from guide: Guitar Wood Types and Tones

Walnut

A darker wood with Ash-like grains, but like mahogany, the density is uniform. It is harder and denser than Mahogany so the tone is brighter, but the open grains make for a complex midrange that seems to be compressed in some frequencies, but dynamic in others. There's a nasal response to rhythms, while solo notes jump out. It has a lot of advantageous features of the other main guitar woods. It has a snappy attack and solid lows like Ash, but with smooth highs like Mahogany, and textured mids like Alder. The drawbacks are that it's heavier, and more stubborn in its sound. It doesn't respond to random pickup changes. The pickups have to be well suited to the guitar. A Walnut body will dictate the tonal signature of the guitar more than the other main woods. A heavy piece will dampen the mids to produce an overly nasal and lifeless sound, so it needs to be light and open grained enough to resonate the main guitar frequencies.

American and european walnuts are different of colour and texture. No doubt - of sound too. Walnut often used in thru-necks and bass guitars.

Production notes: Again watch for heavy pieces. The extra weight adds nothing good to the sound except perhaps more sustain. But sustain is abundant in Walnut already.

Body Top:

Like Koa, the tops would have just a little less high frequency than Maple, but have less compression and combing with Mahogany backs.

Learn more about Woods, Body, Body Tops, Necks and Fretboards at guide: Guitar Wood Types and Tones