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Patching my guitar amp's firmware

mforney.org

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Re: Patching my guitar amp's firmware

#4

Post by alexjplant »

tyfighter wrote: post #3

Nice :) I did this for my Axe-Fx II and III a long time ago, but I never published any of it for fear of being sued. Really, I just wanted to learn about DSP techniques and that was enough for me.

Sorry WHAT?! I was under the impression this whole time that this wasn't feasible due to asymmetric key encryption with the private keys baked deep into the hardware. Perhaps I'm misremembering but Cliff (the founder) is very big on protecting trade secrets so I'm rather surprised you were able to. Or do you mean you were able to flash new firmware, not reverse-engineer the existing one?

Either way I don't blame you for not writing it up. The same guy just recently accused another industry player of "infringing on [his] idea" with a product because he "filed a preliminary patent". I've been using Fractals since long before they were cool but based on the guy's forum posts I think he's having a hard time navigating the modern internet cultural landscape (the tenuous nature of his legal argument notwithstanding). It's a real shame as he's clearly super talented but I think trolls have gotten to him.

Re: Patching my guitar amp's firmware

#5

Post by shermantanktop »

I’m always very impressed by this type of hardware/firmware reverse engineering. So many places to get completely stuck and fizzle out.

I assume that happens a lot, but few people would write a blog about their inability to break a protocol or decipher a memory layout.

Re: Patching my guitar amp's firmware

#6

Post by tyfighter »

alexjplant wrote: post #4
tyfighter wrote: post #3

Nice :) I did this for my Axe-Fx II and III a long time ago, but I never published any of it for fear of being sued. Really, I just wanted to learn about DSP techniques and that was enough for me.

Sorry WHAT?! I was under the impression this whole time that this wasn't feasible due to asymmetric key encryption with the private keys baked deep into the hardware. Perhaps I'm misremembering but Cliff (the founder) is very big on protecting trade secrets so I'm rather surprised you were able to. Or do you mean you were able to flash new firmware, not reverse-engineer the existing one? Either way I don't blame you…

I never encountered any encryption/protection of any kind on the II (had 3 bootloaders: a simple memory loader -> a huffman tree decompressor -> another simple memory loader) and even though I got pretty far on the III I could see there being some kind of key embedded in the firmware somewhere. I was able to disassemble any .syx firmware release that came out. I wrote my own IDA Pro modules for the TigerSHARC (II) and TI-C66x (III). II took a while but I learned a lot. When the III came out I started over. I spent a lot of time reverse engineering the amp block code, but stopped about 8 years ago. Back then he wasn't even compressing the firmware yet, so it was easy.

Re: Patching my guitar amp's firmware

#8

Post by jkingsman »

Wow, that is a deep level of commitment and learning/exploring; I love it. While I'm sure this is informed by deep preexisting knowledge (to a point -- it's still badass in its own right), I can't help but admire these skills and feel a little inferior about my own.

What a badass level of deep dive.

Re: Patching my guitar amp's firmware

#10

Post by webprofusion »

webprofusion wrote: post #9

This is awesome, couldn't the firmware just be extracted from the updater though?

Would love to see this done for the Spark amp as well, this level of hardware hacking is beyond my skill set.

I recently built my own Multi FX app/plugin (https://guitar.soundshed.com) and am looking for ways to squeeze it (or a version of it's signal chain) into commodity hardware as replacement DSP signal chain.

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