Duncan Designed Mustang Pickups, Analysis & Review

[Antigua]

As with other offsets in the Vintage Modified seties, these pickups are "Duncan Designed" pickups, and again, the bridge pickup is a "hot" pickup. In modern times, "hot" can mean over-wound ever so slightly, but the VM Duncan Designed bridge pickups are "hot" in the 80's sense of the word, with an inductance that is 50% greater than the neck pickup.

As can be seen in the pics below, these are essentially flat poled Strat pickups, with the bridge pickup having an inverted orientation in order to fit a route that steers clear of the tremolo unit's cavity. Based on a Google search, it appears that original Mustang pickups were much the same. These DD pickups has plastic bobbins, and, just to aggravate and annoy, they epoxied the pickups into the cover, so that the two can't come apart. Not liking the pickups for personal reasons, I tried to get the cover off so I could mount them over different Strat pickups, but it didn't happen. There is a pic below of the wreckage.

Both the neck and bridge pickup feature ALNiCo 5 pole pieces, though they are a little weaker than comparable Stratocaster pole pieces, because they're slightly shorter in length, and the strength of AlNiCo is rather dependent on the dimensions of the magnet, due to it's relatively low coercive force.

The bridge pickup has an inductance of 3.6H and a loaded peak of 2.9kHz. By contrast, a typical Strat pickup has an inductance of only 2.4H, and a loaded peak around 4.0kHz, so the hot bridge pickup knocks about 1kHz off of what you'd get with a Strat. The bridge pickup has a DC resistance of 11.5k of 43AWG, which is equivalent to about 8.5k 42 AWG, like the neck pickup. Note that the "hotter" wind does not really make the pickup any louder, but merely makes it darker. The plot below shows about a 1dB difference in overall amplitude difference between the two pickups. Even though the bridge pickup has perhaps 1,500 more turns of wire than the neck pickup, it takes a lot more wire than that to get an appreciable boost in voltage output. The higher DC resistance also gives the bridge pickup a lower Q factor than the neck pickup, 4.3dB at resonance versus 5.4dB, with load.

Electrically, the neck pickup is closer to a standard 42 AWG Fender single coil. The inductance of 2.8H is closer to Strat bridge pickup, but not as a hot as a Tele bridge. Hotter than a typical neck pickup, in any case.

What is really worth noting about both the bridge and neck pickup is that they are a lot darker than they should be, given the inductances, and the reason is because they feature aluminum foil shielding around their coils, as can be seen in the pic of the destroyed pickup below. I'm not aware that Fender has ever done this in the US, it seems to strictly be a feature of imported pickups. The foil wrapped around the coil capacitively couples with the coil to produce a rather high capacitance. According the math, the bridge shows about 350pF, and the neck 460pF. A typical Fender single coil has only 130pF capacitance, so this surrounding copper foil causes the capacitance to increase by 200-300pF. For the sake of comparison, a 10ft guitar cable contains about 400pF capacitance, so this foil shielding add about as much capacitance as if you were to extend your 10ft guitar cable out to about 18ft, resulting in a darker overall tone. Despite the very different inductance of neck and bridge pickups, they fact that they both contain this high capacitance results in a similar and low loaded peak resonance of 2.9kHz, which is about 1kHz lower that a typical Strat pickup, with a loaded peak closer to 4kHz. The worst part about it is that these pickups were still very noisy, at least for me.

Though these pickups are dark, due to both a high inductance and capacitance, I notice a lot of Mustangs (and other offsets) come stock his humbuckers and P-90's, apparently catering to guitarists who plan to use their offsets in a hard rock / punk rock capacity, rather than surf or new wave, so these "hot" single coils might be conducive to punk rock, though it should be noted that their output voltage is still rather minimal, and they certainly won't push an amp as hard as a humbucker, or even a P-90.


Measurements:

Duncan Designed Mustang Bridge SC101B/ADWHCD 1707
- DC Resistance: 11.53K ohms
- Measured L: 3.587H
- Calculated C: 353pF (363 - 10)
- Gauss: 900G (600G top of plastic)

Duncan Designed Mustang Neck SC101M/ADWHCD 1707
- DC Resistance: 7.11K ohms
- Measured L: 2.754H
- Calculated C: 463pF (473 - 10)
- Gauss: 900G (600G top of plastic)

Bridge unloaded: dV: 8.9dB f: 4.41kHz (black)
Bridge loaded (200k & 470pF): dV: 4.3dB f: 2.89kHZ (blue)
Neck unloaded: dV: 9.6dB f: 4.46kHz (red)
Neck loaded (200k & 470pF): dV: 5.4dB f: 2.93kHz (green)





The MV Mustang has 250k pots and, interestingly, a 0.05uF capacitor, which I have not come across in any other guitar, but is close enough to the more common .047uF. Because of the high capacitance of these pickups with the copper foil shielding, turning down the tone knob resulted in an especially dark tone, more similar to the result you'd get with a 0.1uF cap.






I wasn't digging the electrical values of the DD's, so I tried to get the guts away from the cover, so I could put something else underneath. It didn't work out though, I ended up having install Strat pickups along with Strat pickup covers.

The plastic bobbin was glued in so tightly to the cover, that the bottom half ripped away from the upper half, and never did come lose. The epoxy / glue is probably stronger than the plastic itself.




At $300 the guitar seems like a rather solid dead, although the fret work and fingerboard definitely look a little rough. It's definitely not quite as neat as the VM Jaguar or Jazz Master I have on hand. It plays and sounds great (now) though. With the shorter scale, lower output pickups and the firmer bridge/tremolo network, it reminds me a lot of the Jaguar with a Buzz Stop installed. The neck profile also feels a bit thicker.

I swapped in a new white pick guard, along with lower inductance flat poled Strat pickups. I really dig the white pick guard against 50's automotive, pastel look, especially with the Fender offsets, and all the accompanying chrome.

[Larry Mal]

Well, that was great!

[Embenny]

Very interesting read! I feel like you probably paid closer attention to all these details of the pickups than Duncan did when they designed them. I've never plaid the Squier mustang so it sounds odd to think of it as having such a hot and dark single coil. My vintage Mustangs are anything but.

[oid]

That is quite the overwind, the only vintage Mustang pickups I ever got to measure had a lower DC resistance then any strat pickups, lower then any pickups I had ever measured. Don't think I have my notes from those days anymore, perhaps someone can provide us some vintage Mustang specs so we can compare.

Would you be able to measure the flux on the string? perhaps on both Es? A measurement without the string but at the height of the string? Always have been curious as to the effects the strings have on the field

Regarding dismantling such a pickup, 30 seconds or so in boiling water should break down the glue, only specialty glues work above boiling, not sure how this would effect the poly coated wire Duncan uses these days though, or the plastic bobbin for that matter.

We have been discussing your write-up of the Jag pickups in another thread, a tad bit of a thread hijack on my park, think that post has rekindled my interest in pickups work and made me realize how much I have let my inductor theory slip! Enjoyed your writeups, interesting stuff, enjoyed them and the resulting discussion.

[Antigua]

Very interesting read! I feel like you probably paid closer attention to all these details of the pickups than Duncan did when they designed them. I've never plaid the Squier mustang so it sounds odd to think of it as having such a hot and dark single coil. My vintage Mustangs are anything but.

All the Squier Vintage Modified offsets with the Duncan Designed pickups appear to have hot bridge pickups. I personally prefer just having two of the same low output pickup in a guitar. No "balanced sets", no "hot bridge". I suppose their thinking is that it gets a single coil closer to a humbucker, but I think most would agree that a hot single coil is no substitute for a humbucker, if that's what a person wants.

[Embenny]

Very interesting read! I feel like you probably paid closer attention to all these details of the pickups than Duncan did when they designed them. I've never plaid the Squier mustang so it sounds odd to think of it as having such a hot and dark single coil. My vintage Mustangs are anything but.

All the Squier Vintage Modified offsets with the Duncan Designed pickups appear to have hot bridge pickups. I personally prefer just having two of the same low output pickup in a guitar. No "balanced sets", no "hot bridge". I suppose their thinking is that it gets a single coil closer to a humbucker, but I think most would agree that a hot single coil is no substitute for a humbucker, if that's what a person wants.

Oh, I agree completely. I love the bite of vintage single coils in the bridge. I've never understood why so many aftermarket pickup winders have "vintage" sets with overwound ("calibrated") bridge pickups. Then you get all these people online complaining that their vintage repro boutique pickups aren't getting them the vintage tone they seek. It's fine to want an overwound bridge pickup, just don't call it vintage!

Didn't know that about the DD pickups. It makes sense, a lot of people these days seem to prefer overwound bridge pickups, it seems.

[Antigua]

That is quite the overwind, the only vintage Mustang pickups I ever got to measure had a lower DC resistance then any strat pickups, lower then any pickups I had ever measured. Don't think I have my notes from those days anymore, perhaps someone can provide us some vintage Mustang specs so we can compare.

I'd like to know of some vintage values. They were supposedly the budget guitar in the lineup, it wouldn't surprise me if Fender put less wire on them in the name of reducing costs.

Would you be able to measure the flux on the string? perhaps on both Es? A measurement without the string but at the height of the string? Always have been curious as to the effects the strings have on the field

That's a fine question. This is the magnetometer I used https://www.amazon.com/gp/product/B075X ... UTF8&psc=1 . It has a nice thin probe that is easy to maneuver around. I measured the low E over the neck pickup. At the string height, which is about 5mm over the pole piece, it measures 25mT when the string is moved out of the way. Then the string in place, it measured 35mT below the string, and, very strangely, only 4mT above the string, with the polarity always being south. With the high E, closer to the pole piece, I measured 50mT without the string, and about 40mT with the string in place, and these value seem a little bogus, so I believe what problem is, is that the little loop of wire in the sensor is actually larger than the guitar guitar itself, so it's capturing both the primary and the return path of the guitar string's magnetic field. In other words, "ERROR!".

Regarding dismantling such a pickup, 30 seconds or so in boiling water should break down the glue, only specialty glues work above boiling, not sure how this would effect the poly coated wire Duncan uses these days though, or the plastic bobbin for that matter.

Well that would have been preferable to the mangle messed I was left with. I'll keep that mind for next time. I'm planning to use the leftovers to test the feasibility of dissolving potting wax.

We have been discussing your write-up of the Jag pickups in another thread, a tad bit of a thread hijack on my park, think that post has rekindled my interest in pickups work and made me realize how much I have let my inductor theory slip! Enjoyed your writeups, interesting stuff, enjoyed them and the resulting discussion.

I've been researching pickups for a couple years now. I might be able to answer questions about general pickup theory, if you have any.

[Antigua]

Oh, I agree completely. I love the bite of vintage single coils in the bridge. I've never understood why so many aftermarket pickup winders have "vintage" sets with overwound ("calibrated") bridge pickups. Then you get all these people online complaining that their vintage repro boutique pickups aren't getting them the vintage tone they seek. It's fine to want an overwound bridge pickup, just don't call it vintage!

Didn't know that about the DD pickups. It makes sense, a lot of people these days seem to prefer overwound bridge pickups, it seems.

The funny thing is that the "hot" bridge is not really much hotter, as can be seen in the bode plot. The excitation input for both pickups is identical (4Vpp into an air coil of about 200 turns of 44AWG mounted over the 3rd or 4th pole piece) and the overall difference in level is only ~1dB. Overwinding a humbucker is generally a lot more effective than overwindign a single coil, because you have two coils close to the strings, and so that added wire is put in a position where it's more able to induce a greater voltage, but with single coils, you add wire and a lot of that added wire is at the bottom of the coil, where it's not very productive.

The primary difference is really just the amount of treble that is exposed by the RLC filtering of the pickups, and the truth is that a darker signal makes for a smoother, "crunchy" overdrive, even if the voltage output is the same. The secret behind a lot of the famous overdrive pedals comes down to frequency attenuation, and not much more than that. The real true way to make the bridge louder, should that be what you want, is to raise it closer to the strings, and lower the neck pickup, for relative volume balance. I'll still say "wound hot" because that's modern parlance, but it's kind of a misnomer, it should just be "wound darker".

[Horsefeather]

How do you think pair of Tele bridge pickups would sound in a Mustang?

[oid]

I'd like to know of some vintage values.

Going from what ever remains of my memory, they were more or less strat flatwork with shorter magnets set flush top and bottom, cross section of the pickups was roughly square, perhaps a bit flatter than wide, coils being 4.6k and 4.7k, so essentially the same. No idea how accurate these memories are, but the pickups were fairly influential on me and my budding pickup interest. I had just started playing around with winding and really thought more was better, was very surprised how good they sounded and the seemingly low impedance they had. They came about just in time to balance out my pickup exploration and got me to explore everything from 300ohm transformer coupled pickups to big 15k windings. That mustang was perfect, guy bought it new in the 60s and forgot about it when he went away to college, found it nearly 40 years later stashed under a bed at his mom's house, looked brand new.

In other words, "ERROR!".

I am not sure about these values in anyway, sometimes I feel like they are good enough to be useful, sometimes I am irritated by the quirks of magnetics.

I'm planning to use the leftovers to test the feasibility of dissolving potting wax.

If it is proper wax just toss it in a double boiler for awhile then stick it in the fridge until the wax has floated to the surface, pull it off and put it back on the stove again and repeat. Two rounds is generally enough for most pickups, some that cast the coil into the cover with wax can take a third.

I might be able to answer questions about general pickup theory, if you have any.

Your Jag pickup write-up has gotten me thinking about ways to figure out the actual effect the claw has on frequency response and perhaps the frequency response of the pickup as a whole. The coil on its own is simple enough but to interact with the magnetic circuit as a string would seems abit of trick, especially when you want to compare the effects of the magnetic circuit on frequency response/harmonic content. So far the best I have been able to come up with is to make up a tone wheel that I can chuck into my hand cranked grinder and spin up to speed. I can get a fairly good frequency sweep this way and it more or less interacts as a string would, but making the tone wheel would be a fair bit of work and actual tone wheels I suspect will be pricey. Any ideas on this topic? A coil would be nice and simple, but I can not see it being all that accurate and its accuracy can not really be tested without a repeatable test of known quality.

How do you think pair of Tele bridge pickups would sound in a Mustang?

I think they would sound fairly good, the main determining factors in sound would be the mustang trem and the pickups, body/neck add some color but would be less so in this case, unless you are comparing an ebony Tele to a basswood Mustang. My hunch is you would end up with the Tele color with Mustang Dynamics in attack/sustain/resonance. So a smoothed out Tele sound, no chicken pickin here.

[Antigua]

How do you think pair of Tele bridge pickups would sound in a Mustang?

Just thick and dark. I bought one of those custom Telecasters with three Nocaster bridge pickups, around 7.5k ohms each IIRC, and I ended up having them custom wound to make them lower inductance, 6k like Strat pickups, so that I could get a more standard tonality out of the guitar while keeping the cool looks.

[Antigua]

I'd like to know of some vintage values.

Going from what ever remains of my memory, they were more or less strat flatwork with shorter magnets set flush top and bottom, cross section of the pickups was roughly square, perhaps a bit flatter than wide, coils being 4.6k and 4.7k, so essentially the same. No idea how accurate these memories are, but the pickups were fairly influential on me and my budding pickup interest. I had just started playing around with winding and really thought more was better, was very surprised how good they sounded and the seemingly low impedance they had. They came about just in time to balance out my pickup exploration and got me to explore everything from 300ohm transformer coupled pickups to big 15k windings. That mustang was perfect, guy bought it new in the 60s and forgot about it when he went away to college, found it nearly 40 years later stashed under a bed at his mom's house, looked brand new.

In other words, "ERROR!".

I am not sure about these values in anyway, sometimes I feel like they are good enough to be useful, sometimes I am irritated by the quirks of magnetics.

I'm planning to use the leftovers to test the feasibility of dissolving potting wax.

If it is proper wax just toss it in a double boiler for awhile then stick it in the fridge until the wax has floated to the surface, pull it off and put it back on the stove again and repeat. Two rounds is generally enough for most pickups, some that cast the coil into the cover with wax can take a third.

I might be able to answer questions about general pickup theory, if you have any.

Your Jag pickup write-up has gotten me thinking about ways to figure out the actual effect the claw has on frequency response and perhaps the frequency response of the pickup as a whole. The coil on its own is simple enough but to interact with the magnetic circuit as a string would seems abit of trick, especially when you want to compare the effects of the magnetic circuit on frequency response/harmonic content. So far the best I have been able to come up with is to make up a tone wheel that I can chuck into my hand cranked grinder and spin up to speed. I can get a fairly good frequency sweep this way and it more or less interacts as a string would, but making the tone wheel would be a fair bit of work and actual tone wheels I suspect will be pricey. Any ideas on this topic? A coil would be nice and simple, but I can not see it being all that accurate and its accuracy can not really be tested without a repeatable test of known quality.

I've really come to appreciate the aspect of magnetic fields. They're sort of like math, everyone hates it because it's confusing, but at the end of the day it is just the truth. It's never confused, only you are. The same is true of magnetic fields, if it behaves in a way that confuses you, it just means your understanding of things requires correction, and that's a valuable piece of information to have.

That's a good idea with the hot water and the freezer. I'm wondering if there is a solvent that could literally break the alkane chains, so that it would just drip out along with the solvent. I have some good leads on compounds to try, but the question is whether it will liquefy the wax, or just turn it into a slurry. A combination of heat and solvent might work well, too.

I actually have a test plot of a Jag pickup with and without the claw, as part of a data collection I have not posted yet:



For some strange reason the claw shield actually brought the output down by about 1.5dB, but the that aside, the more important takeaway is that the steel mass only increased the inductance and capacitance enough to lower the peak resonance by about 210Hz.

In terms of capacitance, the copper foil around the Duncan Design Mustang pickups was MUCH higher because it was so very close to the coil, where as the claw shield is set back from the coil by a two to three millimeters, which make a huge difference. Of course the copper shield has no effect upon the inductance, aside from the eddy current which might reduce it slightly, by acting as a very minor shunt resistance.

I'm not sure what you mean about a tone wheel, but I use a bode plotter, which is described here http://guitarnuts2.proboards.com/thread ... ar-pickups , though that's a little outdated, as I've improved by techniques a bit since, and I need to update it. This performs a frequency sweep, create a bode plot of amplitude by frequency. There is nothing special about the claw shield really, it just helps to complete the magnetic circuit, but doesn't do so to any significant effect, because the air gap is still so large, and whether it helps complete the magnetic circuit in a manner that increases the output at all is still ambiguous.

[Debaser]

Welcome Antigua, glad to see the Mustang analysis here. Did you post the Jazzmaster write-up yet?

[Antigua]

Welcome Antigua, glad to see the Mustang analysis here. Did you post the Jazzmaster write-up yet?

I'll do that right now.

[oid]

Driving the pickup with a coil does not accurately show the effects of the magnetic circuit. As to how far off from reality that is, I do not know, I suppose loading a pickup with poles which have yet to be magnetized would give some clues, but would likely raise more questions then answers. Could be useful though.

A tone wheel is how the Hammond B3 and similar organs generated sound, pretty much a gear spun over the pickup, the teeth of the gear interact with the field similarly as a string would. It is not a perfect analog of a string, but closer then a coil and it allows the frequency to be swept since pitch is a function of rpm.

I have been mulling over how to accurately judge the effects of the magnetic circuit for awhile now and the tone wheel is my best solution yet. I have also considered winding a coil right onto a offcut of a string, has some advantages especially in labor, but still not ideal.