How-to guide - Making a right handed Jazz Bass (1963 onward) spec wiring loom

In this article I'm going to feature how to make a 1963 onward spec Jazz Bass wiring loom, but also touch on some of the finer details too so that hopefully you're not just copying how to do it, but instead learning about the parts and how they're working too. Always good to have some understanding of how your instrument works I think! But by all means, if you just want to get it made, skip through these bits and get to the wiring!

From the introduction of the Jazz Bass in 1960, the model featured two 'stacked' pots which essentially provided a separate volume and tone pot for each pickup. This however was short lived because in 1963 Fender made the switch to the wiring we perhaps know the Jazz Bass for most, because it has primarily been the go-to spec for wiring these ever since. The '63 onward spec features a volume pot for each pickup and a master tone control. Each volume is wired independently, meaning if you roll down the neck pickup volume you will be left with the signal remaining from the bridge pickup, and vice versa. 

So I'm going to show how I prepare a loom for this spec of Jazz Bass, and hopefully it will help you on your own build/install too.

Let's kick things off with what parts you'll need - 

Now of course there are numerous brands and styles of pots you could use but for the sake of simplicity here, I'm just going to refer to the same quality CTS items I use here in my pre-wired looms. If you are wiring a far eastern made Jazz Bass, and don't wish to modify/replace your control plate or pickguard, then you might need to consider using smaller metric sized pots for this task. But on this occasion, CTS pots primarily are made to Imperial sizes/measurements, so if you have a Mexico or USA made Jazz Bass then the CTS pots will be a direct fit for your control plate/pickguard. They have a mounting thread diameter of 0.370" / 9.4mm so I recommend for ease of install a control plate with 0.394" / 10mm pot mounting holes are required. If we're looking at the traditional specs here, Jazz Basses usually feature 250k pots, with solid shafts. Those solid shaft pots measure 1/4" / 6.35mm and will suit the traditional Jazz Bass grub screw secured control knobs. You could of course use 500k or other specifications if desired or if you have alternative pickups installed that are optimal with different pot specs, but again, let's stick to the traditional specs here.
If you need to purchase some CTS 250k pots for this job, perhaps consider doing so through my online store HERE
For reference, on this particular build I am using the CTS 450 series 'SSSP' 250k Solid Shaft pots (x3)

Jack socket
As we're focusing on quality, 'USA' spec traditional parts here, a couple of great options to use are the Switchcraft Mono jacks, or if you fancy something a little more fancy, perhaps the Pure Tone Multi-Contact jack socket will suit. The Pure Tone item features additional contact points for the plug when engaged, which although I don't feel arguing 'tonal' improvement is at all worth it, I do strongly feel that the reliability is greatly improved. Again, should you need to purchase a jack socket for this job, perhaps consider doing so through my online store HERE

For reference, on this particular build I am using the Pure Tone Multi-Contact jack socket in nickel (x1)

I personally love working with Gavitt wire. Yes, it is the 'vintage' style, period correct option, but I don't specifically choose to use it for that reason. I primarily use it because it is very easy to work with, it handles great both to expose the central core wire and to 'manipulate' within the cavity to achieve nice and neat installs. It is also very consistently made, accurate to it's specified gauge (AWG) and also comes supplied pre-tinned which helps during soldering. Should you need to purchase some lengths of wire to carry out this wiring job, perhaps consider doing so through my online store HERE

Most retailers, including myself, tend to offer Gavitt wire supplied in 2ft lengths. As a Jazz Bass wiring loom is fairly compact, you won't need much at all, so a single 2ft length will provide you with plenty to work with and some spare if you need to re-do any bits along the way. What 'colour' of cloth covering you choose is entirely up to you. You may also notice on my documented wiring work here, I apply little cuts of heat shrink tubing to the ends of each piece of wire. This isn't specifically necessary for your own install. I merely do this as I find it helps 'seal' the cut ends of the cloth to further help prevent it from fraying. At the end of the day I am selling pre-wired kits and intend for them to look as neat as possible, and foresee any handling mishaps too, so any extra little details like that are simply done for professionalism. You can certainly attach you wires without these little heat shrink additions, but if you wish to do so, feel free to follow my lead :) Heat shrink is available HERE

I won't go into type here, let's keep the paper in oil, Mustard, orange drop, ceramic disk discussion/argument to the forums! I'll simply focus on the 'value' or spec here. In 1963 onward perhaps the most common spec of tone capacitor you will see in a Jazz Bass will be a 0.05uF / .047uF (Micro-Farad). But in more recent years some models have featured a .022uF for example, which will yield slightly 'brighter' results by comparison. There is no real right or wrong here as ultimately the sound/response from a cap is down to personal preference. On this occasion the kit I am making, the customer requested a 0.022uF, but the exact same installation process will apply regardless of the value chosen. Should you need to purchase a tone capacitor for this job, perhaps consider doing so through my online store HERE

For reference, on this particular build I am using the Tube Amp Doctor 'Mustard' style tone cap .022uF (with one of my custom heat shrinks applied simply for branding purposes)

I'll try to keep this to the bare essentials needed for carrying out this task, but when it comes to specialist tools, the more the merrier I say! 

Minimum 40W soldering iron
I say a minimum of 40W as most solder wire you can buy these days is lead-free, and lead free does require a hotter iron/working temp due to it's higher melting point. A 40w Iron should achieve a working temp of somewhere around 400 degrees C, which is great for lead free soldering and in particular making your ground connections (pot casings etc).

Solder wire
There are varying specs, and quality of solder wire available. If it helps, I personally use Rapid/R-Tech lead-free 22SWG 0.7mm. It has a flux core so you don't need to use flux additionally, but overall I find this to be a good lead-free solder wire to use for guitar/bass wiring work. Techs/luthiers etc tend to have their own preferences though, but this is what I use everyday so hope this helps narrow down your search. Ideally use this in conjunction with some form of fume extraction, or in a well ventilated area. Although lead-free is of course, as the name suggests, the fumes from the flux is still pretty nasty really, so best to think about how to do all of this safely. 

Small or Needle nose pliers
These are really helpful for any wiring work, such as handling smaller parts that your fingertips might struggle to grasp, simply placing onto a wire to keep still whilst soldering a joint or using to shape/bend wires for installation for example.

Wire snips/cutters
You'll need some cutters to trim your wire length, if you have some guitar string cutters for example those might be useful here too for example. 

1/2" or 13mm Socket/spanner
This will be used to tighten the CTS and Switchcraft / Pure Tone jack mounting nut when fitting the pots and jack to your control plate

Philips screwdriver
This will be used to remove/re-fit the 3 fixing screws for your control plate

Small flat head screwdriver or Allen key set
This will be used if you have grub screw secured control knobs for example. Many of these traditional control knobs have a small flat head grub screw to secure the knob to the pot shaft. Some however have allen key grub screws so inspect what control knobs you have and go from there. What size you need will depend on the specific control knobs used. 

These are of course useful for a number of tasks, but primarily here it's useful to measure your pots (and if capable, your capacitor value too) to help ensure they're within tolerance and/or the specs you wish to use. As well as testing continuity for your ground connections too. They're always handy to have around for any guitar wiring work though. 

Wiring style/schematic

So with the parts prepared let's start by looking at the schematic. Thankfully the Jazz Bass is nice and simple, although we have two pickups, we don't have any pickup selector switches or fancy options. It is a simple two volume, one tone, jack socket configuration, with the volumes wired 'independently'. Let's look at why that is; In guitars and basses with 2 or more volume controls, you will likely either see those volume pots wired dependent, or independent of one another. The Jazz Bass is a classic example of a 2 pickup instrument wired with independent volume pots, and if you're familiar with guitars too, then the Gibson Les Paul for example is a classic example of a 2 pickup instrument wired with dependent volume pots.
So how do dependent volumes work I hear you ask, and why isn't a Jazz Bass wired that way? Typically 2 dependent volume pots would be wired with their relevant pickup 'hot' wire being soldered to the input lug (1), with the wiper (2) being used as the 'output' off to the switch, or jack etc. In a bass with two volume pots wired dependent of one another, if you rolled down one, it would cut the entire signal. So you would lose the individual pickup positions, something that is usually particularly useful in a JB. You couldn't have neck only, and you couldn't have bridge only, not ideal eh? If the Jazz Bass left the factory with a 3 position pickup selector switch, then this likely wouldn't be of concern as you could simply flick between the individual and together pickup position with ease via the switch. But seeing as we're solely relying on two volume pots to achieve our pickup isolation, we ideally need to wire our volume pots a little differently. With the pickup's 'hot' wire being soldered to the central wiper lug, and the output moving over to the number 1 lug. That's where independent volumes step in. If you want to learn more about dependent and independent volumes, feel free to read through my article on it HERE.

For independent volume controls, most commonly used in traditional Jazz Bass wiring, our pickup signal needs to be wired to the relevant volume pot 'wiper', or the middle lug. This will allow us to independently control each pickup, providing us with neck only, bridge only, and both together with some element of blend with those too.

We of course simply have a nice master tone here too.

To view the wiring schematic for a traditional right handed '63 onward Jazz Bass, click HERE

Getting started with the wiring
Needless to say, Please take care of yourself and your bass when carrying out any wiring work. I / James' Home of Tone cannot be held responsible for any damage caused by dangerous or incorrect techniques used. But hopefully this guide helps prevent any of that. So let's dive in to the action!

Checking your parts
Do you need to do this? Not necessarily, particularly if you're buying quality tight tolerance components from a reliable retailer. But if you're curious, then why not! You might use this opportunity to test the three pots to check they are within tolerance and the spec you wish to use. These are 250k stamped pots, with a +/- 8% tolerance. Meaning in theory they should each read somewhere between 230k and 270k. Tight tolerances essentially means more predictable results. By comparison, a cheaper pot which might have a 20% tolerance for example, could result in a 250k pot reading anywhere between 200k & 300k.

To check the pot using a multi meter, set it to a suitable Ohm reading (on my UNI-T meter the 2M setting does the trick for a variety of pot values being tested), and with one probe placed on the ground lug (3) and one probe on the wiper lug (2), turn the pot to '10' so to speak as if it was all the way up, and check the reading.

If it's within tolerance, we're good to go. On this occasion we certainly were thanks to the great quality CTS 450 series 'SSSP' pots, with readings of 247k, 242k & 235k for each, all comfortably within the stated tolerance which will provide me with the result I expect to hear in use.

Some multi-meters allow for testing of capacitors, mine does but with limited readings, and I suspect many won't at all though and I don't expect you to have, or buy specifically, a capacitor meter to hand for this so don't worry too much. But for the sake of example, I'll show the testing of the tone capacitor here, to display it is within it's stated +/-10% tolerance spec.

So the .022uF Tube Amp Doctor 'Mustard' we're using on this particular build, it should read somewhere between 0.0198uF and 0.0242uF. I'm actually seeing 0.02263uF so I'm certainly fine with that, it'll perform as expected which is all that matters!

Mounting the pots to your plate
You may of course wish to do the main build off the plate, using a card template for example. But I find it easiest to do it straight onto the control plate as the layout/measurements between components is perfect, and you can check your ground continuity too. So grab your 1/2" socket, or if you don't have imperial set, a 13mm will do fine, and secure the three pots and jack socket to your control plate. Jazz Bass control cavities can sometimes be a little tight, especially when using these traditional full size pot casings too. So get them lined up nice and straight to help prevent any install issues.

Testing for ground continuity
This is a good opportunity to test your ground connection. So with the pot casings secured against the traditional metal control plate, this in theory should provide sufficient continuity. But it's worth checking just in case for whatever reason the plating for example isn't conductive. 

So set your multi-meter to the continuity test setting, and place one probe on the control plate, and then with the other probe simply place it on each pot casing one by one listening out for the beep, then place it on the jack 'sleeve' or ground lug and again listen out for the beep.

If you're getting a good consistent reading throughout those points, then you're off to a good start. You will not need to solder additional ground wires between the pots, as the plate is providing you with sufficient continuity and a ground connection. Adding further ground wires has the potential to introduce a ground loop.
If for any reason though you are not getting continuity, (or you are mounting these parts to a plastic pickguard for example), then there may be an issue with the plating and it will be worth soldering a specific ground wire between each pot casing and the jack ground lug. You will definitely need to do this if you are mounting straight through a plastic pickguard/plastic control plate for example. So please keep this in mind if this is the case for you. 

Preparing for soldering / Pre-Tinning
With our parts mounted, and ground connection tested. We can start preparing for soldering, and 'pre-tinning' where we plan on making our connections. This is particularly useful I find when working with lead-free solder, which as mentioned earlier on has a higher melting temp. This can for some users make it a little trickier to make ground connections, so pre-tinning areas where you plan to make a connection can really help the process. If all of this is new to you, I highly recommend practicing these methods/techniques on any old or scrap pots etc first, you'll thank me later when you've got the technique down and are making nice and neat connections on your new quality pots :)
So later on I will be attaching each pickup ground wire to the back of each volume pot casing, the ground lug to the casing, the ground wire from the bridge as well as the one lead-out from the tone capacitor too. So I'm going to pre-tin and prep the areas of the pot casing I plan on doing each of those connections. Here are some photos of me showing the areas where I plan to pre-tin with solder.

I set my iron temp here to 400 degrees C, my personal preference for fast, effective tinning of ground lugs/pot casings with Rapid 22SWG lead-free solder wire. 

Neck volume pot - Here I pre-tin an area central of the pot casing back, this will be for the pickup's ground wire a little later on. An area for where I'll be soldering the wire coming from the bridge and I also pre-tin a small area just behind the ground lug (3), as I will need to bend that lug back onto the casing and solder it.

Bridge volume pot - As above, but with one less. Here I pre-tin an area central of the pot casing back, this will be for the pickup's ground wire a little later on.
I also pre-tin a small area just behind the ground lug (3), as I will need to bend that lug back onto the casing and solder it.

Tone pot - Here I simply need to pre-tin an area on the pot casing where the outer foil side lead out from my tone cap will be soldered too. I find with the size of the mustard casings I use here, doing this on the casing edge suits really well. 

Jack socket - The 'hot'/tip lug isn't usually pre-tinned on Switchcraft or Pure Tone jacks, so it is worth doing so whilst we're at this stage to make your wire connection later a little easier.

As touched on earlier, if you need to make a ground wire connection between each pot/jack, then you will also need to pre-tin an area on the casings to allow for this too.

If using the same quality CTS 450 series pots as I am here, you won't need to pre-tin the lugs on the pots, those are often pre-tinned from the factory. But if they aren't, due to the material used for those it is usually easier to flow solder onto them anyway (and can use a lower iron temp to do so if you have an iron that enables adjustable temp, something like 350 or 375 degrees C does the trick fine for lugs for example with lead-free solder wire). 

To pre-tin, with the iron up to temp, and a clean/tinned iron tip, simply place the iron tip in the area you wish to flow some solder on to and allow the surface to warm up a little. Warming the joint helps the solder flow and 'take' to the surface. If you've ever struggled with flowing solder onto ground connections/pot casings, this is likely because either the iron tip isn't clean or tinned therefore not effectively transferring heat, or you haven't warmed the connection/area first and solder won't happily flow onto a 'cold' surface. For the sake of example here, running my iron at 400 degrees C, it takes roughly 5/6 seconds to warm the surface for solder to 'take' to it. So I place the iron tip on the surface, allow for around 5 seconds and simply flow a little solder wire onto the iron tip and surface. That should leave you with a little solder circle, and a pre-tinned area to make a wired connection to later. As in some cases here we're doing two or three pre-tinned areas per pot casing, so if you're at all worried about over-heating the pot, Just give it a bit of time in-between each flow to allow the surface to cool down.

Soldering each volume pot ground lug
Here using our needle nose pliers, we'll bend back the ground lug (3) towards the pot casing to little pre-tinned area we did during the previous step. Then with the lug against the casing, we'll again place the iron tip on the area, ideally so it is touching both the lug and the casing for a brief moment to warm the connection, then flow some solder! Be careful not to flow too much solder here as it could in theory run down the casing and pool up in unwanted areas near the internals. In theory thanks to the pre-tinned area, a fairly small amount of solder wire here will do the trick and will flow nicely. Then repeat the process for the 2nd volume pot

Attaching the tone cap
There's no set rules about the order in which you do all of this, I just find it easier to attach the cap at this stage.
Orientation; Some capacitors will have a marked 'outer foil' usually with a band/ring printed on one side of the casing for example, if yours does, then ideally you want to solder the lead out wire on the outer foil side, to ground. This is important practice within amplifier building for example to help reduce unwanted noise/interference, but isn't quite as important with super simple guitar circuits. Some/most capacitors won't have a marking so this isn't always quite as obvious, orange drops spring to mind for example, but don't worry about this too much as within a simple guitar/bass circuit, it isn't hugely important. Unless you have an oscilloscope by chance, or fancy spending time hooking up crocodile clips to an instrument cable plug, then I wouldn't loose sleep over outer foil orientation within a guitar circuit too much. But if the cap you're using does have the outer foil marked, you certainly may as well solder the outer foil side lead out to ground.

I use my needle nose pliers here to help manipulate the lead-outs into the position I want to fit the cap to the tone pot. As the casing on these mustard caps is relatively large, I find it good practice to bend the lead-out downward so I can have it poke through the relevant lug (3 on the tone pot on this example) all whilst keep the cap casing sat nice and flat against the pot casing, like so..

I then place the iron tip on the connection, warm the joint momentarily and flow some solder on. This is a good example too of simply using your pliers or weighted hand tools to help hold components in place/still. You can certainly buy and use lots of fancy helping-hand jigs for soldering, I own one myself, but I find it more hassle to use those with varying results, than to just quickly use the pliers I already had right by me anyway. It is good practice here to leave the solder joint to do it's thing for a moment too. Don't be tempted to instantly move the loom etc as this could lead to a disturbed connection and cold solder joint. So warm the joint, flow some solder and allow it to do it's thing for a mo.

Then with your cutters, snip the excess and move onto the ground side. Again, using your pliers simply manipulate and bend the ground side lead out down towards the pot casing and the area you have pre-tinned. Once happy with the position, snip the excess and proceed with flowing some solder over it.

Place the iron tip on the connection, ideally warming both the lead out and casing for effective transfer, and flow some solder. 

Attaching the wires
As briefly mentioned earlier in this article, I will be applying some small cuts of heat shrink tubing to 'seal' the ends of the cut cloth on my build here, this is simply a personal preference thing and you do not have to do it this way. You can certainly just cut, pull back, solder and push back the cloth covering without the heat shrink. So feel free to follow my lead, or continue on without heat shrink, completely up to you.

I tend to start at the neck volume pot and work my way back to the jack. So first of all I grab some of my Gavitt 22awg cloth covered wire, pull back a portion of the cloth covering to expose the pre tinned central core wire, and place it within lug 1 of the neck pickup volume pot.

Some like to wrap the wire around the lug, but I've personally found this isn't required. I do repairs here at my office also, and trying to work on or replace pots/components when the wires have been wrapped around the lug over and again is, well, frustrating really. It is far easier to work on and repair/replace further down the road when the wire is simply pushed through the lug. But that's just me, everyone has their preferences for sure. 

So I pop that through the lug 1 on the volume pot, place the iron tip on the lug and wire to warm the joint and flow a little solder. Ensuring I keep the connection still after removing the iron to help the joint remain stable and not a cold joint. 

With that wire now in situ, I line it up with the following connection to be made, which is the bridge pickup volume pot lug 1, and cut to length. You might prefer to allow yourself a little 'give' in the wire length, so not quite as tight/neat as I have done here. Leaving a little give in the length might make working on it easier for you, I'm doing these every day so have gotten pretty used to handling looms but if this is a early wire up job for you, giving yourself a little extra working material might prove useful. 

With the wire from neck volume pot lug 1, in place leading to bridge volume pot lug 1, I will now add another length of wire from bridge volume pot lug 1 which will head to the tone pot lug 2(wiper).

So repeat the process from above, pull back some of the cloth covering exposing the central core wire. Place it in bridge volume pot lug 1 alongside the wire you have just also placed there, secure it and flow some solder to make the connection.

Now with that connection made, push back the cloth covering and trim/snip the wire to length at the tone pot lug 2, placing the exposed central core wire in the lug.

Then onto our final wire connection, from tone pot lug 2, to the jack 'hot' lug. This can sometimes be a bit fiddly on a Jazz Bass as they're located fairly closely. But repeat the process as before, placing an exposed end of central core wire into the tone pot lug 2 alongside the existing placed wire, and make your solder connection.

Just so the wire isn't crazy short, and easier to handle, I tend to manipulate the wire to make a 'bridge' shape from the tone pot lug 2, to jack hot. Up to you if you do this also of course! 

And there we have it, loom finished up!

Again, I will note about your ground connections between the pots and jack. As we are using a traditional metal control plate here, of which I have tested for continuity with my multi-meter, I do not need to add additional/separate ground wires between each of those components. But if you are mounting these parts to a plastic control plate, plastic pickguard (neither of which have shielding tape applied for example) or for whatever reason upon continuity testing on a metal plate you were getting no reading/continuity. Then you will need to add a length of wire soldered between each pot casing, so neck volume to bridge volume, bridge volume to master tone, and of course from master tone to your jack socket ground/sleeve lug.After making those wired ground connections, grab your multi meter and check for continuity. 

Hopefully this article has helped you in wiring up your own Jazz Bass loom, ready to attach your pickups and enjoy playing again. I also hope the selection of parts I offer here and have linked to previously in the article, have provided you with the items needed to do this. But if after reading through this you're sat thinking, 'I might just get someone to do this for me', then I also offer pre-wired Jazz Bass looms too. I offer them with the choice of pot and cap specs to suit your needs and are each made by myself with tested components. If you'd like to order one of these pre-wired looms, you can check them out on the online store HERE.

Have you made good use of some of the free resources here? Wired up your bass guitar or found useful info here along the way? Perhaps you might consider kindly supporting this free resource for bassists & guitarists via 'Buy me a coffee'! Thank you so much!

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