Dead spot on a fretless... What to do ?

[Torben Hedstrøm]

Hi...

I own a fretless Warwick Thumb BO, and I am completely in liove with everything about it... Except... After adjusting relief & string height I found that I have a 'dead spot' juuuuust above what would have been the 6'th fret. I could probably just raise the action and get rid of it, but I really like my action nice and low. Guess I need a luthier to have a looke at it ?!.

[bremen]

Guess so. I had a Precision that had more dead spots than [insert bad taste metaphor]; a local luthier scraped the fingerboard, charged me 60 quid and it's been perfect ever since.

[Lfalex v1.1]

Correct me if I'm wrong, but can't adjusting the truss rod help to iron out/shift dead spots elsewhere on the neck?
Perhaps just tighten it a TINY amount (not enough to alter the relief) and see what happens.
Only about 1/32 of a turn against the tension of the strings. It might work. If it doesn't, just reset the rod and try something else?

[Torben Hedstrøm]

Thanks for replies... Already played around with the truss rod, but that particular dead spot stays in the exact same position. Otherwise I would agree, that yes... You can 'move' fret/neckbuzz by adjusting truss rod.

[Kongo]

It's a possibility the wood has swollen slightly. A microscopic bump in the fingerboard is all it takes to choke the notes.
It could cost a small amount to fix, but it's better than forcing high action when you play with low. :-)

[mart]

A long shot, but have you tried changing strings? Last time I got a "dead spot" on one of my fretlesses, it turned out to be a faulty string that had a slight bulge at that spot.

[Stacker]

That area, usually around C-D on the G string, is the common ground for this on some basses. There's a whole science devoted to this symptom on the net but , as stated about, sometimes a tweak of the rod can alleviate the dead-spot in the first instance. I've got it one a Fender CS fretless Jazz; had it since I got it and it's taken ten years or so for it to lessen, possibly due to the neck/body losing more moisture. It's not as bad as it used to be, but you can still hear and feel it!

[3below]

My 85 G&L SB1, had the opposite problem, super loud resonant note at D on the G string. Setup and change of strings fixed it. I think it was the setup since I had tried one other set of strings before and had the same problem.

[ikay]

[quote name='Torben Hedstrøm' timestamp='1350488529' post='1839599']
I could probably just raise the action and get rid of it, but I really like my action nice and low.
[/quote]

Would be worth trying this. If the dead spot does disappear when you raise the action then it's most likely just a slight imperfection with the flatness of the fingerboard (which is relatively easy luthier fix) rather than a dead spot due to structural resonance in the neck (which isn't!).

[Torben Hedstrøm]

Hm, structural resonance... Don't like the thought of that at all. I will experiment a bit, and contact a luthier for a quote on scraping the fingerboard . Thanks for all your comments & ideas guys, much appreciated !.

[chris_b]

You could try a Groove Tube Fat Finger. The bass version is supposed to help with dead spots.

I don't know what you call them in DK but a G clamp will do the same thing, just won't look so good. If the G clamp works then get the FF.

[Machines]

I bet if you tune the string a semitone flat the dead spot moves up the board. Its the resonant frequency the wood cancels out. Give it a try.

[mart]

If it's the resonant frequency, then it'd be the same wherever you played that same note, right? Edit: Er, no, actually, it is more complicated than this: see posts below!

Edited October 19, 2012 by mart

[Machines]

I think the fundamental is key. If its your 5th fret G you might get it on 10th D but not 15th A.

[ikay]

[quote name='mart' timestamp='1350575997' post='1840795']
If it's the resonant frequency, then it'd be the same wherever you played that same note, right?
[/quote]

No, not necessarily. Different resonant frequencies occur in different places along the neck. A dead spot is where the frequency of the fretted note coincides with the antinode of the resonant frequency of the neck at that exact point (or very near). Fretting a note of the same frequency somewhere else on the neck (on a different string) may not result in a dead spot as the resonant frequency of the neck at that point may be different or the position of that fret may not be so close to the antinode.

This article explains it much better than I can - [url="http://www.acoustics.org/press/137th/fleischer.html"]http://www.acoustics.../fleischer.html[/url]

Edited October 19, 2012 by ikay

[3below]

[quote name='mart' timestamp='1350575997' post='1840795']
If it's the resonant frequency, then it'd be the same wherever you played that same note, right?
[/quote]

It is also further complicated by requiring sufficient amplitude to cause the cancellation. The effect is likely to be less at higher frequency notes - less energy transmission. Not a simple situation and no simple magic bullet cure.

If the previous suggestions do not help, in no particular order;

Mass (brass?) plate screwed on back of neck (fatfinger as suggested before). Neoprene gasket in neck pocket ( there will be outcries about poor neck / body contact). Check neck pocket level / flatness. Thin aluminium/ steel plate in neck pocket. Metal plate under bridge. 'Big' metal block/insert under bridge. Metal strip under machine heads. Change machine heads. Rout body under pickguard , remove wood. None of these may work however

[mart]

[quote name='ikay' timestamp='1350593782' post='1841135']No, not necessarily. Different resonant frequencies occur in different places along the neck. A dead spot is where the frequency of the fretted note coincides with the antinode of the resonant frequency of the neck at that exact point (or very near). Fretting a note of the same frequency somewhere else on the neck (on a different string) may not result in a dead spot as the resonant frequency of the neck at that point may be different.

This article explains it much better than I can - [url="http://www.acoustics.org/press/137th/fleischer.html"]http://www.acoustics.../fleischer.html[/url]
[/quote]
Interesting article - thanks for finding that. So yes, it really isn't as simple as I had thought.

[Emanew]

Good advices here,

This dead spot doesn't seem to be too serious

Torben, did you see a luthier ?

Edited October 31, 2012 by Emanew

[Spoombung]

I have two very dead spots on my Wal bass. Nothing will change it. I'm pretty sure you'll have to live with your dead spot. One dead out of 96 notes isn't bad, eh?

[Torben Hedstrøm]

Hi...

Thanks for the concern... Still stalling on the luthoier thing, I'm afraid. Not because I won't pay up, but I feel REALLY reluctant handing over a precious instrument for sanding to just anyone. And case is, I have no references on any Danish luthiers yet. The buzzing is not bad enough to make the bass unplayable, so for now I just avoid that particular part of the neck



Torben

[Schnozzalee]

Jack Bruce says he has dead spots on his thumb, hasn't resolved the issue just says he knows where they are and that it's still his favourite instrument

[iconic]

You will need 3 hands for this but what happens if you play the dead note and then grip the headstock, if it helps hang an electronic tuner off the end...... Just an idea!

Shift race jersey, mx or enduro?

Edited November 6, 2012 by iconic

[Torben Hedstrøm]

Hehe, acually none. Picture is from an offroad trip to the Sahara in February

[Torben Hedstrøm]

Update...


So... Finally got around to getting the Thumb to the shop for a checkup. Hope the results will be satidfactory, and the guy knows what he is doing (he did come highly recommended...). Wish me luck

[3below]

You are wished luck and a good outcome.