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Bluetooth controlled pedals?

Started by junkemail86, October 04, 2017, 12:25:14 PM

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junkemail86

Hey everybody,
stupid question and something I know very little about.  But how close are we to DIY a bluetooth controlled pedal with something like this?  http://www.taydaelectronics.com/pcb/hc-06-bluetooth-transceiver-module.html
Or even without bluetooth, aren't there digitally controlled potentiometers that we can make something cool with?

micromegas

They are, and some people have done cool stuff with it.
Once you have a digital controlled pot hooking up a bluetooth circuit isn't a big problem, but you'll have to figure out the way to send control messages (maybe using Open Sound Control?)

There are 3 ways I have seen it done:
a) digital potentiometers [PROS: easy to control via a microcontroller and from the application side][CONS: most of them (the cheap ones) are not really suited for signal applications]
b) VCAs (voltage controlled amplifiers) [usually not cheap, sometimes a pain to work with and they usually involve some extra circuitry]
c) variable resistors with optocouplers (or variable pots using 2 optocouplers) [PROS: best suited for audio & signal applications][CONS: not cheap, you need to match the optocouplers or at least characterise their curves because they have great tolerances]


Chase Bliss Audio uses option c) for his pedals afaik and RobA posted some circuit & software on this forum a while ago to create a digitally-controllable potentiometer following a similar principle. Usually what puts people off is the amount of extra circuitry & work it involves.

That said, I have done some experiments and it is not really complicated if you have some software dev background.
'My favorite programming language is solder' - Bob Pease

Software Developer @ bela.io

wgc

wow, crazy that this came up just as I was posting about something similar in mb's din thread.

Great info, micro.  anyone know if people are using bt for input/output signals?  could make for an interesting looper.
always the beautiful answer who asks a more beautiful question.
e.e. cummings

micromegas

#3
Quote from: wgc on October 04, 2017, 03:29:05 PM
wow, crazy that this came up just as I was posting about something similar in mb's din thread.

Great info, micro.  anyone know if people are using bt for input/output signals?  could make for an interesting looper.

Bluetooth is not too fast for audio routing, good enough for parameter control though.

Bluetooth latency would be noticeable for real-time applications although a looper is not really "real time", right?.
A looper is not real time but playback needs to be in sync, so depending on who controls the looper's playback you would have ~40ms latency, which is too much.
'My favorite programming language is solder' - Bob Pease

Software Developer @ bela.io

wgc

gotcha, that makes sense.  Any alternatives that might work for this, zigby zigbee, etc?
always the beautiful answer who asks a more beautiful question.
e.e. cummings