12-string Bass: String Spacing?

[Dave_B]

Hello all. Does anyone have experience with laying one of these out? Specifically, I'm planning a 4-string with 2 sets of octave strings.

I know some things:

The octave pairs are spaced to avoid hitting the fundamental strings. In other words, there's a gap between the octave strings and the fundamental.

A 1.9" (48mm) nut is a good place to start.

The Schaller 471 bridge uses 3/4" (19mm) spacing.

For now, I'm trying to figure out where to cut the nut on this thing.

First post, by the way. Greetings.

[sam_c]

I think that may end up too tight for 12 strings. I know the Dean Rhapsody 12 string uses a wide rnut than that.

might be worth checking the specs on that one for a comparison?

http://www.deanguitars.com/rhapsody_12.htm

[Dave_B]

I think that may end up too tight for 12 strings. I know the Dean Rhapsody 12 string uses a wider nut than that.

might be worth checking the specs on that one for a comparison?

http://www.deanguitars.com/rhapsody_12.htm

Wow, you're right.

Rhapsody = 34" Scale & 2-1/8" Nut

I was looking at the TP12

TP12 = 32" Scale & 48mm Nut

[sam_c]

what bridge are you planning to use for the 12 string? I would image the spacing on the saddles between your octave and fundamemtal strings will be almost identical at the nut end, obviously there will be more spread between each 'group' of strings at the bridge, but the distance between the 3 saddle notches would give you a minimum distance to start with at the nut if you put them all next to each other (i.e. no string spread).

Personally, I would like to have the extra 4-5mm width at the nut if it meant I could distinguish each group of strings easily. I havent played many 12 string basses, but I remember that Dean Rhapsody feeling suprisingly comfortable.

You may need to get your string guages all marked down and do some scale drawings. Maybe do them @1:2 so you can clearly so whats going on and how things will sit in proportion to each other.

Edited June 29, 2010 by sam_c

[Dave_B]

what bridge are you planning to use for the 12 string?

The Schaller 471.

Personally, I would like to have the extra 4-5mm width at the nut if it meant I could distinguish each group of strings easily. I haven't played many 12 string basses, but I remember that Dean Rhapsody feeling surprisingly comfortable.

That's a good point. Since this will be my first build, I'm considering a neck-through mock-up with lower-grade lumber. It would have to be low tension though, so I'm not sure it would be worth the trouble. I'll probably make a headstock/scarf at least, just to get a feel for the string angles and tuner placement.

You may need to get your string gauges all marked down and do some scale drawings. Maybe do them @1:2 so you can clearly so whats going on and how things will sit in proportion to each other.

That will help too, thanks. I'm good with Photoshop, and I've been doing some layouts there. That sounds like the next logical step.

[sam_c]

Looking at the schaller bridge, it only has 8 holes on the back for the string ball ends. Maybe you could drill the baseplate and have the extra 4 strings going through the body to rear ferrules on the body?

[Dave_B]

Looking at the schaller bridge, it only has 8 holes on the back for the string ball ends. Maybe you could drill the baseplate and have the extra 4 strings going through the body to rear ferrules on the body?

Hey Sam.

What's typically done is to run both octave strings through one hole. This page has some examples of both 8 and 12-hole tailpieces.

I'm drawing pictures in Photoshop to work some of this out in my head.

This image is based on some info from 12stringbass.net and a lo-rez photo of a Hamer B12L. The spacing looks a little off, but I've been told the fundamentals are typically .5" apart and the octaves then vary from string to string. The courses still look too close to me, so I probably screwed up somewhere. I'm a lefty who plays lefty, by the way.