Guide: From active to passive pickups in a 7-string

[farren]

*I'm using my C-7 Hellraiser FR in this example, but this process can be completed on any guitar with actives*

I recently changed my C-7 Hellraiser's pickups from actives to passives. This required a bit of work and time, but no single step of it was challenging in a way that should deter any novice tech from making this change if their tonal taste wills it. I could only find one other instance of a 7-string active-to-passive conversion, and in that case, a guy put a JB7 in his Jackson Stars in place of an EMG 707. He ordered a custom pickup ring (about $20 each) from a custom guitar parts site, fretsonthenet.com. This was an option for me, but the wait would have been two months, and I like the look of direct-mounted pickups anyway. Here are the tools I used:

• 15-watt and 25-watt solder iron (you can easily do everything with a 25-watt)[/*:m:14qeu6r7]
• Fine gauge solder[/*:m:14qeu6r7]
• Tapered hand reamer[/*:m:14qeu6r7]
• 22 gauge insulated, stranded copper wire[/*:m:14qeu6r7]
• Wire stripper (diagonal pliers will work)[/*:m:14qeu6r7]
• Electrical tape[/*:m:14qeu6r7]
• Yankee (non-powered) drill[/*:m:14qeu6r7]
• Powered drill (preferably variable rate)[/*:m:14qeu6r7]
• Dremel with fiberglass cutting wheel[/*:m:14qeu6r7]
• Medium-fine flat hand file[/*:m:14qeu6r7]
• Phillips and flat-head screw drivers[/*:m:14qeu6r7]
• Socket wrench[/*:m:14qeu6r7]
• Masking tape[/*:m:14qeu6r7]
• Wooden round toothpicks[/*:m:14qeu6r7]
• Compressed air/duster[/*:m:14qeu6r7]
• Naptha[/*:m:14qeu6r7]

And the new components:

• 3 CTS precision tolerance 500 KOhm audio taper pots[/*:m:14qeu6r7]
• 5-way 4-pole blade switch (you can stick with your 3-way blade/toggle, it will work fine)[/*:m:14qeu6r7]
• Orange Drop 0.22 microfarad capacitor[/*:m:14qeu6r7]
• DiMarzio Evolution 7 and Air Norton 7 (or the passives of your choice)[/*:m:14qeu6r7]
• 3 1/4" knobs[/*:m:14qeu6r7]

To start with, clip and remove your strings (block your tremolo first if you have a Floyd or similar). Unscrew the actives which you'll most likely find were directly screwed in to the wood atop some foam. Lift each up and unplug the cable. Take four of your toothpicks and stick them down into the four screw holes left by the pickups. Make sure they're tight, then break them off flush with the cavity. Open up the electrical cavity on the back and unsolder all of the contacts coming from the pickups. Tape the unsoldered wires together at the ends, then pull the cables from the pickup cavities and set them aside with the old pickups.

The old pots are useless for passives. Unscrew the output jack, unsolder all three contacts from it, remove the knobs, and unscrew the nuts holding the pots in place. After removing the pots, you'll be left with a stereo output jack (perfectly fine for passives, you'll just want to solder one contact to ground and the tip contact to hot) and your toggle/blade switch still in place. Remove the switch if you wish you use a 5-way as in my setup. If you choose not to use a 5-way, you'll only be left with a practical tapped configuration in the middle position (I like to use inner coils of each pickup in the center position as this will be hum-cancelling but also tapped). You can compensate for this by buying at least one push-pull 500 KOhm pot which you can wire to tap both pickups simultaneously when pulled, in which you'd have a single tapped bridge pickup in the 1 position and a single tapped neck pickup in the 3 position. I could go on and on about possible configurations here, but if you look at some wire diagrams online, you'll find you can set up your pots/switches to do whatever you like.

Now we can mount the new pickups. If you choose to use custom pickup rings, this is usually as simple as using a drill press (or a hand drill if you trust yourself) to drill 8 holes in the face of the guitar in which the rings can be mounted. You'll still have mounting tabs sticking out, so you'll want to follow the next step, or rout the cavity with a sanding or routing dremel bit to provide room for the tabs (the pickup rings will hide any messy cutting, and taping the finish before cutting will also help). You might have to use a dremel cutting wheel to shorten the pickup-suspending screws as guitars routed for actives typically have shallower pickup cavities.

If you choose to direct mount, you'll have to start by filing the pickups' mounting tabs. These are the "ears" with the screw holes that stick out on the sides of each pickup. Your active route is 3.5" long, and active 7-string pickups meant for traditional mounting are 3.7" long including the mounting tabs. Swineshead Pickups sell their 7-string pickups with an optional 3.5" base which will fit an active route, but as of right now, no other company does that I know of. You'll have to file 1/10" from each tab. This will also make the existing screw holes disappear, so you'll be drilling new holes later. DiMarzio uses fiberglass mounting bases on their 7-string pickups. If you're using them, you'll want to go outside with your flat file, take a seat, and begin filing 1/10" from each mounting tab. Don't file fiberglass indoors as it's about the worst dust you can possibly inhale. It will get everywhere, including your lungs, if you can see it or not. When you're done, make sure both pickups' tabs clear the pickup cavities, and allow enough maneuverability to center the pickups properly. If everything fits well, you're ready for the next step: drilling new mounting tab holes.

[attachment=2:14qeu6r7]P1010003.jpg[/attachment:14qeu6r7]

Put a 5/64" reamer bit in your drill (again, variable rate) and mark your prospective holes with a scratch awl or sharp knife point. Try to do this outside, or at least in your garage with the garage door open and a fan blowing out. Very slowly drill your two holes in each pickup base. A tech from DiMarzio actually told me modifying my mounting bases wouldn't void the warranty and that if I wanted, I could still exchange them for different pickups under their usual 30-day policy, so that's an added bonus of using DiMarzios. Another big perk is the fiberglass mounting bases--other manufacturers of pickups mostly use brass or stainless steel bases (DiMarzio's 6-string pickups use brass as well). You can still file and drill these, it will just be very time-consuming and annoying. You might want to invest in a special steel-cutting bit for your drill.

If you can find wood screws small enough, you can use them for this next step. Another option is drilling larger holes in the mounting tabs to fit larger wood screws, but I wouldn't want to do this for the sake of stability. Instead, I took the 4 flat-head machine screws that came with my pickups (don't use the phillips head screws that may have also come with your pickups--trust me) and, with a dremel fiberglass cutting wheel, cut about a half inch off each. Again, this is because active pickup cavities are shallower than most passive cavities. File your screws where you cut them so as to make sure they'll neatly fit through your new mounting holes.

Now you'll want to figure out how high you want your pickups to sit. I like about 3/8" from the strings, a bit more or less depending on magnet strength. I didn't have any good high-density foam to sit my pickups on, so I improvised with toothpicks and electrical tape. I taped two toothpicks side by side as a base (two such bundles under each side of each pickup), then continued to wrap the bundles symmetrically with more tape till the pickups sat at an appropriate and level height.

[attachment=0:14qeu6r7]P1010009.jpg[/attachment:14qeu6r7]

Once I was happy with how each pickup was sitting on the table, I put the pickups on top of the bundles in the cavities and pushed them down as far as possible to make sure it was a good height. After that, take your yankee/unpowered handle drill and put the same 5/64" bit it in. You can do this step with an powered drill, but you'll have to be very cautious. With the pickups in place and the central pole of each aligned with 4th string of the guitar (add a string really quick to make sure the poles line up perfectly), push down on the pickup with one hand and slowly stick your drill through each new mounting hole and drill your four new holes in the pickup cavities.

[attachment=1:14qeu6r7]P1010007.jpg[/attachment:14qeu6r7]

We used toothpicks in place of dowels earlier so that if one of your new holes is "sharing" part of one of the original holes from the actives, you won't end up with a large, oblong-shaped hole, making your new pickups unstable when mounted. Once your new holes are drilled (you be the judge of how deep as it will vary from guitar to guitar--just be conscious that your bridge pickup cavity might not have much room between it and the tremolo cavity if you have a Floyd-style tremolo), take your pickups out and begin screwing the cut machine screws into each mounting tab.

This was the hardest part for me by far. The fiberglass was of a denser composition on my Evolution 7 as opposed to the softer Air Norton 7's. I managed to strip out two Phillips head machine screws trying to get them through the holes, and had to remove them with vice grips. This is why I recommend using flat-head screws. You can imagine how stuck you'd be if you stripped a Phillips screw trying to remove the pickup once you've mounted it in the guitar... Once you manage to get your screws in each mounting tab, screw them down as far as possible, to the bottom of the foam or toothpick bundles, whichever you used. Time to finally mount the pickups.

Line each pickup up perfectly with the holes you just drilled in the guitar, and with one hand push one of the pickups down while screwing in each screw with the other. Screw them in evenly so you don't end up with a lopsided pickup--you can slightly tweak the height after they're stable if you want to angle up the high-side and angle down the low-side, something I do to ensure a clean low E/B. That concludes the hard part.

[farren]

Your guitar almost definitely had import mini-pots in it stock. You can use 500 KOhm minipots, but you'll lose a very noticeable amount of signal strength, despite the resistance rating (I've confirmed with a multimeter that this happens even with accurately rated minipots). Minipots are inferior, so I highly recommend going all out and using full-size CTS pots. The old minipots fit a 1/4" mounting hole and use 6mm (0.23") knobs. This means you'll need some new 1/4" knobs and you need to ream your current mounting holes from 1/4" to 3/8". This is so much easier than it sounds, but you'll want to take it slow anyway.

[attachment=2:3vz7s056]P1010012.jpg[/attachment:3vz7s056]

Cover your current pot holes with masking tape to ensure the finish won't chip. With your tapered hand reamer, begin by gently putting it in a pot mounting hole (looking down on the face of the guitar) and give it a couple turns. Flip your guitar over, and give it the same amount of turns at the same minimal pressure after sticking it through the hole in the control cavity. Test to see if your new full-size pot fits yet. Probably not. Flip your guitar and give it another turn from the front, flip, then another turn from the back. Eventually, you'll find a very snug fit. Do this on all pot mounting holes.

Now you'll want to use a small drill bit in your yankee drill (or electric...) to drill a hole from your electronics cavity to your tremolo cavity. Thread an insulated wire through it, and solder one end to ground in the control cavity (your volume pot maybe), and the other end to your tremolo claw. If you have a fixed string guitar, I really don't know what to tell you. You need to find a way to wire from your electronics cavity to your bridge. I suggest finding the easiest way to do this by asking on a luthier forum. It's possible, just a bit annoying and you'll have to make a very accurate geometrical projection in drilling the tunnel.

Now you can start wiring. I like to stick the pots and switch(es) in a piece of cardboard so that I can do as much of the work possible outside of the guitar.

[attachment=1:3vz7s056]P1010015.jpg[/attachment:3vz7s056]

Then you just drop the controls into the cavity and screw them in from the front. You can then wire up the actual pickups to your liking. You should be able to find wire diagrams online for any setup you want, but I wasn't able to for my particular configuration. I'm more of an electrician by imitation, so I got a friend of mine to modify a wiring diagram I found to my specs. Here's what I wanted:

1. Full bridge pickup
2. Tapped bridge pickup
3. Inner coils of bridge and neck pickups in parallel (hum-cancelling)
4. Tapped neck pickup
5. Full neck pickup

And here's the diagram in case anyone else wants to try this setup:

[attachment=0:3vz7s056]guitar-pups colored.PNG[/attachment:3vz7s056]

[farren]

Before:

[attachment=2:2p370ccx]P1010014.JPG[/attachment:2p370ccx]

After:

[attachment=1:2p370ccx]P1010016.jpg[/attachment:2p370ccx]

(You'll notice I decided not to use one of the pots in my Hellraiser. I didn't have a need for two independent volumes, so I have a decoy pot currently)

Now you'll want to give your guitar a thorough dusting with canned air, and remove any tape residue with a little bit of naptha on a rag, assuming you have a poly/nitro finish. That should be it. Let me know if there's anything I was unclear about. I realize this information might not be used by anyone for several years, but I joined this forum in order to ask if anyone had experience going from active to passive pickups in a 7-string before, so maybe some weirdo like me will eventually find this guide useful. :P

[attachment=0:2p370ccx]P1010046.jpg[/attachment:2p370ccx]