A Pickup I'd Like to Try

[Rodney Hamblen]

I've modified the magnetic design and terminations of Z Coils and S-500 pickups. The MFD pickups are very accommodating to modification.

Everything I've tried so far has the magnets all oriented N or S on the pickup. That's the industry standard but I believe thats due to how the pickups are made and not a must have design feature.

Magnetic polepieces are all charged at the same time and to the same polarity at some point during the pickup construction. Pickups using pole pieces are assembled with the magnets pre charged, usually these magnets are below the coils. I've no idea if pickups using a full width blade magnet are charged during construction or use a precharged magnet. But when using a bar magnet the individual polepieces are either all N or all S polarity (I'm considering just single coil pickups here).

With a modified MFD pickup (removing adjustable pole pieces and the ceramic bar magnets) allow one to use different magnet strengths (from different magnet lengths) and different polarities. I haven't used different polarities on my modified MFD pickups but I'm considering it now.

There is considerable interaction between magnetic polepieces in a pickup. The magnetic fields interact generally causing the individual magnetic fields to become narrower at the guitar string when the magnets are all oriented the same - along the axis of the pickup. In the axis parallel to the strings the magnetic fields would also be impacted narrowing the magnetic field close the pickup.

What would the result be to alternate the magnet orientations? The magnetic fields would continue to interact with each other but the result would be the opposite - the magnetic fields would become broader at the guitar string along the pickup axis and along the string axis.

What about string pull of a alternating N/S pickup? Would it the string pull be higher or lower? I think it would be less as the magnetic field would be broader and less focused both along the pickup axis and the string axis. And since more of the string is experiencing the magnetic field that the tone would have more bass in it.

I understand that mass produced pickups have all the magnets in the same orientation based on how the pickups are manufactured. For us experimenters the only issue is keeping track of the magnet orientation while assembling our modified pickups. While assembling my S-500+ pickups I learned a better method of placing the magnets in the MFD pickups, I believe this will allow me to build an alternating magnet S-500 or Z Coil pickup.

For a given coil design currently produced single coil pole piece magnet and bar magnet based pickups performance also demonstrates this theory. Pole piece magnets have narrow magnet fields (narrow aperature) in comparison to bar magnet based pickup designs and have less bass in the sound (I'm comparing pole piece magnet Strat pickups to bar magnet type Strat pickups).

Has anyone built an alternating polepiece magnet pickup? If so what were your thoughts on the performance of the pickup?

[Rodney Hamblen]

I've been looking for a decently priced used G&L Tribute S-500 with the intent of modifying the pickups to graduated strengths and N/S/N/S/N/S or S/N/S/N/S/N polarity as I posted earlier. The idea being that the alternating magnet polarity will expand the magnetic fields vs the tightly focused magnetic fields of store bought pickups (which are built using uncharged magnetic materials and after construction are magnetized - all poles the same polarity).

So I've been watching Reverb looking for a good price on a maple fretboard guitar with a swamp ash body and finally found one today. It's a 2011 with a three color sunburst body and maple fretboard.

The biggest part of this build will be the magnet installation. I'll use individual 1/8" diameter neodyium magnets, of varying lengths (lesser magnets on the smaller strings diameters). I haven't thought through the switching yet but may just leave it alone as the standard wiring allows for 3 individual pickups, 3 pairs of pickups, and all 3 pickups together. So maybe this is just a pickup modification project. I'm not a huge fan of that tortoise shell pickguard but it saves a few $$ that I can put into a SKB case.

I'll post some photos as I get going on this project. Swamp ash body Tributes with a reasonable price have been scarce on Reverb/Ebay lately so I was happy to find this one.

[DanDoulogos]

I expect that the magnetic field surrounding a pickup with alternating polarity pole pieces would have a weaker signal than a normal pickup. Instead of having the magnetic field compressed between poles, such that the field is forced up, down, and outward - encompassing the coil and reaching the strings - the field would be much tighter (closer to the magnets) and less pronounced in both the coil and especially in the strings, which, instead of having the magnetic field peaking over the poles, would actually have magnetic valleys above the poles. The peaks would be much lower, and occur centered between the strings. I expect that would like placing a microphone in between two singers, such that neither are heard very well, and what is heard would be less distinct.



I studied electronics a lifetime ago, and though I spent some time in the industry, I switched careers a few decades ago, and so I wouldn't consider myself an expert on these things. This is just my off-the-cuff thoughts.

Pickups have been around since the mid 1930s. Tens of thousands of people have designed pickups since then. Given how the simplicity of the pickup means that any innovation is either going to be related to the coil, or to the magnet - I would find it very surprising if no one had ever thought of trying this just to see what would happen. Expectations based on experience might suggest it to be a bad design - but the final proof is always in the pudding. I expect for this reason, that as many have likely already attempted this, and as we don't see any such pickups on the market like this in all the decades that pickups have been around, that the effect would be deleterious rather than additive.

Nevertheless, experimentation is fun and informative. Let us know how it comes together.

I'd be interested in seeing how such a pickup would work in tandem with a "normal" pickup - like having the n.s.n.s.n.s pickup in the bridge of a tele/asat and the normal pickup in the neck position and see what it sounds like when both pickups are hot. Would they reinforce one another? Would the one pickup pull in tones the other pickup was lacking and vice versa?

While I may think that the pickup you would build wouldn't be all that great by itself, it might help produce a unique sound when coupled with another pickup, especially if they were out of phase. So much tinkery-goodness to be had. I'm tempted to do it myself.

Cheers

[Rodney Hamblen]

Dan
I agree with your analysis. My goal is to raise the coils closer to the strings with the magnetic field less "confined" by the adjacent similarly polarized magnet. Even when using tiny neodyium magnets I get wolf tones on my high E string. I'm hoping to achieve a lower magnetic flux value at the string relative to a standard Strat pickup, with the pickup windings closer to the strings which themselves are hopefully fully charged without wolf tones.

Mixing a standard pickup with a NSNSNS pickup would create an interesting result for the strings which have opposite magnetic polarities. For those strings with opposite magnetic polarities an out of phase sound would result and a standard in phase signal for the strings with matched magnets. So one could have an out of phase sound for say the A G and High E strings for example.

I think that pickups are designed to be manufactured at a low cost without a lot of errors during construction. An alternating polarity pickup will require extra time spent on assuring that magnetic polarities are correct during installation. Contrast that with a Strat pickup construction where the uncharged magnets are pressed into the upper and lower fiber section, winding the wire onto that coil form, and then putting the pickup in the magnetization machine and zapping it to charge the magnetic material.

It hasn't been too long where boutique pickup builders have been mixing ALNICO 5 and ALNICO 2 materials into a single pickup which is charged in the same machine, but after charging provide lower magnetic flux for the treble strings vs. the wound bass strings on the guitar. I expect that this innovation has increased the error rate as the builder now has 2 different kinds of material being pressed into the pickup, which should raise the cost of these pickups relative to a all ALNICO 5 or all ALNICO 2 pickup.

Working with precharged magnets is a pain, even if you have the time to sort it out. Keeping the polarities right also takes time. Time I've got.

Anyway thanks for your response and great questions.

I'm thankful that these MFD pickups allow one to make these sorts of changes for a reasonable expense of time and $$. I'm sure that wasn't Leo's intent when he came up with MFD pickups but its there regardless.

These Tribute S-500's are fantastic guitars to modify.

[Rodney Hamblen]

For this Alt Mag guitar I'm leaving the PTB in the circuit. I'm replacing the 5 way lever switch with a 5 way 4 pole switch (Oak Grigsby) - I'll use this switch for series operation Bridge in series with the Middle, Bridge in series with the Neck, Neck in series with the Middle, and hopefully I can figure out an all 3 pickups series mode.

When operating the guitar in the "normal" single coil mode I'm using 3 ALCO MTA-206P switches (DPDT center off switches). You can switch any pickup on in phase or out of phase with any other pickups.

In series mode the MTA-206P switches will be in the off position. When in the single coil mode the 5 way 4 pole switch will be in an off position. Whatever the combination selected will go through the PTB tone circuit.

I still need to work out all 3 pickups in series. I have 1 available position on the 5 way switch. Note that 1 position of the 5 way is off.

Since I won't have any stereo wiring on this guitar I'm going complicated on the switching.

From Dan's reply above I realize that I'll likely be using slightly longer neodyium magnets than what I used for my Commanche+ and S-500+ guitars. Lots to learn on alternating magnets.

[DanDoulogos]

When you get it built, you MUST make a video to showcase the mods.

It'd be interesting to see the interplay between pickups - especially if you go NSNSNS on one then SNSNSN on the other - Though I'd like to see the interplay between like-modded pickups too.

Have fun with it Rodney.

[Rodney Hamblen]

Dan
I think I'll keep the center pickup RWRP meaning the bridge and neck get NSNSNS and the center will get SNSNSN magnet orientation. This maybe important since I'm wiring this guitar to support parallel pickups or series pickups. Having the noise reduction of the center pickup will be helpful.

If you haven't looked at my Gallery page I've put several photos of past mods there. Although the Strat Superswitch - 5 position 4 pole - is a new feature for me. I'm looking forward to wiring that switch, it looks awesome. Too bad the switch is hidden under the pickguard when the guitar is finished.

I figured out how to get all 3 pickups in series using the switch on the volume control that connects pickups 1 and 3 together ahead of the 5 position switch in the original guitar. Although used as a SPST the actual switch is a DPDT. When I wire it the down position supplies the ground connection for any pair of pickups in series, in the up position I'll put the coil for the third pickup in the circuit (I have to look at the 5 way switch positions to see if this third pickup is the N, M, or B position). Anyway it's nice for G&L to provide this DPDT switch as part of the volume control as a part of the standard equipment on the guitar.

Everything is ordered. I may or may not get a new pickguard, I don't like a tortoise shell pickguard on the sunburst guitar. On the other hand if I reuse the old guard I won't have to change the mounting holes in the guitar body.

I'll take pics and put them in the gallery. The wiring will be complicated on this guitar - lots of connections to solder up in a small area on the back of those ALCO MTA switches. The inside wafer of the Superswitch is a little tight too.

You can get an out of phase tone by swapping the magnet polarity or by keeping the polarity the same and swapping the wire. I am implementing in/out of phase switching on this guitar when the pickups are in parallel.

Mod on.

[Rodney Hamblen]

I'm down to the finishing touches on my alternating magnet guitar. I wanted to share a few things:

1) The concept for the alternating magnets works. I initially tried 5/8" neodyium magnets and found no wolf tones up to the 12th fret. Using these same magnets non alternating I got wolf tones at every fret on every string.

2) The switching is 3 DPDT center off, 1 DPDT push/pull (came on the guitar), and one 5 position 4 pole Oak Grigsley Superswitch. Here are the switch selections:

Oak Grigsley Postion Push/Pull Output

1 Push Any of the three pickups in parallel, in phase our out of phase
2 Pull Pups 1 and 2 in series, phase controlled by DPDT Center Off switches
3 Pull Pups 1 and 3 in series, phase controlled by DPDT Center Off switches
4 Pull Pups 2 and 3 in series, phase controlled by DPDT Center Off switches
5 Pull Pups 1 and 2 and 3 in series, phase controlled by DPDT Center Off switches
1 + Pull Unanticipated selection, similar to position 1 on the Oak Grigsley but pickup 2 is out of phase
5 + Push Unanticipated selection, similar to position 3 on the Oak Grigsley but pickup 2 is added in parallel

3) I tried 1/8" long magnets with the pickups as high as possible and I had some wolf tones at the 15th fret and higher. I ended up picking the 3/8" long magnets. Magnets shorter than 1/8" are really hard to place in these pickups, I had to shim these with some heat shrink tubing. Also keeping track of the alternating magnet polarity was difficuly, I ended up using a reference magnet off to the side to verify polarities.

4) My initial assembly went well but I forgot to terminate the string ground. It's always something on these projects - it's usually a broken wire or bad solder joint, at least I'm getting new gremlins.

5) I keep the PTB circuit stock. The pickup impedance varies between 1.7 Kohms and 15 Kohms and I'm surprised to see that the PTB handles this variation and still works well.

6) The Push/Pull DPDT that came on the guitar is a Parallel/Series switch, one has to select Series for Oak Grigsley positions 2 - 5 and Parallel for position 1. The unanticipated selections are the useful outputs when I forget to select Parallel/Series properly.

7) Lots of wiring and magnet swapping. This is a good project for a rainy day or sick day.

[Rodney Hamblen]

So my table in the above post got scrambled so I'll put some more explanation here.

The controls are - standard PTB, 5 way 4 pole superswitch (SS), one factory DPDT push/pull switch, 3 added DPDT center off switches under the neck pickup.

The factory DPDT is used as a parallel (push) or series (pull) switch. This switch either connects the middle pup to poles 2 and 3 of the SS (series) or to poles 1 and 4 of the SS (parallel).

Each pup goes through it's center off DPDT switch for phase reversal and off/on. This is the first switch every pup goes through.

The SS is an Oak Grigsley with the following positions (down is position 1):

Position 1 - all pups in parallel as selected by their center off DPDT switches.
Position 2 - Bridge pup and middle pup in series, in phase or out as selected by their center off DPDT switches.
Position 3 - Bridge pup and neck pup, in phase or out.
Position 4 - Middle pup in series with neck pup, in phase or out.
Position 5 - All pups in series, in phase or out.

If you have the push/pull switch in series (pull) with the SS in Position 1 you get all pickups in parallel with the middle switch reverse phase.

If you have the push/pull in parallel (push) with the SS in Positions 2 - 5 you'll get just the center pickup in Positions 2,4, and 5. In Position 3 you get the bridge pup in series with the neck pup and the center pup in parallel with that, any of the 3 pups can be set in phase or out.

The pickups were modified removing the base plate, ceramic magnet, and pole pieces with alternating N/S/N/S/N/S (low E to high E) neodyium magnets at each pole piece. The center pickup is RWRP with the neodyium magnets set as S/N/S/N/S/N (Low E to high E).

The SS is wired with the bridge pup connected to the common points of Poles 1 and 2, the center pup to the common points of Poles 2 and 3, and the neck pickup to the common points of Poles 3 and 4. So the negative side of the bridge pup and the positive side of the center pup are both connected to the common point of Pole 2 (assuming the Push/Pull is in the Pull position for series operation).

I need to intonate the guitar and set pup heights and connect the string ground to ground (probably to the output jack if the wire is long enough.

[DanDoulogos]

Suh-Weeet!

I do hope you make a video. I would love to hear how it sounds.

[sam]

I’m with Dan on this one!

Would love to pics too, can’t find way to your gallery.

[Rodney Hamblen]

I'm still working on the photos but will I'll get them into the Gallery soon.

Wiring the Oak Grigsley was interesting, it would have been very easy if all 4 poles were side by side. As it is the poles are a pair of 2 side by side poles. This makes long jumpers necessary.

I finally took the time to intonate the guitar. This is a 2011 and the string adjusters are quite a bit longer, this meant I had to cut 2 of the springs in half to get enough room to intonate the low E and the G string. The string adjusters on my 2007 and 2009 give 1/8" or so of extra adjustment compared to these 2011 versions. The 2007 and 2009 pickguards won't interchange with the 2011.

In Strat mode there's more quack than I get from my Strats.

In Series mode the impedance is double or triple that of a single pickup. The treble goes away as a result. A bypass mode switch would restore that by bypassing the volume and passive tone controls. I'm on the fence about installing a bypass switch. The passive tone controls work well in all combinations surprised me based on the impedance changing from 1.7 K ohms to 15 K ohms.

Selecting a pickup to be out of phase with the others is an acquired taste. Mustangs and Duo Sonics had that option. There are a few songs through the years that have out of phase sounds in it.

I didn't break any windings this time because I didn't remove any pickup covers with this project.

This guitar definitely sounds different than my other 2. In Strat mode the sound is very familiar, in series modes it's more like a high winding humbucker.

As received the neck to body alignment wasn't great. Several of the tuners needed the nut tightened (on the front of the headstock). These two issues would make the guitar as received not much fun to play and hard to keep in tune. It's working great now.

My only expenses other than the guitar itself was the Oak Grigsley switch and the 3 DPDT Center Off ALCO switches (which I bought as NOS on Ebay from an outfit in Little Rock, AR). I really like these ALCO switches. I'm also waiting on a set of aged Strat knobs which have been on backorder for a while on Amazon.

More later.