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How is Pickup Location Decided on New Designs?

Discussion in 'Luthier's Corner' started by Jim T., Jul 20, 2003.

  1. I've always wondered this and now that I'm considering building... How is the "sweet spot" in single pup designs and optimum location for neck and bridge pickups decided without installing them? Do some luthiers have a sliding rail. jig so that they can hear them in action before routing or screwing them down?

    I understand factors such as leaving enough room with a neck pup to slap, angling, etc. But on a completely new/original design, how do you "know" how it will really sound before commiting? Many thanks,.
  2. RobbieK


    Jun 14, 2003
    These days I just use my experience to position a pickup in a design. I angled the pickup in a recent design, because a previous bass of similar design was a little too twangy on the treble side.

    I used to assemble the instrument, then simply wire a pickup or two to a jack and use blu-tac to place them over the strings on little blocks. Its not the same as when they're actually installed in routes, but it helps give you an idea.
  3. Thanks. I figured something along those lines was in order. I haven't heard of blue-tack. Is it a putty? I'll look for it. Anyone else have a favorite method?
  4. RobbieK


    Jun 14, 2003
    My apologies. I just assumed that Blu-Tac had the same name in the states...

    Its that sticky re-usable putty that you stick posters on the walls with.
  5. Ahhh... Thanks RobbieK.
  6. Tumbao


    Nov 10, 2001
    I owned a 35" scale bass with the single pup located 4 inches after 24 fret and the middle of pup and 4 inches from that point to the bridge saddles.
  7. godoze


    Oct 21, 2002
    I have been trying different basses- partly to figure out where i want my pickups
    and partly since all of my gear was stolen i'm just trying out basses.

    I also think for me anyway string tension plays a big part. I have found that if the pup is too close to the bridge my pizzicato tone suffers do to the high tension right near the bridge so I am opting to move my placement about 2.5 " from the bridge.

    I do not get the slanted pup placement thing at all. Someone care to explain ?
  8. JP Basses

    JP Basses

    Mar 22, 2002
    Paris FRANCE
    My 2 cents (keeping it SIMPLE):

    when working on a design, you can begin planning your pickup location with theory. Theroy tells you:

    - near the neck end, more string motion, more basses
    - near the bridge, more treble, more precision

    You also know that having pickups far from each other will give you a wide tonal range but going from one pickup to the other will also give you a more dramatic change (you need to have a great blend pot...hehe)

    Starting from well known positions could help also. Think about the brige pu location on the jazz bass , around 57mm from the 34" scale end.

    Then, there are mechanic, aesthetics...you want to have some room for slapping for example.

    Once you've got all that in mind, trial and error is your best "friend". you gotta save you thoughs about each configuration you made and use that to try to improve the next time you build. Well improve might not be the best word here. Sound is subjective. I personnaly use pickup placement to control the instruments tone in regard to the cutomer request (moving + or - 5mm has a great influence)

    A nice trick is to save the wooden rails coming from cutting the neck taper in the neck blanck (or you could make special rails for that). You can then use them with double stick tape over the body of the almost finished instrument and use more double stick tape to place your pu upside down, over the strings. you'lle ba able to play the bass and determine pickup per pickup which locationsuits you. then just rout at the correct position. This is similar to Robbie advice and works great IMO because you can study pu location for each instruent you build if you want to.

    Peace, JP
  9. wulf


    Apr 11, 2002
    Oxford, UK
    Is the 'sweet spot' theory solid or is it a myth?

    What I'm thinking of is the concept that by putting the pickup at point X you get a richer sound because it falls under various harmonic nodes. However, that seems off beam, since the location of the harmonic nodes will depend on where the string is being pressed down on the fret/fingerboard.

    Or is the 'sweet spot' more do to with how stiff or loose the string is (distance from the bridge - aong the lines of what DonZ posted) in conjunction with the characteristics of the pickup?

  10. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
  11. You're absolutely right, this particular incarnation of the theory is utter nonsense. You wouldn't believe how often it still pops up, though. Or maybe you would.:D
  12. Suburban


    Jan 15, 2001
    lower mid Sweden
    Hey, there's a scientific path to this, too!
    I can't find the link right now, but I think I got it thru TalkBass.

    It's a site where you enter the location(s) of your pup(s), and scale length. Output is a diagram over the frequency response. Seems plausible and quite reliable, actually.

    Where is that link....!:mad:
  13. JP Basses

    JP Basses

    Mar 22, 2002
    Paris FRANCE
    How about THAT ??? ;)

    Peace, JP
  14. Interesting, but I'm not convinced it accounts well for what happens when you actually fret notes.
  15. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    Well, I did test it by putting in values for a 34" open E, and an A fretted on the same string, and got the same plot. I am, however, still having some trouble understanding the justification of the symmetry problem (described and somewhat explained lower on the page).
  16. See, that's what I don't buy. I am absolutely convinced from experience and experiment that tone changes qualitatively, not just in pitch, as you go up the fingerboard. The presumable reason is that the pickup is closer or farther from the center of the vibrating length. I can't see how his model accounts for this. The plot doesn't show you exactly what you hear when you fret any given note. It can't. And let's leave aside the question of what kind of pickup is used, the effects of different strings, etc.

    The only thing I really get out of this is that PUs near the bridge are generally treblier, and those near the FB bassier. And I think we all knew that. BTW, if I read this right, these aren't even measured values but calculated ones. Making them not necessarily that useful in the real world IMO.
  17. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    I think you're right about the points you've made, but I am maybe thinking about the plot differently from the way you are.

    I think the plot is showing how the output of a pickup is limited by its position, due to its physical position. It is assuming a perfectly flat response pickup. And it is not factoring in what the string is putting out. It does show where on the plot the fundamental lies; what it is not showing, and which might be useful, is where on the plot the next dozen or so harmonics lie. So, for example, you'd be able to see something like "for this placement, the 4th harmonic of a 7th-fret B will lie on a node and not be heard."

    The way I am interpreting it (rightly or wrongly!) is: If X is the response of the string (strength of the harmonics in series, as determined by the instrument and string physical characteristics and the plucking technique), and Y is the "response possibility" as defined by pickup placement as shown on Tillman's plot, and Z is the response curve of the pickup (which the plot by itself is assuming to be flat), then the output would be X × Y × Z.
  18. geshel


    Oct 2, 2001
    The pickup response applet is pretty interesting - and generally informative. It's still not clear though how the things Richard and Peter brought up, come into play. The applet just shows the overall response curve of the pickup(s). However, since the the string only produces (roughly) harmonic series of pitches, then a very important factor is how those pitches fit into the resulting curve. If an important harmonic falls into one of those narrow gaps, it will sound drastically different than a nearby note which doesn't.

    I think its good though for seeing the general trend: for instance, put in the Jazz-bass locations and note the big mid-frequency suckout when bot pickups are on. As soon as you blend away from the middle, that region comes back in. To me, that fits with experience.

    Finally: one thing that's done a lot for my understanding of how pickup location and interactions work, is the way my main bass is wired. It has two humbucking pickups, at roughly J-bass locations. I have a switch which lets me choose either the "outside" coils or the "inside" coils of the pickups. When the high mids are emphasized (eg, especially for slap), there's a huge difference. And this is essentially the result of moving each pickup about 1/2"!

    edit: sorry Peter, called you Phil :)
  19. You're probably right; that seems to be what's going on. But again, Tillman's clearest point (bassier vs treblier) seems to be trivial. In particular, I'm not convinced that the valleys on the graph mean much of anything; I think they're just an artifact of the fact that he apparently didn't compute frequency response continuously from 20 to 20k but seems to have tried to sample it at intervals corresponding to fretted notes. So you'd probably get something closer to what most of us would think of as a response curve by just connecting the tops of the peaks. When you do that, what you seem to end up with is the tone getting bassier as you move away from the bridge. Which, again, we knew.

    Beyond that, I don't think this app tells you anything at all about what specific "sweet spots" might exist. There's no magic spot where the response is theoretically perfect. There couldn't be anyway IMO, since every time you fret the bass, the harmonic nodes and antinodes all move.
  20. geshel


    Oct 2, 2001
    Actually, it's the other way around: he swept the frequency from the fundamental all the way up to 20kHz. This was my criticism of the method when this first came up. ;)

    I'll see if I can find the emails he sent me. . . (he noticed people landing on his site via TB references, and read the thread and eventually figured out how to contact me! :hides: )

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