Z Coil Insights

Check my other posts for a bit of detail on my Comanche VI+, a S-500 Tribute I modded with a Chandler 6204 pickguard, Z Coils, and enhanced switching and features. This guitar emulates a standard Comanche, a Comanche VI, and sounds that those guitars can't produce.

I've finally taken the time to look into setting pickup heights, polepiece heights, etc with the hopes of finding some Strat quack tones in the system. What I discovered during this exercise was surprising.

In stereo my guitar sends the bass string 1/2 pickups to one signal chain and the treble 1/2 pickups to a different signal chain. You can also combine these 2 "channels" into one channel using a 1/4" TRS male to 1/4" TS converter ($3.10 on Amazon this weekend).

Here's my findings & thoughts

1) The magnets in each 1/2 pickup are STRONG. IMO TOO strong. When I listen to the signal coming out of just 1 bass half coil I can hear all three treble strings. They're not as loud as the bass strings but they're loud enough to hear at whatever volume I set on my amp.

The goal for a pickup design is for the magnet to magnetize the string to a point it can reliably induce a current in the coil section its vibrating above. Any additional magnetism creates issues. Familiar examples include raising your Strat's pickups too high and generating "wolf tones". On the Zcoil your bass portion of the pickup has treble signal in it, and the treble portion of the pickup has bass signal in it. So 1/2 way across the pickup that E string is coupling to the wrong pickup section.

This helped explain why I was hearing "out of phase" tones in the treble signal when only one pickup pair (1 bass 1/2 coil and 1 treble 1/2 coil) was selected, it was likely being caused by the combination of a treble string's signal induced in the treble half of the pickup combining with that same strings slightly out of phase signal (spatially separated by a portion of the pickup's physical width) in the bass pickup.

I haven't read the MFD patent yet but G&L promotional videos state that Leos goal was to increase the signal output of a pickup while decreasing the induced noise. So stronger magnets and fewer coil turns were utilized to achieve that, in addition of the Z Coil's humbucking design.

How can a stronger magnet be used and not result in "wolf tones"? Obviously we have to keep the magnet a further distance from the strings or shape the magnetic flux to which is in a MFD pickup is achieved by locating the bar magnet underneath the pickup coil and using pole pieces to shape the magnetic flux. In the MFD design the result is a higher magnetic flux at the strings in a shape that is not conducive to creating a "wolf tone". Where an ALNICO magnet pole piece may provide less magnetic flux at the string that flux is in a shape that causes "wolf tones" as the pickup is raised closer to the string due to the shape of the flux, that's not an issue on the MFD pickups. More magnetic flux means a higher string energy induced in the lower wound coil of the MFDs, but it also means that the string can induce string energy a considerable distance from it's respective pole piece and respective 1/2 coil (for the Z Coil pickup).

2) Setting pickup heights on every Fender I've had was always a quick process, raise the pickup until "wolf tones" are created then lower the pickup to some level. Leave it high to get the maximum string energy through the pickup, lower it to "sweeten" the tone. It only took a few minutes.

Not so on my Z Coils. Raising the pickup never induces "wolf tones", instead it magnetizes the string to a high level. I've found that it's best to make an adjustment and give the strings sometime (an hour or so) to reduce the magnetism to the new height of the pickup. I tried a near full up pickup height then reduced the pickup height to the height of the pickguard and heard no change in the signal coming from the amplifier. Take your time in setting your pickup height. I also found that the strings respond rapidly to increasing the pickup height.

Which also indicates IMO that there's too much magnetism in the MFD design. Raising the pickup height seems to rapidly reach the magnetic saturation point of the string. Once we've hit the magnetic saturation point of our string any additional magnetic energy is unnecessary. In the Z Coil that results in treble strings inducing significant signal into the bass coil of the pickup and likely in the treble coil of the adjacent pickup. We don't get a clear string tone in any 1/2 coil of the three Z Coil pickups on the Comanches. And it makes it very difficult to change pickup heights to achieve a specific sound. If not impossible.

3) In my next attempt I removed all 18 pole pieces. The cross talk changed somewhat as the magnetic field was no longer focused on a particular string while the magnetic field got wider. There was less difference in the relative volumes of the cross talk induced in the bass 1/2 coil by the G, B, and E strings vs. the cross talk with the pole pieces in place.

I've never spent much time with pickups with adjustable pole pieces before and this may well be a common issue with that design. ALNICO magnet pole piece pickups create a very focused and "tight" magnetic field. Bar magnet pole piece pickups in comparison have a huge magnetic field that is (somewhat) shaped by the pole pieces. My expectation for the Z Coil was that the issue of crosstalk had been resolved by the displacement of the bass and treble coils of the pickup commensurate with the selection of the bar magnet energy level. In practice this is not the case.

If you look at my Gallery you'll see my reissue 52 Telecaster built with only either 3 bass or 3 treble magnets vs the normal 6 magnet construction in the neck/bridge pickups. Cross talk is present as well in these pickups, the G string induces a very low level signal in the pickup with the bass magnets (bridge) and the D string induces a very low signal in the pickup with the treble magnets (neck). The level of this cross talk is roughly equal in level to the crosstalk induced by the respective E strings on the Z Coil.

So I'm left wondering if a reduction of magnet energy and/or a magnetic shaping device (think Lace Sensor Radiant Field Barriers) would help.

I'm surprised by this level of crosstalk in the Z Coils pickups. I've got to live with the guitar some more but this may well mean that a Z Coil can't be operated in a Stereo guitar without some changes. Stated another way if one wants a Stereo guitar sticking with a magnetic pole piece pickup design may be a necessity.

The crosstalk of the Z Coil design concerns me. Is this the reason that certain classic tones aren't achievable? Or can I achieve those tones with a simple adjustment? I won't know for a while as I'm waiting the strings to demagnetize to the new level supported by my recent pickup height reduction.

Cheers.

I meant to ask Comanche VI owners if you select just a treble or just a bass coil do you also hear this cross talk?

If you don't there maybe a difference in the bar magnet strength between your Z Coils and current Z Coils.

Many thanks. Cheers!

I guess this explains the STRONG magnet fields of this pickup, here's a quote from the summary of the MFD Patent 4,220,069 (available in the gallery):

"According to the present invention, there is provided an electromagnetic pickup for stringed musical instruments which creates a magnetic field which is significantly stronger and better defined than the fields created by prior pickups ..."

The magnet strength is substantially higher in my Z Coils, so much so that the high E string is able to induce a listenable signal in the bass half of each pickup across 3 string gaps which is 1" or more away from the string. The strings I'm currently using are inexpensive Darco's which likely have no enhancements to the core formulation of each string to make them more magnetic (cobalt is commonly used).

Perhaps a grounded shield around the coil with an open top (and bottom) would help. I wonder if someone offers an ALNICO magnetic slug that would thread into the existing pole piece housings on these pickups in conjunction with removing the bar magnets with a neutral shim. Further work is needed.

A split coil pickup was never designed to be able to isolate each half completely. Especially with an MFD design where they share a common base plate (which is part of the magnetic field) you will have bleed and cross over. This is inevitable.

Regarding out of phase tones you might be hearing in different combinations, keep in mind that in order to achieve the phase cancellation to buck hum, the magnets on each side of a z coil are opposite (one side north and one side south).

Other than that, this pickup is designed to have a strong magnetic field and is very sensitive to pickup height. Once you dial that in, it is a sweet sounding pickup but using the PTB to cut a little bass and treble will help you find a nice "vintage" sound.

There are threaded FeFrCo slugs (very similar to alnico) but I don't believe the thread size will match what G&L uses. Here is a link.
https://www.philadelphialuthiertools.co ... -set-of-6/

Additionally, the coils on these pickups were not designed to be used with Alnico slugs of any variety. Removing the steel set screws and replacing with alnico will significantly lower the inductance. It may or may not sound good. Also in regards to the removal of the set screws in your experiment; the two things this achieves is lowering the inductance and lowering the pole piece location to the top of the pickup bobbin. MFD pickups are designed by using a threaded standoff which touches the ceramic magnets on the bottom. The set screws attach to that and give you flexibility to raise the pole piece location to be closer to the strings but the standoff remains a pole piece with or without the set screw in the middle.

I have made both alnico split coils in an ASAT Special size as well as the typical MFD design in the same size. The MFD sounds much better to my ears.

Cheers and good luck with the experiments.

Thanks for your response. Can you share what type and strength of magnet(s) and polarity you used for your split coil builds?

I've pondered the effects of the magnets in guitar pickups and I'm in the camp of the magnets/base plates/pole pieces sole function is to magnetize the strings. All of these elements in the magnetic circuit also impact the shape of the magnetic lines of charging force on the strings. Improperly set magnets can affect the vibration modes of the strings (wolf tones) and that's a special case. Hopefully we can agree to disagree on magnetics and continue our conversation. I'm very interested in what you can share on your split coil work.

I'll also throw a general question out there - does anyone know the detail on what magnets G&L is using on the Z Coils? Make, manufacturer, and strength would be great to know if that's something you can share.

Respectfully
Rodney

I'm not sure we disagree. I was mainly discussing how different pole piece material will affect the inductance of a pickup (all other factors such as number of winds being the same) . This is verifiable with an LCR meter. I am curious though, how do you define an improperly set magnet?

G&L uses Ceramic 5 magnets in their MFD designed pickups. I've used the same when building split coils. The gauss levels vary slightly but there are charts online which give the expected range of gauss readings for ceramic 5 magnets. Split coils are generally built with the same concept as any humbucking PAF style pickup. One side North, the other South. One coil wound clockwise and the other counter clockwise.

Cheers.

In my statement improperly set meant for example placing a Strat pickup too close to the strings and getting those throbbing wolf tones. The magnetic lines of force interact with the strings vibrations to create those wolf tones. Thanks for sharing the magnet information.

In that case we agree completely, "Other than that, this pickup is designed to have a strong magnetic field and is very sensitive to pickup height. Once you dial that in, it is a sweet sounding pickup but using the PTB to cut a little bass and treble will help you find a nice "vintage" sound."

Cheers

After some reading I've ordered some copper foil shielding tape with conductive adhesive. My plan is to shield both the treble and bass pickup halves with a gap on each coil ending near the E strings. My goal is to block/reduce the treble string signals in the bass 1/2 of the pickup and to block/reduce the bass string signals in the treble 1/2 of the pickup. I don't think my changing magnets/pole pieces will help with issue I described in the preceding posts.

I'm still hoping to have other Comanche VI players can tell me if they also get treble string crosstalk when listening to just 1 bass pickup 1/2, and bass string crosstalk when listening to just 1 treble pickup 1/2.

I'll post some photos and the outcome.

I'm still trying different settings for my Z Coil VI+ and keep finding issues with the existing design/implementation.

1) I'd set the Neck and Center pickups to the level of the pickguard and the treble pickup was elevated halfway to the strings. Playing G/B/E strings anywhere on the neck acoustically or through my amplifier gives wolf tones, the E/A/D aren't as bad. I'm used to settings Strat pickups to a height the ensures I can play up the neck (at least to a certain fret) before getting wolf tones and knowing that limit while playing to avoid them. A neck full of wolf tones isn't acceptable.

2) The Z Coil humbucking design uses classic thinking - one coil with N magnet and the other coil RW, wired out of phase with a S magnet. They've been built that way since Seth Lover's creation. If the two separate coils of a humbucker don't interact with all six strings (as in the Z Coil) a S magnet isn't necessary. Since the Z Coil has that N/S magnet pair the overcharged strings above the opposite magnet 1/2 coil induce out of phase signals in the other 1/2 coil. As a result I can't get a clean string tone on the A/D/G/B strings on any pickup pair.

3) I can't achieve a decent tone from these Z Coils playing straight into an amplifier. I don't run distortion and don't employ a lot of modulation (phaser, Leslie, Univibe). If you run alot of these affects most of the time a stock Z Coil's noise reduction maybe a good solution for you.

I'm still waiting for some pickup coil tape. When I liberate these pickups to install the copper foil tape I will also reverse the S magnets to give a N/N 1/2 coil pair on each pickup. This will decouple the magnetic circuit between the N and S magnets that exist in the current design affecting the A/D/G/B strings the most. It should also reduce the magnetic field strength across all of the strings E to E. My goal being to eliminate the out of phase tones induced across the pickup and hopefully help with the magnetic string pull creating wolf tones.

I'll figure out what sort of magnet we have (I'm thinking these are rubberized ceramic magnets having had one partially fall out of my Z coils while I was wiring out the individual coils. I'll also get physical measurements. If the above mods don't resolve it it's time to modify (reduce the current magnets physical size or area) or replace those magnets with something much weaker. I'm also considering the option of punching the pole pieces through the bottom of the pickup to shift the magnetic field below the base plate.

I think once I can get the out of phase and wolf tones addressed I'll get some good sounds out of these Z Coils. The Z Coil employs 2 layers of noise reduction - reduced winding count and humbucker 1/2 coils. To make up for the reduced windings a large bar magnet is used. The current pickup design focuses too much on noise reduction at the cost of creating audible wolf tones and out of phase tones at all volume levels. My opinion.

Cheers.

For a better understanding of pickup theory and to post troubleshooting questions, I suggest this forum. Tons of great information and throughout the years, legends of pickup building and design have posted here. This may clear up some of the confusion. Cheers.

https://music-electronics-forum.com/for ... kup-makers

[Craig]

You have asked, so I'll offer my experience such as it is, with a Comanche Studio VI (i.e., 2007 reissue) and a 1990 Comanche VI signature. I haven't noticed these issues with cross-talk and wolf tones in my years of playing them (the Studio VI was my main guitar for 10 years). Nor have I needed to make extreme adjustments such as setting the pickup heights down to the pickguard. To be fair, I mostly use "standard" pickup combinations. Occasionally, I use bass half neck + both halves middle + treble half bridge (or its opposite). I've also used bass half middle + treble half neck to good effect. No noticeable troubles like you describe. It's possible that one half was bleeding over to another, but not that I noticed.

I've monkeyed a fair amount with pickup heights with these guitars, trying to find optimum sweetness, power, etc. I've always returned to fairly standard MFD heights and had pleasing results.

It's time for today's guitar playing, so I'll change my plans from plugging in my Skyhawk to fiddling with one of these Comanche VIs. I'll report anything unusual.

For the heck of it, here's a link to two tracks that I played the Studio VI on from my band's 2018 CD. I'm in the right side.

phpBB [video]

phpBB [video]

Last edited by Craig on Sat Mar 19, 2022 3:40 pm, edited 1 time in total.
Reason: Amin fixed video links

Thanks for fixing the links, Craig. I don't know why they didn't show inline...

To follow up: I spent time futzing with half coil selections. All of them will amplify the strings on the half that is turned off. But, less loudly than the strings above the coil that is turned on. So, my VI displays the same behavior you have noted.

My feeling is that it's not an issue that can be solved. And, I'm not seeing in what contexts it would be a problem. As long as you have a treble half and a bass half selected from among any of the three pickups, your primary tone will come from there, not the halves that are off.

Conjecture: Do all pickups exhibit this behavior? Does a given pole piece in a traditional flat slug alnico Strat-type single-coil pickup catch frequencies from other strings ? It's only the Z-coil VI setup that allows us to easily hear that. And, Leo developed the Z-coil to function as a single pickup, just like any other single coil. Per this forum (or is it ggjaguar?), it was Dale Hyatt and Steve Reed who had the idea to wire each half separately. Just my 0.02.

Thanks for fixing the links, Craig. I don't know why they didn't show inline...

To follow up: I spent time futzing with half coil selections. All of them will amplify the strings on the half that is turned off. But, less loudly than the strings above the coil that is turned on. So, my VI displays the same behavior you have noted.

My feeling is that it's not an issue that can be solved. And, I'm not seeing in what contexts it would be a problem. As long as you have a treble half and a bass half selected from among any of the three pickups, your primary tone will come from there, not the halves that are off.

Conjecture: Do all pickups exhibit this behavior? Does a given pole piece in a traditional flat slug alnico Strat-type single-coil pickup catch frequencies from other strings ? It's only the Z-coil VI setup that allows us to easily hear that. And, Leo developed the Z-coil to function as a single pickup, just like any other single coil. Per this forum (or is it ggjaguar?), it was Dale Hyatt and Steve Reed who had the idea to wire each half separately. Just my 0.02.

Here is the post which you are referring to, authored by Jos (yowhatsshakin) in one of his Lunch Reports in 2014:
Breakfast Report Thursday, July 31, 2014: Comanche VI stuff

Check it out.

Thanks Craig! Lots of great info there. I think that post conveys what I believe (and almost wrote yesterday), which is that Leo spent more time than anyone on the single coils with reduced hum and the split coil concept. Turns out I was recalling the info on ggjaguar's page for the 1990 Comanche VI Signature—which I can say, with some authority, is a wonderful guitar.

Thanks for the responses Comanche VI owners. I wanted your feedback to get a sense of whether my pickups magnets are substantially different than yours.

Tomanche poses a couple of questions that I'll respond to:

1) On my gallery page you'll find my 52 reissue Tele with pickups wound for me in the early 90s by Lindy Fralin. The neck is a full coil with only GBE magnets, the bridge is a full coil with EAD magnets only. My goal was to be able to run a lot of treble on the bridge pickup and a more balanced tone for the neck pickup via separate amplifiers. I kept the full coil to keep the Tele sound for those strings on those pickups intact (same inductance as a pickup with all 6 magnets). On this guitar I can hear faintly the G string in the Bridge pickup and the D string in the neck pickup - at much lower levels than I'm hearing on my 1/2 pickups on my Comanche VI+. Again the difference here is that on my Tele the G string is being magnetized by the downward flux of the adjacent D string magnet on the bridge pickup inducing a signal in the full coil below - on the Comanche the G string being over magnetized is inducing a signal in the bass 1/2 pickup roughly 3/4" away (assuming similar string heights above the coils).
2) On a standard Strat pickup with all six magnets there's no out of phase signals generated by a single pickup, instead the lines of flux from the D string magnet act opposite the lines of flux from the G string magnet - reducing the overall magnetized level of the G string. The high and low E strings only have their magnetizing energy on their respective strings reduced by the adjacent magnets, all the other magnets have to contend with 2 adjacent magnets reducing the string energies. Staggered magnets offer an interesting solution, they have increased magnetic energy vs. shorter magnets (if magnetized properly) and reduce the string heights which also induces greater magnetism in their respective strings - they also have a greater negative influence on the adjacent strings. But, in all cases, each string is magnetized by an adjacent net N (or S) magnetic force in accordance with the net magnetic lines of force through the strings. Its easy to see which of your Strat/Tele strings are magnetized the greatest amount, keeping the pickup flat raise it until you get wolf tones - those strings seeing the highest magnetic force get wolf tones first. On staggered Strat pickups I hear the G string's wolf tones first.
3) The question of where the Z Coils design/implementation becomes a problem depends on the player. I can't enjoy a guitar with wolf tones up the entire neck regardless of the pickup heights - it's not acceptable. Nor can I enjoy a guitar where every time I play a single treble coil I hear significant out of phase tones (as if 2 treble coils one being out of phase at a lower volume are in use), I like out of phase tones but only when I can switch them on/off to my liking. I felt by now I'd be spending hours playing the Comanche VI+, it sounds awful even when played acoustically because the wolf tones are always present. Thus this guitar is getting little playing time.

My only choice at this point is to try different mods on these Z Coils to improve their performance for my use. Running my guitar as a standard Comanche I get the wolf tones and out of phase tones, to me whether running the Z Coils as split like a Comanche VI or combined like a Comanche the sound is not acceptable. These imperfections are present regardless of the mode I run my guitar in.

If removing half of the magnets on a normal strat coil helped you to achieve the sound you are looking for, have you considered simply removing one of the magnets on the other side of the z coil? You are running a completely unique set up in regards to splitting the coils and running the guitar in "stereo". The pickups were never intended to be used in that way, so it's not a complete surprise you've run into difficulties. If that doesn't work, I am sure that Lindy would consider building you a custom set to fit your needs since he's done it in the past. I don't know if they would fit as is but perhaps you could take a set of Fender XII pickups and use them in the z coil cover. Good luck.

Removing magnets is definitely on the possibilities list. Another is modifying a pickguard with a square cutout like the bathtub route, buying a piece of copper plated steel that fits the bathtub route and making this the new pickup baseplate, and affixing the Z Coil half pickups and magnets anywhere on the plate. I'm really hoping flipping the S magnet to N and possibly trimming the magnets (if rubberized) to reduce the magnetic force (or replacing them with a weaker metal magnet) will be the end point along with copper foil shielding.

If that doesn't work then its time to get creative.

But I really want the Z Coil concept to work for me and to look original from outward appearances. Like a Generation 2 Dodge Polara with a hemi 426 in it. Ho hum boring appearance with exceptional performance. I want my guitar to look like everyone else's but sound like nothing else - a sleeper.

Your idea is definitely on the list.

I want to thank everyone for sharing their guitars performance along with their ideas. I'll share what I come up with and take some photos for those wanting to try similar mods. Again, Tribute models are perfect for modifying, less so for USA models, and definitely not for older Commanches, Vs and VIs. Historic instruments deserve to be preserved in their original condition.

After setting all of the pickups as low into to the pickguard as possible and waiting 3+ days for the strings to reach a new magnetic equilibrium with the pickups the wolf tones on my guitar are gone. The measured clearance to unfretted strings is 3/16" to the neck pickup (low E measurement). This guitar is set up with similar playing action to all of my Fenders so there's nothing unusual about the action height.

I'm positive that playing this guitar for any substantial length of time using other than open chords will bring the wolf tones back. That's excessively high magnet strength.

Pickup modifications to follow.

Cheers.

Have you recorded these wolf tones? If so, can you post here? I am interested to hear the issue at hand.

Also, have you rolled back the bass and treble controls when playing to remedy the sounds you don't like? Not sure if I mentioned but I found the strength of the z coils to be more than I would like but lowering them and cutting the bass fixed that issue and produced more of a typical strat sound.
The z coils have a higher inductance than the ones I've been winding for myself and I've found lowering the inductance fixed that issue. I use a slightly smaller diameter (.21 vs .25) steel standoff and than what G&L uses. That smaller amount of steel in the core of the coil lowers the inductance. This did the trick and requires less tweaks to the bass cut and doesn't require the coils to be lowered as far from the strings.

I have recorded wolf tones on my guitar and I'll have to figure out how to post those. The pickups were set to about 1/2 the height as recommended as a starting point by G&L for guitar set ups.

My Comanche VI+ has not bass/treble controls on it, the two knobs are bass pickup volume and treble pickup volume (which is active only in Stereo mode). I do have a pull switch on the bass volume which switch in/out 1.5 H inductors for both the bass and treble simultaneously - I see now that this guitar has a much more bass than I expected and when I remove the pick guard for some pickup work I'll change that to bass rolloff controls. With just off/on settings I'm sorting out what equivalent setting to put into my controls - this may involve a wait for capacitors. I expect that the standard .0022 uf cap is great for the bass side but maybe a bit much for the treble side of the guitar. I'll have to look through my junk box to see what I can put together.

For those that use them on a Comanche what setting of the bass cut control do you get a good sound out of the bass strings? I was figuring the electric equivalent of a 50% setting. Some feedback from the user community would help.

I've got all the pickup coil tape I ordered to install partial copper shielding on the coils and grounding that shielding to the pickup bass plates. I've also precut some 1/8" wooden shims to install between the magnets and the coils. At my current pickup height I can play up and down the neck without wolf tones but the top of the pickups are even with the pickguard. The shims allow me to leave the magnets where they are currently located relative to the strings while moving the coils 1/8" closer. Its the magnets the cause the wolf tones, not the coils and passive pole pieces (which focus the magnetic fields, only the magnet creates them).

I've decided not to flip the S magnets under the treble strings, I realized today that my current in/out of phase/off switches allow me to put the crosstalk signals induced in the bass pickup back in phase with the same strings signals in the treble pickup - at the expense of losing the benefit of the RWRP noise cancelation (which I'll gladly trade off to achieve a clean string tone). Flipping the S to N will result in the same out of phase sounds for the affected strings due to that RWRP winding on one of the pickup coils, there's no reason to do it.

I may have to shim the pickup height screws between the pickup cover and the base plate. If you have a Will Ray pickup the coils on that pickup are taller than a regular Z Coil and the pickup cover doesn't contact the base plate so it's likely a gap there won't create a problem when I raise the coils. The pickup covers for all the Z Coils keep the coils, magnets, and baseplate compressed together by pushing down on the top of the pickup coils. The assembly glue allows the coils and magnets to pop off fairly easy.

While I have the pickups apart I'll get some magnet measurements and see if it's rubberized or not. I believe Z Coil magnets are an unusual length being shorter than P-90s, humbuckers, or Firebird humbuckers. Drilling and cutting magnets is hard to do from what I've read. I don't mind trying to modify these magnets as long as I can get another set if I destroy a magnet and G&L maybe the only reasonable source for replacements.

I'll take pictures of the progress. And I'll see how to post a video of those wolf tones.

I read through FMIC/ELVH's patent on Z coils 4220069. I especially noted figure 6 in that patent, the feature of interest for me was that the baseplate in this proposed design has the baseplate sides extend up to top of the coil which would focus the magnetic field much better than the current implementation of the Z Coils where the baseplate is fully below the magnet and coils.

Forming these baseplate sides for the Z Coil would complicate the baseplate design but would definitely help focus the magnetic lines of force from the powerful ceramic bar magnet. And a complicated baseplate design would increase the cost of each Z Coil pickup.

Patent 4220069 references patent 2896491 a Seth Lover patent. I was surprised to find a Z Coil with magnetized pole pieces in Figures 7 and 8 of that patent. From 2896491 "Overlapping (of the coils) is held to a minimum to reduce pick up or inductance between the two coils." And "Since each string of the instrument coacts with only one coil 26 or 26A there is no problem of the signal in one coil opposing the signal in the other." There's no mention of either of these statements in patent 4220069 with the result being there is pickup between the coils (and possibly mutual inductance) and there most certainly is signal in one coil opposing signal in the other.

Seth's design with magnet pole pieces addresses (and hopefully achieves) the magnetic separation of the two halves of his Z coil, G&L's design using a strong ceramic bar magnet and iron pole pieces on a flat base plate doesn't.

Which is why I'm shielding and raising the coils in my Z Coil pickups to attempt to address the pickup and mutual inductance issues.