Raspberry Pi for guitar modelling, anyone?

[Sedaxel]

24 / 3 Buffers is completely usable...

Wow... Helix performs quite well there. I think there must be something wrong with my Pi, though. Always suspected it because of the cpu bouncing all the time.

With my hifiberry, I must set it to 32/2 to be useable... and still with some risk of derailing. That said, it gets very good RTL (but it´s a dedicated interface, directly connected to the GPIO port.

 

[Mike Oliphant]

Wow... Helix performs quite well there. I think there must be something wrong with my Pi, though. Always suspected it because of the cpu bouncing all the time.

With my hifiberry, I must set it to 32/2 to be useable... and still with some risk of derailing. That said, it gets very good RTL (but it´s a dedicated interface, directly connected to the GPIO port.

I think going below 64 is likely a bad idea unless you've got a lot of CPU headroom available. 64 is already very good latency, and the lower you go, the more significant the per-buffer overhead becomes. Also, many DSP operations are designed to operate efficiently on blocks of data and you start to mess with that more and more as you go below 128 samples.

 

[Sedaxel]

I think going below 64 is likely a bad idea unless you've got a lot of CPU headroom available. 64 is already very good latency, and the lower you go, the more significant the per-buffer overhead becomes. Also, many DSP operations are designed to operate efficiently on blocks of data and you start to mess with that more and more as you go below 128 samples.

Agree. Lately I put it on 64, yeah. If I remember correctly, it made a RTL of around 5 ms, which is perfectly fine anyway.

 

[Los-D]

Probably like everyone here on this forum, I've been looking into NAM lately. Not because I'm unhappy with my Helix LT, no, but somehow the quest for tone is never over. I definitely didn't want to use my PC, so I fired up my iPad again. And yes, it's great what's happened recently: TH-U remains great, but now also opensource stuff like Chowdhury DSP BYOD, with which you can also run NAM models, and then especially Tonex and Gigfast Lite. But... they all eat up resources, Tonex is totally buggy and Gigfast Lite keeps crashing as a plugin in Loopy Pro.

So I remembered that I had recently bought a Raspi (4B with 2G RAM), but I hadn't touched it yet for fear of falling into another time consuming rabbit hole of tinkering... and... of course I fell into it. First of all, I had to remember the basic Unix commands that I hadn't used in 20 years, and then I had to realize that there is a huge Unix audio community and everything is incredibly confusing and then audio under Linux: alsa, jack, pulseaudio, pipewire... A few days later I had a first overview (if that had been working time for a client, I could have bought a box full of Dimeheads). Whatever. Then I found some possibilities, tried Modep with Patchbox OS - unfortunately too resource-hungry, as is Zynthian

And then a few days ago I found Pipedal (https://rerdavies.github.io/pipedal/): A standard PI-OS installation, install Pipedal, two or three commands to get around a few bugs (that seems to be mandatory in this world) and you're done! Pipedal is a general lv2 host with a few effects and amps already built in. It already includes a version of the NAM plugin (https://github.com/mikeoliphant/neural-amp-modeler-lv2). Super stable and, what's more, high-performance. Great minimalist GUI. Pipedal installs a web server so you can control it from your mobile. You can use almost any profile (the only ones that don't work for me so far are @Slammin Mofo's high accuracy profiles).

I also found another great lv2 Nam plugin: Ratatouile: https://github.com/brummer10/Ratatouille.lv2, runs perfectly under Pipedal. With Ratatouille you can load two profiles in parallel and blend them seamlessly without increasing the processor load (you get two for the price of one). So you can go seamlessly from clean to crunch.

Yesterday I connected the Pi to the Helix and was impressed. Works perfectly. Round trip latency of 5ms - mind you, that's the full latency, measured with a loopback cable and a complex Helix preset. So Helix + Pi. My Helix can now do NAM! For 60 Euros! I'm thinking about buying a Pi 5 now, let's see how it runs

I would really like to know if others here are playing around with a PI (@Sedaxel ) and how you are using it!

I only have an older 3B. Any idea on performance on it? (Will need to check eventually)

 

[panhardleft]

@Mike Oliphant: I'm trying to get stompbox to work - but so far I've had a problem. Stompbox-jack runs on the Raspi after I installed Jack and started the Jack server. However, Stompbox UI doesn't run on either my Win 11 or my Win 10 machine: When I enter the server name, the program simply closes. Apparently the server is found, because if I enter an incorrect server name, the input window pops up again. Only when I enter the correct name does it close again.

In the console window running stompbox-jack I see the following:
Start listening for connection
Connection received
Got message: Dump Config
Plugin Boost already loaded
Plugin Screamer already loaded
Plugin Compressor already loaded
Plugin Fuzz already loaded
Plugin AutoWah already loaded
Plugin Wah already loaded
Plugin Phaser already loaded
Plugin Vibrato already loaded
Plugin Flanger already loaded
Plugin Chorus already loaded
Plugin Tremolo already loaded
Plugin Delay already loaded
Plugin Reverb already loaded
Plugin ConvoReverb already loaded
Plugin NAM already loaded
Plugin NAMMulti already loaded
Plugin EQ-7 already loaded
Plugin BEQ-7 already loaded
Plugin HighLow already loaded
Plugin NoiseGate already loaded
Plugin SimpleGate already loaded
Plugin Cabinet already loaded
Plugin Level already loaded
Plugin Input already loaded
Plugin Master already loaded
Plugin Tuner already loaded
Plugin AudioFilePlayer already loaded
Plugin AudioFileRecorder already loaded
Got message: Dump Config
Plugin Boost already loaded
Plugin Screamer already loaded
Plugin Compressor already loaded
Plugin Fuzz already loaded
Plugin AutoWah already loaded
Plugin Wah already loaded
Plugin Phaser already loaded
Plugin Vibrato already loaded
Plugin Flanger already loaded
Plugin Chorus already loaded
Plugin Tremolo already loaded
Plugin Delay already loaded
Plugin Reverb already loaded
Plugin ConvoReverb already loaded
Plugin NAM already loaded
Plugin NAMMulti already loaded
Plugin EQ-7 already loaded
Plugin BEQ-7 already loaded
Plugin HighLow already loaded
Plugin NoiseGate already loaded
Plugin SimpleGate already loaded
Plugin Cabinet already loaded
Plugin Level already loaded
Plugin Input already loaded
Plugin Master already loaded
Plugin Tuner already loaded
Plugin AudioFilePlayer already loaded
Plugin AudioFileRecorder already loaded
Got message: List Presets
Got message: PluginOutputOn
Got message: List Presets
Got message: PluginOutputOn
Got message: List Presets
Got message: Dump Program
Got message: List Presets
Got message: Dump Program
Got message: SetParam Tuner Enabled 0
Set on: Tuner
recv failed with error: 104
Connection closed
Start listening for connection

 

[panhardleft]

I only have an older 3B. Any idea on performance on it? (Will need to check eventually)

I fear that running NAM-profiles will be difficult. But try it! So far I would recommend Pipedal, since it's very easy to install an run. Right now, I'm struggling to get stompbox to work, so I can't compare. But I can tell you that Pipedal is much more performant than modep, and I assume you can use the other "blocks" on the 3 just fine.

 

[panhardleft]

This sounds like I need a PhD.

That's part of the fun!!

 

[likitlikeyoulikeit]

That's part of the fun!!

Not gonna lie....i have been entertaining the Pi for making a midi loop switcher from scratch.

Effects and NAM seem fun and neat.....but not something reliable for my use. But I like fiddling with stuff too. So that's cool.

Anyone here make a midi controlled loop switcher? With the Raspberry Pi?

If so....any recommendations?

Not trying to thread Jack.

Site I used for my reference project.... haven't started yet.

MIDI-Controlled Loop Switcher | Scientific Guitarist

A DIY 5-loop, MIDI-controllable loop switcher for electric guitar, bass, and other instruments.

scientificguitarist.wixsite.com

 

[Mike Oliphant]

@Mike Oliphant: I'm trying to get stompbox to work - but so far I've had a problem. Stompbox-jack runs on the Raspi after I installed Jack and started the Jack server. However, Stompbox UI doesn't run on either my Win 11 or my Win 10 machine: When I enter the server name, the program simply closes. Apparently the server is found, because if I enter an incorrect server name, the input window pops up again. Only when I enter the correct name does it close again.

I recently made some changes to the wire protocol that might be causing this.

If you building stompbox on RPi from the latest source, but downloaded the latest StompboxUI release (rather than build it), then they'll be out of sync. I should do a new StompboxUI release. Meanwhile, you can always get the latest by building it yourself, or by downloading the binary from the latest github build - currently here:

Merge branch 'master' of https://github.com/mikeoliphant/StompboxUI · mikeoliphant/StompboxUI@80a957e

Remote GUI and VST3 plugin for Stompbox guitar simulation - Merge branch 'master' of https://github.com/mikeoliphant/StompboxUI · mikeoliphant/StompboxUI@80a957e

github.com

If you continue to have problems, can you open an issue on github? Thanks!

 

[Mike Oliphant]

@panhardleft There was actually a bit more of a problem. I've pushed fixes to both the stompbox and StompboxUI github repositories.

I'll push a new StompboxUI release soon, but for now you should be good if you build the latest of both.

 

[Mike Oliphant]

For those who may be interested, Stompbox is also available as a Windows VST3 plugin. No Ph.D required.

Just download the "StompboxVST3Plugin.zip" archive from here:

Release Release v0.1.15 · mikeoliphant/StompboxUI

Support multiple plugin output parameters Added "power" output parameter type Compressor overhaul Two-row knob layout when appropriate

github.com

This is what it looks like:

 

[panhardleft]

@panhardleft There was actually a bit more of a problem. I've pushed fixes to both the stompbox and StompboxUI github repositories.

I'll push a new StompboxUI release soon, but for now you should be good if you build the latest of both.

i’ve got it up and running! Thanks a lot!

 

[rerdavies]

Yeah... The Pi can work perfectly.

I tried PiPedal, but ended up giving up on it because my Pi was always bouncing in CPU usage (jumps from 50% to 90% continuously without a reason).

A little later, I discovered Mike Oliphant's Stompbox, which is essentially the same as PiPedal, but I liked much more the GUI and effects. Also, Mike was of great help to getting it working, and my process helped to fix some bugs too.

I then discovered that my Pi, for whatever reason, makes those CPU jumps anyhow... It wasn't PiPedal's fault. And found out that forcing the CPU to be constant at the max frequency (instead of letting it go down and up depending on the load) solved completely the issue. Then it became stable.

Mike also added a fantastic noise gate when I told him that hi gain captures were noisy. Seriously, such a great work in no time.

As I needed to make some theatre gigs, I didn't dare to use the Pi and went with a normal rig. I still have to install the hotspot app to be able to control it out of my home WiFi... And I suspected that it would take me time (I'm not a Linux expert, every little task is a challenge for me... I'm proud of had been able to get there with all these software). But I could perfectly hook it up with my Boss ms-3 or any other midi controller.

One more reason for me to go with a Nano Cortex instead of the Pi (NAM) was that I wanted to try consistent captures (in terms of input gain), and NAM is not still on par in that regard. It's getting there, it's getting standardisation in latest updates. Let's see what I do in the future.

The response is a bit late but....

Pipedal does set the CPU governor to "Performance" mode, which should prevent the CPU use swings you reported. In fact it goes out of its way to make sure that the CPU Governor IS in "Performance" mode, and stays in Performance mode, and actually monitors and sets it back to performance mode if something else has switched it. Did you have something on your system that was trying to do differently?

You can confirm that the CPU governor is in "Performance" mode by opening the Settings menu. The Governor mode is actually displayed at the top of the Settings menu along with the current CPU use and CPU temperature.

In theory, you might be running into heat throttling problems (which would also show up in the status info at the top of the settings menu). But in practice, I haven't ever seen my Pi heat throttle when running PiPedal. It beats the heck out of only one of the 4 CPU cores on a Pi, which doesn't seem to be enough to stress out the Pi. I do have a heatsink and a fan; but the temperature is fine without the fan. If you don't have a heat sink (ridiculously cheap), you might want to try orienting the Pi board in a vertical position, which seems to improve cooling even if you only have passive cooling.

 

[rerdavies]

Wow... Helix performs quite well there. I think there must be something wrong with my Pi, though. Always suspected it because of the cpu bouncing all the time.

With my hifiberry, I must set it to 32/2 to be useable... and still with some risk of derailing. That said, it gets very good RTL (but it´s a dedicated interface, directly connected to the GPIO port.

DON'T set a 2x buffer configuration. It leaves very little time for the host software to process audio, since all the processing has to be done in the time it takes to flip the buffers. Much better is 32x3, or 16x3, or 16x4. These

 

[quadgear]

What's the round trip latency looking like these days for a basic setup with model/profile, can reverb, and a few FX?

 

[ChordInversion]

I've been using Linux for over 30 years, and I have a few Raspberry Pis lying around the house doing various tasks. But...no, I won't be doing this. I don't care for captures.

 

[Sedaxel]

The response is a bit late but....

Pipedal does set the CPU governor to "Performance" mode, which should prevent the CPU use swings you reported. In fact it goes out of its way to make sure that the CPU Governor IS in "Performance" mode, and stays in Performance mode, and actually monitors and sets it back to performance mode if something else has switched it. Did you have something on your system that was trying to do differently?

You can confirm that the CPU governor is in "Performance" mode by opening the Settings menu. The Governor mode is actually displayed at the top of the Settings menu along with the current CPU use and CPU temperature.

In theory, you might be running into heat throttling problems (which would also show up in the status info at the top of the settings menu). But in practice, I haven't ever seen my Pi heat throttle when running PiPedal. It beats the heck out of only one of the 4 CPU cores on a Pi, which doesn't seem to be enough to stress out the Pi. I do have a heatsink and a fan; but the temperature is fine without the fan. If you don't have a heat sink (ridiculously cheap), you might want to try orienting the Pi board in a vertical position, which seems to improve cooling even if you only have passive cooling.

Well, it´s been a long time and I´m not using the Pi currently. Obviously, PiPedal and Stompbox must have been much evolved since then.

I always suspected that there might be something wrong with my Pi. The CPU bounced all the time. I have an all alluminum case which is a heat sink itself (one of those armours, you know). I think it´s working OK. The Pi was just used for this project, no other software loaded in, just formated for either PiPedal or Stompbox exclusively.

I didn´t check the performance mode at the time (or I don´t remember), but I can tell you that the CPU was bouncing continuously. And it wasn´t more stable when switching audio interfaces or increasing buffer and samples. I also suspected about the PSU. It was original, even when it was plenty powerful and measured correct voltage.

When I forced the CPU speed in the Pi, then the bouncing dissapeared. And then I also added a fan, just to ensure that temp didn´t raise in excess. With that config, I was able to run the Pi at 40C (if I recall correctly) at the minimum fan speed, without bounces or any temp increase. This was already using Oliphant´s Stompbox.

But even when it was stable and it looked like it was rock solid... it wasn´t 100% so. Sometimes, maybe once every couple hours, the system made some crackles. Some other times, it just restarted without an apparent reason. MIDI also gave some weird behaviour once in a while when recognizing devices and whatnot. I remember having some troubles with WiFi connections too, which I ended up not understading nor finding a solution. At home that wasn´t an issue for me, but... too many risk factors for me to deal with in gigs.

Then I had some gigs, and wasn´t confident about using the Pi. Took my traditional rig and never used the Pi again.

I think it´s great for having fun and for home use. Also, if you´re very confident and skilled in Linux and computers, you can use it live without fear. It sounds stellar (We all know NAM). But it´s not a comfortable rig for peace of mind in a proffesional gigging scenario for a normal user. You have, of course, more risks of having issues than with a multieffects unit. There are lots of things that can go wrong... and the solutions are not easy to solve on the fly. And if you had to tweak something... well, it´s not the same experience as using a modern multieffects. It doesn´t tries either. It´s a much affordable way to get the best amp tone quality.

In the end, it´s an awwesome work by you and Mike. You have my total admiration, mate.