Neck Relief Question....

[Hot Tub]

Hi again,

I've just about got my bass set up the way I like it; I'd just like to get the action down a bit. Problem is that if I lower it any more, there's fret buzz when I hold a note at or above the 12th fret. This applies to all strings. The truss rod is backed off as far as possible (any more and it's loose!), and with the instrument tuned up the neck is dead straight. I just need a wee bit of positive (up) bow, but can't figure out how to do it.
The Spector [url="http://www.spectorworld.com/setupprocedure.htm"]website[/url] says that the truss rod is "dual action", meaning that it can tighten in either direction past a null point, but this isn't true. It's a bog standard truss rod that gives back bow when tightened. And it's neck-thru, so shimming is out of the question......

[PlungerModerno]

How low are we talking here - e.g. 2mm @ 12th fret (or lower) and you get buzz? If it's low already I'd say play it like it is.

If it's about 3 mm or more I'd be unable to play that comfortably with almost any string - have you tried heavier gauge strings or tuning up a few semi-tones? I'm currently working on a bolt on guitar with a similar issue. Didn't have strings tuned up and was left with truss rod tension. I'm leaving it over tuned with the truss rod loose - seems to be having some effect.

Exercise caution if it's a pricey one!

[Hot Tub]

Cheers! Didn't think about over-tuning. I'll take it up - gently - for a couple of days and see if it has any effect.

[HowieBass]

With the strings at normal (standard tuning) tension are you sure the neck is completely flat? If you hold a string down at the first and last frets (or use a straight edge) is there no gap whatsoever between the string and all frets? I'd expect with normal relief you'd see a gap of a bit less than 0.5mm at around the 8th/9th frets. The reason I ask is that you usually get fret buzz at the dusty end of the neck (as you're experiencing) when there's slightly too much relief in the neck rather than too little.

[Andyjr1515]

[quote name='HowieBass' timestamp='1412676338' post='2570889']
With the strings at normal (standard tuning) tension are you sure the neck is completely flat? If you hold a string down at the first and last frets (or use a straight edge) is there no gap whatsoever between the string and all frets? I'd expect with normal relief you'd see a gap of a bit less than 0.5mm at around the 8th/9th frets. The reason I ask is that you usually get fret buzz at the dusty end of the neck (as you're experiencing) when there's slightly too much relief in the neck rather than too little.
[/quote]

I agree with Howiebass on this one. Hold down the first fret, hold down the 16 th fret (you may need a friend!) and tap the E or G string at the 8th fret. There should be small but perceptible movement. If it's more than a credit card thickness, tighten the truss rod accordingly. If it is hard down against the 8th fret, you may need to 'induce' a bit of relief if the rod is fully slackened off.
As Howiebass says though, the symptoms indicate too much relief rather than too little.

[DiMarco]

If the neck is completely straight the frets should start buzzing around the 2nd and 3rd frets first when lowering the action.
What you're describing (lowering the action on a straight neck causing buzz only from the 12th fret) would mean your bass is in need of a fret leveling/sanding job for at least the frets beyond the octave.

[PlungerModerno]

Interesting contributions . . . I'm pretty sure both HowieBass and DiMarco have points - depending on the situation.

My understanding is low action needs a straight neck or slight relief. IME Medium (in my book 3 mm ??) to high action(5 mm +) will work with anything that isn't backbow - although too much relief and very high action make playing a nightmare.

Uneven frets can be hard to diagnose - often the lower frets get worn / dented first, and a sloppy fret job might not take the same amount off all the frets - leading to issues.
I've heard the neck joints on some basses (e.g. set neck on a hollowbody) can change as it ages - meaning frets can come loose or move enough to make a nice setup impossible. I've used a homemade version of this to examine frets and it seems to work:

[HowieBass]

Low action needs a neck with the correct amount of relief and that's certainly not a straight neck. IMHO there's no advantage in having more or less relief than is recommended by the manufacturer for the neck in question. This obviously assumes that the frets have been installed and levelled to a decent standard in the first place of course.

[PlungerModerno]

[quote name='HowieBass' timestamp='1412680819' post='2570946']
Low action needs a neck with the correct amount of relief and that's certainly not a straight neck. IMHO there's no advantage in having more or less relief than is recommended by the manufacturer for the neck in question. This obviously assumes that the frets have been installed and levelled to a decent standard in the first place of course.
[/quote]

If you want little or no buzz I'd agree fully - but to get a harsh sound with lots of clank without having to really dig in with each note - a straight neck can be ideal. To still be able to get a cleaner sound some relief would probably help. AFAIK some manufacturers recommend little or no relief (see the Rickenbacker owners manual, which I won't link to here because of reasons.)

The recommended settings work perfectly for the vast majority of players, with only the odd exception - In my experience anyway.
They definitely make a good starting point.

[HowieBass]

A neck with the right amount of relief will buzz all along its length with a very low action. If you have a dead straight neck (no relief at all) it'll tend to buzz first up around the nut as you lower the action and by the time you've got fret buzz at the dusty end you've possibly got note choking near the nut.