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I've been on a big pickup replacement spree lately, and to my surprise installing Wolfetone Timbre Wolf pickups in the bridge of my '85 Soloist and my Soloist Jr. led to wildly different results. The '85 sounds god-like with the new PU, while Junior sounds kind of mushy and indistinct.

Both have 500k pots. The differing scale lengths of the two guitars probably account for some of the difference (25.5 on the '85, 24.75 on Junior), but I believe the bigger factor is the placement of the pickup itself.

Throw into the mix how good the Duncan Distortions sound on my new SL7 (uber-crunchy and not harsh), and I decided to measure the distance on my various Soloists from the back edge of the pole piece to the point of contact on the low E saddle. Results vary quite a bit:

Soloist Pro (the yellow one): 37mm
'85 Soloist: 33mm
Soloist Jr.: 46mm
SL7: 37mm
SLXT: 39mm

Well, there's your explanation, right there! Look at that huge difference between the '85 and Junior. There's probably no way any Alnico pickup is going to sound good in the bridge of Junior. It needs a ceramic to get enough cut. I've already got a Duncan TB-6 on the way...

My guess is that Jackson decided to move the bridge pickups forward sometime in the late '80s when they started shipping the bulk of their guitars with ceramic pickups (J50BC or J80C, mostly). They then just kept the placement there regardless of pickups.

It also indicates that intonation will play a part, since this moves the saddles in relation to the pickups.

I've got Junior set up with 11-52 in C# Standard for the song I'm currently working on, and I had to move the saddles on the Floyd way back almost as far as go they'll in order to get it to intonate. Probably having 9-42 or 10-46 on it at E Standard would brighten it up slightly, since I'd have to move the saddles forward to intonate it. However, even then it's still going to be a dark-sounding guitar, since I expect the measurement will still be at least 40mm.

Let's expand this out beyond Soloists. Why are Les Pauls always so fucking chimey with most A5 bridge pickups and tinny with ceramics? Sure, the maple cap plays a part, but check out these measurements from my LP (and LP-ish) guitars:

LP Classic: 31mm
LTD EC-1000T: 33mm
Jackson Monarkh: 35mm

Since I've got my soldering rig set up, I'm interested to try out a spare Timbre Wolf I have in my LP Classic. I use this one for more classic rock stuff, but it's always tough to get rid of enough of the chime in my mixes and get more of the crunch that you want even for classic rock.
 

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It does definitely make a difference. The Jackson ones are slightly further away from the bridge on older ones, especially the ones with oversized pickup rings, some don't like that.

What point are you measuring from though?

Technically due to saddle adjustment range if you want to get down to the mm nitty gritty you would have to measure from where the string leaves the saddle to the pole pieces.

Gibson TOMs are also angled, so even if you are measuring from the center of the posts to the poles, the bridge isn't mounted parallel to the row of pole pieces.
 

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For a "Scientific" comparison they usually also map out the harmonic node locations of the string and compare the pickups pole placement due to that.

So you would also have to take into account that distance fro the bridge isn't the only factor, where the poles are located in proximity to the harmonic nodes of the string matters as much, if not more.

A 24.75" guitar and a 25.5" guitar that both have the same distance from the poles to where the bridge leaves the saddle isn't a 1:1 comparison, because the harmonic nodes for a string at ~24.75" and ~25.5" aren't at the same location.

You would have to actually diagram the locations of the harmonic node locations on the string and compare them to the location of the poles for a more accurate picture I would think. It wouldn't be as obvious as the location change relative to the node location as it is on a 22 fret guitar to a 24 fret one, but you would still need that information for an accurate picture.



Of course, on almost all guitars, the bridge pickup isn't at a node, how close it is to the node varies though.
 

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Discussion Starter #4
I'm measuring from the back edge of the pole piece to the saddle's point of contact with the low E string. Your point about the angled vs non angled is valid, but my overall method should work across most different pickup and bridge types.

Jackson's pickup placement is interesting, because both of my USA Soloists have "San Dimas specifications" (even though one is an '87), and they both have the bridge pickup much closer to the saddles than any of the other Soloists I currently own. It could be that they still are further toward the bridge on the current USA ones, but my "eyeball test" of pictures of current USA Jacksons doesn't look like that. The pickup position on my '85 is nearly identical to what ESP typically does--which makes sense, since the M-1/Mirage Custom was mostly a copy of the San Dimas-era Soloist.

Edit: you're correct in terms of the difference between scale lengths. However, it's always going to be true that a pickup closer to the bridge is going to be brighter than one further away from the bridge. I originally measured this just to compare my Soloists, so it's more apples-to-apples than comparing a Soloist to a Les Paul, for sure. The difference in my various 24.75" guitars is instructive, however.

From everything I've measured, it looks like Chushin Gakki should have placed the bridge pickup slightly closer to the bridge on the Soloist Jr., compared to a regular Soloist, rather than further away as they did.
 

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I'm measuring from the back edge of the pole piece to the saddle's point of contact with the low E string. Your point about the angled vs non angled is valid, but my overall method should work across most different pickup and bridge types.

Jackson's pickup placement is interesting, because both of my USA Soloists have "San Dimas specifications" (even one is an '87), and they both have the bridge pickup much closer to the saddles than any of the other Soloists I currently own. It could be that they still are further back like that on the current USA ones, but my "eyeball test" of pictures of current USA Jacksons doesn't look like that. The pickup position on my '85 is nearly identical to what ESP typically does--which makes sense, since the M-1/Mirage Custom was originally just a straight-up copy of the San Dimas-era Soloist.

Edit: you're correct in terms of the difference between scale lengths. However, it's always going to be true that a pickup closer to the bridge is going to be brighter than one further away from the bridge. I originally measure this just to compare my Soloists, so it's more apples-to-apples than comparing a Soloist to a Les Paul, for sure. The difference my various 24.75" guitars is instructive, however.
You would definitely have to take into the proximity of the bridge pickups pole pieces to the nearest harmonic node for a holistic view though. It's not exclusively a function of distance from the point where it leaves the saddle.

That becomes trickier when you consider that you would have to remap it out for every fret, since the length changes for non open strings.

How close it is to the bridge does definitely affect how tight or trebley or tinny it is, but standing wave harmonics on a string and shit like that complicate it significantly. It's not the only relavent measurement.

It's a can of worms no one really wants to open for sure. The sound is also significantly affected by the pole pieces proximity to the nearest node. So it's possible to end up with a flubbier sound closer to the bridge, and a brighter sound further from it, depending on relative locations of the harmonic nodes and overtones, which change when you fret strings.

It's more notable for neck pickups probably. The difference between a neck humbucker on a 22 fret and 24 fret guitar isn't strictly due to the distance from the bridge, the 22 fret one usually happens so that the pole pieces are directly under a harmonic node if the string is played open.

On 24 fret guitars you can hit the natural harmonics by putting your finger on the 24th fret without pressing down, the same location for those natural harmonics on a 22 fret 2H guitar is usually pretty close directly above where the neck pickup pole pieces are.
 

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Generally speaking I would agree that you can determine how tight or tinny a guitar will sound in the bridge position on the basis of how far the pole pieces are from the bridge, but there are a huge number of other factors at play.

Including ones that aren't fully understood, like exactly how the natural resonant frequency of parts of the guitar interacts with how the pickups pick up sound.

It's far from scientific. Especially since the magnetic field from the poles isn't projected in a 2 dimensional plane.

There's actually next to no understanding of how many parts of the process work. :lol: People can agree that the wood the guitar is made out of affects the sound as well, but explaining it scientifically hasn't been done yet. There is a lot of shit going on. Including if the natural resonant frequency of the wood/guitar matches up with the frequencies of the notes you are playing in a way that ends up sounding good. Which is obviously why some guitars lend themselves better to certain tunings than others.

The general model of how pickups work, like, how it's diagrammed, is an oversimplification. Which is why tonewood is such a contentious issue. The basic understanding of how a pickup works means that the composition of the guitars body shouldn't be taken into account at all. It's exclusively a relationship between the pickup and the movement of the string.

I'd say generally distance from the poles to the bridge is the easiest to understand measurement and safe to bet on. But the relationship between what you are playing and the natural resonant frequencies of the guitar, or parts of the guitar, and changing locations of harmonic node locations on a standing wave on a string set up make it very difficult to figure out exactly what is causing what.
 

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Garrett that was beautiful.
 

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Partly on the same topic, I'd be interested in trying a Strat with the pickups angled the opposite way to how they're usually angled. As it is now, I think the angle makes absolutely no sense for the kind of music I play. I don't know how dramatic the difference would be, but it would pretty much halve the distance between the bridge and the low E polepiece and on the other hand double the distance for the high-E.
 

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Discussion Starter #9
Partly on the same topic, I'd be interested in trying a Strat with the pickups angled the opposite way to how they're usually angled. As it is now, I think the angle makes absolutely no sense for the kind of music I play. I don't know how dramatic the difference would be, but it would pretty much halve the distance between the bridge and the low E polepiece and on the other hand double the distance for the high-E.
Jimi Hendrix obviously played his entire recording career on upside-down strats essentially configured like that, and he seemed to do okay. :lol:

I've often wondered the same thing. It's like Fender was trying to make the bridge pickup as shrill as possible back in 1954.
 

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You can actually get optical pickups these days (don't know if they've gone to market yet) that work closer to the hypothetical simplified model people talk about when discussing how magnetic pickups work, which involve the field in which vibration is being detected being projected in a two dimensional plane instead of being omni directional, which is how magnetic fields work.

As it is though, anecdotally, the evidence is strong that "closer to bridge = tighter/shriller", but there are at least three or four other factors at play that are more difficult to conceptualize that also have an effect.

Magnetic fields don't exist in two dimensional planes, the location of the harmonic nodes on a standing wave on a string (which changes whenever you fret notes) also affect what kind of sound you are getting, and the simplified hypothetical model of electromagnetic guitar pickup theoretical discussion doesn't take into account the interplay of resonances between what is happening on the string and the natural resonant frequency of parts of the guitar. "Parts", because a guitar body made out of wood doesn't have a singular resonant frequency like a wine glass.

It's a safe guess to make that will end up holding true in a lot of situations, but there will be plenty of situations where it's not true.
 

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The "benefit" (which would not really be a benefit IMO, would probably end up sounding worse) of the optical ones is they actually do pick up sound purely on the basis of what is happening directly above them. As opposed to the incredibly unfocused way in which magnetic fields work.

 

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Honestly, I'm reaching the opinion that DiMarzio might be the way to go with most Japanese Jacksons of that era. They're excessively bright to me normally, but it seems like they might work in the Jacksons from that era. Maybe.
 

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I found this article on pickup placement related to frequency response, which shows pretty clearly how the low end drops close to the bridge (which we all know).

Response Effects of Guitar Pickup Position and Width

When close to the bridge, a difference of 1 cm probably would have quite a dramatic effect on the amplitude of the strings above the pickup.
 

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I found this article on pickup placement related to frequency response, which shows pretty clearly how the low end drops close to the bridge (which we all know).

Response Effects of Guitar Pickup Position and Width

When close to the bridge, a difference of 1 cm probably would have quite a dramatic effect on the amplitude of the strings above the pickup.
Yeah, good stuff. Technically he's not saying there is less bass the closer you get to the bridge though. There is less bass whenever you get closer to a node.

Being that the bridge is going to be a node no matter what note you are fretting there is almost always going to be less bass there.

But, there is also less bass when you move further from the bridge, provided you are moving towards a node.

So if you have the bridge pickup located where the position of the poles is at an anti node (which will of course change depending on what is being fretted), you can also get less bass by moving further away. Due to the fact that the position of the nodes changes, but the bridge is always going to be a node, it's usually a safe generalization to make.

Of course, he outright says in the beginning the same thing I did, that this is using an innacruate simplified model of a magnetic field being projected in a flat plane, which is not how it actually works.

Closer to the bridge is also going to be tinnier due to sympathetic resonance. Which is harder to quantify. Whenever a string vibrates, the metal of the bridge is going to experience sympathetic resonance.

The fact that it's not actually proximity to the bridge, but where the pickup is in relation to nodes and anti-nodes, is more apparent on pickup positions like a middle single coil. Where the sympathetic resonance of the bridge is less of a factor.
 

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You see it less frequently on guitars in popular music genres, but it's fairly popular on bass and jazz guitar to lessen the effects the sympathetic resonance the bridge has on your tone by using mutes.







Part of the original purpose of bridge covers was actually to high the unsightly mutes. Which are there to dampen the sympathetic resonance from the bridge.



Palm muting works on the same principle. Part of why that position is bright and tinny is because your metal bridge is bright and tinny and is causing sympathetic resonance.
 

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Discussion Starter #16
Honestly, I'm reaching the opinion that DiMarzio might be the way to go with most Japanese Jacksons of that era. They're excessively bright to me normally, but it seems like they might work in the Jacksons from that era. Maybe.
The Timbre Wolf turns out to sound really good in my yellow Soloist Pro. That pickup was too messy on the low end to work in the Les Paul, but does well in the Pro.

To further Garrett's point, the Pro has the PU further from the bridge (37mm in my measuring method above) vs. my '85 Soloist (33mm). And yet the Pro has a somewhat brighter, more upper-mid focused tone with the TW than the '85 does when both are tuned to D Standard. So clearly PU position is not an absolute variable even in guitars with the same basic construction.

You see it less frequently on guitars in popular music genres, but it's fairly popular on bass and jazz guitar to lessen the effects the sympathetic resonance the bridge has on your tone by using mutes.
I had heard of these mutes but had no idea of the reason for them. Very interesting.
 
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