I purchased a 2006 Highway One Precision Bass about a month ago.  I knew I wanted to make some changes to it because Fender instruments are among the easiest to modify and ever since I shielded the Spector, I wanted to do more.  I decided to follow Lyle Caldwell’s Jazz Shielding Guide down to the semi-star grounding scheme.  This would make it easier to open up the cavity with only two wires connecting the body to the pickguard.  

I also wanted to swap out the capacitors in favor of the popular Orange Drop.  There were many good reviews from members on TalkBass so it seemed like a good way to go.

I dug into the project by first opening up the bass and surveying what I was dealing with.  I must admit, I knew very little about the Highway 1 when I bought it, other than it had some nice upgrades like the BadAss Bridge 2, a nitro finish, and a great neck.  When I removed the pickguard I noticed immediately that this wasn’t a traditional tone circuit.  I consulted with the TalkBass experts and found out that it was in fact the Grease Bucket circuit.  The goal of the circuit was to allow for a cut in highs without a boost in lows, resulting in very growly, mid heavy sound, when the tone was rolled off.

This development led to a moment of decision: keep the Grease Bucket or switch to the traditional P-Bass tone circuit, consisting of a single cap that bled the highs off to ground.  The decision was too difficult so I decided to use both.  Basically, there would be a switch that would toggle between the two different circuits, allowing me to get two different sounds out of one bass.  With a lot of help from a fellow TBer, I was able to come up with a circuit that would make this possible.

So first things first, take everything out.  On a Precision this is simple to say the least.  The only thing that really holds the electronics package to the body is the ground wire from the bridge and the grounding terminal in the cavity.  Once unsoldered/unscrewed I was able to pull out all the electronics.  After cleaning out the cavity, I laid down the copper shielding and then tack soldered all the seems to make it last.  I also laid the copper tape on the back of the pickguard to make a complete shielded box.  Step one done.

Next, I replaced the bridge ground with a little thicker wire and ran it to the cavity.  This wire, as well as the ground from the pickup, and a third wire that would be attached to the ground terminal of the input jack, were coupled to an o-ring connector and then screwed into the shielding.  This is the basis of the star grounding system, maintain one common point for electricity to travel to ground through.  

After that, I was able to start piecing together the lion’s share of the electrical components.  I completed the volume wiring, so there was signal going to the input jack.  Then I wired up the common leads of the first switch, using the lead from the volume pot and running the other side to outside terminal of the tone pot.  Then I constructed the traditional tone circuit and then finally the Grease Bucket.  Everything was connected, grounded, and ready for run.

The first hang up was fitting it all in.  The Orange Drop caps were at least 5 times as big as the Fender caps, so squeezing three of them in there was a slight challenge, but I managed to make it work.  Once everything was in, and some pickguard screws were put in to hold it all together, I was having a grounding problem.  This was because the input jack was oriented the wrong way and was being pushed into the copper foil.  A quick adjustment and the bass was fully functional.  I had pulled it off.

I had decided to use two switches instead of one mainly for the look of the switches.  All of the 3PDT switches (which is what I would need if I used only one) were just not going to cut it for me.  I think it looks great with two and am glad I went that way.

The difference in tone circuits is not humongous but it is definitely discernible.  I have not had the chance to rehearse with the new system yet, but I am anxious to see what it can do.

Even if this project did not have a lot of utility, it was still really amazing to completely rewire the entire bass myself.  I feel like I understand how it works significantly better than before, and if anything should go wrong, I will be able to diagnose the problem with confidence instead of trepidation.

It has also inspired me to revisit the notion of adding a kill switch to the Spector to prevent prematurely draining the battery when I forget to unplug the bass.  I ordered a push/pull pot when amassing my parts for the Precision but couldn’t use it because it had a split shaft where the pots for the Precision are solid shaft pots.  The Spector uses split shaft pots and wiring it up should be incredibly easy.  I could also remount the batteries in the bass better than they are now and possibly star ground the whole bass.  First, however, I need a break to enjoy the Precision and get back to playing.

Just picked it up last night.  It is a 2006 Fender Precision Highway One.  I love the nitro finish on it and the upgraded bridge is nice.  I need to clean it up, slap some new strings on it, and then play the crap out of it.  Can’t wait.