Crawls Backward (When Alarmed)

IconProjects, musings about guitar builds, guitar repairs, vintage tube amplifiers, old radios, travel, home renovation, and other stuff.

Building the Jack Orman Booster, Pt. 2

Continuing on with the Mini-Booster build.  After stuffing the board, I wired the off-board leads to the input and output jacks, the pots, and the switch.

I decided early on to add a tone control to this puppy, and the circuit is Jack Orman's modified BMP.  I built the "New AMZ" version, but I do want to try the second variation at some point.

I knew it would be a tight fit, and it was.  I need to recalibrate my thinking when I do stompboxes.  I'm used to using high-voltage capacitors and full-size (say 24mm or so) potentiometers, and I keep those "in stock."  Now I need to get more small (16mm) pots and low-voltage caps.  I have some, but most of the ones I bought are 63 or 100 volts, and those are a bit too big.  These circuits generally don't need caps rated that high.

Anyway, I put the board in the box and wired it up to test and it worked fine.  You can see the test stage in the picture at the top.  Looks like a mess, but the leads will get trimmed and tidied up.

Here's the finished wiring.  It is tight...and did I say these parts are small?  A couple of notes here.  I decided to wire it for 18 volts - two 9 volt batteries in series - to get more headroom.  Also, I took off one of the 2.2 uF caps (it's C3 - where the arrow is) to lower the gain.

This is a clean boost, and I found with the volume up all the way, it would distort.  I'm trying to avoid distortion in this build - I just want a bump in gain.  I have other boxes for distortion.

I have these way cool blue knobs I got from Small Bear Electronics in Brooklyn.  Turns out they won't fit all the way down onto the shafts on the pots, so I had to open the bottom up a bit (drill joke...hee hee) with a 5/16 drill bit.  I just did it by hand. 

Argh.  Vhut ees dat?  No no no no no!

I had a setback.  After I had the whole thing together, I discovered I had scraped up the paint on the box in a few spots when I was tightening the nuts for the pots.  It bugged me so much I decided to repaint the box. 

What I did was unbolt the pots and jacks and drop the whole assembly out.  That's what we have here.  I should be able to just drop it back in after the repainting is done. 

And I need to be very careful on the reassembly!

 
 
 
 

Post a Comment 0 comments:

Post a Comment