S.S. Stewart fretboard lengths

[Richard Katz]

I have two S.S. Stewart banjos. Both are Special Thoroughbreds.
One has a fretboard length of 19 3/4" and the other is 19".
Both have 22 frets.
Was there a reason for this?
Just struck me as odd

[Jody Stecher]

If the "scale length", (the vibrating length of the string from bridge to nut) is longer on one banjo than on the other then the length of the fingerboard will necessarily be longer. the length of the fretboard itself is not itself a significant measurement, it's just a natural result of scale.

There can be two banjos of the same scale with a different number of frets. So long as the frets in common coincide in placement, and the bridge is placed properly,  all will be in tune. I have a banjo with an 28.5 scale. That is very long, an inch and a half longer than the scale of a typical Special Thoroughbred. But my banjo has 18 frets and yours has 22. The end of my fingerboard (which is 20") is fretless. It was built that way sometime in the 19th century.

[Richard Katz]

So the length of the fretboard doesn't dictate how many frets there are?
Was there no decided length consistent with fret count?
Seems odd you can have different lengths, the same number of frets, and still tune the same.
Excuse my ignorance, but I am just figuring things out.

[Jody Stecher]

It's the other way around. If a builder decides to have x number of frets and a scale of y inches then there must be enough fretboard to accommodate x frets. Sometimes this means a longer neck, sometimes there have been fretboard extensions over the pot. It's more about proportions than about absolute lengths. On a shorter scale the frets are necessarily closer to each other. So long as they are placed in the right proportion all will be well.

The twelfth fret must be placed at half the scale length. If the scale length is 4 inches ( a mini banjo) then the 12th fret must be at 2 inches from both nut and bridge. If the scale length is 40 inches or 40 feet or 40 miles, the 12th fret must be placed half way. 

How many frets *above* the 12th fret (like fret 13 and 14 etc) depends on the era, the type of music the maker expects will be played on the banjo, and other factors. 

There is nothing odd about the same tuning at different lengths. What cannot be expected is the same tension at the same length and pitch and with strings of the same diameter on each banjo.

Richard Katz said:

So the length of the fretboard doesn't dictate how many frets there are?
Was there no decided length consistent with fret count?
Seems odd you can have different lengths, the same number of frets, and still tune the same.
Excuse my ignorance, but I am just figuring things out.

[Jody Stecher]

I'm thinking of two examples of the fretboard or neck length being directly related to the number of frets. The Turkish tanbur is the central musical instrument of Ottoman Turkish music. In this music, in theory at least,  the octave has 53 divisions not 12.  A tanbur typically has 40 to 60 frets. To actually get them all on the neck it is necessary for the neck to be very long. The Indian sitar also has a very long neck. it has *fewer* than 12 frets to the octave. the space between the frets needs to be wide  to allow the hand to pull the strings to the side to obtain characteristic ornaments.   But a fretted banjo generally has 12 frets to the octave. 

[Steve Harrison]

The fret distances between frets increase or decrease in logarithmic increments of the length of the string. There is a mathematical formula called the rule of 18.to work this all out. You can look up the detail on Google. Its's a mathematical constant and works for any string length. Logarithmic incrementalism is a natural phenomenon and is why heat and volume as examples don't increase in linear increments and is why the volume control on an audio amplifier uses a logarithmic rather than a linear potentiometer....Steve.

So the length of the fretboard doesn't dictate how many frets there are?
Was there no decided length consistent with fret count?
Seems odd you can have different lengths, the same number of frets, and still tune the same.
Excuse my ignorance, but I am just figuring things out.

[Brian Kimerer]

The positioning of the frets depends on the scale length not the neck length. If the neck extended all the way from the nut to the bridge, it would be theoretically possible to calculate the positions of an infinite number of frets, their distances continually getting smaller. That would not work in a practical sense since the last few hundred million frets would tend to bunch up on top of one another.

However, a banjo neck does not go all the way to the bridge, so the number of frets that will fit on a neck depends on the length of the neck in proportion to the scale length. It is therefore possible to make a neck of any length and put 22 frets on it. You simply have to calculate the fret positions on a shorter neck for a shorter scale length. That is not difficult on a banjo because the bridge is movable. After the banjo has been assembled, you simply adjust the bridge position, i.e. the scale length, until it plays in tune.

The positions of the frets relative to one another must be correct or the banjo will not ever play in tune, but the absolute length of the neck is irrelevant.

I suspect that in the 19th century the banjo builders were not so much into standard sizes as they are now.

[thereallyniceman]

I think this sums it all up for you Richard, but taking it one step further, if there were NO frets on the neck (a fretless banjo) the bridge can sit anywhere on the vellum for the best tone to suit your ear. The spacing on the fingerboard to play the individual notes in tune will be closer or further apart dependent on the bridge position.

The one position that will be guaranteed, no matter where the bridge is placed, is the octave of open string note (except 5th) which would equate to the invisible 12th fret and be exactly 1/2 the scale length. 

[Richard Katz]

Thanks for the clarification. I always wondered about this and now I know.
It's so nice to have experts available to answer my questions. Much appreciated.

[Steve Harrison]

As a bit of extra info on this issue, last year, I had to make a new fret board for a banjo I was restoring and rather than doing the maths myself to calculate the fret distances, I found quite a few websites that did it all for me, all that was required  was for me to enter the scale length....Steve.