Truss rods

[Don W]

I have an entry level and inexpensive Yamaha CG142. It has really nice tone and the neck is straight as an arrow (which I like). It has no truss rod. I like the fact that the guitar is so light. What are your feelings on truss rods in classical guitars?

[rmp]

I've read that they should not need them, due to the reduced tension, not sure I agree though.

I once owned a Manuel Rodriquez A Cut model. The neck developed a significant bow, I had to have it repaired. The tech put the neck in a heat press for a few days. That fixed it, and fortunately it never reoccurred in the time I had it.

I have a 500 series Taylor nylon now, and it has a truss rod, I've had to adjust it a bit now and then.

I'm no expert, so I can't speak of the physics involved, but I'm sure glad my 514 NY has one.

[gmr]

I don’t see any reasoning that a truss rod would compromise any tone of a well built classical guitar. Truss rods are a concept that is much newer than traditional classical guitar construction techniques but they do not detract from any tonal potential, in my admittedly amateur opinion.

[charles Tauber]

A traditional classical guitar is a very specific instrument, one that is usually very lightly built. Many makers use a light-weight material, such as Spanish cedar, for the neck. Embedding a heavy rod in the neck can upset the physical balance of the instrument making it neck-heavy. In theory, if one used a very light-weight material - rather than the steel usually used for truss rods - it would not upset the balance. Some makers have used wooden and/or carbon fibre stiffeners in the neck that add little additional weight but do not provide adjustability to the amount of relief in a neck/fingerboard.

Traditional classical guitars were designed to be played un-amplified and to fill concert halls. Consequently, they typically have fairly high action (string heights) - much higher than normally seen on steel string guitars - allowing the strings to be plucked with considerable force without buzzing. Arguably, subtle changes in neck relief are largely irrelevant.

Many nylon-string "crossover" guitars - a different animal than a traditional classical guitar - often have adjustable metal truss rods. The adjustable rod allows the player and/or repair person to adjust the amount of relief in the neck. Crossover guitars, typically, have much lower string heights and, arguably, and subtle changes in neck relief might be more relevant.

The lower tension of nylon strings - and a traditionally thicker neck - largely negate the need to adjust the amount of neck relief. Far too many people who have adjustable truss rods adjust them "because they can", not because that is the appropriate adjustment required. In general, once the desired neck relief is achieved, there is no need to adjust the truss rod at all unless the relief changes, as it might if subjected to seasonal humidity changes. If one maintains one's instrument in a reasonable range of humidity levels, there should be little reason to change the neck relief. Many who adjust the truss rod do so to counter a change in string height that occurs at the bridge as the top arches more in higher humidity, rather than in response to an actual change in neck relief. What should be done in such a situation is to exchange the saddle for a shorter one.

Some classical guitar makers have experimented with purposely using heavier necks for tonal purposes. It isn't conclusive that using a heavier neck produces a positive or a negative result.

There are the occasional examples of classical guitars that do develop excessive relief and/or need neck resets. These are exceptions, rather than the norm. One can design for the exceptions, or one can design for the norm. It also makes sense to design for how most people are going to use and care for that instrument.