The Story of a Vintage Pickup and Q - (also, we introduce some new models)

This all starts with a vintage pickup pulled from an old Fender lap steel. It’s kind of a long story, so if you don’t want to read the whole thing, here’s the carrot-

We fingerprinted a vintage Fender pickup and then developed the most vintage correct Strat pickups we have ever made - the Z-Series Tru-Gauge ZV55 and ZV63.


Here’s how-

I was shopping for a lap steel towards the end of last year, and vintage lap steels are still a pretty good deal (I think, if you’re into that sort of thing). Certainly, some of the least expensive vintage wood you can buy. I homed in on Fender Champs, and I found a nice one, reasonably priced, from 1963. People generally complain about the pickups in the Champs (at the time an inexpensive, “student” model) as being “weak”, and I already had the plan to take the pickup out and replace it with a Convertible. The Convertible (along with its cousin the Juicy Bucker) makes a fantastic lap steel pickup with the two modes. But I received a very nice surprise when the guitar arrived.


As soon as the guitar showed up, I took the pickup out to measure it. I suspected this might be the case, but I was pleasantly surprised to find what amounts to a flat pole, low wind Strat pickup. The ’63 Champ pickup has 3/16” diameter AlNiCo5 pole pieces, as well as the same pole piece spacing, flatwork dimensions and coil height as a standard Strat pickup. The poles are slightly shorter to accommodate the flat, solid cover, but otherwise this is effectively a ’63 Strat pickup wound to mid ‘50s specs. After getting it fully measured, I started comparing it to my closest analog, the stock Z-Core5 Underwound (ZVU5), and I was surprised by what I found.

But before we get into that let’s back up a bit and talk about one of the most important measures of pickup performance, the electrical parameter known simply as “Q”. Q is the Quality Factor and it’s a measure of the extent to which an entity will resonate. Take a pendulum, for example. A pendulum with a high Q will swing for a long time before it stops. A pendulum with a low Q will stop swinging rapidly after a push. In guitar pickups, Stratocaster style single coils tend to have higher Q and PAF style Humbuckers tend to have lower Q.


A good way to get a feel for what Q “sounds like” is to consider what happens with tone and volume pot loading as in Figure 2. Figure 2 shows the impedance response of the neck pickup from my Fender JV Strat. Unloaded, the Q is about 5.9. Loaded with only a single 250 kΩ volume pot, the Q drops to 2.5. With a 250k Volume and Tone pot, the Q drops to 1.6. As the volume knob is lowered, the Q would drop further as the resistance to ground drops, the “resistive loading” is thereby increased, and more and more high frequencies are bled to ground.


In a very real sense, the Quality Factor is a measure of the “efficiency” of an oscillator or electrical device. And it’s one of the things that define the sound of, in particular, Stratocaster pickups. One of the reasons that it’s hard to make an authentic sounding noiseless Strat pickup is that things that are done to cancel hum tend to make the design less efficient, leading to a loss of Q. So, I was surprised to see that my ZVU5 had a higher Q than the vintage pickup, as shown in Figure 3. Initially I suspected that there was something different about “vintage AlNiCo”, driving the Q down a bit. Maybe this was part of the secret to that “vintage tone”?! But no, I soon realized that I just hadn’t measured enough pickups.


That leads us to another aside. Among other things, over this pandemic I’ve done a lot of work to automate and improve my measurement capability. I now do all of my basic measurements on a Quadtech 9600 LCR meter, which I’ve been able to automate to do full frequency scans between 20 Hz and 1MHz. I spent quite a bit of time doing basic measurements on pole piece materials over the pandemic, and I’ve made a lot or progress on my fundamental model for eddy current effects, but I’ll talk more about that at a later date. What I hadn’t been doing was measuring a lot of full pickups with this new, more accurate, rig. So, I got to work doing that, and rebuilt my database of improved, more accurate pickup measurements.

Some of what I was able to clarify is illustrated in Figure 4. Figure 4 shows the Quality Factor as a function of pickup inductance for a range of conventional Strats as well as the best examples of competitive noiseless Strats, and Zexcoil Strat-style pickups. As the figure shows, the Quality Factor of Zexcoil Z-Core5 models goes up as the inductance goes down. Where I dialed in the Z-Core5 line, around the ZVH5/ZMD5 level, they match with conventional pickups extremely well. But below that level, the response of AlNiCo5-based Strat pickups levels off at a Q of around 2.5, while the response of Z-Core5s continues to go up. I didn’t notice this effect at the time; I guess I just assumed that the Z-Core5 pole piece material response would be similar to AlNiCo5 since it was already matched up where I dialed it in. I developed the ZVU5 and ZVN5 models by simply reducing the winds compared to the others, the same way you would a conventional platform. It’s also pretty clear that there is nothing particularly special about the vintage Fender Champ lap steel pickup. It sits on the same line shared by the JV Strat pickup, a Tokai E bottom pickup, a couple of pickups from a Mexican Fender Robert Cray Strat, a couple of Fender Texas Specials and a Seymour Duncan SSL1. You’ll also note that all of the competitive noiseless pickups have significantly lower Q values than the conventional Strats.


So, now I had a job to do, close the Q gap at the lower output level. And I’ve got a few ways to do it. The first one is easy. Historically, and this goes back to the perspective of electrical efficiency, I’ve used the biggest wire I can in any given situation. That starts paying some big efficiency benefits in the low output regime, to the point where the stock ZVU5 measures only about 4400 Ω compared to a conventional pickup of the same inductance at about 5750 Ω. In fact, the stock ZVU5 uses mostly 40.5 gauge wire. Simply by increasing the wire gauge (decreasing the wire diameter) at the same number of turns results in a resistance increase of about 1000 Ω, lowering the Q as shown in Figure 5 (note that this shift in Q is conceptually similar to what happens with pot loading as in Figure 2, but that in this case it’s the resistive load of the pickup itself, not the pot, driving the change). But that still results in a Q of about 2.7, higher than the conventional AlNiCo5s. I had to change the pole piece material in addition to the wire gauge to fully close the gap, at least at the ZVU5 output level. A pole piece with slightly more significant eddy current effects is utilized in the ZV55 to drive the Q down just a little bit more. With the understanding I have of these effects (the core of our Tone Tuning Technology), it’s actually pretty straightforward to do this in a very targeted fashion, I just need a target. At the ZVN5 output level a different pole piece was not required, simply changing the wire gauge was enough. So the ZV63 shares the same pole piece as the rest of the Z-Core 5 line, but it uses 42 gauge wire wherever possible.


So what? Well, we’ve got two new pickup models that close the gap between Zexcoil and conventional single coil performance in the low output regime. The ZV55, at a similar output level to the ZVU5, uses all 42 gauge wire (the same wire gauge as most conventional Strats) and has specs that are almost identical to the Fender Champ lap steel pickup it was modeled on. It also sports a unique pole piece material that we don’t use in any other design. The ZV63, at the ZVN5 output level, uses 42 gauge wire in 5 of 6 coil positions and also has specs that almost identically match conventional AlNiCo5 pickups.

The slight Q tweaks to these new designs are like smearing a slab of butter over the already luscious tone of the current designs. And while these new pickups work great on their own, they also work fantastically well when paired with the stock Z-Core5s. Here’s an example. Use a ZV55 in the neck with a ZVU5 or ZVN5 in the middle to enhance the quack. This is the approach I use in my Pink Floyd tribute band rig. I was already really happy with my tone with a ZVU5 in the neck (for stuff like Shine On You Crazy Diamond), but with the ZV55 in there I’m just ecstatic.

We’re extrapolating this “Tru-Gauge” approach to our upcoming line of ZCore Tele bridge models as well. Look for them in early 2022.


The LMP Z-Series™ Manifesto

Some changes are coming from Lawing Musical Products, the makers of Zexcoil® pickups.

We started this company about 7 years ago, after a preceding 2 or 3 years of development, to market our unique line of one-coil-per-string, hum-canceling pickups. We founded our company on a few underlying principles:

  1. A commitment to providing great products for the best price we could,

  2. A commitment to domestic supply and manufacturing, and

  3. A commitment to establishing a viable, independent and growing company that would help sustain us, as well as employ others, at a living wage.

We’ve learned a lot in these 10 years or so, both about the musical instrument business and about how to build great pickups. What we’re about to do now is borne out of both of those learnings.

We’ve come to realize that our relatively complicated pickup design is too expensive to produce, to the point that we can’t achieve all of our goals under the current paradigm. We needed to make some significant changes to how we produce these pickups to really become viable. What we’ve done is redesign the Zexcoil pickup to make it as inexpensive as we can. We’ve done this by eliminating redundant parts, commonizing parts where we could and streamlining the process required to build a pickup. As a result of this effort we have a less expensive pickup that retains the Core Zexcoil design, and because it’s inherently more efficient, sounds at least as good and in many ways better than our Legacy models. The only significant practical difference between our new Z-Series™ and Legacy™ Zexcoils is that the Z Series pickups are potted in their covers. This makes the Z-Series covers non-removable, while the Legacy pickups have interchangeable covers.

After much thought, we’ve also decided to continue with our direct internet business model. This allows us to cut out all of the middle men and give our customers the best possible price on these pickups. While we know that our superior performance can and always has commanded a premium, that’s not what this is about. It’s not about making as much money as possible. It’s about making enough money to be viable and sharing the benefits of our efficiencies with the end user as much as we possibly can.

So here’s what’s happening. Our model line and pricing structure will change significantly. We will be introducing the new Z Series pickups with the full range of analogs to our current Legacy models, and at the same time expanding our output range into the lower end of the scale, with new models that are closer to vintage pickup specifications than we have ever been.

Our Z-Core™ 5 family of pickups will be priced at $79.99. That’s 20% lower than any pickup we’ve offered to the general public before. The Z-Core product line represents pickups designed by us and assembled at our US partner factory, the same factory where our coils have always been wound. The initial Z-Core offerings will include our most popular voicings, with analogs to the Legacy SV5 and SV5O, and some new lower wind AlNiCo 5 voiced pickups that are closer to vintage single coil specs than anything we’ve ever made. These new lower wind sets are also designed for the same 250 kΩ controls that most conventional single coil equipped guitars use.

We will have a range of Custom Shop options based on the new Z-Series platform (including new Tele bridge pickups), with voicings analogous to our Legacy models, priced from $89.99 – 105.99. These Custom Shop models will include our 2, Fat 5, Convertible, Juicy and Throaty voicings. Custom Shop models will be built by us, and our handful of local builders, by hand. As demand warrants, we plan to migrate as many Z Series models as we can from the Custom Shop to the lower priced Z-Core line. Design and performance of Z-Series Custom Shop and Z-Core pickups are identical, the only difference being the economies of scale at which they are manufactured.

We will be offering a range of sets featuring 3 Z-Core 5s starting at only $225, and multiple options for mixed Z-Core/Custom Shop sets below $250. We also have Custom Shop Tele bridge/Z Core (Strat) neck sets starting at just $170.

We will continue to offer our Legacy product line through the Custom Shop, although the prices will be adjusted to reflect the realities of the costs involved in producing these pickups. We’ve designed the Z Series product line to cover all of the same bases as our Legacy pickups and there are Z Series analogs of just about every Legacy model. All of the new pickups incorporate the design concepts and philosophy of our Legacy products, in fact we believe that they represent the most advanced evolution of our approach to pickup design. The Z Series pickups are just a more efficient and streamlined version of the same great one-coil-per-string hum cancelling idea we’ve always had.

We will be raising the prices of our Legacy models to $129.00 with the full release of the Z-Core and Custom Shop Z-Series lines. We are targeting August 1, 2017 for the full release, and we will take orders for the Legacy models at the current prices up to that date.

 

The New Z-Series™ Pickups from Zexcoil®

You may have heard some rumblings about our new Z-Series™ pickups.

Well, the rumblings are true, we have been developing a new Zexcoil® platform for the past year or so. As you can imagine, producing a six coil, hum canceling pickup is expensive. Every part in a Zexcoil pickup is custom made to our specs, and we don’t share any common parts with any other pickup. You can’t go to a guitar parts supply house and set yourself up to make Zexcoils, like most conventional pickup winders can. We came to the realization that, in order to remain viable, we needed to come up with an improved version of our unique design that would retain all the good parts of our current line while being less expensive to produce. We did that, and more.

The new Z-Series pickups share much with our Legacy Series™ (the new name for the original line). Both incorporate our patented, hum canceling Zexcoil one-coil-per-string platform and both use our patented T3 Tone Tuning Technology™, our catchy name for the underlying materials engineering that shapes the tone of our pickups. The Z-Series is basically just a re-engineered version of the original Zexcoil, where we’ve communalized parts, eliminated unnecessary parts and removed multiple laborious production steps. In effect it’s a refined, improved and more efficient imagining of a Zexcoil in many respects.

Figures 1 and 2 illustrate exploded views of the Z- and Legacy Series pickups. These designs share the same bobbin and coil. Similar pole piece materials are used in both designs (with some differences that I will explain below). The Z-Series uses six magnets, a dedicated magnet for each bobbin/coil, while the Legacy Series uses only two, with each magnet serving a group of 3 coils. The Z-Series does not utilize the pole piece caps that most Legacy Series models do. Many of our models incorporate a laminated pole piece, and the pole piece caps on these models serve to provide a nice finished look, while also adding a significant mass of magnetically permeable metal in the flux path, close to the string. Since Z-Series models are potted in the covers, pole piece caps are not required. Potting in the cover also serves to eliminate a large part of the labor involved in producing a Zexcoil.

There are a few other things that make the Z-Series different, and in some sense “better” – at least more efficient from an electrical standpoint. One thing that isn’t obvious from Figures 1 & 2 is that we have rebalanced the coil and pole piece allocations in each slot. As a result, we get more of the output via pole piece mass (more magnetically permeable material in the core of the coil concentrates more of the magnetic flux in the core and results in higher output) so we can reduce the number of windings in the coils. Fewer windings yield lower resistance. So in tech speak, we get more Henries with fewer Ohms. We’ve also folded this improvement back into the Legacy line, because we can!

Elimination of the pole piece caps is effectively the elimination of an “eddy current speed bump” in the middle of the flux path. While the Legacy Series Zexcoils incorporate caps, these designs were also optimized around the caps being in place so they sound great the way they are. But the fact is, the caps aren’t required to generate a signal and when the caps are removed the pickup becomes more efficient. For instance, all other things being equal, a pickup without pole piece caps will generally have a higher Q value (see below) than a pickup with caps.

The incorporation of individual magnets for each coil also results in an efficiency gain. While we originally did it just to simplify the design (the Z-Series magnets are interchangeable in terms of North/South magnetic orientation – so only one part is required – while the Legacy Series magnets are “handed” – requiring two parts), what we didn’t appreciate until we built one, tested and played it, is that decoupling the coils magnetically is a fundamentally more efficient way to do it. The same way that removal of the pole piece caps improves Q, magnetic decoupling of the coils results in a similar “improvement”.

Add all of these benefits up and it enables us to use a less exotic, and also more magnetically permeable, pole piece material in the Z-Series. For instance, the pole piece configuration that sounds like slightly lower Q AlNiCo 3 in the Legacy Series design sounds like higher Q AlNiCo 5 in the Z-Series format. And, in relation to the efficiency gains from increasing pole piece mass discussed earlier, a more magnetically permeable pole piece allows us to get higher output at even lower resistance. So much so that the “vintage” output Z-Series models have similar or even lower resistance than their conventional counterparts. A significant implication of this efficiency gain is that these vintage output models are totally compatible with, in fact optimized for, 250 kΩ potentiometers. You can just drop them into your existing controls!

We will be officially introducing Zexcoil Z-Series pickups very soon.

Appendix – A brief discussion of “Q”

The parameter “Q”, or the quality factor, is used in many branches of physics. In a general sense, Q is a measure of the energy stored in a system compared to the energy lost by the system in a given cycle. For an oscillator, a high Q means the oscillator will ring for a long time. For a mechanical system, like a pendulum, a high Q means the pendulum will swing for a long time. Systems with higher Q can generally be thought of as more efficient since they make better use of the energy that is input to them. For an inductor, like a guitar pickup, Q is a function of frequency. The most convenient definition of Q for a guitar pickup is taken at the resonant frequency. The Figure below shows how Q at resonance is calculated from a plot of impedance versus frequency for a guitar pickup. So for a guitar pickup, a taller, narrower resonant peak is indicative of higher Q.