Here we explore various ways of controlling pi-Stomp in realtime via MIDI, analog expression and from a phone/tablet via OSC.
Any plugin parameter can be controlled by MIDI CC messages coming from a pi-Stomp footswitch, tweak knob or external MIDI controller. Assignment of the parameter to the physical control is done via the MOD-UI.
IMPORTANT: Due to a quirk of the MOD software, once an physical control is assigned to a parameter on a pedalboard, it cannot be reassigned to another parameter without first unassigning it from the original. That will be the case for any of the default pedalboards that have footswitch or tweak-knob assignments. See instructions below on how to un-assign.
Now turn the knob, push the footswitch, adjust the MIDI controller, etc. And if that actuator sent a MIDI CC message, the parameter should now be assigned/mapped to that plugin parameter. Look for a confirmation dialog in the upper right.
To retain this assignment, make sure you then Save the pedalboard.
If you are not seeing a confirmation. Make sure your physical control is not already assigned to another parameter (see “Un-Assigning a Control” below). Also make sure that your MIDI mode is set to “Separated” NOT “Aggregated”
There is an “Advanced” option on the modify dialog. That doesn't offer anything interesting for toggle parameters like plugin bypass, but for continuous controllers, you can specify a different range than the default for the parameter.
Say the default Drive range was 0 thru 10. Maybe you never want your drive to be that low. You could set the low value to 5. After assigning to a tweak knob, with the knob at full counter-clockwise the value should now be 5 giving you only the values that are useful to you and providing finer control over that range.
Because a control can't be assigned to a parameter if it is already assigned to another parameter on the pedalboard, you must first un-assign.
Now click “None”, then “Save”
There is no confirmation, but if the un-assignment worked, you should then be able to reassign the physical control to another parameter.
pi-Stomp v2.1 software includes the latest version of MOD which includes file management and Impulse Response loading.
An impulse response, or an IR, is an audio file (.wav) containing a recording of a short audio signal being played through a certain piece of equipment or in a certain space (eg. concert hall, studio, cave, etc.) Take a listen to an impulse response file and you’ll discover that it sounds like a short burst or a pop. But, load that same file in an impulse response loader and you will hear a faithful sonic recreation of the space in which the IR was recorded. The most realistic reverbs and acoustic treatment for recording these days are typically achieved using IRs. You may be able to recreate John Bonham's huge drum sound from “When the Levee Breaks” in the comfort of your bedroom. Elvis’ bathroom? Sure! Ok, maybe not Elvis Presley’s, but the bathroom of a guy whose wife calls him Elvis when he sings in the shower.
In the case of a guitar cabinet impulse response, you will hear the frequency response of the sampled amplifier. Yes, you can get the tone of a cranked Marshall stack without the hearing damage and pissed off neighbors!
It's even possible with a decent microphone and recording setup (computer with audio interface) to capture your own space or amp cabinet.
2) For space/reverb loading, add the “x42 IR Convolver” plugin (under the Reverb category) to your pedalboard signal path. For amp cabinet loading, add the “IR Loader Cabsim” plugin (under the Simulator category) to your pedalboard signal path
3) Click on the gear to open the plugin settings and choose the IR
There are literally thousands of impulse response files (free and paid) on the inter webs.
A list of free and paid:
Treefallsound's favorite free cabs (“Get the Free IR Pack” at the bottom of this page):
… And this one:
Some nice plate and spring reverbs:
Another with 135 Halls, Rooms, Plates, Ambiences and Spaces:
And an open share of interesting spaces:
Archaeoacoustics (Caves, Castles, Silos, etc.):
In the new version of MOD (part of pi-Stomp v2.1 software), there’s a new plugin category type “Control Voltage” with 25 new plugins. Yes, now you can control virtually any parameter of any plugin via control voltage (CV). Basically, the building blocks of a modular synth (LFO, VCA, VCF, Envelope, etc.). Create your own crazy modulations of synths or effects, or even new effect types without coding! Use an LFO or “Audio to CV” to automate anything (pitch, delay repeats, drive level, eq sweep, etc.)
CV “cables” are a 3rd type of signal in MOD (audio and MIDI being the other two). Assigning Control voltage works somewhat like MIDI CC learning.
Will demonstrate here with an example. Let's build a “Harmonic Tremolo” (like in a Fender Brownface) that modulates the bass/treble balance instead of just volume.
The audio path is simply a “Tilt Tone” which controls both lows and high with one control. Turning “Tone” clockwise boosts the highs and reduces the lows. Counter-clockwise boosts the lows and reduces the highs.
An LFO module will produce the oscillation. Feed that to CV Parameter Modulation module, to give control over the offset and depth of the modulation. I usually add a CV to the end so I can verify the voltages created match what I'm trying to do. After you've connected all your CV lines, click the “Manage CV Ports” at the top.
Now click the gear icon on the Tilt Tone. Then click the mapping button for the parameter to be controlled
Choose “CV”, then select the CV port you want to do the controlling. Then click “Advanced”
Setting the Range and Mode isn't always required, but to have the Tone modulated properly, I found I needed to have a unipolar (positive) range from 0 to 1v.
Then click Save. Once back on the pedalboard page, you should see the Tone knob being modulated in realtime and hear a rich harmonic warble. You can tweak the modulation using the Frequency knob on the LFO and the Depth and Value controls on the CV Parameter Modulation module.
pi-Stomp includes a service (mod-touchosc2midi) which allows it to be controlled via OSC (Open Sound Control) protocol.
This means you can have a control surface on your phone/tablet/etc. that you use to toggle/tweak MOD plugin parameters over wifi!
TouchOSC exists as an app available for IOS and Android devices. Here we'll show the basics for getting set up.
The TouchOSC MK1 app is free: https://hexler.net/touchosc-mk1
Click on the dot in the upper right:
For connecting to the pi-Stomp, the TouchOSC app must be configured.
Click on the top “OSC” field:
Now Enter the Host and Port settings as shown:
Then click < TouchOSC to go back to the main settings page
Click on the second field “TouchOSC Bridge”
If your pi-Stomp is found, you should see pistomp in the FOUND HOSTS list
Click on that, then click < Back
Now you should be able to use your TouchOSC surface as a MIDI controller
To map a control, see the guide at the top of this page and when it comes time to “learn” the control, adjust it on the TouchOSC app and look for the assignment notice to appear.