EDP Clone - A Raspberry Pi Project

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colinbrogan
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Joined: Thu Oct 25, 2018 8:15 pm

EDP Clone - A Raspberry Pi Project

Post by colinbrogan »

Update 11/23/2017: This thread has moved here viewtopic.php?f=21&t=4972&p=7192#p7192

I have recently dove into the world of building raspberry pi's with self-booting audio software, running on low cost audio cards. I have an extra Raspberry pi and Arduino, and am interested in building and sharing the steps for a self-contained headless (no monitor or laptop) Superlooper which either clones the physical setup of an actual EDP, or takes inspiration from it with a few design changes (presumably for the better). As far as I've seen, a used Gibson/Oppenheimer EDP is running around $500 used on ebay and reverb.com, and since it is discontinued there are no new buying options. The intent here is to provide steps and a bill of materials for building a device as good or better in the $100 - $200 range for anyone with a power drill, soldering iron, and a weekend to devoted to following the instructions.

Is anyone interested? If so, I will post the development as I go, providing the instructions if I hit the finish line.
Last edited by colinbrogan on Sat Nov 24, 2018 12:08 am, edited 1 time in total.

Freasy
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Re: EDP Clone - A Raspberry Pi Project

Post by Freasy »

Since this forum is not the most active in the world, there might be a lack of answers.
I'd love to see your concept, as far as I understand you're not finished yet?
Making SL into a physical looperpedal would be really great!

colinbrogan
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Re: EDP Clone - A Raspberry Pi Project

Post by colinbrogan »

I can get answers to technical questions by other means. However, if there is anyone left around with opinions about the ideal design (I mean in a non-technical sense. Like the question: "If you could wave a genie wand and your ideal headless switch / led / control layout for Sooperlooper appeared, what would it look like?"), then I'll keep posting my progress here.

I am nearly done with the jack and sooperlooper self-booting scripts, running on a RPI 3 B+ and Alesis IO2 EXPRESS external sound card with successful capture and playback. I just ordered parts for building a custom OSC pedal using the GPIO in/out on the RPI, and am waiting on the $25 Audio Injector sound card (will be a more replicatable low-cost design than the Alesis I currently am using).

colinbrogan
Posts: 26
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Re: EDP Clone - A Raspberry Pi Project

Post by colinbrogan »

Screen Shot 2018-10-26 at 3.29.13 PM.png
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There is this guy, who spearheaded a similar-ish project:

http://journeytounknownsoundscapes.blog ... -with.html

However, he is doing a TouchOSC project, which I find inconvenient for guitarists who don't usually have a free-hand in live settings. Also, he is using the Cirrius Audio card which appears to be discontinued, and not as good (by what I can surmise by reading, will confirm when it comes in) as the newer low-cost Audio Injector


Here are some initial designs ideas:
Screen Shot 2018-10-26 at 3.29.13 PM.png
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So, the housing starts out with 2" x 4" x 20" steel tubing, already ordered and on the way here:
https://www.metals4uonline.com/steel-sq ... x4x188wall

The "o"s are stomp switches ("momentary action"). The bottom row starts out the same as the original EDP (Record Overdub Multiply, etc), each stomp switch has a solitary Red LED indicating whether that action is activated or not at a given time. However, at the end, instead of the "Next Loop", we have the "Redo", which as far as I've read wasn't a function on the original, and in my screwing around with SL appears to be a great and natural addition. To make up for the lack of "Next Loop", the top right has 4 stomp switches for switching between 4 different loops. Each of these have a single RGB led per item. The channel is lit up as green if the loop has something recorded on it and playing. It lights up as "Red" if your editing that loop at a given time. Ofcourse the Bottom row of actions are now set to manipulate that activated loop.

Finally, the "@" signs are potentiometer, with the 4 standard faders you find already on the EDP. "Looptime" is a 3 or 4 character LED indicating the time in seconds you are on in a given activated loop (again like the original edp).

Thoughts? I have some smaller / cheaper switches I can use for toggling semi-permanent setting (things you don't need to manipulate live), and for lack of room in this post, I haven't worked out a layout

colinbrogan
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Joined: Thu Oct 25, 2018 8:15 pm

Re: EDP Clone - A Raspberry Pi Project

Post by colinbrogan »

One more update:
Playing around with the Midi bindings in Sooperlooper last night, it appears that there is only a single-direction of control, from midi interface to Soolooper. This would mean that with an RPI + Arduino as midi server setup, one could not populate looptime or control the LED lights from SooperLooper states.
After looking at the OSC api, it appears this has full bi-directional control. I decided that the best setup would be to write a simple OSC server to run on the same RPI, communicating over localhost with Sooperlooper, and controlling the LED lights / etc directly over the RPI's own GPIO headers. This would eliminate the need for an Arduino in the first place, reducing the total cost of building (And simplifying setup). The only possible con I can think of to this setup may be the RPI's lack of analog input over the GPIO for custom potentiometers. However, I trust there are workarounds to this problem out there. Furthermore, the Audio Injector already has our input and output potentiometers, so worst-case scenario we can toss out other custom potentiometer (static mix and feedback). I will table that problem when/if we get to it.

With this setup, I can release a single ISO with the Linux + Jack + Sooperlooper + OSC server auto-boot, such that when the build directions are solidified and tested on my end, anyone else can buy the list of materials, follow the build directions, and have it running immediately afterward with no required Raspberry pi or linux knowledge.

bjj91
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Re: EDP Clone - A Raspberry Pi Project

Post by bjj91 »

Sounds like a great project! I have been messing around occasionally with prep work for something similar, but don't have any tangible progress to report (still trying to get SL working correctly with MIDI CC bindings.) I'd love to give your ISO a try when it's ready.

Any idea if a Raspberry Pi Zero would have enough RAM to make a useful looper? That's what I have on hand. I'm willing to to limit myself to one channel (not stereo) and possibly even 24 Khz sampling (lower audio quality).

jesse
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Re: EDP Clone - A Raspberry Pi Project

Post by jesse »

Very cool!

I haven't played with RPIs yet, but in terms of memory, even the RPI Zero has 512MB of ram, which should be plenty of space depending on your looping needs. SL uses single precision float samples (4 bytes) internally, so at 44.1kHz sample rate a single channel loop will allocate about 10MB per minute of loop time.

Definitely interested in how these projects turn out!

colinbrogan
Posts: 26
Joined: Thu Oct 25, 2018 8:15 pm

Re: EDP Clone - A Raspberry Pi Project

Post by colinbrogan »

OK, I am glad this forum is not dead, and that I am getting responses.

I got my parts in, along with my 2" x 4" x 18" steel channel (for the pedal case). Will send pics of the box as soon as I can, I am happy with the size and the ergonomics of a very wide pedal enclosure. I don't want the guitarist reaching over 1 button to get to the one above. I have been spending today working out my autoboot script for Jack. On Raspbian stretch lite with a realtime linux kernel, it is looking like a ~27 second boot time. This is not as good as I wanted, but there is a good bit of boot time optimization that can be done after the fact. I think I am going to table that until I write the OSC server and have all the buttons communicating with SooperLooper. Then I will know all the minimally sufficient things needed to boot, and I can rework the image as a super-minimal Archlinux.
Any idea if a Raspberry Pi Zero would have enough RAM to make a useful looper? That's what I have on hand. I'm willing to to limit myself to one channel (not stereo) and possibly even 24 Khz sampling (lower audio quality).
I actually have a Raspberry Pi Zero laying around also. The sound card I just got is for the 3 B+, but the same guys that make that one have an even cheaper card for the zero, which can be found here:
https://www.amazon.com/Audio-Injector-Z ... B075V1VNDD
Also has full stereo duplex.
I may can try this after the fact. If it works well enough, cost-wise this would be better than the 3 B+. But to play it safe, I'm going to start with the Raspberry Pi 3 B+.

colinbrogan
Posts: 26
Joined: Thu Oct 25, 2018 8:15 pm

Re: EDP Clone - A Raspberry Pi Project

Post by colinbrogan »

I've migrated this thread to "Alternative GUI's", because I think it is a more appropriate place for this sort of thing. Also posting new developments there. See below:
viewtopic.php?f=21&t=4972&p=7192#p7192

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