Compound radius fretboards – what’s all the fuss?
One of the key factors separating low-end guitars from high-end models is the ‘compound radius’ fretboard. At first the concept of compound radius seems a little confusing, but its nature and application are actually quite simple once understood.
The giveaway is in the word ‘compound’. Dictionary.com defines a compound as being “composed of two or more parts, elements, or ingredients”. A radius can be accurately described as the distance between a circle’s centre and its edge. With this logic in mind a ‘compound radius’ fretboard would be one where the curve of the board was different at different locations along the board.
I began by using fixed radii on my earliest prototype guitars but soon re-tooled and began offering a compound radius on every build. I’m yet to sell a guitar without a compound radius.
The best way to describe a compound-radius fretboard is to imagine it as a cone. Because the nut is approx. 43mm and the end of the board is 57mm, as the notes rise in pitch the fretboard flattens out.
So here are the practical applications of this in my experience and opinion:
- A compound radius means that the actual distance across the fretboard (think circumference) remains the same for its entire length
- The conical nature of a compound board means that the string action can be set lower. So when you bend or pre-bend (especially full or tone-and-a-half bends) you don’t run the risk of ‘fretting out’ or having the string contact another fret higher up the fretboard.
- A tighter radius at the nut allows more room for the fingers and easier chording
- A larger radius towards the bridge allows for faster playing/soloing due to a ‘flatter’ action
There is also an aesthetic benefit from using a compound radius, which is that both the thickness at the centre and the edge of the fretboard remain the same the whole way along.
My favourite compound radius so far, and the one my customers like most is 9.5” – 12”. It feels like a modern Tele or Strat at the nut, and a Les Paul towards the bridge.
Now on some guitars there are some limitations around what radii you can use. For example on many traditional fixed-bridge designs the bridge has a set radius which the fretboard for optimum playability should match. Likewise for guitars with locking nuts (Floyd-Rose or Kahler) for example. Most tremolos are made with individual string saddles which can be either adjusted or shimmed to achieve the correct radius.
By now I trust that you’ll have an advanced knowledge of the compound radius fretboard that you can use to both impress your friends and head into your next guitar purchase or setup with a greater understanding. If you have any further questions or comments don’t be afraid to post them below!
Thanks for reading and being part of the Lucas Guitar community.