Another Champ  |
Purpose |
Tweaks on an already fun amp |
| Design |
Fender Champ 5f1 with mods |
The funny part about me building all these amps is that I don't play guitar - at least not well enough to say that I "play" guitar. So I have been working with friends to tweak these amps to get something they like. One this we wanted to do was try a Champ with a 12" speaker, to add a bit of low end and get that killer 12" tone. I decoded that a Celestion Greenback would be a good choice, since it is has a nice low power handling rating (25W). I built the cabinet roughly acording to the dimensions of a Fender Deluxe. I really like the "narrow panel" look. The material is veneer core baltic birch. There is a lot of voodoo about using fingerjointed pine, but I couldn;t find any pine boards this large, and the plywood didn't agree with my fingerjoining jig - it would pretty much explode when the router hit it. Maybe a tablesaw jig, or a sharper router bit would help. Instead of fingerjointing it, I used a sort of pinned dado joint. This makes assembly real easy because you can use wood screws instead of clamps, and then remove the screws, dill out the holes, and glue the pins in.
Also check out that little nameplate. It says Boozhound Laboratories and is actually a pet collar tag :)
My plan for mods to the circuit was to add a couple tonal options without resorting to a true "tone" knob. I added a bright switch, which selects the value of the cathode bypass cap on the first half of the 6sl7. This gives the circuit a little more gain than the original Champ, which makes up for the 6sl7 having slightly less gain than the 12ax7. I also added a feedback in/out switch. With feedback gives a nice round sound, without feedback makes things sound a bit looser and more ragged, with a bit more gain. The last switch allows you to remove the cathode bypass cap from the 6v6. The lack of cap gives the sound a feedback-ey roundness that is kinda nice. Of course the lone knob is volume.
I just love these vintage turret lug terminal boards. Too bad I went a little crazy selling them on eBay and am running out of them. Unfortunately I built this with Sequa paper-in-oils before I got a box of Russian military surplus paper-in-oils that I can't wait to hear.
The Greenback speaker is really nice. Killer low end and midrange, way more "punch" than the alnico 8" I used on my other Champs,and a bit more efficiency - which might be a bad thing for those seeking a quiet amp. These things need some time to break in, and this one still sounds a little "green". I expect it to get better and better. I can see why vintage greenbacks command such high prices. I would like to try an alnico magnet 12" speaker to hear the combination of increased low end, with the smoothness of an alnico.
I would be interested in selling this amp to fund new projects. If anyone is interested, please contact me at "jsn at boozhoundlabs dot com".
