Figuring out octave string gauges

[knucklehead G]

I saw on here that you should take about half the string gauge when finding the octave string, does that work for all tunings?

By that logic an 8-string tuned F#BEA at .175, .135, .105 and .085 per Rotosound would need octaves of about .085, .065, .050 and .40, rounding to the nearest 5.. So it would effectively have two .085's on it, right? One tuned F# and one A?


Would that work, would it even be playable picking that much string at once?

[knuckle_head]

Tensions on the Rotos is as follows;

.175 - 35.6 lbs
.135 - 39.2 lbs
.105 - 43.2 lbs
.085 - 48.3 lbs

The balance is whacky, but if you're looking for a singles set to match, then;

.084 - 34.1 lbs
.068 - 40.7 lbs
.052 - 43.5 lbs
.040 - 46.7 lbs

A better set pair, IMO, would be;

.182 (38.8) .136 (39.2) .100 (38.7) .076 (40.2)
.088 (37.9) .064 (35.9) .046 (34.6) .033 (32.3)

[knucklehead G]

Any chance you have a place in mind that makes those gauges?

EDIT: Just realized who I was talking to! Checking out Circle K strings right now.

[knucklehead G]

So I'd be looking at about $92 for my strings.. Well, awesome rarely comes cheap.

Knucklehead, if I'm going fanned-fret 36-32", will your standard strings work for the 32" side? It says 34-35".. Most of those are all-scales so the .100 is really the only one that is questionable, that one would run about 33" if my 3:10AM math isn't failing me.

Just want to make sure I'd be ordering the right stuff.

[knuckle_head]

If you are 36" on the bass side your best bet is a medium length set - especially the low octave strings. Make sure you are top loading and not going through body. The high octave set is scale-length-agnostic.

Fanned makes a difference - a big difference. I can run the numbers for you if you like but I'll wager a couple of traditional gauged medium length sets with .174 and .084 on bottom will do what you want them to. I won't be able to get you numbers until this evening, but the two sets combined should cost no more than $80.

[knuckle_head]

You sure on the measure of the long and short scales in that fan? That's 1.33" difference from string to string - Dingwalls are on/y .75" from string to string.

Running the numbers now...

[knuckle_head]

Assuming the fan is right, this is what I'd suggest;

Scale Gauge Tension
36.0 - .166 - 36.42 - F#
34.6 - .130 - 37.33 - B
33.3 - .100 - 37.16 - E
32.0 - .076 - 35.60 - A

36.0 - .084 - 38.27 - f#
34.6 - .064 - 37.29 - b
33.3 - .049 - 37.13 - e
32.0 - .037 - 35.43 - a

[NateS]

being a fanned fret, wouldn't you also have to consider the fact that the octave strings aren't the same scale length as the root strings? because they aren't at the same space on the nut, i would assume. I don't know if it would make a lot of difference

[knuckle_head]

You're right, that will fudge the tension a little bit. It will be negligible I suspect as the difference would be quite small and dependent on spacing between strings at the bridge and at the nut.

[NateS]

ok, cool. i don't know much but i couldn't imagine that the tension would be affected enough to really notice, any way...

[knucklehead G]

Its not a Dingwall, its a DIY project, 36-32". I want that F# to not be floppy.

I appreciate your help on this one, and I'll definitely be headed to your company for strings once I get the approval from Mrs. kG (or find a way to trick her) so I can build another bass.

[knuckle_head]

You oughtta be set then - good luck!

[ixlramp]

36" to 32" is an extreme fan for only 4 courses of strings. Thats 1&1/3 inch increase per string course.

I agree 36" is a good idea for F#, but I can see no good reason for shortening the treble side to 32". Seeing how low this bass is, the .076 on the highest course could actually benefit from being 34" instead.

I'm also thinking fretting a string pair next to a fret at an extreme angle might not be ideal.

Dingwall with 3/4 inch scale increase from string to string is already pretty extreme:

[knucklehead G]

I've never played a fanned-fret bass, and nowhere around here has one for me to test out. So considering A is the low string, you think 36-34 would work better?

Knucklehead, can you post whatever formula you are using to find the string tension? I apparently have a few things to tweak here and I'd hate to keep bugging you to plan string sets for me.

[knuckle_head]

I'm happy to help, but I'm much happier to see you help yourself.



Download the XLS file

Use this frequency table

Use this PDF for unit weights

All you'll need to plug in are your scale length variables.

FWIW the fan you want to do would work but you won't have a full fret board to make use of - the fan will get radical eventually. Standard Dingwall variant would be 36"-33.75", 336"-34" would work well, and you could push it to 33.5 or 33.25 and be comfortable.

Mind the parallel point.

[knucklehead G]

Been trying for twenty minutes and I made it to the directory once, otherwise I keep getting, "Problem loading page."

Once at the directory it said the one XLS file was not found. Think its a temporary thing?

[iiipopes]

I have a fanned fret bass and guitar, and I have a 12-string guitar. Everybody is missing a few things:

1) Without going into all the physics and math, its the mass of the string that matters. The mass of the lower octave string should be four times of the upper string at a given scale length to have the same tension. Look at D'addario's chart, and you will see the mass is given. They don't use a scale or a tension gauge, they use the math and derive the tension.

2) For conventional round wound strings, which are all similar, this generally translates to twice the diameter. But again, if you're in the treble range with plain strings, they will have a lesser diameter than the equivalent round, because the gaps in the windings mean less mass for a given diameter for a wound string. So if the string of choice is something like a 20 plain, it would have to be about a 22 conventional wound for the same tension at scale length. The same type of issues arise when using different or multiple wraps. So when you get beyond conventional rounds, the mass of the string must be considered. Unfortunately, the only company I know that publishes such specs is D'Addario.

3) Regarding fanning, as scale length increases, so does tension, so you have to do the math to see what the tension would be for the different scales, and downsize the mass of the string accordingly. As a practical matter, my bass is a 4-string from 33 1/4 to 34, so the difference in scale does not make a significant difference in tension, so I use conventional strings.

4) The Dingwall is about as differentiated in scale that you can get and still be playable. Sheldon Dingwall fretted my bass neck, and he does a wonderful job. Unless you have something absolutely specific, like I did, with a square nut fanning forward instead of a square 7th or other fret and fanning both ways, you're better off getting one of his basses that has already been tested as a viable instrument.

5) If you fan too much, you're either not going to be able to find strings, or if you do, you will be getting into such different scale lengths on the strings that finding consistent sets is going to be a big problem. That, and the fact my particular fanning fits me like a Saville Row tailored suit, is one reason I only went with 3/4 inch total fan.

6) Flexibility is overlooked. There are other threads about the importance of flexibility in maintaining a consistent overtone structure from string to string, and therefore consistency of tone. That's why conventional instruments have wound and plain strings, and why some manufacturers use multiple wraps on the larger diameter strings. A solid string .100 diameter would simply go thunk, because it is not flexible enough to generate overtones. But as stated above, any time you add a winding, you change the mass verses diameter ratios, so you still have to be careful about string selection. That's the main reason, until modern construction with multiple wraps, that the low E string, and still the low B string, tend to be lesser diameter than the simple math would indicate.

7) And finally, about the quote, "It is a common misconception that one's first build will be playable," my first build is my only build, and it has earned me many gig bucks over the past years, and continues to do so. The key is planning, planning, planning and extreme care in the execution of the design.

[FunkMetalBass]

Most of that has already been covered, but thanks for the TL;DR version.

[NateS]

yea..i'm sure knuckle_head covered that in his math to begin with....it is what he does....

[/fanboy]

[ixlramp]

Originally Posted by iiipopes

Unfortunately, the only company I know that publishes such specs is D'Addario.

Unit masses for Circle K Strings are published here.

knucklehead G, It would be good to see a double-course F# bass I don't think it has been done before.

It's worth downloading the D'Addario string tension guide pdf and reading the page titled 'Understanding what determines string tension' to understand the formula.