Zynthian Box with Audio-input (Audioinjector soundcard)

Hi @Zynthianers!

I just finished my first Zynthian with audio input. I’ve used the audioinjector soundcard and i’m pretty happy with the result :wink:

It’s an almost-official Zynthian Box with only some little modifications:

  • Audioinjector soundcard replacing the HifiBerry
  • Modified laser-cutter wooden case to fit the audioinjector. The modified design is in the case repository.
  • I’ve changed the wiring. For some strange reason, the ground in GPIO pin 34 doesn’t work with the audioinjector. Perhaps there is a hardware “bug”. I’ve rewired to pin 39 and it works like a charm, so this is the official wiring layout from now, as it works with HifiBerry and Audioinjector. I’ve replaced the schemes in the wiki and repository. There is no need to change anything in the software configuration.

Regarding the software, only 2 tips:

  • Change the driver layout in /boot/config.txt
  • Enable output and input with alsamixer, as explained by @rod_amaral here:

Nothing more!

For testing i’m using my electro-kalimba :sunglasses:

with a pre-amp, as the audioinjector input is not suitable for high impedance transducers:

I’m crazy with MOD-UI!!! This is my last patch:

You can control everything from the Zynthian interface, including the super-looper!
And the sound is clear … really!! I see tons of fun this weekend … :stuck_out_tongue_closed_eyes:


P.D: I will try to upload some video or audio demo …


Can you measure latency from input to output signal with the pedalboard shown in your picture?

Hi @Axeman!

In theory, with jackd, the complexity of the patch doesn’t matter for the latency. Unless you overload the CPU, the latency is fixed, in that case, 5.8 ms. Of course, you must add the audioinjector latency.

I will try to measure on monday and will see …


For guitarists like me, the zynthian with audio input can be a great simulator of amplifiers (using guitarix) and effects. I’m testing a midi pedal to control the effects and the results are great!

Something like this: (with a 7 inch touchscreen)

In the future I want to include a midi controller with some potentiometers, mounted in the same box as the zynthian, to get a feel for a real amplifier.


I was indeed thinking about CPU limits…

According to the website of AudioInjector the latency is 0.54 ms! https://www.kickstarter.com/projects/1250664710/audio-injector-sound-card-for-the-raspberry-pi

@Axeman, CPU was very relaxed all the time, <20% :wink:

@rod_amaral, i read that this latency is for input OR output, so, total latency would be 1.08ms. Adding the internal Jackd latency we have 6.88ms. This the theory, of course … let’s see what is the reality!


Wow. I’d have said that the cpu would have been much more stressed…

Hi all,

Yesterday I started to use my pisound card. Just had not enough time until now - but I got MOD-UI working. So for guitar it is like a MOD-Duo - but the RPi3 has more power.

The latency question was one of the most questions on the last Maker-Faire. I own a BitScope and I am thinking about a showcase with a simple adapter: One channel of the scope for MIDI and one for audio. Trigger on MIDI and than we can show how much latency a Zynthian has.

Regards, Holger


Hi @C0d3man!

I’ve a BitScope too … and i will use it to measure the latency on monday :wink:


Guess what? I have a Tektronix 60MHz digital scope, what I have not is the audioinjector card… it seems impossible to buy one from Italy :frowning:

The audioinjector is out of stock for international buyers, it’s only available from USA?? I will try to contact @flatmax and try to get come units for the zynthian community …


1 Like

Hi Guys!

I’m from Brazil and I bought from Ebay:


1 Like

Thank you for the link. Last time I checked the official link from AudioInjector site, it was sold out and can’t be bought.

On this auction, insteat, counter says that is sold out (3 available/3 sold) but ebay accepted order anyway. Let’s see what happens…

(or, maybe, i misunderstood the meaning of ebay counter :wink: )

Hi @rod_amaral!

Thanks for the link! There are several products, but only one ships to Europe and other countries outside USA:


I’ve ordered a pair of units more right now :wink:


Hi @Zynthianers!

I’ve tryed to measure the Zynthian’s full audio loop latency (input->output) with my Bitscope. This is the result:

Zynthian’s full audio loop latency (AudioInjector Soundcard) = 13 ms

As you can see, it’s quite higher than the theoric one (6.88 ms), probably because the 2 x 0.54ms latency for the AudioInjector soundcard is too low. Also, probably i’m ignoring some delay in the I2S bus and the kernel itself. I’m not an expert, so any contribution to this discussion will be very welcome!! :wink:

Anyway, i don’t trust completely the BitScope, so i will try to repeat the measure with a decent DSO, probably this week :wink:

Kind Regards!

1 Like

Hi @Zynthianers!

I’ve recorded a little audio demo with my electro-kalimba and the Zynthian Box with Audio-Input:

I’ve used the MOD-UI patch shown in the main post in this topic. Sorry for the tempo/sinchro pitfalls. It’s my first time using a looper and i hadn’t got a foot-switch, so i had to switch the super-lopper by hand, rotating the zynthian controllers … :wink:

The recording itself was also done with the Zynthian Box, using the “jack_rec” tool from the command line. I will include a simple recorder utility in the admin menu to ease this task.



I Just bought this card and a rpi3 … :slight_smile: Let’s begin !

Hi guys!

Here’s a sample of the preset I’m using with my zynthian:

It was recorded with the jack_rec on zynthian using a Gibson Les Paul Custom.


We should find a way to share patches and presets easily … ideas? :wink: