Grateful Dead Music Forum

A place to talk about the music of the Grateful Dead 

 #87174  by gdrfk1990
 Mon Sep 27, 2010 8:31 am
Anyone know where to start learning about this ?? I want to convert my old Blues JR either that or I am going to recap it and mess with the tone stack as well as add upgrades to pots switches, jacks and tranformers But if I am doing all that I figure Might as well try and make my own hand wired circuit board etc. I am thinking of something like the SMS preamp or Twin circuit with the same sort of EL84 power amp already in the Blues JR. Does anyone know if this is possible ?? or where I would even start to learn ?? I know they sell a kit with all the parts to make a Blackface Champ will this fit in my Blues JR. can I tweak the preamp on this kit to make it the Twin Circuit. Would I be able to use the Reverb Unit inthe Jr. with the new handwired circuit board ???
 #87177  by WilliamC
 Mon Sep 27, 2010 9:17 am
One place to start learning about amps is

The BillM Blues Jr. mods are easy to do and highly reccomended. The "basic mods" plus the output transformer make quite a difference. The only scary part is drilling a couple of holes in the PCB. Speaker upgrades also make a big difference - BillM's website has a good summary page. If you're going to do the mods make sure you have a good soldering iron - the Hakko that BillM reccomends is not too expensive and works beautifully.

Beyond that, the BJr is a pretty sweet little amp already and the way it's built doesn't really lend itself to major changes. If what you really want is the "Jerry tone" front end, the path of least resistance is most definitely the SMS. There's lots of info here about building a "Jerry Rig". You'll also want to get the buffer and effects loop into your guitar(s)

There is TONS of info on amp (and pedal) building on the web - just google!
 #87179  by gdrfk1990
 Mon Sep 27, 2010 10:04 am
I am looking to build my own circuit board and amp you are right though it probably pays just to buy a cab on ebay and recap my BJ wich I am sure it needs I have been using it consistantly for 10 years. It's funny I have had the imput jack replaced 2 times at my local music store and once on my Deville and asked for metal Jacks every time originaly they told me they would do it and when I got it back they were stock fender they told me they couldn't get metal ones I see them on ebay etc. I might try the simple reacap orange drop caps etc. and tone stack mods but not adding prescence etc. though a standby switch is cool. Right now I am happy with the Deluxe Reverb Re-issue and I am re-wiring with TPC-1sm as soon as it arrives Just lloking for a new project learning how to build a twin circuit similar to the SMS would be a cool project that's all I built the guitar I might as well build the amp too. I think I am going to try and find an empty Hot Rod Cab and chasis and Build a Twin type preamp and smaller power amp with 1 12 JBL and an output for an additional 12 if needed Any Thoughts anyone try this project ???
 #87182  by WilliamC
 Mon Sep 27, 2010 10:36 am
Got it.

Google "DIY alembic preamp" for the front end. I'd want to do it "old school" with point to point wiring and a turret board (like this: ... uitar.html ). But there's a PCB layout here: if you'd rather etch. I'm sure someone can chime in with the parts values to make it more guitar oriented (if any).

Thread about building various versions here: ... .msg643942 is a great site, mostly about effects but with quite a bit of amp stuff as well.

Fender schematics are here:

Not surprised about the input jacks - dealers only have what what's on Fender's (or whoever's) service parts list. Just order the BillM parts and DIY.

Be sure to post a build report and pictures!
 #87184  by tigerstrat
 Mon Sep 27, 2010 11:09 am
gdrfk1990 wrote:recap my BJ wich I am sure it needs I have been using it consistantly for 10 years.
Just a hunch, but those caps are probably fine. They'd be in worse shape if the amp hadn't been used regularly during that time.