Fingolfen
Well-known member
- Build Rating
I hadn't done a rat in a while, and the only Rat I'd ever done was the AionFX Helios, which has three clipping modes and the Ruetz mod as external knobs/switches. I've gotten mixed results with the Ruetz mod, and I wanted to go with a basic Rat / Dirty Rat clipping switch for this particular build... so... on with the report!
I was going for a sort of "old school" Rat build, but I decided to stick with film capacitors rather than ceramics (a mix of Panasonic, Topmay, and Apex) and carbon film (rather than carbon composition) resistors (5% 1/4W Yageo for the most part) to minimize the noise floor. The electrolytic capacitors are all brand new production Nichicon. The PCB is another one from South Obolon FX's Ukraine Support line, so I got the files to make these through a donation to Ukraine's ongoing defense. In some areas it can be hard to source the 2N5457 JFET, so alternate resistor / transistor options are provided (the unpopulated R8_A and Q1_A spots on the silkscreen) so a normal silicon NPN transistor could be used instead. I haven't tried that particular mod as I had a lot of JFETs I'd picked up from Pedalhacker, but I may in a future version.
In the interest of trying to keep it old school, I also had what I hope is a genuine LM308N op amp - it seems to be working properly. That being said, I also have a supply of OP07 op amps I can pop in to compare the two. The board incorporates two of the most popular modifications of the Rat as well. Both were originally designed to be internal, but with a little back and forth with South Obolon FX, we found a way to move one of them external! The Ruetz mod changes the cutoff frequency for one of the op-amp stages' high-pass filter. I could have taken this external with a trim pot, but decided to leave it internal. The other mod is the choice of clipping diodes. The board includes space for the original Pro Co Rat silicon diodes (1N914) as well as the Dirty Rat's germanium diodes (1N34A). You could hypothetically also make the Turbo Rat version with two Red LEDs - or mix and match. I decided to stick with the Rat / Dirty Rat combo.
For the off board wiring, I decided to try something different on this build - I ran all of the power, ground, and connection wires from the bottom of the PCB rather than the top. These boards were originally laid out to where people could etch their own PCBs rather than having to get them fabricated, so almost all of them are effectively one sided to the bottom. This board was also originally designed to go into a 1590B enclosure with side mount jacks, but I wanted to transfer it over to a 125B with top mount jacks. That made the knob placement a little unusual, but it also gave me room to add a sub-miniature SPDT switch to the clipping control and bring it to the front of the unit.
The enclosure features more dino art from Ukrainian artist Estelkatrin. This time around, it's the Ratchasimasaurus (a mouthful for sure, bit we've effectively got the Rat - asaurus). Yeah, it's a fairly obscure dinosaur, but there were some interesting life interpretations online, and the artist was able to run with it. Since it is an Asian dinosaur, I sort of went with my Asian theme for the rest of the pedal art using licensed clipart.
As to the pedal - well, it's a Rat. It sounds like a Rat and responds like a Rat. Because the Ruetz mod is internal, I just sort of set it where I like and leave it. I love having the option of going between the regular Rat and Dirty Rat modes at the flip of a switch. The AionFX pedal has a clipping switch, but his interpretation of the clipping stage and its functionality is a bit different, and if I'm being honest I kind of like the raw, basic Rat sound of this one better.
A bit more at the blog: https://steggostudios.blogspot.com/2023/01/another-filthy-rodent-cloning-old.html
I was going for a sort of "old school" Rat build, but I decided to stick with film capacitors rather than ceramics (a mix of Panasonic, Topmay, and Apex) and carbon film (rather than carbon composition) resistors (5% 1/4W Yageo for the most part) to minimize the noise floor. The electrolytic capacitors are all brand new production Nichicon. The PCB is another one from South Obolon FX's Ukraine Support line, so I got the files to make these through a donation to Ukraine's ongoing defense. In some areas it can be hard to source the 2N5457 JFET, so alternate resistor / transistor options are provided (the unpopulated R8_A and Q1_A spots on the silkscreen) so a normal silicon NPN transistor could be used instead. I haven't tried that particular mod as I had a lot of JFETs I'd picked up from Pedalhacker, but I may in a future version.
In the interest of trying to keep it old school, I also had what I hope is a genuine LM308N op amp - it seems to be working properly. That being said, I also have a supply of OP07 op amps I can pop in to compare the two. The board incorporates two of the most popular modifications of the Rat as well. Both were originally designed to be internal, but with a little back and forth with South Obolon FX, we found a way to move one of them external! The Ruetz mod changes the cutoff frequency for one of the op-amp stages' high-pass filter. I could have taken this external with a trim pot, but decided to leave it internal. The other mod is the choice of clipping diodes. The board includes space for the original Pro Co Rat silicon diodes (1N914) as well as the Dirty Rat's germanium diodes (1N34A). You could hypothetically also make the Turbo Rat version with two Red LEDs - or mix and match. I decided to stick with the Rat / Dirty Rat combo.
For the off board wiring, I decided to try something different on this build - I ran all of the power, ground, and connection wires from the bottom of the PCB rather than the top. These boards were originally laid out to where people could etch their own PCBs rather than having to get them fabricated, so almost all of them are effectively one sided to the bottom. This board was also originally designed to go into a 1590B enclosure with side mount jacks, but I wanted to transfer it over to a 125B with top mount jacks. That made the knob placement a little unusual, but it also gave me room to add a sub-miniature SPDT switch to the clipping control and bring it to the front of the unit.
The enclosure features more dino art from Ukrainian artist Estelkatrin. This time around, it's the Ratchasimasaurus (a mouthful for sure, bit we've effectively got the Rat - asaurus). Yeah, it's a fairly obscure dinosaur, but there were some interesting life interpretations online, and the artist was able to run with it. Since it is an Asian dinosaur, I sort of went with my Asian theme for the rest of the pedal art using licensed clipart.
As to the pedal - well, it's a Rat. It sounds like a Rat and responds like a Rat. Because the Ruetz mod is internal, I just sort of set it where I like and leave it. I love having the option of going between the regular Rat and Dirty Rat modes at the flip of a switch. The AionFX pedal has a clipping switch, but his interpretation of the clipping stage and its functionality is a bit different, and if I'm being honest I kind of like the raw, basic Rat sound of this one better.
A bit more at the blog: https://steggostudios.blogspot.com/2023/01/another-filthy-rodent-cloning-old.html
