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  #1  
Old 06-01-2018, 10:17 PM
bayoubengal bayoubengal is offline
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Default Conversion of a Guild 12 String to a 6 String.

I am not a luthier, but I'm lucky to have access to two good ones here in New Orleans, and I thought some on this forum might find this project interesting.

I was wanting to buy a 70's Guild F30 because I love the tone and body shape (mahogany b/s) and they can be bought at a pretty reasonable price compared to old Gibsons and Martins.

The problem is that the nut width on many of them them can be as tiny as 1 5/8" (the specs say 1 11/16" but in my experience they seem to really run smaller).

As luck would have it, during the same era Guild made a 12 String called the F112 which had the exact same body shape as the F30. Two main differences: a slightly heavier build (which doesn't bother me) and of course a bigger nut width (1 13/16" or maybe 1 7/8") to accommodate 12 strings. Nice!

When I got on the Let's Talk Guild Forum forum I found that a member had converted an F112 into a six string and was very happy with the results. He had done the work himself. I found and purchased a 1972 F112 and started corresponding with the guy about his experience. He was very gracious and helpful. I do not have his skills so I enlisted Aaron and Benjamin at Strange Guitarworks here in New Orleans to do the work.

They did this:

1.) They used the tuning keys at the 2, 4 and 6 positions and filled in the unused holes at the 1, 3 and 5 on the headstock.

2.) I bought six replacement tuning machines to replace the 6 on a plate that came with the guitar.

3.) Then of course they had to cut a new nut to get the spacing correct since the old nut was for 12 strings.

4.) Since we were only using the 6 front end pin holes, they filled in the back 6 holes.

5.) They refinished the headstock to somewhat camouflage where the six holes have been plugged.

I got it back a few days ago and I could not be happier! It looks great and sounds even better. The nut width makes it so comfortable to play and it is a fingerpicker's delight.

Here are the before and after pictures:
Before:


After


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1974 Martin D-28 (A gift for my 20th birthday from Mom and Dad)
"Frankenstein" 1948 Gibson J-50 Body/1938 L-00 Neck
2008 Martin 000-18 Norman Blake
2006 Jubal Jumbo
2016 New Era Crooked Star Prairie State Jumbo
2016 New Era Crooked Star Senorita
2020 Iris Smeck
1972 Guild Killdeer F112-6 Part Deux
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  #2  
Old 06-01-2018, 10:34 PM
mirwa mirwa is offline
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First off, your happy that’s all that matters, I think the work done looks good.

But

It is extremely unusual for a 12 string to sound okay when modified to a 6 string, the body has been built and stiffened for the additional load, without the same rotational forces on the bridge, the top is stiff and sounds dead.

We shoot when building a guitar for a certain degree of bridge rotation, the rotation is a must for it to sound good.

Steve
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  #3  
Old 06-01-2018, 10:40 PM
bayoubengal bayoubengal is offline
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Quote:
Originally Posted by mirwa View Post
First off, your happy that’s all that matters, I think the work done looks good.

But

It is extremely unusual for a 12 string to sound okay when modified to a 6 string, the body has been built and stiffened for the additional load, without the same rotational forces on the bridge, the top is stiff and sounds dead.

We shoot when building a guitar for a certain degree of bridge rotation, the rotation is a must for it to sound good.

Steve
I get what you're saying and I was concerned about that, but I use it with mediums and it sings, at least to my ears. You may hear it and think it sounds dead. The luthiers were surprised at how resonant it was. Sometimes things don't make sense.
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1974 Martin D-28 (A gift for my 20th birthday from Mom and Dad)
"Frankenstein" 1948 Gibson J-50 Body/1938 L-00 Neck
2008 Martin 000-18 Norman Blake
2006 Jubal Jumbo
2016 New Era Crooked Star Prairie State Jumbo
2016 New Era Crooked Star Senorita
2020 Iris Smeck
1972 Guild Killdeer F112-6 Part Deux

Last edited by bayoubengal; 06-01-2018 at 10:56 PM.
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  #4  
Old 06-02-2018, 07:26 AM
Quickstep192 Quickstep192 is offline
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What's kind of cool about this it that it looks like you could put it back to a 12 string if you wanted to.
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  #5  
Old 06-02-2018, 08:40 AM
Wozer Wozer is offline
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Quote:
Originally Posted by Quickstep192 View Post
What's kind of cool about this it that it looks like you could put it back to a 12 string if you wanted to.
not "easily" as that would require redrilling all the holes, etc.

ages ago I was changing the strings on my Takamine FP-400s and noted the nut wasn't glued in place...hmmmm...so I had a new nut made for 6 strings and when I got the desire I would simply swap out the nuts and configure for what I wanted to use it for at that moment in time. in general I would use it as a secondary guitar in case I broke a string on stage, or have it in a different tuning for stage work. don't think I ever used it as a 12 on stage, but did so plenty of times recording.

yeah, it wasn't the most lively guitar when set up for 6, but it worked just fine all things considered.
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  #6  
Old 06-02-2018, 05:29 PM
viento viento is offline
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Well, I wouldnīt have done what you did, but if you like the result,itīs ok,itīs yours.
If you go further into the 6-strng direction, you could lighten the braces a bit to make the top lighter and more resonnant, swinging easier...

Better sell the axe and buy a real 6-string guitar.
Only my 2 cents
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  #7  
Old 06-02-2018, 06:07 PM
Earl49 Earl49 is offline
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You like it and that it all that really matters. I might have been inclined not to fill in the peg head or bridge holes to make reconversion (reversion?) easier.

I tried this years ago with a Seagull S-12 so I could experiment with a wide 1.8" neck. I made a new six string nut and used the same bridge pins holes that you did, and the original saddle. The only difference is that I kept all twelve tuners in place, using the far ones. That way if a string broke at the tuner, I could re-use it on the shorter peg. It worked OK with that cedar top, but a few months later I put the twelve string nut back and returned it to the factory configuration.

Your guitar might be a bit over-braced. I say "might" because the typical light gauge twelve string set (10-47) is about 250 pounds total tension. The typical medium gauge set (13-56) is 185 pounds, only 74% of the intended string tension. But if it sounds good to you, that is the "answer". If you went with heavy gauge EJ-18 (14-59) set that would give you 217 pounds of tension when tuned E-e, much closer to twelve string numbers. I sometimes use those strings tuned down to C# or even C as a pseudo-baritone on a regular guitar.
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  #8  
Old 06-02-2018, 06:58 PM
bayoubengal bayoubengal is offline
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Quote:
Originally Posted by Earl49 View Post
You like it and that it all that really matters. I might have been inclined not to fill in the peg head or bridge holes to make reconversion (reversion?) easier.

I tried this years ago with a Seagull S-12 so I could experiment with a wide 1.8" neck. I made a new six string nut and used the same bridge pins holes that you did, and the original saddle. The only difference is that I kept all twelve tuners in place, using the far ones. That way if a string broke at the tuner, I could re-use it on the shorter peg. It worked OK with that cedar top, but a few months later I put the twelve string nut back and returned it to the factory configuration.

Your guitar might be a bit over-braced. I say "might" because the typical light gauge twelve string set (10-47) is about 250 pounds total tension. The typical medium gauge set (13-56) is 185 pounds, only 74% of the intended string tension. But if it sounds good to you, that is the "answer". If you went with heavy gauge EJ-18 (14-59) set that would give you 217 pounds of tension when tuned E-e, much closer to twelve string numbers. I sometimes use those strings tuned down to C# or even C as a pseudo-baritone on a regular guitar.
The mediums sound great to me, but I may give the heavies a try for a comparison. Thanks!
__________________
1974 Martin D-28 (A gift for my 20th birthday from Mom and Dad)
"Frankenstein" 1948 Gibson J-50 Body/1938 L-00 Neck
2008 Martin 000-18 Norman Blake
2006 Jubal Jumbo
2016 New Era Crooked Star Prairie State Jumbo
2016 New Era Crooked Star Senorita
2020 Iris Smeck
1972 Guild Killdeer F112-6 Part Deux
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