4strings bass : one or one truss rod with carbon fiber rods???

[joke_retro]

4strings bass : one truss rod or one truss rod with carbon fiber rods???

[Gone]

Just the trussrod is normally sufficient for a 4 string.

[jordan_frerichs]

what is the neck wood? some woods are softer/more prone to bend. i am doing carbons and truss on my 34" scale 4 string with a walnut neck

[erikbojerik]

In general, the use of CF rods will permit you to make a thinner neck than you normally would. My last 4-stringer was 0.77" thick including the fretboard.

[Son of Magni]

I don't understand why people want to put CF stiffeners in a neck. If the neck is too stiff the strings won't be able to pull in the relief you want. Then you have to build in relief by scooping out the fingerboard.

On the issue of trussrods, you have to remember they add a lot of weight to the neck. So balance will suffer unless you compensate by some other means like an extended upper horn. On a 4-string the neck isn't wide enough for the two rods to really have independent action and it's debatable whether they do on a 5. For 6 and up I use two rods but that's more to even out the stresses than to be able to adjust the two sides differently.

So short answer (imho) is for a 4 string, one rod / no CF.

[jordan_frerichs]

Originally Posted by erikbojerik

In general, the use of CF rods will permit you to make a thinner neck than you normally would. My last 4-stringer was 0.77" thick including the fretboard.

i assume that was cf only, correct? i am considering using only ck on my short scale maple/bloodwood neck-through, mainly because i am having difficulty finding a quality truss for 32" scale, and i might be able to get away with it because of reduced tension. btw, does an un-radiused fb need a relief?

[erikbojerik]

I used both CF and a 2-way truss rod on Chris' bass, it was a 3-piece maple lam bolt-on. At 0.77" thickness (wenge board) the string pull was just enough that I didn't really have to use the rod. But it is needed there for future adjustment.

In addition to allowing you to build a thinner neck, the CF rods also help A LOT with stability. 20-30-40 years from now a neck with CF rods will be straighter than one without.

IMO you always need a truss rod, because even if the neck is perfect on Day 1 it might not be on Day 365 due to changes in temp, humidity, etc etc (again why I use CF). You WILL find yourself wanting to adjust the rod at some point, and if you can't then you're either stuck with milling the frets or making a new neck.

Neck relief has nothing to do with fretboard radius - the amount of relief you need depends a lot on your playing style (heavy RH=more relief) and string tension (lower-more relief). A short scale tuned to standard will have lower tension than a 34" scale, so my guess is you'll need some relief.

Use a 2-way bass rod from Allied Lutherie and make it a 24-fret neck. On a 32" scale your distance nut-to-#24 is 32*0.75=24" and the Allied rod is 22-3/4" end to end.