Spare Parts Slasher (Keeley Katana Clone)

When I first started building pedal circuits I wanted to build a Keeley Katana clone. It seemed all the rage, so I figured I may as well have one. Back before I built all of my Klon Centaur clones, paying a few bucks for a 7660S chip for voltage adjusting seemed useless to me. I questioned why I even needed a charge pump when I could just use an 18v power adapter. At that time the only layout for the Katana Boost clone was from tagboard effects. It sat in the back of my mind for ages, because while I really wanted to build it, I didn't see the need for the charge pump, and I didn't quite understand how to remove it from the circuit/layout. Maybe one day... well today was that day! Actually, a few days ago was the day, because I decided to finally do the modification. I'm not a professional musician, so having the internal charge pump isn't as important to me as it would be to them.

The basic bones of the layout were left the same, but I did sub some oddball JFETs for the 2N5484s. I had a J103, J112 and K223 laying around, so I asked ChatGPT which would work best, and it claimed J103 for the clean boost (Q1) and J112 for the high gain (Q2). It claimed the K223 wasn't a really musically unusable JFET; this will be addressed in just a moment. I only had a C250k potentiometer, so I used that too. Everything else was left the same, and when it came time to test the circuit I got nothing whatsoever. After about an hour of back and forth with my old pal AI bot, I decided it was time to take the J103 out and replace it with the only JFET I had left, the K223.

The issue was J103's gate couldn't be pulled down to 0v, no matter what I tried. The little bastard fought me tooth, nail, source, drain and gate. There just wasn't anything I could do. Once I had subbed the K223 in as Q1 the circuit came to life. I adjusted it to the maximum clean boost and it sounds ok. Does it sound like a Keeley Katana boost? HAHAHA no. The transparency just isn't there. Does it work as a boost with two gain stages? You bet your skid marked underwear it does! Would it sound better with 2N5484s? Probably. I was scared to order parts to build this, being completely unsure if it would even work. I did make sure all components are rated above 18v, but this sounds perfectly serviceable even at 9v. The C250k doesn't sound too bad either, a bit of an odd sweep, but not unusable. Crucial detail: The J103 and K223 have different pinouts, and were adjusted to the required pinout.

I'm sure there are circuit builders who will come across this and think I'm an idiot. *tips hat* Howdy! I simply overthink everything, usually until I talk myself out of it. When I do follow through with something I've created or modified, I'm never confident in it. Ever. Even after the circuit has come to life, and it's been tested thoroughly. There's always a shaky voice in the back of my head telling me it's going to break and never work again. Especially once I've removed it from my test rig and packed it away. Weird stuff happens sometimes, and it makes no sense. For better or worse. Well, if you want to omit the charge pump and build a stripped down clone of the Katana boost, here you go. Full credit for the original layout goes to its original author in the link above. In the future I may build an external charge pump to have around, but for now an 18v power adapter works just fine, but it still does just fine at 9v.