration stable.

      Eagerly awaiting your response, and enjoy your summer, I'm getting sick of snow :)

    35. Flatmax Studios 2-time creator on January 19

      Hey all,

      To get more stretch goals, we have to generate more interest !
      For that reason I have put together a little scoop for the media on the personal side. If you can get it out there, or know anyone who can do an article on this project, it would take us a long was for getting word out and more stretch goals happening !

      Here is a link to the personal scoop article article :

    36. Flatmax Studios 2-time creator on January 19

      The pin outs are the I2C pins and the I2S bus pins. You can see these pins on the audio injector support forum post here :…

      Regarding chips, I will be uploading the drivers to the Raspberry Pi github Linux repo. after the campaign finishes. The codec is standard and has support for Linux. There is an FPGA onboard and there are a few pins used to signal the FPGA. Once I release the device tree sources I will point out those pins as well.

    37. Missing avatar

      Jeff T on January 19

      @creator, thanks for the info, I had a further look and I think original Pi doesn't seem to have i2s so probbly not. Anyway, I also have other boards such as the PINE64 which has support for I2S, can you give us pin out of the octo if we wanted to use this on other devices that also have i2s?
      Could you also give us an idea of the chip being used in this project?

    38. Flatmax Studios 2-time creator on January 17

      Hey Jeff,

      Unfortunately we don't have the original Pi and haven't tested it on that device.
      Check the following FAQ question for updates on what devices we have tested on.

    39. Missing avatar

      Jeff T on January 17

      Just want to clarify which versions of pi can be used with this. Is the original pi fast enough to make full use of this?

    40. Flatmax Studios 2-time creator on January 17

      Hey Matthias,

      Yes you can use this for FIR convolution (e.g. room correction). Not sure how long your filters could be. You could use FIR crossovers and add them to the room correction filters, or they could be IIR are pretty low cost to implement.
      I have seen free software out there for FIR convolution with ALSA.

    41. Flatmax Studios 2-time creator on January 17

      Hey Christian,

      Because there is one I2S bus, you can use only one sound card at a time. Your project sounds great !

    42. Flatmax Studios 2-time creator on January 17


    43. Flatmax Studios 2-time creator on January 17

      Hey Paul,

      Yep the stretch goal was pioneered by the board games campaigns. It will let us improve the product and hopefully push it in the direction which backers think is important.

      I also think that you idea for a Octo case is good, perhaps face plates for panels as well. It is possble the best way to do that is to give 3D printable downloads so people can make their own ?
      Perhaps that can be our next stretch goal if we make the first one ?

    44. Missing avatar

      Matthias Pollin on January 17

      Will this be usable for convolution tasks?

      I'd like to build a FIR-Crossover with room correction.

      Besides: more detailed information on the hardware used would be cool.
      (DAC/ADC and so on...)

    45. Missing avatar

      Christian Gatzlaff on January 17

      Great project. Since I am planning a multiroom audio hub (like Jan suggested below) with your soundcard I would like to know if your soundcard is stackable - means can I put more than one soundcard on one RPi? This would be great as I could route any of the inputs to any of the outputs.

    46. Missing avatar

      Paul on January 17

      Love the stretch goal idea. Sweet!

    47. Missing avatar

      Paul on January 16

      Fair point re something everyone can use as a stretch goal.
      How about a pi3 plus Octo case? Maybe too much to do as a stretch? I'm struggling to think of something to be honest �
      Maybe just use any extra funds to deliver the Octo even faster?

    48. Flatmax Studios 2-time creator on January 16

      Hey Michael,

      Sounds great !
      I was wondering, you see, I want to make the balanced breakouts smaller and more portable. For that reason I was planning to check out a TRS (1/4" socket) for this purpose.
      Would you be able to use TRS terminated cables ? Would you have to use TRS to XLR converters ?

    49. Missing avatar

      Michael Pirker on January 14

      Awesome you hit the goal! Great work and great ideas you are working on. I'm excited and look forward to use the AudioInjector.

      (1) I hope to use it as a 6 channel (surround sound) recorder. 6 XLR Mics with phantom power. Pi and phantom power from a power pack. All as slim as possible. Recorder controls via Pi or mobile phone. Two scenarios: standalone environment to record live concerts in surround sound. Use it as audio recorder for films using Canon, Leica, etc.
      (2) I used RME Babyface with AudioEvolution on my Android phone (2 channel). if the sound could be exported via ADAT/optical I may be able to use Totalmix from RME and even do live filtering.

    50. Flatmax Studios 2-time creator on January 14

      Hey Paul,

      First the good news. Our last kickstarter project was also a sound card. It was used by a few different people with interests in SDR. I can recommend contacting The South African Radio League ( as they can most likely answer all your questions and even point you to people local to you who you could work with.
      In fact, if you can post a question on the AudioInject SDR forum (, I can point the SARL at the question so that they can perhaps help you ?

      Now the tough stuff ! Of all backers, a small number will be using these products for software defined radio. I think the purpose of the stretch goals are to give everyone a reward for great support and sharing of this project to help get it out there. In other words, a reward for everyone which everyone can use.

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