Digital Looper

[mfrebuilt]

I've searched and searched but found nothing useful, so I thought I'd just give in and start a new topic.


I've wanted to build a looper for a long time now, and considered building one of the ones based on the recording chips. The parts are a bit hard to come by in Australia and the maximum recording lengths also put me off. Surely a looper would be best implemented with a programmed microcontroller? The length of a recording would be limited by how much memory you have and it would most likely also make it easier to have several samples playing at once. I haven't done any DSP but I would imagine that everyone has the ADC/DAC part done already, so the only challenge I can see is maybe being able to store the samples on memory (if the µC memory isn't enough for this kind of thing).

I may be completely ignorant of some of the technical difficulties faced by this kind of task, so I would appreciate it if someone could enlighten me as to what I would need to do to make a looper like this for myself. Ideally I'd like most of the hard work to be in the programming since that's what I'm naturally better at, and it would allow me to easily change how the device behaves just by recompiling the program for the µC.

[mfrebuilt]

I guess digital still hasn't really taken off here

[luke691]

brilliant idea.... im really interested in the whole concept aswell..
just read up on the boss rc-2.. 16 minutes and several different recording tracks.... even a simple 1 track would be a good start...

its a compact pedal at 299 au... i guess if it was possible to make something for less than that it would be worth a shot...

[Andre]

Check ToneGod's Payback

http://www.diystompboxes.com/smfforum/index.php?topic=46680.0

[mutant_guitar]

i've been kicking around this idea for the last few days, myself. as far as the technical side goes, there are many  considerations.

input/output buffers - these need to be set up  based on the voltages coming into the ADC and out of the DAC
oscillator - depending on how fast the uc's internal oscillator you chose is, you may want to set up an external oscillator.
memory - you're probably gonna need alot of it. depending on the uc you chose, you might need to wire up external memory
DAC/ADC's - resolution and data communication. how many pins are you going to need on the uc, etc

as for my thoughts, i haven't researched a whole lot of parts. i've been thinking of going with one of PIC's DIP uc's. i  won't consider anything less than 16 bit resolution for the converters, and it has to be able to talk serially to the uc. my main worry is how much memory will i need. i've also considered initially building a development board and going from there.

unfortunately, i believe the grunt of the work in doing a project like this is mainly hardware/technical considerations. the programming will probably be the lightest work. you're going to have to choose a uc, and design the rest of your project around it.

good luck. read the data sheet.