My first amp build ever was this Champlifier. After modding my Blues Jr. successfully, I figured...why not build an amp? It's just some resistors & capacitors & tubes & transformers....how hard can it be??
Read a bunch. Asked a few questions. Then dove in this week....
Impressed overall by the quality of the parts, and the clarity of the instructions. That being said, there were a couple of small snags. The board went together smoothly...not one bit of trouble on the assembly. Read an earlier post about making the leads 1/4" longer than instructed....that was helpful in most cases. When mounting the OT, found that one of the 6/32 nuts was actually 8/32. Oops. Had an 8/32 screw handy, so I enlarged one of the mounting holes and used that. Then found the screws on the standoffs were too long...fixed that with some small washers outside the chassis. For some reason the 7" (plus 1/4") white wire in step 13 came up a bit short. Wound up pulling the board, cutting the wire in the middle, and adding another 1 1/2" or so underneath the board.
Toughest part to wire up was the 12ax7 socket. The leads coming off the board were way too short to run as instructed in step 20. But by rotating the socket 180, pins 6, 7, and 8 were now within reach. Just had to keep re-checking to be sure the leads were going to the correct pins. Since the connections were in such close proximity, I used a bit of heat shrink as a precaution. (Also used heat shrink on the power switch, fuse, and non-ground part of the volume pot.)
Another change I made was to the grounding, per some of the discussion in another topic in this forum. Basically added a point using an existing hole in the chassis nearer the inputs. Slightly changed the layout of the inputs to accommodate the changes in grounding, but the circuit's still the same.
When it was time to power up, I ran through a power strip for extra protection (maybe?) and super quick disconnect in case of an "OH NO!" And, well...there were no "OH NO!"s. Everything appeared to function normally through all steps. No sparks. No smoke. No weird smells. No unusual hum or buzz or squeal. No shocks!! Plugged in the Tele, and let 'er rip!
I don't have any experience with these smaller amps, so I don't really know what "correct" Champ tone is. But low on the volume knob is clean and Fendery, and dimed it has that Derek and the Dominoes vibe on input 1. Input 2 is, as expected, less volume and less distortion.
As for actual volume...it's definitely less loud than the Blues Jr. But I can also imagine the wife asking me to turn it down too. To be fair, it's not yet in a cabinet. That's a couple weeks out....being built by Mather Amp Cabinet in Nashville. I read some post somewhere about a Champ keeping up with a drummer. Should a Champ be that loud??
So aside from not knowing how loud this thing should really be, the other thing I'm unsure about is the indicator light. It tends to fluctuate in brightness.....is this normal??
Meant to put in a screen resistor, but I forgot.....dang! I'll add that this week. Probably gonna make the negative feedback switchable as well.