Bridge Height

I just received an excellent question from Justin Z:

Hello, I was wondering what bridge height you'd recommend for the dixie?
I recently scored one from the local salvation army and it was missing its bridge.
Can I just use a tenor banjo bridge? if so, does a 1/2" or 5/8" suit it best?

I appreciate your insight.

And I appreciate the question, Justin! You've made me think.

I have 1/2" high bridges. The string "grooves" are 7/16" apart. Be danged if I can find the measurements for a tenor banjo bridge, but I'd bet that's exactly what my bridges are (they came with the Dixies I've bought).

The actual height of the bridge is 1/2", but with the "give" of the Dixie's head, the height above the head tightening rim is 6/16". So there's a 2/16" "dip" where the bridge has pushed down on the head.

Here are some things to consider in all of this:

• Head tension is important. It affects the height of the head rim and the height of the bridge (and therefore the height of the strings).

The feet of the bridge have pushed the head down to where they are below the level of the rim. Of course this lowers the bridge and the strings. It could cause the strings to come into contact with the rim. See the next photo.

The rim height depends upon the amount of tension you put on the head. The more tension, the lower the rim (but the higher the bridge as it won't push the head down so much with greater tension. Here, the space between the strings and the rim is a good bit less than the space between the strings and the frets. The head is as tight as I dare make it here, so I have to live with the rim being higher. On this Dixie, the frets above fret 12 can't be played as the rim hits the strings when they are played above fret 12. The smaller diameter strings can be played a fret or two above fret 12.

• You can have control over this head tension/rim problem by putting shims under the feet of the bridge. But remember that will raise the strings where you'll have to use more finger pressure to get them down to the frets. That, in turn, could cause the strings to sound out of tune, since you'll be changing the tension of the strings a good bit when you have to push them further down to come in contact with the higher frets.
• Remember that bridge placement affects intonation (tuning) as you play on higher frets. This was explained in an earlier post on tuning. But, basically, you have to move the bridge to a point where the strings are in tune when played open and on the 12th (octave) fret.

After saying all of this, I would think that a 5/8" bridge would be too high for a Dixie. And I don't think you'd want to have to trim its height. Of course, with a 1/2" bridge, you can always add popsicle stick shims to raise the height of the bridge (see instructions to doing that at Banjo Bridges by Bart -- http://banjobridge.com/sizingabridge.htm).

And finally, you have to take the time to play around with all of these parameters. I would get the head tightened enough so that pushing the bridge down on it at the approximate proper location* won't have it sinking down into the head by more than about 1/8th inch.

Then I'd put the bridge under the strings and see that I can play at least to the 12th fret. If the strings buzz against the rim (or hit it) at fret 12, shim the bridge as suggested above.(see these instructions at Banjo Bridges by Bart -- http://banjobridge.com/sizingabridge.htm.

* The approximate proper location for the bridge on a Dixie is 13 inches from the fret side of the nut. The nut is the thing below fret one that has the slots to keep the strings in place. It's the first thing the strings contact running from the tuning pegs. It's approximately 6 1/2 inches from the fret side of the nut to the middle of fret twelve. The nut could be considered as fret zero. Pressing down in the space between the nut and fret one causes the string to come into contact with fret one and raises the tone of the string by 1/2 step. So, to find fret twelve, press down at the first space and count one, move to the second space and count two, and so forth until you reach twelve.

You can also measure 6 1/2 inches from fret twelve up onto the head to find the approximate bridge location.

I hope this is helpful to you! If I've confused any of you, please comment and I'll try to clear it up.