dberkowitz wrote:
David,
I'm not sure where your getting your number for the string tension, but according to D'Addario's string tension chart, which calculates the string tension based upon the unit weight of the particular gauge and formulation (UW), the scale length, and the frequency to which it is tuned, I calculate a string tension for your set on a 29" scale, in B-B at 266.25lbs of tension. A B-B tuning includes the following frequencies, gauging, and unit weight, tension.
B (61.7hz) 70w, UW: 0.00096833, 32.09316762lbs
E (82.4hz) 59w, UW: 0.00070535, 41.69442255lbs
A (110hz) 49w, UW: 0.00049151, 51.77696595lbs
D (146.8hz) 39w, UW: 0.00031125, 58.39562899lbs
F# (185hz) 27w, UW: 0.00014834, 44.19983019lbs
B (246.9hz) 18p, UW: 0.00007177, 38.08938807lbs
These were calculated using the unit weights for plain steel and phosphor bronze strings from D'Addario's string tension guide. The formula is:
[UW x (2 x Scale length x Frequency)EXP2]/384.6= String tension
I couldn't figure out how to put the font in super script so EXP2 means squared.
D'Addario's String Tension Guide:
http://www.daddario.com/Resources/JDCDAD/images/tension_chart.pdfDavid,
If you read my post you'd have seen that I said that I use D'Addario EJ18's but replace the bottom string with a 70. So you have 14,18,27,39,49,70. On a 29" scale length tuned BEADF#B this give 166lb tension. There is still plenty of lattitude to customise these gauges further up to around 180-190lbs if you want to.
I have only made three baritones which represent around 10% of the instruments I have made so I have no claim in a "urinating" match - although Martin Simpson played my first baritone and liked it a lot, and I did post a sound clip in my defense - and have the greatest respect for both you and Lance McCollum, even though I have never played any of your instruments.
I know all about the difficulties of tuning really low and getting the box/bracing design to support purely acoustically the really low notes and register, but I would love for you and Lance to explain to me more why, in the top five strings that sit within the "normal" guitar register you need to increase string tension by between 37-91%!!
Comparing with a set of EJ16's (12-53) tuned EADGBE on a 25.5" scale length and the strings you calculated for on a 29" scale length on the first five strings you get:
1st: 23.35lb plays 32.09lb an increase of 37%
2nd: 23.3lb plays 46.9lb an increase of 79%
3rd: 30.24lb plays 51.78lb an increase of 71%
4th: 30.53lb plays 58.4lb an increase of 91%
5th: 29.93lb plays 44.2lb and increase of 48%
If a builder wants to build an instrument to support 200-260lbs of string tension (12 string territory) then by all means do so and brace accordingly but why wouldn't you do the same for a 25,5" scale guitar for the first 5, or middle four strings?
_________________
Dave White
De Faoite Stringed Instruments". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010