Has any builder ever used a single-action compression rod

[murrmac123]

...with the adjustment inside the soundhole, at the neck block ?

I see no technical reason why it wouldn't work, and with a volute at the headstock it probably wouldn't weaken the neck any more than a conventional headstock adjustment.

The reason I ask is because the voices in my head tell me that a single-action compression rod, pre-tensioned to give a back-bow in the neck, subsequently planed flat prior to fretboard fitting, may well contribute significantly to the stiffness of the neck, once the tension is counteracted by 180lbs of string tension. This stiffness may well contribute towards better tone, (and maybe increased sustain) compared to a dual action trussrod.

Oh, and also ...the voices tell me that a headstock just looks better without a truss rod cover ...

But ...has anybody ever done it this way ...???

[Julian Gaffney]

Because of the inherent curvature in a compression rod the threaded/exposed/adjustable end will be curved upwards. Making adjustments inside the body of the guitar very difficult.

That's the only reason I've never installed a compression rod that way.
Of course I can't speak for other builders, but I don't think I've encountered an acoustic with that configuration.

I couldn't agree with you more about introducing a little back bow into a neck prior to final truing, if only just to make the neck a little more predictable down the road. A good thing to strive for I think!

[murrmac123]

Originally Posted by Julian Gaffney

Because of the inherent curvature in a compression rod the threaded/exposed/adjustable end will be curved upwards.

Thanks for reply, Julian.

I would contend, however, that the "upwards curvature" to which you refer, ( and which I acknowledge is the way many builders do and did install single action truss rods) , is in fact an unnecessary complication.

The compression works just the same with a rod installed in a dead straight channel ...no need for any curvature ...when you tighten the rod , it compresses the neck the same way and gives the same back bow.

The original Gibson compression rods were dead straight, no curvature.

[LouieAtienza]

I'd say it would have to depend on how you join the neck. If it were joined mortise-and-tenon style then the trussrod could then go through a hole in the neck block and the trussrod nut would rest against the neck block instead of the neck; which would possibly allow a bolt-on neck style to use one bolt instead of two... Since you'd want the conpression rod to be set as low as possible on the neck, it might not be a practical thing to do if you use a dovetail joint, unless you bore a clearance hole in the neck block to access the trussrod nut. Then you'd risk getting glue around the trussrod nut, and it won't be easily accessed to be cleaned.

I guess it's a good idea if weight was a concern, but then again I'd still want a dual-action trussrod...

[murrmac123]

Originally Posted by LouieAtienza

I'd say it would have to depend on how you join the neck.

Sorry, I was presupposing a bolt-on neck ...like the Huss and Dalton configuration, except with a single action rod rather than a dual action.

[ZekeM]

Cumpianos book uses a single action rod with adjustment in the soundhole. It's what I did on my first guitar. It works fine. Just tighten it slightly, plane flat and you are ready to go.

[jeff crisp]

Originally Posted by murrmac123

The compression works just the same with a rod installed in a dead straight channel ...no need for any curvature ...when you tighten the rod , it compresses the neck the same way and gives the same back bow.

Robert Benedetto suggests it should work just fine in his DVDs.

As far as having access at the sound hole goes I would be concerned about the size and shape of the anchor at the other end, even with a volute. Though I'm sure it could be made to work.

Jeff.

P.S. A laminated neck might be a good idea.

[royd]

I think that is what Lowden uses in their guitars.