| Author | Message | ||
| oujeebass
Junior Username: oujeebass Post Number: 42 Registered: 10-2002 |
I have an Epic and I have read several discriptions on how these necks work,but I want to ask a question. With the truss rod nuts loosened to finger tightness my neck should be straight..in theory? So when I tighten what will happen to the neck? | ||
| rami
Advanced Member Username: rami Post Number: 286 Registered: 6-2002 |
I believe that tightening the truss rod nuts would cause the neck to bend back in order to counter the tension of the strings. If the truss rod nuts on your bass are only finger tight, the string tension should cause the neck to bend in a concave (forward) form. You can observe this best by pressing down on the first and fifteenth frets (on the E string). You should notice a gap in the middle of the bend. You can also look down the length of the neck under tension and observe it's curve. I believe the main advantage of dual truss rods is that you can counter any twisting force exerted on the neck by uneven string tension. You counter any string tension by tightening these nuts in order that the neck appear straight. You must ALWAYS however, have a small gap in the middle between the 1st and 15th fret. If the neck is too straight or bending too far backwards (Convex) your strings may either buzz or the bass may become unplayable altogether. The convex bend is the most dangerous. Good luck, Rami | ||
| bob
Intermediate Member Username: bob Post Number: 127 Registered: 11-2002 |
Once again, I spent too much time writing, and Rami beat me to it by a few minutes. But as long as i've got it, might as well post it... Rami is exactly right, I'm just elaborating. (Personally, I like to hold a string down at the 1st and 24th and measure at the 7th, but there are lots of variations on this - the general idea being to use the string itself as a straightedge.) oujee, My first thought was to suggest you go back and do some more reading... but then I realized that maybe nothing posted here explains the basic concept, so I'll give that a try (but once that's clear, then I encourage you to go back and read some more). First of all, there's no rule that says your neck will be straight when you loosen the nuts to just finger tight. *If* you took the strings off, it might be close, but just forget about that for the moment. Think of it this way. Suppose you have a long piece of slightly flexible wood, and on one side it has a set of strings, and on the other side it has a truss rod or two. If you tighten the strings, the wood will bend towards the strings; if you tighten the truss rods, the wood (neck) will bend back towards the rods. If the wood started out straight, and you applied exactly the same amount of tension to both the strings and the rods, then the wood would remain straight. If you switched to strings with higher tension, then they would try to bend the neck more, and you would want to tighten the truss rod to compensate; with lower tension strings, that were exerting less forward bending pressure on the neck, you would need to loosen the truss rods so that you didn't get a reverse bow. And even without changing strings, sometimes the neck itself will shift as a result of humidity changes and so forth. In other words, whenever you tighten the truss rods, the neck will first get straighter (assuming it was already bowed forward), and then eventually start bending backwards - but hopefully you won't go that far. You have to check the relief with the strings tuned to pitch, because they make the neck bend forward, and this is the force you want to balance with the truss rods. As a general rule, it is not a great idea to loosen the nuts to finger tightness and then work from there. For one thing, there's no guarrantee that both rods will require exactly the same number of turns. Or to put it another way, if both nuts were just finger tight, you might have more relief on one side of the neck than the other (though usually it would be close). Secondly, you don't really want to make major changes to the truss rod tension all at once. It takes a while for the wood to adjust, so some people suggest you don't go more than about a quarter turn in one day, or at least let it sit for a few hours before deciding whether you really need to go further. But if you've already loosened them, don't panic. Alembic seems to deliver their instruments so that they require very little truss rod tension, and unless the wood has shifted over time I suspect it would be rare that you'd have to go much more than a half turn for them to become loose (often less). Start by comparing the relief of the highest and lowest strings. If they're not close to the same, then adjust one of the rods to make them so. Once they're close, then you would generally adjust both rods evenly, in the same direction. If you have too much relief (bow), then tighten the rods. If the neck is too straight, loosen the rods. Just think about it a little, and it should be pretty clear. Good luck. -Bob | ||
| bigredbass
Advanced Member Username: bigredbass Post Number: 239 Registered: 9-2002 |
oujeebass: A terrific resource for this is the Dan Erlewine book, "The Guitar Player Repair Guide", published by Miller-Freeman. This book assumes you're interested enough to ask the type of question you asked, and walks you through it from that skill level. Erlewine properly recognizes that basses are indeed HARDER to adjust due to the longer scale, bigger strings at higher tension vs. a guitar. I can't recommend it enough. With the strings loose and the nuts loose, the neck WAS dead straight when it was built. How much bow (relief) it now has is a function of time, strings, and the individual wood in your bass. Detuned and with the truss rod nuts loose, it may return to dead straight, or more likely may retain a slight bow, or could even 'relax' to where it's higher in the middle of the neck ('up' bow, or convex relief). It doesn't matter. Tune to pitch, and gradually tighten the truss rod nuts until the action comes to where YOU want it. With ALEMBICS, adjustments are a breeze. The bridge is pre-cast to match the curve of the finegerboard, and the nut is height adjustable. While the two truss rods are capable of correcting a twist in the fingerboard, the real luxury is that it allows you to adjust the action exactly on the high and low side of the fingerboard. ALEMBICs are the PERFECT bass to teach yourself adjustment because of these features. The short version of my routine: 1. Tune to pitch. 2. Adjust the bridge height to where you have 1/8" clearance between the top of the 24th fret and the bottom of your E or B string. Repeat for your G or C (didn't know if you play a 4,5, or 6). Re-tune. 3. Check your nut height: As you fret each string at the third fret, press the string with your other hand directly onto the first fret. There should be a slight clearance; you should hear a little 'clink' when the string hits the fret. If you moved the nut, re-tune. 4. Press the E-string down at the first fret and at the last fret with your elbow (or use a capo where the neck meets the body), and look at the gap between the bottom of the E-string and the top of the 7th or 8th fret. You want that gap to be about the thickness of a thin to medium pick. Then repeat this for the G-string. If you moved the nuts, re-tune. 5. Once you finish step 4, adjust the bridge saddles to tune your intonation, and you're done. 6. Live with this setup, and fine tune it over time to where it's perfect for you. You may want the nut higher, the bridge lower, more or less relief, etc. But you had a standard starting point from which to begin your perfect setup. The wood will take time to respond. IF you are very demanding set-up wise, you're gonna live with this daily until you really 'get it'. The clearances I speak of are small, 16ths, 32nds, etc. Make SMALL adjustments. Don't snug the truss rod muts REAL tight: If you hear them make those 'popping' noises, you've gone WAY too far/tight. Back them off to loose and start over. And don't worry about fret noise that you hear unplugged, but CAN'T be heard through the amp, because you will have a little of the former but almost none of the latter once you get it right. Setup is a combination of several things, and is really maddening at first. But once the 'little light comes on' and you get it, you'll be thrilled. J o e y | ||
| eastcoastepic
Junior Username: eastcoastepic Post Number: 27 Registered: 10-2003 |
Gentlemen, Is there a certain period of time from when an Alembic is new that one should wait before making a truss rod adjustment? Does a neck need to 'set' and/or 'cure'? My 4 month old 5-string is great, although the B and E string seem just a hair high above the 12th fret (yes, bridge height adj. has been done). I don't want to do anything too soon that may cause problems later. Many thanks...... | ||
| bob
Intermediate Member Username: bob Post Number: 128 Registered: 11-2002 |
You can be sure that Alembic made some adjustments before you even got it, so there's no reason for you to wait - you're not going to hurt anything. If you're in a much different climate than where it was built, you might give it a day or two to get acclimated, but that's about it. You may also find it requires more frequent adjustment over the first few months because it's still settling in or something, but there's no reason not to adjust it to your liking during this time. | ||
| mica
Moderator Username: mica Post Number: 1406 Registered: 6-2000 |
The truss rod's action is counter to the pull of the strings - so tightening the rods will force the neck to backbow. With fingertight nuts, the necks are usually fairly straight, so unless you have an increase in string tension, you won't want to tighten the nuts. Bob's right... adjust away eastcoastepic! Sounds like you might want to tighten the rods a touch - move in 1/4 turns and move both rods the same amount. You may reverse that bridge adjustment once you get the neck a little flatter. | ||
| eastcoastepic
Junior Username: eastcoastepic Post Number: 29 Registered: 10-2003 |
Thanks for the input, bob, rami, joey, and for the reassurance, mica! I'll give her a tweak in the next week or two. I must say, the support and advice on this board is second to none.... | ||
| musikill
Junior Username: musikill Post Number: 43 Registered: 12-2003 |
Just thought I would include this link to another conversation on a similar subject. There are some interesting thoughts here: http://alembic.com/club/messages/393/7798.html |
