The design John had in mind is a chambered body, loosely based on a T-style body shape. The front and back are pine from a dresser he grew up with back in the 1960s, and the hollowed center core is from old waterbed frame rails. John fashioned the 4-bolt necks from slabs of curly maple, with medium-jumbo frets and Kluson tuners.
Greg Droman
He told me to choose whatever pickups I wanted. After talking it over, we both ended up with Seymour Duncan Antiquity II Humbuckers. He's a big fan of the Pigtail wraparound bridges, so those are what we used. A sprayed-on lacquer finish completed it.
I modified the Karma MTN-10 circuit boards to make it easier for John to mount them inside the guitar. The overdrive is true-bypassed with a push-pull pot on the tone control. John cast the bigger volume and tone knobs (inlaid with white arrow pointers) from his own mold of some vintage 1960s Atwater Kent knobs he found in an electronics store back in the late '70s. A battery bag holds the 9V battery, which activates when a cable is inserted into the output jack.
This guitar surprised us both! It's a total joy to play, weighing in at a back-friendly 6 pounds. It has a cool, hollow, woody tone without the feedback. The pickups sound amazing, with plenty of bite in the bridge and lots of warmth in the neck.
The neck itself feels like silk—fast and comfortable. I wasn't sure how I would bond with an overdrive built inside a guitar, as it's not usually the first in my chain, but it seems to take on a whole character of its own inside this guitar. And it's just plain fun!
We'd been calling it the "Tagg/Karma," but we've now changed that to "Karmatar." It's a beautiful, unique work of art. Definitely a keeper!
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Fig. 1
So, what is this all about? Let's start with coil-splitting humbucker pickups, which is much more common in the guitar world compared to tapping, and we've discussed this many times before. In technical terms, splitting a humbucker means shutting down one of the two coils to ground so the other coil remains active as a single-coil for a much brighter tone, but also with less volume. In other words, splitting a humbucker means making a single-coil out of a humbucker pickup, with all the single-coil pain and glory you know: hum, noise, and reduced volume.
In reality, it never really sounds like a good single-coil pickup. At best it sounds "single-coil-ish," and most of the time, more like a kind of P-90 than a Strat or Tele pickup. Besides this, you'll struggle with an unbalanced volume between the humbucker and the single-coil tone, which is the nature of the beast in any passive guitar circuit, but I'll address exactly this issue in detail soon, in a future column.
"Splitting a humbucker means making a single-coil out of a humbucker pickup, with all the single-coil pain and glory you know: hum, noise and reduced volume."
The humbucker is usually much louder compared to the split version. I think this is no surprise to anyone. Many companies tried to find a compromise for these issues, so there are special humbuckers that sound really good in split mode and like real single-coils. On the downside, these special humbuckers usually don't sound very good as full humbuckers ... choose between the devil and the deep blue sea, it's all up to your personal choice. There are also special humbuckers that try to compensate the volume drop when split. (As mentioned before, we'll cover those in detail in a future column.)
Generally, you need a humbucker with a 4-conductor wiring to split it, so you have access to the start and finish of both coils (Fig. 1). It's not possible to do this with a standard two-conductor humbucker, like a standard PAF-style pickup. With 4-conductor wiring, it's possible to split a humbucker in two different ways.
The first way is by shutting down the slug side (north coil) of the humbucker, leaving the screw side (south coil) active as a single-coil pickup. This is also often referred to as "splitting to the south coil" and is recommended for neck humbucker pickups.
Technically his means:
- South coil start = hot output
- North coil start + north coil finish + south coil finish = soldered together with the bare wire to ground
Fig. 2
- Fig. 2 shows what this looks like for a Seymour Duncan humbucker pickup, but you can use this diagram for any 4-conductor humbucker pickup by simply using a color-chart diagram to transfer the different pickup wires to the humbucker you have.You can also split a humbucker with 4-conductor wiring by shutting down the screw side (south coil) of the humbucker, leaving the slug side (north coil) active as a single-coil pickup. This is usually referred to as "splitting to the north coil" and is recommended for bridge humbucker pickups because it gives a fuller sound than compared to the screw side. You can see this illustrated in Fig. 3.
- Techically this means:
- North coil start = hot output
- North coil finish + south coil start + south coil finish = soldered together with the bare wire to ground
Please note: In split mode, the humbucking function is no longer active, so you'll receive all kinds of hum and noise, just like with any other single-coil pickup. Besides using a switch to split the humbucker, it's possible to use a pot for a variable split (aka "spin-a-split"), but this goes too far for our column today.
Fig. 3
Now, what's the deal with tapping? A standard single-coil pickup is a spool of wire wound around a set of magnets with a start and a finish, connected to the two pickup wires usually referred to as "hot" and "ground," with the hot wire usually coming from the finish of the coil. A tapped pickup has two hot wires with one connected to the finish of the winding, just like with any standard single-coil pickup. The other one is connected to a point somewhere in the middle or close to the end of the winding, effectively "tapping" (hence the name) into the coil to access a different tone. The tapped connection gives you a lower-output version of the full coil for two different tones from the same single-coil pickup. Usually tapped pickups are overwound single-coil pickups, so you have the full power but also a more traditional vintage-flavored tone at your fingertips when using the tapped connection.
Getting access to both tones is very easy to do. With a standard SPDT on-on switch, you can simply engage the full or the tapped connection following this basic schematic shown in Fig. 4. Instead of the additional mini-toggle switch, you can use any standard push-pull or push-push pot for this option, so you don't need to drill any holes into your pickguard.
Fig. 4
It's also possible to replace the switch with a pot to make it variable, so you can blend between both sounds. Technically, it will work, but it's not recommended, because you'll have a good portion of sound loss in a passive system. This is a complex system and, in the background, you'll see that besides the blend pot there will also be a volume pot somewhere for this pickup, so here is a shortened and simplified version.
To make it work in a passive system, you need a high-impedance blend pot— i.e., a 250k pot—to avoid any load of the upper winding, resulting in massive treble loss. Most single-coil pickups use 250k volume pots, but the blend pot needs to be smaller than this to avoid a massive volume drop. In technical terms: The blend pot should not act as a series resistor for the volume pot. Both issues are contrary to each other, so in reality a 100k blend pot would probably work, but only with a good portion of tone loss.
Why? Think of the following scenario: The volume pot is fully opened with the cable capacitance passing through, forming the typical operational resonance together with the pickup's inductance. That's the normal behavior and tone we all know. With such a blend pot explained above that is, let's say, in a middle position, the cable capacitance will not reach the pickup because of the attenuation of the pot. The typical operational resonance gets lost and even worse: A low pass will be created, killing the high-end—a really bad scenario.Next month we'll return to our relic'ing project, talking about aging new electronics. Until then ... keep on modding!
Photo 1 shows the 4PDT switching matrix design for the "up" position, which will put the pickups half out-of-phase.
Let's start with what we'll need to get out-of-phase or half out-of-phase sounds:
- You will need to engage at least two pickups to get such sounds. A single pickup played by itself will always sound the same, no matter if you play it in phase or out of phase (more about this later). The magic starts when you engage two (or more) pickups with one in phase and the other one out of phase or half out of phase.
- In general, you'll need one switch for each pickup you want to put out of phase. This can be only one switch, like on the middle pickup of a Stratocaster, to cover both in-between switching positions (bridge+middle and neck+middle), or three phasing switches, like on Brian May´s "Red Special," with one switch for each of the three pickups.
My design of a multi-phase switch that we'll cover today can be used to expand already existing out-of-phase switches in a guitar or to design a new wiring of your choice, integrating such a switch. With this switch, you'll be able to cover all three possible phasing options: in phase, out of phase, and half out of phase.
The magic starts when you engage two (or more) pickups with one in phase and the other one out of phase or half out of phase.
All you need for this mod is the switch, plus a capacitor and a resistor for the half out-of-phase option. So, let's start with the switch itself. For this mod you need a 4PDT on-on-on switch, which means a switch with three switching positions (up-middle-down) and a total of 12 lugs, arranged in four independent sections. Such switches are on the border of being exotic, but they're still available. Since every manufacturer uses a slightly different switching matrix for such switches, you'll need to get one with the same switching matrix I used, which is more or less the quasi-standard for it. It's possible to use 4PDT switches with a different switching matrix, but you'd have to adopt the wiring to it. I've provided three photos of the switching matrix and the switch design for each position. Photo 1 shows the "up" position, which will put the pickups half out-of-phase. Photo 2 shows the "middle" position, which will give you the full out-of-phase option. And Photo 3 shows the "down" position, which is just the normal in-phase operation.
Placing such physically large-sized switches on a pickguard or control plate can be a challenge, so you'll have to be creative. There is no way around such a switch when you want this mod because there are no existing push-pull or push-push pots with on-on-on switches. If you can find a 4P3T rotary switch, you can use it to substitute the switch by replacing one of the pots with it. There are also 4PDT slider switches available, but they're physically about the same size, and therefore, not a real alternative.
Photo 2 shows the 4PDT switching matrix design for the "middle" position, which will give you the full out-of-phase option.
Image courtesy of singlecoil.com
Here we go with the wiring of the switch, shown in Fig. 1. With the lever down you have the normal in-phase operation, with the lever up the pickup is half-out-of-phase, and in the middle position you have the full out-of-phase option.
Anyway, there you have it, all in one switch as shown in Fig. 1. On the left side of the switch, you see a capacitor in series with a resistor for the half out-of-phase option. A good average value is using a 0.01 uF capacitor with a 6.2k-ohm resistor in series as an additional serial attenuation of the system, preventing an impedance peak.
When looking at the switch, you'll notice that one switching stage is not populated at all. You might ask: Why don't we use a 3PDT switch for this if we only need three switching stages? This is because of the asymmetrical switching matrix of the 4PDT switches in the middle position (Photo 2) and there's no way around it. If the on-on-on switch had a completely symmetrical switching matrix, then three switching stages would be enough, but such switches aren't available today.
Photo 3 shows the 4PDT switching matrix design "down" position, which is just a normal in-phase option.
Image courtesy of singlecoil.com
In general, you add a controlled degree of reversed phase of the pickup when using the half out-of-phase option, which is great to mimic Stratocaster in-between "quack tones" on a Telecaster, like on the Jerry Donahue Tele models or with the Bill Lawrence Telecaster wiring.
Phase differences are measured in degrees. Totally in-phase sounds have either 0 or 360 degrees of difference, meaning none. Totally out-of-phase sounds have a 180-degree difference. So, half out of phase is either 90 or 270 degrees of difference. That's the reason why you can only achieve a fully out-of-phase effect when using two pickups together with one wired out-of-phase. (When both pickups are wired out of phase, they sound the same as both pickups in phase, because there are still 0 degrees of phase difference between them.) When a signal passes through a capacitor, the voltage leads the current by 90 degrees, so when a pickup's signal gets routed through a capacitor, it shifts the phase by 90 degrees—exactly half of 180 degrees—and therefore half out-of-phase ... in simple terms.
The cap connected to the switch is the phase-shifting cap mentioned above. A 0.01 uF cap is a great starting point, but you may try caps between 0.005 uF (5000 pF) and 0.022 uF. The smaller the cap, the sweeter the sound will be, but this really depends on your particular pickups. I recommend experimentation and fine-tuning to get as close as possible to a Strat's in-between tones.
As for the attenuation resistor, a 6.2k-ohm resistor works pretty well with the 0.01 uF cap and standard single-coil pickups. As a simple guideline, you can follow this rule by choosing and experimenting with this resistor: The higher the value, the more attenuation in the system, the smaller the impedance peak. A good starting point is the DCR of the pickup that's connected to the switch. For example, if your pickup measures a DCR of 6.8k ohms, you should start with a 6.8k-ohm resistor on the switch for a balanced sound and experiment from there. A good option is to use a small trim pot first so you can experiment until you find the value you like best. You can measure the trim pot and solder a fixed resistor with the measured value on the switch, or simply leave the trim pot where it is. A 10k or 15k trim pot is perfect for this.
That's it for this round. In honor of Fender's 75th Anniversary, next month we'll take a deeper look into Fender's history, busting some myths, misunderstandings, and urban legends, while celebrating the man behind the company that started it all: Mr. Clarence Leonidas Fender, or Leo Fender, as the world calls him.
Until then ... keep on modding!
