I'm going to put a Stratoblaster preamp in the yellow Danelectro DC-2. I've never had one in any guitar, and for some reason it seemed like an interesting thing to try.
I've always been curious to try the Stratoblaster. One of my old guitar heroes, John Lees, had Alembic do some mods many years ago on his famous gold sparkle 1961 Stratocaster, including the Stratoblaster. After all these years, I figured, why not try one myself?
I have the kit from General Guitar Gadgets. There are some mods J.D. Sleep made to the circuit, including the use of a 50K reverse audio taper pot instead of an audio taper pot, which he says provides a better taper.
Now, the original Alembic circuit had a trimpot on the PCB, but it seems to be to be a better idea to put the pot where it's easily accessible on the fly - on the pickguard of the guitar. I also want to include a switch to turn the preamp on or off, again, while playing.
Which brings me to the point of this post. I don't want a separate switch - I'd like to have a push-pull pot to switch it on, and also to control the gain. However, try finding a push-pull pot with a 50K reverse audio taper! Does not exist.
Unless, that is, you modify a standard push-pull switch/pot to use the carbon track from a 50K reverse audio taper pot! Ha!
On the left you see a B250K ('B' meaning linear taper) switch/pot, and our
victim donor C50K ('C' is reverse audio, aka reverse log) pot on the right.
Trust me, this is not rocket surgery.
Not too hard, huh? Even I can do this!
I laid the parts out in order and I'm glad I took this picture. I needed it later.
We're going to swap out the B250K carbon track wafer that's the second piece on the right with the C50K one. Easy.
You could do this with any value or taper you'd like - I see 250K, 500K and 1 Meg push-pull pots out there, but you could easily make a custom pot to whatever value and taper you need.
Originally I tried to drill out the tab, with no luck. Then I tried to cut off the wiper. I had the right idea, but I cut the wrong side (!), destroyed the carbon track, and had to get a new pot.
The things we sacrifice in the name of science.
Put your saw between the carbon track's wafer and the body of the pot. If you put it on the wiper side, you will destroy the carbon track. That's what happened to me, and held me up for a few days while I procured a new pot (I got three from Small Bear in case I wrecked another one...).
What we need is the C50K wafer on the left. Now we'll transplant that into our push-pull switch! Bwahaha!
Note there are some scrape marks on the 50K wafer - no big thing. It doesn't affect the performance at all.
I'll use the white wiper from the push-pull switch since the control shaft can go right through it.
Pulling the shaft up then moves the switch up, and pushing it down moves the switch down. It contacts the respective contacts as it is moved.
Simple and effective.
An electro-mechanical device at work.
Note that the switch terminals should face in the same direction as the pot terminals. It will sort of work the other way around, but it won't fully 'click' into place.
Don't ask me how I know this.
A custom value push-pull pot! Works perfectly.
Now to install it on the guitar.