Hey!
So, I’ve been into electronics for a while. Recently, I built a +/- 12v power supply to get into modular. I am almost done making a basic 1v/oct oscillator, and I already have a synth and a Keystep, so once that’s running I’ll have some decent chords and bass. However, I want to get into drums.
Synthesizing them is probably hard, so I figure I want something to trigger a sample. The sparkfun wavtrigger seems a little overfeatured for what i want and is VERY expensive. I think I will buy a Teensy 3.2 microcontroller. it’s arduino-compatible and has a builtin DAC (perfect for audio!) and teensy has a super robust audio library.
Does anyone have experience with this? Is there a super simple solution I’m missing?
Isn’t the WavTrigger, like, $40? For a full set of drum samples, that seems fairly reasonable
2 Likes
It’s $51. It’s a totally reasonable price don’t get me wrong. I just want something with fewer features that costs less.
1 Like
I think your main problem is space: audio files of ~good enough quality can get pretty big (for a microcontroller), so you’ll probably need an external memory (and also for the sake of simplicity of use). You can also try to generate them on the fly (this can be quite nice, as you can adjust everything live, and have a more random analogy sound!), like this: https://www.youtube.com/watch?v=ANN4cP7pn2Y.
You also want to check the speed of your DAC, and generally speaking, microcontroller’s DACs are relatively slow. But this Teensy seems to have a fairly fast DAC (see here: https://forum.pjrc.com/threads/26036-Fastest-DAC-speed-possible-for-Teensy-3-1-using-Arduino). But I couldn’t find this info in the datasheet (https://www.nxp.com/docs/en/reference-manual/K20P64M72SF1RM.pdf)
2 Likes
Thanks for the reply! I think that the teensy 3.2 has enough memory for just a few samples, and I’m not sure I need very high fidelity right now. I’ve seen projects (notably this one https://m.youtube.com/watch?v=gL5llIO3NcU) that seem to do fine in terms of space for samples. DAC speed totally didn’t occur to me, but you’re right that that is super important. Thanks for all of the advice!
1 Like
woah! Nice project!
It seems that you can also use the PWM with the audio library (see here: https://www.pjrc.com/monolith-synth/) ?
And the github page: https://github.com/PaulStoffregen/MakerFaire2017
2 Likes
Ooh that’s super cool!
1 Like
Take a look here if you want cheap sample playback at a reasonable quality :
He (Jan Ostman) has also an open source eurorack drum module, and other goodies worth looking at :
https://www.hackster.io/janost
4 Likes
Ive experimented with I2c EEPROMs and arduinos and DACing the audio. It worked, it was just slow. Have yet to try with teensy to see if the bottle neck was the arudino, which i suspect it was. It coulda been the serial speed wasnt high enough to retrieve and process across the pwm. I do know it worked however because recorded the output, and sped up the result and it sounded perfect. So its just a matter of playing back at the right sample rate.
Here is the v1 experiment if you want to see:
If you just want a solution that works rather than an experiment that might not, get the wav trigger. You might find it a lil cheaper in the long run.
If you rather risk not having a project that works and would rather experiment, go for it, thats how new awesome things get built.
Just keep in mind polyphony is a thing with the wav trigger, and what you build may not have that support.
4 Likes
Ooh, thanks for the reply! I’ll check out your project.
1 Like
i just want to be clear, the wav trigger is absolutely the best way to go if you just want something that will work with the least money, quality, and time investment. Mine was for fun, challenge, and hubris. I also like low fi samples.
3 Likes
I am fine with lofi samples, and this whole thing is mostly for fun and hubris! That’s my I’m building my own KOSMO mixer modules instead of buying them for like $80 a pop.
2 Likes
In that case, just lemme know if you need to know how serial interfacing and talking to the eeproms works.
2 Likes