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Tr-umBela an FX box for the Roland TR 8 based on ther Fx above. The assignable A and B outputs are used as sends and the mix in is used as returns. Specifically built for the toms, rimshot and Clap but any of the voices can be assigned to Mix out, A or B as usual.



Trumbela pd ver1.png

Using other peoples patches as modules

I removed the dac~ and adc~ from each of the tutorial fx units and replaced them with inlets and outlets. This allows me to use them as modules in the master pedal board.

Confining number of inputs and outputs to match the bela

I can now add 8 faders and 8 switches. In order to have some control we are limited to 3 fx by two inputs equals six volume knobs, six on/of buttons and 6 leds.

That leaves us with two knobs and two buttons that can act as toggles to access more functionality. Press Button 1 to access fx, button two to access fx 2 and both buttons to access fx 3.

The main six volumes could be default if no button is pressed and act as further controls for the fx too.

Pins labelled replaceme.png

Choosing in 'parallel' over 'in series' or both

I started on the trumbella 'in series' version (just to investigate). It looks to me that unlike the parallel version, one cannot have two mono inputs feed a stereo output. Instead I'd need a second set of 3 fx (doubling the CPU). Compare the 'in parallel' and 'in series' WIP images.

the three effects are in series and each toggle switches between effect and bypass the effect? The issue is to do with each of the fx having a mono in and stereo out.

If one wants:

A-fx1 on, A-fx2 on, A-fx3 on

B-fx1 on, B-fx2 on, B-fx3 off

B-fx1 feeds into the mono input of fx2 A-fx1 also feeds into the mono input of fx2.

So the output of fx2 is two stereo signals summed NOT A-fx2 out on the left and B-fx2 on the right.A double set of three effects is required when they are in series. If both inputs go through one FX2 the signals are merged, and they can't be separated again if just one of them should go through FX3. can only be done with two sets of three effects. In series.png