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.
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.
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!
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.
@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!
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.
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 …
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!!
Anyway, i don’t trust completely the BitScope, so i will try to repeat the measure with a decent DSO, probably this week
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 …
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.
Let’s begin !