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Essential Banjo Licks with Ross Nickerson
by: Ross Nickerson

Harmonics on the Banjo: Part 2

by Bob Altschuler

Part 1 in the February 2009 issue discussed where to find and play banjo harmonics and why they occur. There were also tabs and an MP3 for sample harmonics and those in “Bugle Call Rag” and a YouTube video of a song played entirely with harmonics.

In addition to playing them as effects, you can use harmonics to set the bridge location on your banjo. Unlike guitar and mandolin, where bridges are permanently fixed to a certain spot, banjo bridges are held in place only by string pressure. That is why you see pencil marks around bridges on many banjo heads to indicate bridge placement, in case it is accidentally moved.

By moving the bridge back toward the tailpiece or forward toward the neck, you change the length of the vibrating string. A critical part of banjo setup is to set the bridge in the proper spot so string length is correct. Banjos (and other stringed instruments) have a certain scale length based on a formula to determine where the frets are set. If the bridge is in the wrong place, this will make the string too long or short in relation to the scale length. Intonation (pitch) will be off and fretted notes will not sound true.

Checking bridge position is part of overall banjo set up. The banjo should have the correct amount of neck bow (curvature) and head tightness before you set the bridge, since these can affect bridge placement. The neck should have a very slight bow (with the center curved downward) because flat fingerboards will cause strings to buzz. Tightening or loosening the truss rod inside the neck will adjust this, but be extremely careful. Very small adjustments are needed, and you can break the rod or crack the fingerboard if you over tighten the rod. I recommend asking someone show you this or using an instrument repair expert.

Other important parts of banjo set up are to check string action (height above the fingerboard) and adjust tailpiece pressure on the strings. Very good set up information can be found on Bill Palmer’s site www.banjowizard.com, at www.stellingbanjo.com, www.banjotrain.com, www.desertrosebanjo.com and on other Internet sites.

The following are the steps to set the correct bridge location.

1. Measure from the inside of the nut to the center of the 12th fret, which is at the center of the vibrating string between the nut and the bridge.
2. Measure from the center of the 12th fret onto the head and locate the bridge at the same distance you first measured (see #1), plus approximately 1/16th inch. This will give you the approximately correct spot for the bridge.
3. Tune the banjo and compare the harmonic and fretted notes on the 3rd string at the 12th fret, using an electronic tuner if possible. If the notes are identical, bridge placement is correct. See Part 1 in the Feb. 2009 issue for information about how to play harmonics.
4. If the harmonic sounds higher than the fretted note, carefully move the bridge slightly toward the neck to shorten the length.
5. If instead the harmonic sounds lower than the fretted note, move the bridge slightly away from the neck (toward the tailpiece) to lengthen it.
6. After the 3rd string harmonic and fretted notes match, try the same operation on the 1st and then the 4th strings. As a final adjustment, the 4th string side of the bridge may have to be tilted a little closer to the tailpiece (making the string slightly longer) to get the harmonic and fretted notes to match. Since this also changes the 1st string side of the bridge, you may have to compromise the tilt between the 1st and 4th strings.
7. After you compare strings 3, 4 and 1, you can also compare the 2nd string harmonic and fretted 12th fret notes.

Each time you move the bridge, retune the strings and continue to compare the harmonic and fretted notes until they match. Only very small movements (1/32nd inch, etc.) are needed, and the bridge should be moved so it stays perpendicular to the strings.

Be careful moving the bridge because, under string tension, the thin wood can break. You can pinch the bridge for support on all three feet and gently wiggle it back and forth while pushing or pulling. You can also pinch a pencil flat against the bridge for support on the side opposite the way you want it to move and gently pull the pencil and bridge back and forth. This puts even pressure on the bridge as it moves. After you move it, make sure the feet are flat on the head. I’ve adjusted bridges both ways over the years and never broken one, but be careful, since good bridges now cost $30 and up.

Correct bridge position is a compromise from “perfect” placement because of differences in string tension, thickness and distance to the fingerboard (action). When you press a string down, the string bends slightly which increases tension. This makes the note sound sharper, and to compensate for this the bridge must be slightly farther away than the mathematically “correct” length. Differences in string tension also affect how sharp a string will sound, with a string under greater tension sounding sharper when fretted. This also affects bridge position. With a straight bridge (and sometimes even with a compensated one), every string will probably not have an exact match for the harmonic and fretted notes. However, both compensated and straight bridges give satisfactory results.

Most bridges are straight, some are compensated for the 3rd string and others are compensated for multiple strings. They are constructed so that certain strings are longer than others. This compensates for the difference between the mathematically correct string lengths, where the 12th fret is exactly halfway between the nut and bridge, and the actual string lengths needed, caused by differences in string thickness, distance to the fingerboard and tension.

If you look at bridges from Nechville, Snuffy Smith (style 2), Moon and others you will see variations in compensation for one or more strings. You can also see string compensation at the bridge on an electric guitar, where the length of each string can be individually adjusted.

Tom Nechville of Nechville Banjos told me he uses harmonics and fretted notes at the 19th fret to set the bridge, and Bill Keith also mentions using the 19th fret in “Masters of the 5- String Banjo” by Tony Trischka and Pete Wernick.  I believe this is more accurate than using the 12th fret. You can try it both ways and see if there is a difference in bridge placement on your banjo

Adjustments to your banjo can also affect bridge placement. If you tighten or loosen the head to adjust tone (which will also raise or lower the string action), change your bridge height, use different string gauges or adjust the action with the coordinator rods, the bridge location may change.

After you have placed the bridge correctly, it’s a good idea to use a pencil to lightly mark the banjo head around two corners of the bridge in case the bridge is accidentally moved.
Now we’ll go back to harmonics as song effects. The tabs below have harmonics for “Foggy Mountain Chimes” by Earl Scruggs, “New York Chimes” by Tony Trischka and “Banjo Boy Chimes” by Sonny Osborne.

Also, check out Bobby Lunde on “YouTube” playing the harmonics in “Banjo Boy Chimes” at http://www.youtube.com/watch?v=9Y0dZGnNmfY.

Have fun picking, and I’ll see you next issue.

About the Author

Bob Altschuler lives in upstate New York and has played bluegrass banjo since 1970. As a banjo instructor, his 25 years of experience includes teaching many students at Banjo Camp North, where he has been the Beginner Bluegrass Track Coordinator since 2003. Bob's training and work as a public school teacher sharpened his teaching abilities, and helped him become a patient and sought after banjo instructor (his day job is now with the NY State Retirement System).

Bob performs with the Dyer Switch band at concerts and festivals across the Northeast, Midwest and South, and recorded American Airwaves and Family Business CDs with the band. His banjo playing has also been heard on Northeast Public Radio and on television and radio commercials.

You can contact Bob at arobanjo@aol.com, or through the Dyer Switch website at www.dyerswitch.com.