The Pro Co Rat is a, if not the, classic distortion guitar effect1. It’s still around though “vintage” effects can go for hundreds of dollars. There are many variants and, like any classic guitar effect, there are many clones. It’s also one of those pedals that many of the mods and clones have improved upon the original.

I got a complete pedal kit from Aion effects — the Helios Vintage Distortion. I have built one of their effects using just a PCB before, and the instructions are top-notch. The kit was equally well done, with quality components. The Helios is basically a Rat clone that uses an OP07 chip (instead of the hard to find LM308N and most folks who seem to know say they sound the same, anyway). The Helios also includes a couple of very common modifications to the Rat: an additional “sweep” control and a clipping diode selection. The former adds an additional EQ control to the pedal where as the latter adds the ability to select different clipping diodes that decide the characteristics of the distortion.

I’m not sure if I’ve really mentioned this in any posts of effects building, but I prefer to tape down all of the components for each build onto paper along each of their descriptions. This is sort of analogous to “knolling” a LEGO kit, I suppose (though taping them down makes the components easier to identify later!).

As I mentioned, the Aion kit comes with what all seem to be high quality components. I have to admit, the all red resistors had me confused. They were clearly labeled with text as to each value (which is much better than trying to read color bands!). They appear to be 1/4W 1% metal film resistors with a coating and printed value is all.

The kit comes with literally everything you need, including pot isolation covers. The fit-up of the top-mount audio and power jacks is very precise, so I did have to re-work the solder joints on one of the jacks. But the resulting finish of the enclosure is that much nicer.

The wiring in the pedal is done using headers and small ribbon cables. If you really hate off-board wiring (I don’t mind it so much), this is really nice. Here you can see the custom dressing nut used over the stomp switch (there’s a similar custom nut for the clipping switch!), which gives the pedal a very high-end made feel.


I do have a few complaints about the kit, though. First is that the PCB just refused to lay flat on the selector switch and pots. I could have fiddled with it more, but it seemed like things just didn’t want to line up. Even though Aion states the 3PDT footswitch is a premium switch, with longer life, I’m not a fan of the feel of it (I guess I’m just so used to either a relay or the Taiwan blue switch!). Lastly, and this is something I absolutely plan to change on this pedal: the LED is insanely bright! I mean, it hurts to look at and is actually distracting, even when you’re not looking directly at the pedal! I’m going to swap out the LED resistor to dim it down. A lot!

But these are great kits and this is an amazing pedal for less than $75 (on sale, regularly $82). The assembly took me about 2 hours or so (that includes taking a few minutes to put my son to bed). Of course, your mileage may vary. Some of their pedals are sold fully assembled on Reverb or you can also reach out to a builder to see about pricing an assembled pedal. Even at that price, it’s a good deal! With the clipping options, it can cover ground from almost a transparent boost all the way to a medium gain distortion pedal (I mean, it’s no Boss Metal Zone…). It’s honestly cheaper than you could purchase a used Rat pedal and mod it, and already modded Rat pedals go for much more.
Now, none of this matters if it doesn’t sound good, of course. Once again, I’ve managed to build a pedal and write a blog post without bothering to record any audio. Part of that is because I don’t yet have a mic and I’m not pleased with the cabinet simulator on my amp head. But mostly, it’s because I’m lazy and not really a great guitar player! I’ll try to get some audio posted soon, though.
- Now, when I say “distortion effect”, I’m not referring to fuzz pedals or distorted amplifiers, I really do just mean distortion effects pedals. Hendrix never played one of these! [↩]