Hi and a question about a 12 string acoustic build

[Blackstar1099]

I've been lurking for a while but this is my first post so hello everyone . Some seriously talented and experienced people here. I hope to learn a lot. I've built 10 electrics and 1 acoustic so far so I've got some experience under my belt.

I've just started on a 12 string acoustic and I'm wondering what I need to add/change as opposed to a 6 string other than the obvious. I used Chris Wynne's DVD and my reference for my 6 string and it came out really well. I've purchased some plans from ALS that call for more bracing on the soundboard and a 48mm fretboard width at the nut. Do I need to add more reinforcement to the neck other than a standard truss rod? i.e. carbon fibre rod? Any other tips would be appreciated.

[kiwigeo]

I've been lurking for a while but this is my first post so hello everyone . Some seriously talented and experienced people here. I hope to learn a lot. I've built 10 electrics and 1 acoustic so far so I've got some experience under my belt.

I've just started on a 12 string acoustic and I'm wondering what I need to add/change as opposed to a 6 string other than the obvious. I used Chris Wynne's DVD and my reference for my 6 string and it came out really well. I've purchased some plans from ALS that call for more bracing on the soundboard and a 48mm fretboard width at the nut. Do I need to add more reinforcement to the neck other than a standard truss rod? i.e. carbon fibre rod? Any other tips would be appreciated.

Major changes:

1. Bracing. Beef it up a bit but don't end up overbracing like I did. I added an extra tone bar and a brace along back of bridge plate. The need for the extra tone bar depends on size of lower bout (I built a Dreadie)
2. Fretboard width at nut a bit wider.
3. Decide how youre going to handle string spacing at nut. IMO Visually using outside of string for string spacing calculations looks a bit better visually on a 12 string
3. Neck thickness and truss rod same as for 6 string.
4. Compensation will be your biggest challenge. Use a wider saddle to give yourself maximum leeway for saddle compensation.
5. Consider bridge pin options. You can go for one pin per string or one pin for each pair. There are posts on this forum dealing with this one.

[Blackstar1099]

Thanks Martin. I didn't think about intonation. I've built a Gibson EDS1275 style double neck that intonates ok with 6 saddlles on the 12 string neck but I'm thinking heavier strings and a slightly higher action would probably need separate compensation for each string.

I didn't know you could get bridge pins for each pair. I like the one pin per string look anyway.

[Mark McLean]

Hi Blackstar, it is great to have you contributing to the forum. Do you have a real name that we can call you by?

My few thoughts on 12-strings:
1. I like the look of the 6-pin bridge for a 12-string guitar. Take a look at this old thread with plenty of good information provided by Craig Lawrence.
viewtopic.php?t=354&highlight=6pin+12string+bridge

2. The headstock needs some careful planning so that each of those strings can get a clear path from the nut to its respective tuner without running into each other. It gets crowded. Draw a full-sized mock-up on paper. Consider using a tapering headstock shape so that the D & G strings are pulling pretty much straight through the nut. This will keep the string lines from getting too close to each other (the last photo in Craig's post shows this, and Google the Breedlove 12-string headstock for a good example). The traditional Martin-style headstock gets crowded enough with 6 strings and definitely is NOT the ideal for a 12er. DON'T EVEN THINK ABOUT A SLOTTED HEADSTOCK FOR A 12-STRING. Have you ever tried to restring one of those bastards?

3. Yes the bracing needs to be a bit beefier, especially between the soundhole and the bridge because that part wants to collapse while the lower bout bellies, and the whole bridge area rotates under the increased string tension.

4. The great old Guild 12-strings had two truss rods adjusted at the top - but that makes even more congestion at the headstock area. I think your idea of a single truss rod (adjusted through the soundhole) and some parallel carbon fibre rods would be a good plan.

Cheers and welcome again

Mark

[Mark McLean]

I meant to add a comment about nut width. Taylor, Martin and Guild all use 1 and 7/8 inches at the nut (=47.6mm) for a 12-string. I have a 12-string with a set-up that suits me well (I have pretty big hands) - it is 1 and 15/16 inches at the nut (49.2mm), 2 and 1/4 inches (57mm) at the 12th fret, and at the saddle 62mm between the bottom and top string (measuring outsides of the strings, not string centres).

[kiwigeo]

2. The headstock needs some careful planning so that each of those strings can get a clear path from the nut to its respective tuner without running into each other. It gets crowded. Draw a full-sized mock-up on paper. Consider using a tapering headstock shape so that the D & G strings are pulling pretty much straight through the nut. This will keep the string lines from getting too close to each other (the last photo in Craig's post shows this, and Google the Breedlove 12-string headstock for a good example). The traditional Martin-style headstock gets crowded enough with 6 strings and definitely is NOT the ideal for a 12er. DON'T EVEN THINK ABOUT A SLOTTED HEADSTOCK FOR A 12-STRING. Have you ever tried to restring one of those bastards?

+1 for doing a full scale drawing of the guitar so I can be sure of string runs and other issues. Especially important if youre planning a straight string pull headstock etc.

Buy in your tuners before doing your headstock. Consider tuner size....youve got 12 of the suckers. I like Schaller minis...

[Blackstar1099]

Hi Blackstar, it is great to have you contributing to the forum. Do you have a real name that we can call you by?

My few thoughts on 12-strings:
1. I like the look of the 6-pin bridge for a 12-string guitar. Take a look at this old thread with plenty of good information provided by Craig Lawrence.
viewtopic.php?t=354&highlight=6pin+12string+bridge

2. The headstock needs some careful planning so that each of those strings can get a clear path from the nut to its respective tuner without running into each other. It gets crowded. Draw a full-sized mock-up on paper. Consider using a tapering headstock shape so that the D & G strings are pulling pretty much straight through the nut. This will keep the string lines from getting too close to each other (the last photo in Craig's post shows this, and Google the Breedlove 12-string headstock for a good example). The traditional Martin-style headstock gets crowded enough with 6 strings and definitely is NOT the ideal for a 12er. DON'T EVEN THINK ABOUT A SLOTTED HEADSTOCK FOR A 12-STRING. Have you ever tried to restring one of those bastards?

3. Yes the bracing needs to be a bit beefier, especially between the soundhole and the bridge because that part wants to collapse while the lower bout bellies, and the whole bridge area rotates under the increased string tension.

4. The great old Guild 12-strings had two truss rods adjusted at the top - but that makes even more congestion at the headstock area. I think your idea of a single truss rod (adjusted through the soundhole) and some parallel carbon fibre rods would be a good plan.

Cheers and welcome again

Mark

Hi Mark. Thanks for the welcome. I'm Piero. Italian descent but unfortunately no relation to Stradivari

That's all good info that I'll keep in mind.

Mini tuners sound like a good idea Martin.