bridge location on box

Hi Steve.

I build stick dulcimers (strummers, strums sticks, call 'em what you like) using a "paddle box" design not that different from Bob McNally's Strumstick (as well as other rectangular and triangular sound box designs). My choice of location for bridge location depends on three considerations.

First, using an object like a pen, pencil or finger, I tap on the soundboard of the box to see where it sounds best. This test I call the "tap test", and I usually find the best sounding part of the sound board is in the middle.

Second, I try to choose a fairly symmetrical location when laying out the other "components" of the sound board, like fretboard, sound hole and tailpiece. With the paddle box design this symmetrical location is the point of intersection between the two midlines of each corner with the midline of the box. That is to say, for the two lower corners of the paddle box, I subdivide each corner into 2 equal sub angles and extend the dividing lines to the middle of the box. Where these two lines meet the midline of the box is the target location for the bridge.

The third factor is the length of the neck and fretboard (as defined by the scale length). My typical instrument has a 50cm scale length. Assuming the fretboard will span two full octaves, the fretboard length will typically be 37.5cm long (i.e. 3/4 times the scale length) plus a cm or two between the first (and last) fret and their respective ends of the fretboard. Typically my fretboards are 39cm long splitting the 1.5cm difference equally on each end of the fretboard. After fabricating the fretboard, I place it on the neck and check its position relative to where I plan to put the bridge. With the paddle box design, there is a sizable overlap between the fretboard and the soundboard... The fretboard just does not end where the neck meets the soundbox as seen on many cigar box based instruments. Additionally, the paddle box design allows fo a single sound hole which I place on the midline of the soundbox; ideally, halfway between the end of the fretboard and the location of the bridge. Incidntly, I use a fret 0 in addition to a "nut" for greater ease of accuracy when building the fretboard.

The final location of the bridge is then determined after tuning up the instrument and adjusting the bridge for optimal intonation across the two octaves of range allowed by the fretboard. This is the test that often results in the bridge being angled relative to the strings and it's quite a balancing act as it is a compromise between each octave and between each string. I begin by measuring the scale length (50cm) from fret 0 to where the bolt & nut bridge will be initially placed.

To do this intonation test, I use a digital tuner and check the intonation of string 1 usually checking fret 0 (open string) verses fret 7 (octave) and I adjust the bridge positionuntil I get the closest tuning to the note I'm tuning for (usually d in a DAd tuned instrument). Then, while maintaining the position of the string 1 end of the bridge, I repeat this again for string 2 (tuning for the A note and it's octave). Then I do it again for string 3 (tuning for note D and it's octave). Actually (being a lazy person) I tend to only tune for string 1 across the two octaves as strings 2 and 3 are usually just used for drones or at the most the first few notes in the first octave. If you are into chordal playing or like to use higher notes on strins 2 and 3, then this fine tuning for optimal intonation is probably worth doing on strings 2 and 3 as well.

It will take you a few builds to get the feel for the right bridge location, but even if you get it wrong, your instrument will more than likely sound okay. When playing I find the place where I pick the strings with my right (strumming) hand seems to have a far more effect on sound quality. The sound is richer when picking somewhere over the last few frets of the fretboard as compared to over the sound hole (or going for the opposite effect, picking/strumming near the bridge. Try it for yourself to hear what I'm talking about.

Good luck with your build(s)

-Rand
(Sleepless in America on my first day back... Jet lag!)

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Rand Moore June 28, 2012 at 8:33am

Hi Steve.

I build stick dulcimers (strummers, strums sticks, call 'em what you like) using a "paddle box" design not that different from Bob McNally's Strumstick (as well as other rectangular and triangular sound box designs). My choice of location for bridge location depends on three considerations.

First, using an object like a pen, pencil or finger, I tap on the soundboard of the box to see where it sounds best. This test I call the "tap test", and I usually find the best sounding part of the sound board is in the middle.

Second, I try to choose a fairly symmetrical location when laying out the other "components" of the sound board, like fretboard, sound hole and tailpiece. With the paddle box design this symmetrical location is the point of intersection between the two midlines of each corner with the midline of the box. That is to say, for the two lower corners of the paddle box, I subdivide each corner into 2 equal sub angles and extend the dividing lines to the middle of the box. Where these two lines meet the midline of the box is the target location for the bridge.

The third factor is the length of the neck and fretboard (as defined by the scale length). My typical instrument has a 50cm scale length. Assuming the fretboard will span two full octaves, the fretboard length will typically be 37.5cm long (i.e. 3/4 times the scale length) plus a cm or two between the first (and last) fret and their respective ends of the fretboard. Typically my fretboards are 39cm long splitting the 1.5cm difference equally on each end of the fretboard. After fabricating the fretboard, I place it on the neck and check its position relative to where I plan to put the bridge. With the paddle box design, there is a sizable overlap between the fretboard and the soundboard... The fretboard just does not end where the neck meets the soundbox as seen on many cigar box based instruments. Additionally, the paddle box design allows fo a single sound hole which I place on the midline of the soundbox; ideally, halfway between the end of the fretboard and the location of the bridge. Incidntly, I use a fret 0 in addition to a "nut" for greater ease of accuracy when building the fretboard.

The final location of the bridge is then determined after tuning up the instrument and adjusting the bridge for optimal intonation across the two octaves of range allowed by the fretboard. This is the test that often results in the bridge being angled relative to the strings and it's quite a balancing act as it is a compromise between each octave and between each string. I begin by measuring the scale length (50cm) from fret 0 to where the bolt & nut bridge will be initially placed.

To do this intonation test, I use a digital tuner and check the intonation of string 1 usually checking fret 0 (open string) verses fret 7 (octave) and I adjust the bridge positionuntil I get the closest tuning to the note I'm tuning for (usually d in a DAd tuned instrument). Then, while maintaining the position of the string 1 end of the bridge, I repeat this again for string 2 (tuning for the A note and it's octave). Then I do it again for string 3 (tuning for note D and it's octave). Actually (being a lazy person) I tend to only tune for string 1 across the two octaves as strings 2 and 3 are usually just used for drones or at the most the first few notes in the first octave. If you are into chordal playing or like to use higher notes on strins 2 and 3, then this fine tuning for optimal intonation is probably worth doing on strings 2 and 3 as well.

It will take you a few builds to get the feel for the right bridge location, but even if you get it wrong, your instrument will more than likely sound okay. When playing I find the place where I pick the strings with my right (strumming) hand seems to have a far more effect on sound quality. The sound is richer when picking somewhere over the last few frets of the fretboard as compared to over the sound hole (or going for the opposite effect, picking/strumming near the bridge. Try it for yourself to hear what I'm talking about.

Good luck with your build(s)

-Rand
(Sleepless in America on my first day back... Jet lag!)
- Rand Moore > Rand Moore June 28, 2012 at 9:10am
  
  I meant to include a link to some info on the paddle box design in case you are interested in this more traditional stick dulcimer design and to see where I'm coming from mentally. Here is the link...
  http://www.cigarboxnation.com/group/HMRB101/forum/topics/the-boat-p...
- Steve Jeter > Rand Moore June 28, 2012 at 9:21am
  
  I printed that link out yesterday. Excellent! It scares me a bit,,, but I will try it eventually. thanks
  
  Ive got a cigar strummer build Iworking on now,. i am building it as Ive been doing banjos with a spike,, nothing touching soundboard hope it works
  
  Steve
Wichita Sam June 28, 2012 at 1:25am

Closer to the center...more banjo-Y sound
Closer to the tail...more guitarist sound.
I like strummers more banjo-Y...bright sounding.
The Phrygian Kid June 27, 2012 at 10:12am

im entirely with you mate,think youre onto something..

i just do more frets (and more neck) clear of the box to bring the bridge forward. makes em louder, and rounder sounding, less spiky..
- Steve Jeter > The Phrygian Kid June 27, 2012 at 11:20am
  
  Im going to try that. spiky is a perfect description

This reply was deleted.

DULCIWORLD: Dulcimers & Strummers

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