PiAMP is a DIY guitar amplifier which uses a neural network to emulate the sound of any guitar amplifier or pedal.
It consists of the following components
- Raspberry PI which processes the audio, provides bluetooth connection and receives signals from the controls and footswitch
- HifibBerry DAC+ ADC is the audio interface used for high quality audio
- Power amp which converts the low level audio signal into a signal which can be fed into a speaker
- Speakers/Cabinet
- Screen and controls which allow to set the current Amp model, cabinet and other controls (gain, bas, mid, etc.)
- Footswitch which allows to quickly switch between saved channels
- Bluetooth app which allows to connect to the PiAMP and set its parameters via phone
Here a picture of my PiAMP with my DIY guitar
This is how it looks like when its turned on
And here is a picture of the foot switch
And finally, here a video which shows some more details of the PiAMP (and my DIY guitar) and a demo. Please excuse me for the poor quality - I simply don't have the patience and skills to make a good video...
https://www.youtube.com/watch?v=HTpMu2ALkGg
This project is open source and everyone is very welcome to build its own PiAMP. Also everyone is very welcome to contribute to this project!
The following instructions are not (yet) meant to be complete, I'm just writing down what I remember from building my amp. I am very happy to help you if you want to build your own amp - it would be great if you could contribute in creating a more comprehensive guide!
Here is a very crude schematics of what's going on inside the PiAMP:
The Raspberry PI takes the input signals (guitar + line in) from the HifiBerry shield and processes the signals using the NeuralPi sushi plugin. The processed audio signal leaves the PI again via the HifiBerry shield and enters the power amp which amplifies the signal and drives the speakers.
On the Raspberry PI there is also a nodejs service running which does the following things:
- Controls the NeuralPi plugin using OSC
- Provides bluetooth connection to allow connecting via app
- Connects to an arduino mega via USB + serial to receive commands about changing parameters
- Connects to the footswitch via USB + serial to receive commands about switching and saving channels
Here is the list of components I used. Please note that I don't want to promote products/sellers; these are just the components I used and most of them can be replaced with similar components:
- Raspberry PI 4
- HifiBerry DAC* ADC
- Raspberry power supply
- the t.amp TA50
- 2x Celestion BL15-300X 4 Ohm
These were the mandatory components, now the optional components
- Arduino mega for the controls (screen + knobs)
- 3.5inch Arduino display
- KY-040 rotary encoder
- Turnigy TGY-1551A Analog Micro Servo for the knobs (gain, bass, mid etc.)
- Raspberry PI pico to run the foot switch. A small arduino should also be fine
Then you will also need a lot of accessoires and connectors. This depends a bit on how you want to build it, e.g.
- A cable to connect the HifiBerry shield to the power amp
- Jack connector for your guitar input. I also used these to connect the power amp output to the speakers
- Footswitch switches
- XLR male and female to connect the raspberry to the footswitch
- USB to TTL adapter to connect the raspberry to arduino + footswitch
- LEDs, switches, cables, etc.
- Wood or other material to build the frame, footswitch etc.
- Several 3d printed parts (STL files in this repo)
Please follow the guide on Elk-Audio to set up your raspberry pi: Guide
At the end you should have a Raspberry PI up and running elk os.
You need to have a /udata/libs folder on your pi. If not, create it by running
sudo mkdir/udata/libs
Next go to Releases, and download all files to your PI, e.g. by using wget
cd /udata/libs
wget https://github.com/Thomas-Sparber/PiAMP/releases/download/1.0/NeuralPi.vst3.tgz
wget ...
Next, install the sushi plugin by running
tar xf NeuralPi.vst3.tgz
mv NeuralPi.vst3 ~/plugins/NeuralPi.vst3
Copy the config file to its correct folder by running
cp config_neuralpi.json ~/config_files/config_neuralpi.json
Finally, download some tones and Irs (Impule responses = Guitar cabinet emulations) and copy them into the corresponsing folders:
mkdir -p ~/Documents/GuitarML/NeuralPi/tones
mkdir -p ~/Documents/GuitarML/NeuralPi/irs
Tones/Models can be found on GuitarML's home page. Both, Proteus and NeuralPi models can be used by PiAMP. Please check out his homepage, he did great things and research. The json files need to be copied into the tones folder on the PI created above
IRs can be found e.g. on tonehunt. Please note that this webpage is actually for NAM but the IRs work anyways. The wav files need to be copied into the irs folder created above.
If you visit the tonehunt website to download IRs you will probably notice that there are MANY great amp models available too! Unfortunately they cannot be used directly. I tried to implement the whole NAM stack into PiAMP (and it also worked), but the CPU usage was too high on the raspberry so it couldn't properly handle them, so it didn't sound good. The good noews is that you can convert NAM models to NeuralPi/Proteus models. Please check out my other repo
The next command enables the NeuralPi plugin on startup, see here
sudo cp sushi.service /lib/systemd/system/sushi.service
sudo systemctl enable sushi
Then install the PiAMP server by running
tar xf node-v20.9.0-linux-arm64.tar.xz
tar xf piamp.tgz
sudo cp piamp.service /lib/systemd/system/piamp.service
sudo systemctl enable piamp
Now, as everything is installed you can start it by restarting you pi or running
sudo systemctl start sushi
sudo systemctl start piamp
Now as everything is up and running you can access the web interface of PiAMP by opening http://<raspberry-ip-address>:3600/ in your browser.
Alternatively (/additionally) you can of yourse also install the mobile app on your phone by installing app-debug.apk on your phone. Please note that is app is not (yet) available from any app store (If PiAMP gets popular I will probably publish it), so you need to manually install it. Please check online how to install unsigned apk files on your phone.
Cutting out the aluminium front plate on my snapmaker
Opened mounted front plate
Back view
You probably need to change the jumpers on the hat to enable 12db gain, please check the datasheet how to do it
As already said I used an USB to TTL adapter to connect the Raspberry to the Raspberry Pico (/arduino) of the foot switch. I connected the 5V+ out pin of the TTL adapter to the XLR + pin, the GND of the TTL adapter to the GND pin of the XLR connector and the RX pin of the TTL adapter to the remaining pin. On the other XLR connector I of course connected the same pins to the PI pico to power it and enable data transmission. XLR unforunately only has 3 pins so only one way communication (footswitch --> Raspberry PI) is possible
Here I also used the USB to TTL adapter and connectoed TTL GND to arduino GND and TTL RX to arduino TX and TTL TX to arduino RX. This makes two way communication possible.
This section describes how to connect the display and the servos to the arduino. Unfortunately it is not yet done. If you want to contribute, please let me know
The poweroff button is used to power off the PI to enable a smooth shutdown before power is disconnected. A simple push button needs to be connected to GPIO4 and GND. If the button is pressed, the PI shuts down.
I added some additional old laptop cooling fans to the PI and the power amp to prevent overheating. I think this is more of an optional step.