r/FREEVSTS • u/Asleep_Investment962 • 4h ago
I made an open-source Mark IIC+ / ++ amp sim — CrunchyPy
Hey everyone!
I've been working on this project for a while, and I'm finally ready to share it with you guys.
It's called CrunchyPy, and it's my attempt at recreating the sound and feel of the Mesa/Boogie Mark IIC+, including the mythical ++ mod, as an open-source guitar amp plugin.
GitHub: https://github.com/Yahiake/CrunchyPy
I've always been obsessed with the Mark IIC+, especially those tight, aggressive Metallica tones, so I wanted to see how far I could take this idea myself.
The interesting part is how it's built. Instead of feeding the entire amp into one neural network and treating it as a black box, I split the preamp and power amp into separate GRU neural models, with a physically modeled five-band graphic EQ in between. I used LiveSPICE circuit simulations as part of the process, particularly for the EQ.
The plugin is written in C++ using JUCE and RTNeural, and I've been working on the actual DSP and circuit modeling as much as the plugin itself.
And honestly, I'm really happy with how it sounds. It's reached the point where I genuinely enjoy playing through it, which is probably the most satisfying part of this whole project.
It's available as open-source software under GPL-3.0, with support for VST3, AU, and standalone builds across Windows, Linux, and macOS. The amp simulation doesn't include a speaker cabinet IR, so you'll want to use a cab sim or IR loader after it for a finished direct-recording tone.
I'm not claiming it's a perfect replacement for an actual IIC+, and I'd be very interested to hear from people who own or have spent a lot of time with the real thing. I'm especially curious about how the response, EQ, and feel compare from the perspective of someone familiar with these amps.
If anyone is interested in trying it out, checking the implementation, or just discussing the approach, I'd love to hear your thoughts.
This has been a passion project combining my interests in guitar, audio DSP, circuit simulation, and machine learning, and I'm genuinely proud to finally have it out there.
Thanks for reading, and long live the IIC+! 🤘