The Function of Wood in a Banjo Rim.

(Sound production in a Banjo

 

There was a time in my life that I decided to what I could to improve musical instruments. I played the banjo, so one of the first instruments I chose to work on was what I played; a 1957 Gibson arch-top Mastertone. So, I built a replacement rim of: Koa, Mahogany, Black Walnut, Black Walnut, Mahogany Koa. The results were not very desirable It was very sweet tone but not a sharp punch. I abandon this rim going back to original. Several years later I made a Rim of Rosewood. It was much better than Maple. I also got to thinking about older banjoes their rims were much thinner some only ¼” thick. I dismounted the neck and took out rim crossing hardware but left everything else a “Pot” as Stewart MacDonald call them. With a sharp hunting knife I started scraping on the rim thinning it. I left the tone ring contact intact. I would scrape a little then tap the pot with butt of the knife. I continued doing this until overtone converged. I scraped about ¼” from the ¾” thick banjo rim. Thinning the rim greatly improving the sound of the banjo.

 

A friend brought me inexpensive banjo and asked me if there was anything I could do to improve the sound. The rim was solid cast aluminum I found by placing two layers of wood in side the aluminum it dampened the un wanted over tones.

So unlike many instruments the wood in a banjo rim serves to dampen unwanted frequencies. Too heavy too thick it dampens too much too light harsh overtones.

A corollary to this if the tone ring is loose it will also produces harsh overtones. So if there is gap fill the gaps with wood veneer of the parent material. Maple rims use maple. Rose wood use rosewood. You should almost have to pry of the tone ring in dismantling a banjo!

 

John Alden Robinson

jrobinson@maliposamusic.com

Maliposa Music

17415 N. 75th Ave

Glendale, AZ 85308

Maliposamusic.com