Daisy as an onboard effects processor

[jclegg]

So years ago, when Electra made a line of guitars and basses, discontinued some time in the 80's, that featured built in effects that could be swapped out via plug-in modules:


A couple of drawbacks to this approach: only two effects could be used at any given time, each module only had one control on the front, so adjusting other parameters required opening up the back to twiddle the corresponding knob.

I regularly enter the annual Winter Build-Off over at TalkBass; the theme this year was rather broadly defined as "Rebirth/Renewal", so I decided to take a fresh approach to the onboard effects by using a Daisy as an onboard effects processor. I've decided to address some of the shortcomings of the by using by including a display in the upper horn of the bass and replacing the two pots with rotary encoders that can be used to adjust any of the parameters . My build thread over there focuses primarily on the bass building aspects; I decided to post a thread here to deal with the Daisy development side of things.

 

[jclegg]

While looking around on the Daisy forums, I found a multi-effects project that someone had posted there along with a link to the source code. Since the author had things pretty well worked out, I decided to adapt the infrastructure that he had developed. The controls will be 2 rotary encoders, 2 pushbuttons, and the two toggle switches. I'm setting the signal chain up for 4 slots, 2 of which can be active at any given time:
I adapted his code to worked with a 128x64 OLED display. Since I'm using a tiny little 0.96" diagonal display I reduced the number of lines from 5 to 4 to make the text a bit more readable.

 

[Mentaltossflycoon]

I just took a look at your build thread, that things going to be nice!

 

[jclegg]

I just took a look at your build thread, that things going to be nice!

Thanks! I've submitted the bass for the contest.

The two unmarked knobs are rotary encoders, the function changes with the current context. the two push buttons change function with context as well. The 2 toggles are basically bypass switches.

I'm looking at using one of the pushbuttons for tap-tempo.

 

[jclegg]

As mentioned previously, I'm using a terrarium board for the the buffers, +5 V regulator, etc. I have re-purposed the control inputs as follows:

The 6 pots are being used for rotary encoders: each encoder has a 3 lines; 2 for rotation and a push to click.​

The 2 footswitch connections are being used for the push-buttons, the LED connections go to LED's in the pushbuttons.​

The 4 toggle switch connections are used for 2 (ON)-OFF-(ON) momentary SPDT's.​

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Here's what the back looks like:​

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And how the controls are (currently) assigned:

I ended up adding a small daughter board to each encoder with a 10k/0.01uF RC filter for the clock and data lines. I also tacked on a vero-board daughter-board to the Terrarium to break out the I2C lines for the OLED display and an I2C EEPROM module.

 

[Feral Feline]

Fan-freqn-tastic!

So this pic from your TB thread shows where the OLED is mounted?

 

[jclegg]

Yep, that's it. I was worried at first about being able to read such a small display, but even my old eyes can do it.

 

[daeg]

This would be phantom powered right? DC injection over the R of a TRS cable?

 

[jclegg]

I'm using a 7.2V RC battery -- 2200 mAH. Should be good for ~20 Hours between charges. I'm using a soft switch to turn it on/off I'm thinking that I'lll add a auto-off output if the software detects long periods of no activity.

 

[Matmosphere]

For a sec I thought "why would you do that to that cool old bass" but the result is excellent. Looks great and I bet the daisy is fun to have on board.

A lot of us cut our teeth on the Electra Distortion when we were getting started.

 

[jclegg]

No, I wouldn't do that to an original. I've been enjoying working with the Daisy; expanding on the effects (the flanger is now a through-zero flanger) , dreaming up other improvements.

 

[Robert]

This is really cool!

If I had known you were going to do something as crazy as this we could have worked up a custom fit PCB for it.

 

[jclegg]

This is really cool!

If I had known you were going to do something as crazy as this we could have worked up a custom fit PCB for it.

Umm well I AM planning to do a six string version Had I known this was a possibility, I would have hit you up!

 

[jclegg]

A few updates: after playing around with it for a bit, I decided that 2 rotary encoders didn't make a lot of sense, so I replaced one of the encoders with an analog thumbstick:

The thumbstick doesn't mount easily to a pickguard, so I made a small bracket that attaches uses the tone pot and the rotary encoder to attach to the pickguard.

The software is set up so that I can attach any one parameter of any effect to each axis of the thumbstick, pushing the thumbstick freezes the values currently assigned to the stick.

Here's what my Terrarium looks like now: The 4 switches are wired to the DPDT (ON)-OFF-(ON) toggles, FS0 and FS1 are wired to the pushbuttons, the LEDs are wired to the LED's in the pushbuttons. Pots1-3 are wired to the thumbstick and Pots 4-6 are wired to the encoder. There's also a vero-board daughter-board attached underneath to bring out the required I2C pins for the display and the I2C EEPROM on the right.

 

[Bobbyd67]

This is pretty slick ! I started a multi effects on board guitar project more than a year ago too... Nothing digital but I am stuck at repainting the damn thing :x kept getting drips with the spray paint and just gave up. This thread is making me want to get that thing finally done!

 

[jclegg]

This is pretty slick ! I started a multi effects on board guitar project more than a year ago too... Nothing digital but I am stuck at repainting the damn thing :x kept getting drips with the spray paint and just gave up. This thread is making me want to get that thing finally done!

Nicest thing that you could possibly say!

 

[jclegg]

Tucked into the bay, USB connected while I update the software:

 

[Dali]

Woah! That's amazing!