After all that logging in stuff, I forget the question. Oh yea, lol. First this is a class A tube amp. By it being a tube amp, there's more power per watt than a solid state amp, and a class A amp has more power per watt than a class AB amp. So this little beast is really powerful. Iv'e been looking for some mods to do to this all over the internet. All I get is a bunch of hype about replacing tubes etc. Replacing tubes is not really going to do much. There are only 3 tube manufaturers in the world, and several dozen Tube brand names. All the same tubes just with different stampings/ slik screen on them. 12ax7 tubes are all made in Cihna. Switching to higher output tubes is not a good idea. Some say going from 6V6 to 6L6 or whatever, changes your bias makes things run hotter doesn't give that much more power wth running higher voltages on the whole system. Youre gonna fry something. Name brand tubes like Groove Tubes are the same. They "hand select" for matching tubes and are not seconds, so thats OK. Not any better that what came with your amp. Upgrading to a 10" speaker is not really a mod. you have a plug that unplugs the speaker and you can plug it into any speaker you want as long as it's not under 4 ohms. I went tied several speakers and wound up replacing the 8" with an Eminence 10" from a Fender amp that had 2 10" speakers. Going to a good 10" is a good idea IMO. All the first stage of the preamp is done with the effects and modeling section. The 12AX7 is a dual preamp tube. Has two triodes in one tube. One is not used The other one is a buffer booster for the 6V6 power tube. The Gain knob adjusts the input level to the first stage (the modeling and effects) with is half of the preamp. Then the volume knobe turns that up or down.
the direct out come directly from that stage. The direct out is not tube amplified whatsoever. What I want to do is bypass the effect/modling pre-amp stage and wire up the other half of the 12AX7. In other words, a true modification, that isn't that complicated. I want to be able to switch from the effects/modeling to the unused half of the 12ax7 and thus have a totally tube amp. It's hard to find any info regarding this other than looking at the schematic of an old Fend Vibro Chmp and see if it's doable without a lot of fuss. Finding full schematics of the XD is not easy (many of the details of the XD are omitted. The old Vibro Champ schematics are all over the web. I hope this post answered some of the questions ppl here have, and I hope someone out there can help me with want I'm trying to do. Well I'll keep working on it, and if I get some answers and can convert this awesome little amp into even something better, I'll post an update. I'm sure there are others who'd be interested in doing this also.
