Why I did this... While the OR15 is a fantastic amp, after a few months and the honeymoon period was over it seemed to be lacking the characteristics I was looking for. I am primarily a metal player and while the OR15 does a decent job, it's not the greatest. Blues and classic rock is what this was made for so I felt it was time to try to trade for a #4. I could have sold it and purchased a #4, but I didn't want to take a loss on it.
After a few weeks of trying to trade the OR, a friend of mine who is more knowledgable about amps and has some connections that I don't was able to give me the information I needed to convert it to #4 specs. The information that was mentioned in another thread was accurate, it was still missing something. I did see and compare the schematics for both amps confirming the accuracy of the component swaps but I do not have a copy of the #4 nor can I get it. I also have NOT compared it to a #4 but I did compare it to another stock OR15 and my amp has much more bottom end and treble making it very aggressive and more suited to what I play normally (Mastodon, Down, Deftones, Alice in Chains). Like the stock OR15, it still does everything really well, it just needs to be EQ'd a bit differently.
I also experimented with making the changes switchable using a 3PDT switch. Since the treble caps are in series, I couldn't really get it to work right since I couldn't get all four components on the switch. Honestly I don't think I would use the stock OR15 setting though, the modified amp sounds much better to me. I play this through an Orange PPC112 with a V30 and an L-Pad attenuator to knock the volume down a little bit for more volume control in my condo. My two guitars are a PRS Singlecut Trem loaded with Lace Hammer Claws and an old Ibanez AX120 that I refinished and loaded up with a DiMarzio X2N in the bridge and a Tone Zone in the neck... Yes in the neck. It has a .022uF cap in series with it to take out some of the mud and it compliments and balances with the X2N nicely. As a finishing touch, I bought a Fantastic Four logo sticker (looks close enough to the numbers on the Slipknot coveralls) and a piece of white vinyl to cover the OR15 text on the amp.
I want to thank jontheid and Man1ak for their help in the other thread for teaching me a few things and pointing me in the right direction. Also to my other friend for the valuable info. Anyway, here is a picture of the modified faceplate and a gut shot. I added everything from the top but I'll most likely remove the board and solder everything in properly. The capacitor next to the modded section melted a bit when one of my dogs decided they wanted to play while I had a soldering iron in my hand. Oops.
