The Lab Rat -- A bass for pickup experimentation

[Jon Clegg]

Received my high quality (CHEAP!) long scale neck:

Fret board has some ugliness, and of course it arrived with a slight back bow due the truss rod being cranked down a bit. Loosened the TR and it seemed to straighten out nicely. Really won't know until it's strung up. Worse case, I have to jack up the action higher than usual -- hey this thing is for experimentation.

In any event, I'm ready to rout and fit it and trim the excess from the body.

I've also decided to abandon the idea of magnetically mounting the pickups; instead I'm going to put aluminum rails in for the pickup carriers to clamp to.

 

[Jon Clegg]

Neck pocket is routed and the body has been contoured and re-shaped, sligthtly:

Guess I've been looking at @JIO 's Teisco-Birds too much!. Originally I had reolly only planned to play around with really flat low-Z pickups with this bass. and so I wouldn't need to rout out a whole swimming pool. I've since decided to play around with some other pickups as well so I'm going to rout out a 5/8" deep swimming pool that should allow enough depth to play with a few different pickup designs.

 

[Jon Clegg]

Neck all fitted up:

I had some spots on the back where some wood had been removed, so I fitted some excess maple and sank the neck bolt inserts:

Routed out the swimming pool and the control cavity
:

I decided to play around with some of the Red Mahogany stain just for laughs:

All bolted up with a pickguard and my mounting rails. Just need to wire up and string up and set up some pickups to play with.

 

[RBS_Johnson]

I really should build me a test mule like this at some point. Maybe I'll do up a quick one before the winter build off the help hone my routing and general woodwork skills a bit?

 

[Jon Clegg]

I really should build me a test mule like this at some point. Maybe I'll do up a quick one before the winter build off the help hone my routing and general woodwork skills a bit?

Not a bad idea. You could even prototype what you plan to build and then turn that prototype into a test mule.

 

[Five String]

Sub'd

 

[Jon Clegg]

Not a bass, but a bit of retro-coolness for folks like @JIO and myself that like funky old MIJ stuff: A 1965? Tele-Star RD2V. Chrome pickguard very good condition:

Hell, it even had what I believe to be the molded patch cable that it orginally came with, coiled up and hanging off the headstock.

 

[JIO]

Not a bass, but a bit of retro-coolness for folks like @JIO and myself that like funky old MIJ stuff: A 1965? Tele-Star RD2V. Chrome pickguard very good condition:

View attachment 2812504
View attachment 2812507
View attachment 2812508 Hell, it even had what I believe to be the molded patch cable that it orginally came with, coiled up and hanging off the headstock.

Sweet! Is it as cool/fun to play as it looks?

 

[Jon Clegg]

It is actually. Needs new strings (these might be the originals -- they're flatwounds) and the neck was built by the Japan division of Louisville Slugger. To make it a decent player I'd need to put a tune o matic bridge on it to get it to intonate properly, roller saddles would work better with the whammy bar. It might be a cool subject to pull a JIO on.

 

[RBS_Johnson]

I've got a similar guitar hanging around. Mine's redburst and shows it's age a little more. I've been debating about swapping tuners and bridge out and tweaking it to make it more playable. Ive got it strung up B-b right now.

 

[Jon Clegg]

Yeah, I'd definitely change out the bridge and the tuners. Also needs a neck shim to make the action lower without lowering the bridge too much to work with the trem. Already thinking what I would need to do for a JIO treatment... Find rocker switches, make a pickguard out of aluminum, get either mini-hums or gold-foils for pickups. get a tune-o-matic with roller saddles, use a Mustang trem...

 

[RBS_Johnson]

At that point you might be better off to make another guitar. Then you could keep this one original for wall art, hang it next to the new one

 

[Jon Clegg]

At that point you might be better off to make another guitar. Then you could keep this one original for wall art, hang it next to the new one

Well that's what I mean by the JIO treatment: build a new one using the same approximate shape with better quality components while keeping the vintage MIJ feel.

 

[RBS_Johnson]

Cool, I got confused by the talk of neck shims in the same vicinity.

 

[Jon Clegg]

OK here's an update! First, my incredibly over-engineered pickup mounting system:

Now some controls: the 3 toggles are for coil on/off and series/parallel, 500k Audio for volume:

Time to hook it up! I used small 3-terminal blocks to connect the pickups to the control harness:

Ready to rock (sorta):

Quick little doomy clip for proof of concept: The setup is still a little off, so I kept it simple:

 

[Jon Clegg]

Made another clip; this one starts with the pickup in the 'JIO' position, then I move it to a Jazz Bass bridge position, then Jazz Neck, then PB and finishes at a RIC bridge position, each position gets a passage or about 9 seconds. Sonically, nothing too earth-shattering, cool thing was being able to reconfigure so quickly.



Anyway, the next step is to start building some wacky low-Z (or Hi-A?) pickups.

Also the light pine body on this thing makes it neck-dive like crazy. May install a counter-weight under the bridge

 

[Jon Clegg]

New toy to play with But I have to wait till Christmas.

 

[JIO]

Made another clip; this one starts with the pickup in the 'JIO' position, then I move it to a Jazz Bass bridge position, then Jazz Neck, then PB and finishes at a RIC bridge position, each position gets a passage or about 9 seconds. Sonically, nothing too earth-shattering, cool thing was being able to reconfigure so quickly.



Anyway, the next step is to start building some wacky low-Z (or Hi-A?) pickups.

Also the light pine body on this thing makes it neck-dive like crazy. May install a counter-weight under the bridge

I just listened to a Jack Bruce retrospective CD and your "doom-loop" could be the baseline for "Sunshine of Your Love"

 

[Jon Clegg]

I just listened to a Jack Bruce retrospective CD and your "doom-loop" could be the baseline for "Sunshine of Your Love"

First song I learned to play when I started playing bass.

 

[Bruce Johnson]

About ten years back, I made up a bench mule specifically for testing out pickup position. It's much cruder than what you've built here. The body is literally a rectangle of 3/4" plywood. The neck is a partially completed leftover, not even fully carved on the back, and with pencil lines for frets. Bridge, tailpiece, pickups, neck are all just screwed down to the plywood. A small electrical panel with lab-type binding posts for quickly configuring wiring.

All the geometry is set up to match one of my Scroll Basses. And it's fitted with a used set of Chromes, which are my standard strings. The only pickups I tested were my own, not any standard models. I built this rig specifically to figure out where I wanted to position the pickup on the body of my Scroll Bass design.

After playing around with it for a while, my conclusions are:

Putting the pickup in the middle of the body, about the 36 fret position plus or minus an inch, gives the pickup its fullest, truest sound. That's where the pickup has the fullest range, and the flattest version of its built-in EQ curve.

From there, sliding the pickup towards the bridge basically just cuts the Bass. It doesn't turn up the Treble, but only lowers the bottom end of the curve. This is assuming that the pickup height in relation to the strings is kept the same. It's as if I had reached over to the amp and turned the Bass knob down two or three notches and changed nothing else. Not a drastic change, but a reduction in the bass end.

Sliding the pickup from the middle towards the neck, to around the 24th position, resulted in a small increase in the Bass. Like turning the amp's Bass knob up one or two notches. Again, without much effect on the Treble or Mids.

The other thing that pickup position affects is the depth of the attack curve; specifically the level of the pulse on the beginning of the note. The closer the pickup is to the neck, the louder the "pop" on the beginning of the note. But the sustained part of the note stays the same. The closer to the bridge, the lower the pop goes in relation to the sustain.

Conclusion: Adjusting the position of the pickup on the body is mostly about raising or lowering the level of the bottom end of the frequency curve, but it also affects the depth of the attack curve. Towards the neck is more percussive and heavier bass. Towards the bridge is less percussive and less bass. It's a smooth logarithmic curve in either direction. No magic sweet spots where something strange happens.
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That's what I learned. I'm curious to hear what you find.