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Truss Rod Voodoo

Discussion in 'Hardware, Setup & Repair [BG]' started by pd_5string, Aug 24, 2002.


  1. pd_5string

    pd_5string Admin: Accnt Disabled

    Jan 23, 2002
    NY
    Recently, I spoke to a luthier about adjusting the truss rod. I told him that I adjusted the truss rod by "feel" and he scolded me right there on the spot. At first I didn't understand what he was talking about, but as he explained it to me, it all made sense.

    Everything starts with the relief, he said, all measurements of string height, etc. He mentioned that the relief is set ideally .014 - .016 thousandths of an inch (using a feeler gauge, straight edge, and at the 7th fret). The ONLY reason to tweak a truss rod, he explained is to get it back to this measurement.

    He further explained that any bass, if it has a good fret job, won't need any more or less relief to play "right" (and by that I mean with less fret buzz). Once this adjustment is set, all one has to do is raise or lower the strings to their own preference. His feeling is that there is an ideal numerical measurement that one should maintain (when weather changes, string gauges, etc), that will guarantee playability, rather than tweaking and adjusting the truss rod to "feel" b/c this is like chasing your tail, as all the adjustments are working off each other: Start with the relief, go from there.

    He also taught me that relief doesn't just effect concavity, etc. It also effects how high the frets are relative to the string in the UPPER register as well (i.e., the neck becomes more like a "U" rather than a J as I had once thought.

    So, I would argue from the above, statement, that a bass such as a Zon or Modulus doesn't need a TR, as the relief is dialed in from the get go utilizing the stiffness of the graphite neck (and flex characteristcs...) and it never moves.

    Not trying to start a flame war here, but I was wondering why everyone feels the need to adjust a truss rod on a graphite instrument when it's relief is already set up for you at that ideal measurement, where the string has enough room to vibrate, but also feels low enough to play comfortably (.014-.016")

    Seems to be two schools of thought: Adjust truss to where it feels good (hit and miss) or adjust truss rod to where a neck was designed to allow for a bass string to freely vibrate (a discrete measurement), and go from there.

    Using this method, I have been able to set up my Fender's very nicely (and much to my surprise, the necks stay put after the adjustment!) It is nice to know that I have a concrete measurement that I can always go back to if things get out of whack, and it is no longer voodoo.
     
  2. Brad Johnson

    Brad Johnson Commercial User

    Mar 8, 2000
    Gaithersburg, Md
    Boom Bass Cabinets, DR strings
    Let's see if we can keep this from becoming a flame war. Should be interesting.

    If you like what this luthier is telling you, cool.

    OTOH I've never used a straight edge to set any of my basses up, I do it entirely by feel. Why? Because if it feels good, it is good. I don't have any hit or miss issues, I set mine to what "I" want because ultimately "I' will be the nut behind the wheel. It takes very little time. I've also heard that trussrod adjustments need to be done 1/4 of a turn at a time and then let the bass settle for a day or so. Again, never done that and never experienced any issues because of it. People I hand my basses to seem to love the ease at which they can be played. There are exceptions... some feel my setup is too low.

    I also don't measure my string or pickup height when adjusting them. So far, so good. Same goes for spacing.

    If OTOH I did setups for other people I'd probably try to find some rules of thumb, not necessarily concrete rules, to go by... but I wouldn't think that that would do any more than get me in the ballpark of what someone else may desire.

    Now, why would someone with a graphite neck want to stray from your luthier's maxim?

    Because they want to. Because their "feel" can't be determined by one single measurement for all basses. That's my guess. My Zon is fine (actually, perfect) for me but if I used strings that put more tension on the neck and it changed the relief, even slightly, the only option I'd have would be to deal with it. I can see where that would be a problem.
     
  3. pd_5string

    pd_5string Admin: Accnt Disabled

    Jan 23, 2002
    NY
    Just a comment on the last point. Your neck will move so slightly you won't even notice (if you put a different gauge on the Zon) and as someone that is more of an adaptive player than an anal one like myself, it would be that much less of an issue for you.
     
  4. Ryan L.

    Ryan L. Moderator Staff Member Supporting Member

    Aug 7, 2000
    West Fargo, ND
    Methinks that this is more of a Setup topic.

    I am sending it down thataway.:)
     
  5. I like your luthiers approach very much. By establishing a basis for all subsequent measurements, he can return to that easily. "Feel" is fine but it too can be quantified. If you are the only one doing your setups then "feel" will work but if someone else does them, "feel" has no place in the setup. If the tech or luthier knows what measurement your "feel" is, then he can return the neck to that condition.

    The question about why people adjust carbon necks when the relief is built has at least one simple answer IMO. If string brand, model, or gauge is changed, then a new setup will be required in most cases. That new measurement will work with that string set but none other. I also don't think carbon fiber necks are as perfectly stable as to allow going without a trussrod. The ones I've read about have some wood in them and, in my mind, that means that they can be made to change. I might be all wet with that but why else would they build a trussrod into them?

    Where's Steve from Moses when you need him?
     
  6. narud

    narud Supporting Member

    Mar 15, 2001
    santa maria,california
    yup the string gauge thing is the biggest reason i could see for the truss rod.

    chuck m. over at the pit mentioned getting a fretless zon(i think) a while back. irc, he felt that there was more relief than he cared for on a fretless bass. once he changed to a lighter gauge string set his problem was solved but if it would have had a truss rod, the string change wouldnt have been needed.
     
  7. Brad Johnson

    Brad Johnson Commercial User

    Mar 8, 2000
    Gaithersburg, Md
    Boom Bass Cabinets, DR strings
    That could be true. Then again, I don't like heavy strings so it probably wouldn't be an issue for me anyway.

    BTW my Legacy fretless sounded excellent tonight at the gig. Played with a new drummer... he loved it.
     
  8. Brad Johnson

    Brad Johnson Commercial User

    Mar 8, 2000
    Gaithersburg, Md
    Boom Bass Cabinets, DR strings
    That's what I alluded to. For me working on my basses, feel is cool. Doing it for someone else is a horse of another color. My position is that no one knows what I like better than me... that's why I learned how to do adjustments for me. For example, you should see the string spacing on my Zon, definitely non-standard;)
     
  9. lump

    lump

    Jan 17, 2000
    St. Neots, UK
    I think it's convenient to be able to quantify things, but ideally all this is going to do is confirm what you "feel." The guy that built my bass says to use as little relief as your playing style permits. For me, .014-.015" is perfect. I can usually tell if it drifts outside of this window, either higher or lower. When it does, I adjust it back to those specs. But the feel comes first, not the measurement, IMO.

    But what if my style lightens up, and .010" is enough? I'd rather not be locked into relief that is "perfect" for "most" people.

    If you have a bass with a wooden neck, you WILL have to adjust the relief from time to time. I mean, it used to be a LIVING CREATURE. It responds to temperature and humidity. If you are exceptionally anal, and can detect even the slightest variance in relief, it might be more trouble than it's worth. Because it WILL move.
     
  10. While I agree that relief is essentially the setting around which you base the others, I still think that the amount of relief you use depends also on how and what you play.

    The amount of mwah you go for on a fretless is, IME, best controlled by a playoff between relief and string height at the bridge rather than just string height alone.

    The truss rod is also one of the tools you have in dealing with dead spot problems...I have found that tweaking can reduce and move the spot.

    A low cut nut will also mean more relief necessary for a lower action.
     
  11. pd_5string

    pd_5string Admin: Accnt Disabled

    Jan 23, 2002
    NY
    I have talked extensively with Joe Zon about this topic...the necks aren't like wood where they just keep bending. They bend to a point, and then STOP. No, they really STOP, like you can't budge them ANYMORE. This is engineered into the "recipe" of the neck. String gauge changing doesn't significantly effect neck relief on a GC (Graphite composite) instrument. Any addition of a truss rod, will change the acoustic characteristics, add weight, and basically is a nuisance IMO. One more thing to go wrong. Likewise, if you go to a lighter gauge, the neck still won't move significantly.
     
  12. pd_5string

    pd_5string Admin: Accnt Disabled

    Jan 23, 2002
    NY
    Brad, you can now "measure" your feel (relief and string height) and use it as a template for all your basses which will give them a consistent feel...
     
  13. pd_5string

    pd_5string Admin: Accnt Disabled

    Jan 23, 2002
    NY
    Not to be an egomaniac here, but I think anyone that has heard my fretless (or other good Zon player's fretless's) would have to agree that Zon's fretless basses are second to none, and there is no adjustment for relief there. Mine mwah like crazy. There is an ideal relief that is set (usually between .014-.016", so there is some adjustability within the "ideal" range), and that will make the mwah thing happen very nicely.
     
  14. I have no doubt, and I am delighted you have found the bass for you. But my point is that there are some people who do NOT want mwah on their basses. And people who like a different amount of mwah. I am, I guess, about a 20% 'mwaher' (if that makes sense!). I go for a touch of mwah, and that's it. In getting this, I find I play bridge height off against relief.
     
  15. pd_5string

    pd_5string Admin: Accnt Disabled

    Jan 23, 2002
    NY
    Mwah is adjusted how your hands play off each other. I can actually play up by the neck PU if I want to with or without Mwah. The mwah factor has to do with left and right hand touch/feel, and should be this way, rather than a play off the bridge and relief (although they have to get you close, technique carries you the rest of the way)

    Relief has a particular function, and really only one function, and it isn't to make up for technique shortcomings. It is to dial in the right curve of the neck to allow for string displacement. That is it. Trying to use the truss to adjust mwah factor is like trying to use the clutch of a standard shift car to hold yourself in place on a hill. It CAN do it, but it isn't the function, and you will create other problems by using this "feature."

    Perhaps, a truss rod to achieve mwah factor is needed on a wood necked bass, as it will move over time. So be it, you adjust the truss, put it back where it should be, and mwah away (or in your case, don't mwah by altering your technique, which is how it should be anyway).

    I will give you an example. Suppose you adjust the truss rod for less mwah like you say...in this case, you would increase the relief (make it more "u" like) at the same time you do this, you are lowering the action up towards the joint (b/c the neck up there curves too) So, now up there you will have relatively MORE mwah than down by the nut and in the middle of the bass. At this point, you will try to raise the strings up to get that 20% mwah factor you want (b/c you want to decrease the mwah amount) and now your action feels too high. You are now doing what is known as the tail chase.

    I am just sharing...cause I always did it by feel too, but once these things were explained to me, I feel like I can set any bass up to my liking, b/c I know approx what measurements work for my style, and it starts with a concrete range of measurements with the relief. (.014-.016")
     
  16. Brad Johnson

    Brad Johnson Commercial User

    Mar 8, 2000
    Gaithersburg, Md
    Boom Bass Cabinets, DR strings
    Why?

    Seriously, I've set everyone of my basses up for me. It takes very little time. I've never needed a straight edge or any measuring device to do it.

    I understand what you're saying and I hope you understand what I'm saying too. By adjusting my neck to a predetermined point (.014-.016"), do I then:

    - Leave it there, as it "should" be "perfect" or;

    - tweak it further to get exactly what "I" want?


    When I first receive a bass, if it does not feel exactly like I want, it takes me maybe ten minutes max to do every adjustment I'm likely to make. There's nothing wrong with anyone using a straight edge or whatever else they need to set the bass up. OTOH... I simply don't need it.

    Then again, who's to say I don't eyeball my necks to the same range you posted? Until I get a straight edge... I guess we'll never know;)

    For the record I've also seen luthiers sight necks and not use straight edges or rulers. When you know what you're looking at (and for) it's pretty easy.

    I'll end by saying this. While some may actually feel there is a "perfect" relief, I think that perfect relief and perfect relief "for me" are not necessarily the same thing.

    I think we just disagree.
     
  17. Well, there we have it. I make up for my lousy technique by setting up my bass incorrectly!

    Actually, I am perfectly able to control mwah! My point is that a bass has an essential character which depnds on set up and which will be different for different players. And my taste is for a bit more relief.
     
  18. pd_5string

    pd_5string Admin: Accnt Disabled

    Jan 23, 2002
    NY
    I bet you a steak dinner that you are a total pro at setting up a bass, and the spot at which you probably settle on is in the .014-.016" range :)

    I just like "knowing" that the bass is set up properly at a particular measurement, that way, if a fret buzzes, etc., I know it is a fret issue, and not a setup issue. It is nice to be able to eliminate causes, and when you set the relief at a proper measurement, and you have to then work on the frets, that is easier then setting the bass at a "feel" (which can change over time) and then having a bass worked on.

    If you had a problem with a fret (unless you know how to level and polish yourself) and you brought it to a luthier, the first thing he would do is measure and check relief, and go from there. It was here that I got "educated" by a very firm, yet understanding luthier about how to do setups, and how everything acts of one another...
     
  19. Brad Johnson

    Brad Johnson Commercial User

    Mar 8, 2000
    Gaithersburg, Md
    Boom Bass Cabinets, DR strings
    Cool :cool: