Brazilian Raspberry Pi 3 + Guitarix Device

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Brazilian Raspberry Pi 3 + Guitarix Device

Postby rod_amaral » Sat Nov 26, 2016 6:51 pm

Hello guys!

This is a summary of the progress of mounting my simulator with guitarirx and raspberry pi.

1) Hardware Used:

- Raspberry PI 3
-Power Supply 4A (Note: I am using a step-down power module because I already had a 12V 5A power supply at home.)
-32Gb microSD card Class 10
-Touch Screen HDMI LCD 7 "(Waveshare)
-Behringer UC6102 USB Audio Interface
-Arduino Mega (For MIDI Controllers)

Image

Image

2) GPIO Buttons

To improve the use of guitarix without mouse and keyboard, I put some buttons connected to the GPIO ports of raspberry sending some functions like:

CTRL + X - Preset Selection
Ctrl + S - Save Changes
Ctrl + M - "Fold"
Ctrl + E - "Show"
Ctrl + D - "Live Mode"
Reboot
Shutdown

3) Midi Controller

To remotely control the guitarix, I used an Arduino Mega as a MIDI controller.
There are 16 buttons and 16 leds (with possibility to include more) and an 16x2 LCD for display of the selected bank and preset.

My controller has the following switches:

5 switches for selecting presets (from 1 to 5)
5 switches to control preset effects
2 switches for changing banks (Bank up and bank down)
2 switches for changing preset (preset up and preset down)
1 mute switch
1 switch for activating the Tuner

The code was made based on this link: http://forum.fractalaudio.com/threads/d ... ct.119882/

Below are some pictures of the controller, which was mounted on a form for cakes.

Image

Image

4) Performance:

The whole system is running with a CPU consumption and memory less than 50% most of the time.

5) Limitations:

It is not possible to use some plugins for lack of memory, such as JCM800Pre and Detune. When you try to use these plugins the audio starts to fail.

6) Some problems:

- When you change the presets via MIDI there is a small delay or mute (I'm not sure). Is there any way to solve this?

- I'm using a resolution of 1024x600 (because of the LCD), the convolver configuration window is not being fully displayed. Is there any way to use a scroll bar in this window? Image below

Image


7) Samples:

Below are two samples recorded directly on the Raspberry with the St-Recorder. As a cabinet simulation i'm using the convolver plugin.

https://dl.dropboxusercontent.com/u/606 ... ssion0.ogg

https://dl.dropboxusercontent.com/u/606 ... ssion1.ogg

The samples were recorded with a Gibson Les Paul Custom plugged directly into the sound card.

8) To do:

For the future I think of putting a MIDI controller connected to the raspberry (also with a mega arduino) to control 16 pots of the presets and also some buttons to change banks and presets.

I am also designing a cabinet layout to house the simulator. The initial idea is based on designs such as Kemper Profiling and Bias Head.

I'm writing a tutorial with the step by step assembly (only in Portuguese). This document can be accessed through the link: https://docs.google.com/document/d/1bt2 ... sp=sharing

I would like to thank the guitarix development team for doing this amazing software!
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Re: Brazilian Raspberry Pi 3 + Guitarix Device

Postby brummer10 » Sun Nov 27, 2016 8:26 am

Hi rod

Nice to hear that you make such a good progress!!

The sound samples you've posted sounds great.
rod_amaral wrote:5) Limitations:

It is not possible to use some plugins for lack of memory, such as JCM800Pre and Detune. When you try to use these plugins the audio starts to fail.


To the JCM800Pre, here we need to disable the oversampling, that will reduce the sound quality a bit, but allow to run it on the pi.
rod_amaral wrote:6) Some problems:

- When you change the presets via MIDI there is a small delay or mute (I'm not sure). Is there any way to solve this?

- I'm using a resolution of 1024x600 (because of the LCD), the convolver configuration window is not being fully displayed. Is there any way to use a scroll bar in this window? Image below

To the preset switching delay/mute, We use a ramp down/up when switching presets, to avoid clicking noise when powered a new plug or changing the amp(tube). This is really needed. For the arm version I've already reduced this ramp time to a minimum value, if we go lower, we properly get clicks and pops when change a preset. However, you could experiment with the ramp time by yourself, if you wish, it is defined in gx_engine_audio.cpp line 49:
Code: Select all
void ProcessingChainBase::set_samplerate(int samplerate) {
    steps_down = (256 * samplerate) / 48000;
    steps_up = 8 * steps_down;
    //steps_down = (64 * samplerate) / 48000;
    //steps_up = 4 * steps_down;
    steps_up_dead = 0;
}


just comment out the first step_down and step_up definitions and uncomment the second pair will reduce the ramp time by /4.

To the convolver widget, well, I've uploaded a new guitarix version (0.35.3) for arm
https://sourceforge.net/projects/guitar ... z/download
were I've added a scrollbar to the convolver widgets, so they will fit your screen. In that version I've as well disabled the oversampling in the JCM800Pre plug, so this one should work as well now.

regards
hermann
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Re: Brazilian Raspberry Pi 3 + Guitarix Device

Postby gimmeapill » Mon Nov 28, 2016 1:47 pm

Hi Rod,

Sounds nice, what kind of latency can you run at?

BR,

LX
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Re: Brazilian Raspberry Pi 3 + Guitarix Device

Postby rod_amaral » Wed Nov 30, 2016 1:31 pm

Thanks for the reply, Hermann!

The 0.35.3 version worked perfectly! Convolve with scroll bar and JCM800pre working properly.

About the delay/mute in the change of presets I will still try some values in ramp down/up.

gimmeapill wrote:Hi Rod,

Sounds nice, what kind of latency can you run at?

BR,

LX


~ 10 ms
See the jack config:

Image
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Re: Brazilian Raspberry Pi 3 + Guitarix Device

Postby brummer10 » Thu Dec 01, 2016 3:28 am

rod_amaral wrote:Thanks for the reply, Hermann!

The 0.35.3 version worked perfectly! Convolve with scroll bar and JCM800pre working properly.

About the delay/mute in the change of presets I will still try some values in ramp down/up.


Great.
If you found values which suite better for the PI, let me know please, may I could change it in the next tar ball, so that other PI users will benefit from it.
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