Anyone peeked inside a Seymour Duncan Pickup Booster...?

[WGTP]

Seymour makes a variety of humbuckers designed to fit in a stock strat without routing.   I think making a single coil sound like a HB is a lot more complicated than anything mentioned.

A HB senses the string in 2 different places and each coil (especially at the bridge location) sounds different.  What you hear is a combination of the 2 coils.  The coil closest to the bridge tends to have sort of a Tele/Rick sound and the coil on the neck side tends to sound more like the middle sounds of a strat.  

Also, if one coil has screws and one studs, each coil sounds different.  I doubt even Seymour's SC size replicas sound exactly like a full size HB.  They have a great forum there, much like this one.  Check it out.  

[MR COFFEE]

WGTP and all,

You're right, nothing sounds like a Gibson-style humbucker except a Gibson-style humbucker. And mounting it on a guitar with mahogany body with a mahogany set-in neck makes quite a difference in the sound, too. Play one of the Fender strats with a humbucker in the bridge and it's definitely a different-sounding animal.

But in terms of emulating that sound with a strat single coil, which is what the Duncan gizmo is supposed to do, my post stands. It gets you as close as electronics can.

One widely-disseminated misconception you mentioned - humbucker pickups don't actually "sense the string at two different places." It's true that the magnetic aperture of a humbucker is much wider than that of a single coil, which means that the magnetic flux flows through a wider segment of the string because of the magnet structure (compared to a single coil pickup). In a Gibson-style humbucker, the magnetic circuit is off the top of one coil's pole pieces, through the string, back to the top of the other coil's pole pieces, down through the pole pieces, out of the bottom of the pole pieces through the bar magnet to the other coil's bottom pole pieces, through those pole pieces back to the top where this explanation started out. The magnetic circuit of a strat-style single-coil pickup is quite different. There is a LOT more air and wierd magnetic loops, including through the whammy bar springs, with single coils.

Put two single coils pickups with rod magnets next to each other, connect them in series, it's still very different from a Gibson humbucker, even if you match other aspects of the coil geometries. Magnetic flux follows the path of least resistance to magnetic flux, even if it is a hell of a long way around. Air is a lousy conductor of magnetic flux, so substantial air gaps make a big difference. Remove one coil of a Gibson-style humbucker from the circuit electrically (single coil mode, sometimes mistakenly referred to as a "coil tap"), and the magnetic flux path doesn't change to the pattern associated with a single coil. It doesn't change at all. You simply lost the hum-cancelling and about half the pickup gain, and removed a BIG inductance that was in series with the signal which rolled off the highs relative to the single coil mode.

Think of how different playing one coil of a humbucker sounds from a strat pickup. Or how different a telecaster pickup sounds if you mount it on a brass tailpiece or switch the pickup mounting screws to brass instead of steel. It changes the flux circuit, and that changes the sound. Yeah, it still sounds tele-ish, but it's noticeably different to any seasoned tele player. Even stainless stell screws mounting the tele bridge pickup make an audible difference.

Think about the tone of a Gibson-style humbucker in "parallel mode" - both coils in parallel so it still bucks the hum, loses half the gain, and you don't lose so much of the highs from the major increase in inductance caused by the other coil being in series with the signal in the normal "series-mode" wiring.

Still doesn't sound like a Strat, even mounted on a strat, right? The equivalent Q and resonant frequency just aren't high enough, and the magnetic circuit is still quite different.  But add a circuit to emulate the characteristic Fc and Q of a strat pickup, and heads WILL turn. (If some asshole out there patents this idea, just get in touch with me and I'll help you bust it with prior art. I've been building them into guitars since the late 70's on a custom basis. Jeez, the Patent office is so overwhelmed these days you could patent farting).  :lol:

The tonal differences between pickups are, as you pointed out, not just the changes in the frequency response curve, which is essentially equivalent to a resonant low-pass filter function with, usually, an equivalent Q-related resonant peak before cutoff (Q of 2.5 to 4.5 on typical pickups like Gibson and Fender stock). Bartolini makes some pickups with multiple resonances by using assymetrical structures, but they are virtually the only manufacturer I know of that has gone that route.

And as I am sure you know, the hot rails and other single coil form-factor "humbuckers" don't sound all that much like a Gibson style humbucker either. Yeah, they are hotter, and will overdrive an amp easier, and they can be made so that the resonant peak can be dropped to 2-3.5 khz from the usual 6-7 khz of a stock strat, but they sound no more like a Gibson humbucker than the circuit of the Duncan gizmo will do to a plain unmodified Strat pickup electronically - or vice versa. The magnet circuit is just too different. That doesn't mean they don't sound GOOD, however.

This kind of circuitry (the Duncan unit) is a way for people to get a more-like-a-humbucker sound without changing guitars or locking yourself into a replacement pickup that takes away the strat sound in exchange for a hotter pickup that is still sigtnificantly different in tone from the Gibson Humbucker. "Hot rails"-style pickups DO get rid of the damn hum, however.  

At some point, if you really want to get a sound like a Gibson and you're playing a Strat or Tele, just buy a second guitar (duh) and switch guitar when you want that sound. Lots of player's do.

But if you just want to do a solo and you just want a sound a bit closer to a humbucker sound, the SPC, the Duncan unit, or roll-your-own from all the info posted above, will get you significantly closer, in that order.

Putting an Alnico Pro II HB on my Steinberger GM doesn't make it sound like an old Les Paul with a mahogany body and a midrangey mahogany set neck - but it's in the same neighborhood, even though the neck is composite and the body is maple. And it does sound VERY good. IMHO, better. I prefer it, anyway, for most of my playing.

The sound of Strat single coils with boosted mids from an electronically-derived lower equivalent Fc with resonance can sound really good, too. IMHO.

And if you don't mind active electronics, you can lose the damn single coil hum with a "dummy coil" (humbar) and an out-of-phase combining amplifier circuit. (Sorry folks, I have a thing about hum and noise). But I still play my Strat occasionally... Especially with the "in-between" pickup sounds, where the hum DOES cancel.  

Hope this clears up a few things. Build you a variable active LPF with variable Q and listen to how it can shape the sound of pickups you already have on your guitar. If it isn't trash with saturated magnetics, the circuit can do AMAZING things. What is it RG says, YMMV?  

[WGTP]

Excellent explaination.  I was going from my experience with using HB pickups with identical coils in the bridge possition (DiMarzio Super II and SD Full Shred) and adding a switch to change between the single coil modes.  They do sound different and I tend to prefer the coil away from the bridge for the single coile mode, although the Duncan Custom Custom did have a nice Rick sound to it with the bridge coil.

Do you think the coil away from the bridge is louder due to increased string movement?

I'm curious about the resonance frequency numbers your quoting.  They are about 1/2 what SD lists for the same P.U.s.  His basic strat is around 9kHz and many of the HB's are around 6kHz.   The SC size HB's are about the same though.  

[saultime]

A lot--and I mean a LOT of the difference in tone between Fender and Gibson style guitars has to to with scale length. Fender guitars have a slightly longer scale--strings are stretched longer and tighter, yielding a brighter, twangy tone. This has a greater effect on tone than set vs. bolt-on neck in my opinion, especially if you've ever seen a cutaway of Gibson's recent sloppy neckjoints.

[MR COFFEE]

WGTP,

The difference in volume you hear with the Dimarzio using different single coils of the humbucker has to do with the location of the coil on the sensing magnet structure. The magnetic lines of force cutting the coils differs slightly between the two coils in the bridge position since the coil right up next to the bridge doesn't really sense as much amplitude of vibration. When the traveling wave on a string reaches the end of the string, the energy wave turns into primarily a "pull" force against the bridge saddle and reflects back off with an inverted amplitude and slightly attenuated traveling wave that is a mirror of the wave that just reflected.

Those figures for Duncan SCs are not very different acoustically in how a pickup sounds (6-7 versus 9 khz). Not much happens except brief transients on a guitar string above 5 khz. Fender has made a lot of pickups over the years and they have varied in Fc and Q. Those figures come from Bartolini's work and measurements of pickups he made - I believe IIRC from modelsmade back in the 60's. On Duncan Gibson replacements, keep in mind that Gibson has made a LOT of different humbuckers over the years too, and that you can up the Fc by replacing an alnico bar with a ceramic since this lowers the inductance and to a slight degree, the stray capcitance to ground, since coil is now conductive. Also replacements often go for a different sound. Check out Bartolini's research - worth a read.

[MR COFFEE]

WGTP and all,
And one more thing I should have said - Gibson Humbuckers also have been made in a variety of models over the years with differing characteristics, and I WASN'T saying Gibson humbuckers have an Fc of 2-3.5 khz - although some do get down as low as 3.5 khz measured in a guitar (see below). I was talking about emulating the humbucker overdrive sound with a strat.

The Gibson 1959 PAF versions have measured as high as 5.9 khz from what I have read, but most stock Gibson Humbuckers have a Fc of less than 4.5 khz, and the best "power guitar sound" (classic rock overdrive sound) comes from pickups with an Fc lower than that - the EMG 81s Zack Wylde uses has an Fc of 2.1 khz, and sound pretty good to my ears.    

But also keep in mind that a lot of what Fc you measure/cite for a really high impedance pickup like Gibson humbuckers (or soapbars for that matter) has to do with whether you measure it UNMOUNTED with a 10" lead wire, or mounted in a guitar and hooked up with a regular guitar CORD (not to mention the effect of the LENGTH of the cord, and what KIND of cord (capacitance per foot) you use. The cord capacitance greatly effects the resonant peak/rollof of a pickup, especially really high impedance models). And Gibson humbuckers with covers ON have a lower Q and Fc - again (mostly) because of the capacitance, although nickel silver or brass covers also effect the magnetic field radiation. Chrome-plating on cheap covers really effects sound because of it's potent magnetic properties. Humbucker Q is usually much lower than Fender Single coils, too (Q= ~2.5 versus ~4.5 for a strat pickup) And if you understand what that high a resonant peak does to boost frequencies just before cutoff, 4.5 is one heck of a lot more boost to the highs than the lower Qs associated with Gibson-type humbuckers. As an aside, auditory research has found that with high Q lowpass filters, frequencies above cutoff just aren't audible anymore.

Saultime,
I agree that scale length makes some difference in tone; longer strings generate more harmonic content. Tone is also much effected by string guage and alloy (nickel and stainless steel differ quite noticeably in highs); quality of construction and wood;  and, of course, the mass (weight) and modulus of the wood or other materials involved. It is a complex equation.

I also agree the "set-in" neck isn't a major determinant of the tone of a particular guitar design, especially in terms of brightness. It's more about the choice of woods - maple versus mahogany versus very light woods like alder, ash, or even basswood. But I think the main reason Gibson and others use set-in necks of one kind or another is the characteristics of the mahogany chosen for the neck as a construction material. You don't see too many "bolt-on" mahogany necks for good reason!  :lol: It's just too soft a wood.

I played a Les Paul with Bartolini pickups once (I forgot the type - it's been a quite a while) and it had so much brightness and high end it almost sounded like an acoustic. And they were humbucker in construction (although I bet their impedance wasn't 7000 ohms, either). Pickups make a tremendous difference in the sound of a guitar. Mass, wood, scale length, yada-yada-yada aside.

IMHO, the MAJOR determinant of the bright sound of Fender guitars is due to the pickups, with their lower impedance, higher Fc, and high Q.

And since this thread is about getting away from that sound without changing guitars or replacing pickups, the point is that it can be done to a significant degree electronically as described above. A Duncan-like device is easy to DIY, and right up the alley for those who hate to change guitars just to get a better power guitar tone out of their axe for some lead work or power chords. It does take a battery or other power source, though  :cry:

[GFR]

Those figures come from Bartolini's work and measurements of pickups he made - I believe IIRC from modelsmade back in the 60's. On Duncan Gibson replacements, keep in mind that Gibson has made a LOT of different humbuckers over the years too, and that you can up the Fc by replacing an alnico bar with a ceramic since this lowers the inductance and to a slight degree, the stray capcitance to ground, since coil is now conductive. Also replacements often go for a different sound. Check out Bartolini's research - worth a read.

Very nice thread

Can you give some references to this Bartolini research? It seems really interesting!

[MR COFFEE]

Hi GFR,

Long time no hear.

The link for Bartolini's site is

http://www.bartolini.net/

His site has some of his studies posted on it.

I just checked it, and several of the studies has been removed!  :cry:

I will look around and see if I can locate it in all the stuff I save. It was a LONG time ago (1970's), and I depend on my memory for a lot of that sort of thing.

I will email Bill and Pat and see if they will send copies to me, also. They are nice folks, so I'm hopeful.

He also has a number of patents worth reading. His most novel invention was the "Hi-A" pickup (for High Assymetry), which he patented long ago (US patent # 3983778) - about 1975. It had a lot of good information in it about research he had done on string vibration and sensing. Look by number or under Bill Bartolini (probably William)


Cheers,

Bart