Adjustable Truss Rod -- good or bad?

[Aaron Smith]

Originally Posted by 00-28

we get the same old arguments from the few who believe that if a guitar isn't built like a pre war Martin Dreadnaught, then it just ain't right.

I think the point those people are trying to make is that if it isn't build like a pre war Martin Dreadnaught, it may not sound like a pre war Martin Dreadnaught.

If that's not the sound that you're trying to reproduce exactly, then a whole world of design possibilities opens up. There are literally millions of great guitars that were not built in that fashion.

But if that is the sound that you're trying to reproduce exactly, then there's plenty of evidence to show that small movements away from the original design can add up to a big difference in sound.

As a player I often find the "magic" in all sorts of guitars without adjustable trussrods. While I can't directly correlate that magic to the absence of the adjustable feature, it has led me to question how much I really need that feature. And after exploring that, I find that the advantages of an adjustable truss rod are often misunderstood and overstated. And accordingly, the tradeoffs that come with an adjustable truss rod are often misunderstood, and may well be understated.

[Rodger Knox]

Almost all necks flex a little under string tension, and those necks need an adjustable truss rod.

It is possible to build the neck stiff enough that there is no measureable flex from string tension, either with steel or carbon fiber reinforcement. The relief would have to be built into the fretboard/frets, and would not change with changes in string gauges. I've been thinking of building one like this, but all my builds so far have had double action truss rods.

[Silly Moustache]

Originally Posted by Todd Yates

Stability and tone....post#21.

Can you be more specific about which guitars (generally) have exhibited that type of problem in your experience? The reason I ask is to parse out whether the problems you've seen are really with non-adjustable necks, or with particular design/application of the idea. One bridge collapse doesn't mean all bridges are bad.

well, that's a challenge! My first experiences were with D18s and D28s in the mid to late '70s.

Due to my ignorance of guitar structure I bought some that really needed planing and refretting or had to have bridges filed down to compensate.
I bought the guitars that people were getting rid of because they had problems.

My last Martin six string was a '74 D35-S. I had to have the neck reset but sadly the luthier didn't replace the filed down bridge. Lovely old guitar but not at its peak when I got it or even when I sold it. New owner adores it however.

A friend bought an HD28 and asked me if it was OK. No.l Neck like a banana.

Another frind custom ordered a fancy 0004x something or other it arrived needing a neck reset and the fretboard straightened out.

I quite understand why Martin did not fit adj. truss rods in the Authentics but I decided that they aren't for me - mainly for this reason.

[kydave]

Originally Posted by The Bard Rocks

This is a useful thread, good info here. My thinking is that if the luthier recommends it, and nearly everyone of them does, then maybe I should have it.

I had an M38 that went through 3 neck resets in the 20 years I owned it. No truss rod of course. Maybe I would have had less trouble had there been one. It was one of the last guitars me before they went to them.

The neck reset has nothing to do with the truss rod.

(Sorry, late to the feast...)

[wrathfuldeity]

Originally Posted by wrathfuldeity

Interesting...I have 2 old harmony H165, same early/mid 60's era of "steel reinforced neck" non adjustable. Both have had neck resets, one I'm sure nothing was done with one tress rod; in the other the orginal steel rod was replaced with heavier steel rod (non-adjustible) and epoxied in. This resulted in a significantly heavier and more solid feeling neck. The guy that did this said that the guitar should never need another reset, the neck is great, no dead spots, no movement with a change of string gauge. It seems...but IDK...its like with this solid neck...the sound doesn't travel up the neck and keeps the vibrational energy in the body...and this guitar is louder, has more projection and has more headroom. However the one with the orginal condition neck, is light as a feather, has a fast response and can be played with a feather touch and easily overdriven...very intimate.

kydave, I do understand a reset has nothing to do with the tress rod. However was wondering what your and others' thoughts/experiences of the above bold part of the quote. I really have no idea of why the modded tress rod would result in the effect that I'm noticing. Thanks

[flaggerphil]

Originally Posted by Todd Yates

Stability and tone....post#21.

Never had that problem.

[Howard Klepper]

Originally Posted by Rodger Knox

Almost all necks flex a little under string tension, and those necks need an adjustable truss rod.

Not necessarily. They can have an appropriate amount of back bow built into them, so that under string tension the relief is correct. Doing this well is an uncommon skill among steel string guitar luthiers.

A good fixed reinforcement neck gets the major part of its stiffness from the reinforcement, and the reinforcement is not affected by humidity and will not cold creep. This results in a neck that is not significantly affected by humidity or minor changes in string tension.

Martin in the 1960's went to a less stiff, lighter gauge T bar, and then went to the square tube that is also less stiff than the earlier T bar. These necks relied more on the wood and less on the reinforcement for their stiffness, and hence were subject to issues caused by humidity change, string tension change, and cold creep. Martin's eventual solution was to go to adjustable rods, until the Authentics recreated the original T bars.

While the majority of my guitars use an adjustable steel rod for reinforcement, for my fixed reinforcement necks I use a system of three carbon fiber rods. I have had no problems with their stability.

[brianmay]

Are you saying the truss rod has nothing to do with neck resets . . . wow, I wonder why I hadn't noticed that before . . . ?

[sam.spoons]

I would add that if you have two different woods in the neck (i.e. pretty much everything except Fender all maple bolt ons) the neck will be susceptible to climatic changes and ageing (possibly part of the reason for old Martins needing neck resets). Two different pieces of wood of different species will always age/change differently and will affect the profile of the neck. I'd accept it's possible for a builder (luthier or factory) to build a large percentage of their necks to be stable but there must always be some that are not over time (I don't believe in precognition). For me the trade off of playability means I prefer a truss rod, I simply don't get on with baseball bat necks. The other point is that there are so many things that affect acoustic guitar tone tone that the difference between a solid reinforced neck and a truss rod must be relatively small IMHO (and I accept my knowledge in this area is only moderate so I may be wrong).

[charles Tauber]

Originally Posted by sam.spoons

I would add that if you have two different woods in the neck (i.e. pretty much everything except Fender all maple bolt ons) the neck will be susceptible to climatic changes and ageing (possibly part of the reason for old Martins needing neck resets).

Everyone, let's repeat this together:

The neck design has nothing to do with a neck reset.

Again,

The neck design has nothing to do with a neck reset.

And, now in three-part harmony,

The neck design has nothing to do with a neck reset.

Got it? Good.

[kydave]

For me the trade off of playability means I prefer a truss rod, I simply don't get on with baseball bat necks.

The implication there being that a non-adjustable reinforced Martin neck is a baseball bat?

Obviously you have not played many of them or you'd know better.

Some are, some are not.

[zhunter]

Originally Posted by kydave

The implication there being that a non-adjustable reinforced Martin neck is a baseball bat?

Obviously you have not played many of them or you'd know better.

Some are, some are not.

The neck on my ebony reinforced D18 is actually pretty thin. Last time I bothered to check the relief was just fine. But then that was after a neck set...

hunter

Andy, thanks for answering back. If your main experience has been with 1970's square tube Martins, I can understand the hesitation. The 3/8" square tubes combined with PVA glue used to join the fretboard are among the most likely to develop excess relief. Not all do, but they are not nearly as robust as the earlier T-bar. My dad and I have 5 between us, and 4 of the 5 required compression fretting to fix the excess relief. One was near 0.025" relief before the work, and about 0.006" now - many years after the repair. So, even the worst of them are correctable and stable after that work.

My non-adjustable Martin necks vary less than 0.003" through any season. I couldn't ask for better stability than that.

[Russ C]

Late to be joining in, but a point or two about low actions and neck relief ..

There is a "correct" amount of neck relief - it's the centre of an acceptable small range of neck relief, but I find that the "best" relief can vary from player to player - if they like a low action, where they want the least buzz. I've even found the odd guitar that seems to behave better either dead straight or with more relief than I'd have expected. (I'm looking back over hundreds of set-ups).

Many guitars are on their way to needing a neck reset but are not really there yet. The "acceptable range" of relief I referred to can provide some indirect and temporary benefit for the owner - in the same camp as lowering the saddle further than ideal to get you by.
The number of players who believe their guitars which have never been tampered with are still spot on support that "acceptable range" may be a lot bigger than I would claim.

[ewalling]

Personally, I wouldn't entertain the idea of buying a steel-string guitar without an adjustable truss rod. It's a feature that helps provide a cheap way of countering climate, seasonal, and age effects on a guitar, to say nothing of those induced by varying string tensions. I have bought one or two classical guitars without one, and I might again for something special, but even on classical/nylon strings, I much prefer the added security of an adjustable rod.