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Bridge humbucker location very critical

9/25/2005 5:15 PM
Steve A.
Bridge humbucker location very critical
    I tried replacing the Epi '57 bridge humbucker on my brand new Alley Kat with two different hb's, and they did not sound at all as I expected them to (not as bright as they sound in my other guitars).  
    A user review at H-C suggested that the bridge pickup was mounted too far away from bridge and recommended moving it 1/8". If 1/8" is good then 5/16" should be even better so that is the distance I moved the pickup. (Actually that was the width of the top from the center block under the bridge to the opening for the pickup.) This is a semi-hollow bodied guitar so I used a Dremel tool to start the cuts and moved the cut piece to the neck-side of the opening, putting a tongue depressor underneath to hold it in place as I glued it. :D  
    After moving the pickup it sounded a million times better to me. Here are the "after" dimensions:  
Scale length (high E) 24 5/8"  
Scale length (low E) 25"  
Bridge saddle to edge of pu cover (high E) 25/32"  
Bridge saddle to edge of pu cover (low E) 1 1/8"  
Bridge saddle to adj screw (high E) 1 3/16"  
Bridge saddle to adj screw (low E) 1 7/16"  
Bridge saddle to neck mtg screw (high E) 5 9/16"  
Bridge saddle to neck mtg screw (low E) 5 7/8"  
(string spacing 1 7/16" at nut, 2" at bridge)  
    So what is the scientific principle involved here... the relation of the pickup to the full length of the string, or the relation between each coils and the full length of the string? Fretted position should make a difference, but as you go up the fretboard it would make it as though the pickup was proportionally further from the bridge- right?  
    In any case, I had never run into this before so I guess that most guitars are designed with this factor taken into consideration. But I can see how it could complicate things for the boutique winders here ("your pickup sounds nothing like the sound sample on your site!") Connoisseurs will talk about how pickups will sound different with mahogany vs. alder vs. swamp ash bodies, but I don't usually hear the difference. :( But with pickup location even a deaf person could tell the difference.  
Steve Ahola
9/26/2005 8:38 PM
Greg Simon
When I built my first guitar, I was really worried about where to put the bridge pickup for months. Finaly I decided to just stick it somewhere and call it good. It sounds great where it is so maybe I got lucky.  
9/27/2005 2:07 AM
Dave Stephens
Steve: in the ampage home page look to the rigth column in the frames, you really should read all of those articles there just for education but there is one called "Response Effects of Guitar Pickup Position and Width " Its really kinda basic stuff, position in relation to the bridge has a big effect on tone and there is no standard. Your Alley Kat or whatever was, was designed for P90s, not humbuckers, right? Also did you make sure you had the adjustable pole screws closest to the bridge when you installed the humbucker in the first place?  
The primary reason someone will say that "sound clips don't sound like your pickups in my guitar" (actually has never happened to me....) is that every guitar is an individual piece of wood, everyone's hands sound different, even same models of amps can sound different. Even to the extreme that some kid might buy a cheap Korean guitar and actually use the guitar cord that came with it, really cheap cords have a big effect on tone :-) I always tell my customers that the sound clips are a guide for chosing between pickups and that your results will usually be different. One big reason I use live recordings at gigs for sound clips is because that says way more than for example the Duncan site does. You can't tell jack about his pickups from those sound clips, they all sound the same :-) A cranked tube amp in a room full of people with a pro on the guitar isn't going to sound anything like a guy sitting in a room making sound clips :-)
9/28/2005 7:12 AM
Steve A.

Dave said:  
Your Alley Kat or whatever was, was designed for P90s, not humbuckers, right?  
    There are several varieties of Kat guitars from Epiphone, all with the same basic body but routed for different pickups. The Wild Kat has two dog-ear P-90's, the Flame Kat has two mini-humbuckers and the Alley Kat has a mini-hb at the neck and a full-sized hb at the bridge. I'm not sure which one came first. Here is a link to the Epiphone page for their archtops:  
    If you click on the Alley Kat and then click on the Dot you can see how the bridge pickup is positioned differently. If you click on the Alley Kat and the Flame Kat it looks like both pickups are the same distance from the bridge, but since the mini-hb is much narrower the average distance to the bridge would be less.  
    I've noticed some differences in the same pickup mounted in different guitars but nothing this drastic. I think that most Gibson style 2 humbucker guitars try to keep the same location for the bridge pickup: pretty damn close to the bridge.  
Steve Ahola
9/27/2005 4:39 PM
I can't remember where I read it but there was a thread about how the P90 in old stop-bar Jr.'s were not real consistent in placement. This person was a LP Jr. nut and had owned a bunch of them. He said that in his opinion, the best sounding ones always had the p'up closer to the bridge. And IIRC, he said that on the best sounding one the p'up was so close you had to move the stop-bar just to get the ball between the p'up and stop-bar (or something like that).  
My question is: in what way did it sound better?
9/29/2005 5:48 PM
Steve, I too have had a similar experience and agree location is critical in getting the best sound.  
Back in '79 I had an SG and back then some SG's made in the '76-'78 era (with the big Schaller "harmonica" bridge) had their bridge pickups mounted noticably further from the bridge than others, I had one of these back-in-the-day and it never really got great pinch-harmonics and was too "Fat" sounding in the bridge position, this would start my pickup swapping trek.  
After trying a few different pickups, mostly DiMarzio, and still not getting my sound (back then we called "tone" our "sound") I realized pickup placement location was the real issue with this SG. I didn't want to get rid of the guitar because it had an ebony fretboard and those cool small square fret markers like an old ES335.  
I was in a band back then with another guitar player who had an L6-S and I also had a friend with a Les Paul, one day they were over working out some songs I noticed the bridge pickup was closer to the bridge on both their guitars, and both their guitars got better harmonics than mine and sounded less fat.  
After thinking about it and measuring the guitars pickup locations I arrived at the theory that the pickups need to be located as an "aspect ratio" (AR) of the scale length, which eliminates neck scale from the equation.  
For instance the Les Paul having a 24-3/4" scale, it's bridge pickup is located 23-3/8" and the neck at 18-5/8".  
(I locate off the adjustable screw poles of a humbucking pickup in their normal Les Paul orientation)  
This equates to an AR of .94 for the Bridge pickup location and .75 for the Neck pickup location.  
So as an example when placing humbuckers on a Strat and wanting Les Paul type voicing, the strat having a 25.5" scale would have the bridge pickup at:  
25.5 x .94 = 23.97" (23-31/32")  
and the neck the pickup screw poles would be placed at:  
25.5 x .75 = 19.12" (19-1/8")  
This works for me when locating pickups.  
PS, the AR on Strats is...  
Bridge: LowE=.931 HighE=.946  
Mid: .85  
Neck: .75  
Note the highE pole on the bridge pickup and the neck pickup AR's on the Strat are the same as on the Les Paul....Hmmmmmm....coincidence? I don't think so Tim, I think those are the "sweet spots" on electric guitars.  
Side-note: SG's made today have the bridge pickup located closer to the bridge, in the right spot ...BUT... now the neck pickup isn't in the sweet spot at AR=.75 dang!  
9/30/2005 5:35 AM
Steve Ell.
I'm assuming you know why the "sweet spot" is at 1/4 the scale length, right? It's because that is where the harmonic point is- also where a 24th fret would be positioned. That is why there is a distinct difference in neck pickup tone on a 24 fret guitar vs. a 22 fret axe. It's all physics.
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