Programmable fx looper design

[stirfoo]

Hello people, hope this is a good place to post this.

I've been looking at various programmable loopers. Cost is pretty much keeping
me from getting one I'd like. $500 to $800 bucks is just out of my range. I
figure a home-brew looper would cost less than half that. So... just how hard
would it be to make one from scratch? I've been reading the manuals for quite
a few different loopers. There is a lot of functionality built in to some of
them.

If I were to build one I'd want:

* 1 input
* 10 loops
* amp ctrl out
* 2 amp outs (in my case to switch amps, not for stereo)
* 3 modes: Preset, Manual, and Programming

Don't care about a tuner out, buffers, bypass, MIDI, etc. Although the ability
to modify the signal level per preset (gigrig) is pretty sweet.

I've taken a top-down approach and started with the board layout. Here's an
image of the board.



At boot-up, you're in Preset mode (far right blue LED). Only LP1-LP10, BANK,
and MODE are active. If BANK is tapped, the digit will increment and begin
flashing until one of LP1-LP10 is tapped. Then that preset becomes active.

Step on MODE and you enter Manual mode (far right green LED). Here, everything
but BANK is active. LP1-LP10 toggle their loops, CTL1/2 toggle amp tremolo,
reverb, channel, etc. OUT1/2 route the final signal.

Step on MODE once more and you enter Program mode (far right red
LED). LP1-LP10, BANK and MODE are active. At this point, the system is waiting
for the spun out rock star to optionally select a bank, then step on one of
LP1-LP10. If bank 2 is active and LP1 is tapped, the current state of the
loops, CTRL1/2, and OUT1/2 are written to that preset. Once the data is
written, Preset mode is automatically selected with the just programmed preset
active.

The remaining red LEDs indicate which relays are active. The remaining blue
LEDs indicate which Preset is active.

So, there is the grand plan.

I've just started looking into the implementation of this. Microcontrollers,
relays, switches, how many interrupts I'll need, power supply, etc. I'm more
interested in comments on the overall design. Does it look sound, sane, do-able.
Any gaping holes?

[slacker]

Sounds doable to me, pretty steep learning curve depending on where you're starting from but there's plenty of resources out there for all the different elements.

Your design seems pretty well thought out, I would maybe think about adding a mode where you can override the current preset so if you suddenly decide you want to kick in a boost you can just stomp its loop. Basically like going into manual mode but with the ability to jump back to preset mode rather than program mode, if that makes sense.

Welcome to the forum

[stirfoo]

Yep, the ability to select a preset and still be able to toggle one or more loops would be nice. Stomping a random pedal, like an octave generator while improvising is a hellofa rush sometimes.

I plan on giving the design a lot more thought before starting a prototype. A couple of rules I definitely want to try to follow are:

* do everything with my feet
* keep the interface as simple/intuitive as possible

I'm comfortable with a soldering iron and a few programming languages but no, I don't expect this to be a walk in the park.  One thing that's going to take a lot of thought is which microcontroller to use.

Where I will definitely need help is the audio signal routing. How to keep buzzes, cracks, pops, hums, etc. from getting into the path. Also ground loops if both OUT1 and 2 are used simultaneously. I don't quite understand that.

[caldersm]

I Tried to put on a picture of the 4 channel programmable Looper that we built, Our Gen 1 prototype, but I cant figure out how to do it.  Do you have to host the file....?  It wont let me paste it in this box.   

It is Very Simple to use....programs each channel independently to any/all of the four DPDT relay outputs.  The LED above the switch is to tell when you are in program mode, and the LED below the outputs are tied to the outputs, so you know what channels are on.  The fifth switch is what I call a "bypass" switch of sorts....it is a maintain switch that when pressed, puts all the switches back to their "Non-programmed" state.  When you press it again to release it, all the switches go back to their program state.

Our Gen 2 prototype is almost done.....and it has a few tricks up its sleeve.....and I will let you know all about it, when we are done with testing.

Reply with any questions....but I warn you....I have "zero" musical skill.....I am just the Gear head EE that does the design and programming.

Regards,
Steve

[stirfoo]

I Tried to put on a picture of the 4 channel programmable Looper that we built, Our Gen 1 prototype, but I cant figure out how to do it.  Do you have to host the file....?  It wont let me paste it in this box.

DIYStompboxes may have their own media host, not sure.

I use http://imgur.com. You don't have to sign in, just browse to the image and upload it.

If you just want a hyperlink like the imgur link above, use:

Code Select Expand

[url]link-to-foo[/url]
If you want the image to display in the post:

Code Select Expand

[img]link-to-foo[/img]

[caldersm]

Thanks for the info stirfoo.....!!

http://imgur.com/MBbqOP4   Here is the link to the picture of the completed prototype.  We are going to sell them just above the cost of a non-programmable Looper, so that most normal humans can afford it.

[m4t7chu]

Was this ever build?

[Hatredman]

Thanks for the info stirfoo.....!!

http://imgur.com/MBbqOP4   Here is the link to the picture of the completed prototype. 

Why not post the picture directly using the [ img ] tag?

And yes, was it ever built?

[vigilante397]

And yes, was it ever built?

I bought a PCB and IC from caldersm a year or so ago and built it, and I can confirm it's legit. If I remember right he was working on a modular one that you can add more loops to...?

[gtudoran]

Maybe it will help you along if you like to spend some time to look

Regards,
DeX