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Using Audio Injector and Flat Max DI box for custom looper pedal

Posted: Sat Dec 15, 2018 10:52 am
by colinbrogan
I am in the middle of working on an EDP like looper pedal using the Audio Injector cards and DI direct box (as guitar preamp) by Max Flat, and Sooperlooper by Jesse Chappel, the progress of which is documented here: ... 7192#p7192
loop_pedal_design.png (41.48 KiB) Viewed 366 times
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loop_pedal_design.png (41.48 KiB) Viewed 366 times
I thought I would share this with the community, as I didn't realize until recently the existence of the DI box to be able to run a preamped guitar line direct into to the Audio Injector without building custom circuits. Furthermore, the mixing functions on the DI box are fantastic for a looping pedal, as I can pass the immediate guitar signal analog straight to the output (without any computer latency), and then mix into that output the computer-generated loop output which is latency adjusted. The work of Max Flat and Jesse Chappel are a fantastic marriage, as Sooperlooper was designed largely with a headless linux setup in mind. The hardware offered by the AudioInjector products make this doable on the Raspberry Pi in a low-cost, simple way which was not easily possible before.

I will be posting how I run the DI box and audio injector together here soon, for anyone else interested in using the Raspberry Pi for guitar pedals (loop or not). Furthermore, I am running a Realtime pre-empted Raspbian version with autoboot scripts for running guitar related software, I will be sharing this via an .iso image soon, as it took some serious work and learning to get to that point, and by sharing it, many people could use this as a basis for such loop pedals and not go through the same frustration to get the right linux setup.

Re: Using Audio Injector and Flat Max DI box for custom looper pedal

Posted: Thu Dec 27, 2018 11:52 am
by colinbrogan
I desoldered the rca jacks off the Flat Max Stereo DI box. Strangely, the motherboard labels the RCA inputs and outputs like so:

| Rrca1 | | Rrca2 | |
|______| |______| |
________ ________ |
| Vrca2 | | Vrca1 | |

(Top being output, and bottom being input)

See pic:
IMG_0379.JPG (170.12 KiB) Viewed 363 times

However, when the RCA jacks were on, the furthest right jack and both input and output were Red (Suggesting right channel), and the left-sidde jacks we're left (Suggesting left). I am about to solder cables, and I need to know which input will come out of what output. If I read the board, than it would suggest that input Vrca1 will come out Rrca1. However, if I read the RCA jack colors, than it would suggest Vrca1 will come out of Rrca2.

This is crucial for figuring out a guitar pedal setup using the Audio Injector plus the Flatmax DI box found on Amazon. Anyone know the answer to this? I would test it if I hadn't lost my jacks.