Gibson 1961 LG-0 Cross Brace Conversion

Background

I looked up artists that play LG-0s and no one does.  Plenty play all mahogany small body acoustics but they are usually x-braced Martins 15 or 17 series played by Dylan, Eddie Vedder, Ed Sheeran, and many others.  The Gibson LG-0 body and neck is as good or better but everything else is  second rate- plastic parts and braced so the top soundboard can barely move. 

These LG-0s are available since Gibson made so many and they are currently going for $800 to $1,200 depending on the year and condition.  These are student mahogany guitars built with some cheap parts and heavily braced so if they are abused they can keep going.  Gibson also built them fast with a screwed on pickguard and the inside bracing is very rough since parts were not finished. Top coats are good and the necks generally are very good. 

Gibson purists love them 'the way they are' which is fine but most at least change the plastic bridge on the post 1961 models. Other common changes are listed below -plastic pins, nut, saddle and in addition a sub industry has come around to change the stiff Gibson ladder bracing (low cost 40s, 50s, 60s L models) to x-bracing. Bracing conversions $700 to $1000.

http://baxendaleguitar.com/conversion.html

https://grahamparkerluthier.com/tag/improve-the-tone-of-your-vintage-acoustic/

http://www.ronnienichols.com/?page_id=770

History (http://www.guitarhq.com/)

1958 LG-0 Introduction specs:

14 1/8" wide Mahogany top, mahogany back and sides, straight ladder bracing, black bridge pins, screw-on black pickguard, tortoise binding on top and back, 3 on-a-plate tuners, rectangle rosewood bridge, rosewood fingerboard, 20 frets total, 3-on-a-plate tuners, natural finish. Bridge pad was spruce, which unfortunately would wear out from the string's ball-ends.
In 1962 plastic bridge used. $85 list price.
In 1963 an injection molded styrene pickguard was used.
In 1966 rosewood bridge with adjustable saddle was used.
In 1968 spruce top on some models.
In 1974 discontinued.

From W. Shaw article 2018-

"The Gibson LG-0 is a wonderful guitar for a young person to own. I know this because I was once a young man who owned one. This is a pretty inexpensive guitar for a Gibson. And if you search out pawn shops and flea markets, you just may find one for little to nothing.

This guitar is not, however, comparable to the ones listed above in my review (Martin 00-15, Santa Cruz 00, Collings 001) except that it is small and made from mahogany. This guitar is a student's guitar. A student's guitar which will perform fabulously for someone at a great price. And Gibson guitars hold their value. After you or your loved one outgrows this guitar it can be handed on down to the next generation, or used to get into a more expensive instrument for the newly serious amateur.

Most of the Gibson LG-0s out there date back to the mid 1960s. And to be sure, these guitars have a small sound. They originally came with a plastic bridge except the early production years. Yes, you read that correctly. Well, people have been changing out those plastic bridges since the 1960s. If you buy an old LG-0 with that plastic bridge on it, you will certainly want to have that replaced with a rosewood, or even an ebony bridge ($200 done correctly).

Some simple modifications can be done to improve these guitars vastly, provided the bridge has been replaced already. Simple hot rodding can improve them by miles and miles. The plastic nut, saddle, and bridge pins, were they all replaced with superior materials; i.e., bone nut and bone saddle - and dense ebony bridge pins - and your tiny sounding Gibson LG-0 just grew larger and louder."

Project- Find a cheap LG-0 and modify it to sound better

The project guitar is a 1961 LG-0 which was incorrectly listed as a L-60 on ebay so no one bid on it except me and I got it for $300 (see picture above). The 1958s to 61s are most desirable since the have brazilian rosewood bridges before the 62 plastic trash bridge Gibson installed on many acoustics in the 60s.

The main work is to change the bracing and these changes have been documented by others if you check the links above. My approach was to open the back and install scalloped bracing in a pattern of the Gibson early L-00 models. I have a L-00 and it has a much louder and fuller sound than you would expect from a parlor guitar. So the project will be to use the L-00 as a model and turn the LG-0 to a light x-braced guitar.  The bracing and internal changes from some of the links above ignore the Gibson history and seem to jump on putting Martin bracing in a Gibson guitar. I expect they drank the Martin cool aide and never played an old L-00.

Bottom line is here is where we started compared to where we finished.

Here is the start with the ladder braced body and you can see why these sound so weak.  The portion of the top sound board below the soundhole is where the resonance and flex vibration occurs and 50% or more is covered by the bridgeplate and bracing. 

Here is the target and notice how the 2 bottom tone bars are not parallel to the x-brace.  

Reference 1936 L-00

Luthier plan L-00

The project final before putting the back on

Below is what some of the others are doing- to me it seems they are off compared to Gibson patterns:

 

Finished Project

Here it is with the original tuners, bridge, nut and pickguard.  Original until you play it and the body shakes like an old guitar. Easily as nice as Martin 00-17 or 15s I have tried at a fraction of the cost. It is 60 year old mahogany freed up to vibrate the way it should. 

Next to an L-00.  Not as basey/bluesy but wonderful full balanced tone.

Tone fingerprint:  See the high overtones for the LG-0 on the right of the graphs

LG-0 xBraced

L-00 round full base tone. peaks on the low end

Martin D-41 Perfect deep balanced tone

37 Epiphone Zenith.  Balanced bright tone.

Work was:

• Remove back
• Remove braces from top.  They were actually rough and hairy since Gibson did as little work as possible on this model.
• Thin the top to 2.2 to 2.5 mm below the soundhole and thinner around the edges using scrappers. Hours of work. Let me repeat that-hours of work. 
• Glue gaps in top and back center seam- tightbond
• Made the braces and scalloped them before glueing
• Glued the bridgeplate in 1st. Not typical but wanted to get the pin holes right
• Bridge holes were too big.  Made plugs from mahogany and redrilled the pin holes. 5 degree ream to fit the pins- tightbond the plugs and chisel/sand smooth
• Glued the braces then trimmed based on sounding the top resonance- hide glue
• Final sanded the inside top
• Added kerf pieces to the x-brace ends
• Glue the back onto the body- hide glue
• Crown the frets
• Lower the saddle - action at the 12th fret is 5/64 with no buzz anywhere
• Finish- 
• Dropfill with superglue small surface cracks in back from separation
• Mahogany grain filler small openings from back separation. stained to match.
• Center seam in front and back looked white from accumulated dust/dirt in the separated wood. Stained to match.
• Note this has 2 bolts in the bridge that helped mounting the bridgeplate in the factory.  I left these in although many others remove them.  They are original and do no harm.

Future consider:

• Bone saddle
• Bone bridge pins
• Bone nut
• Thin glued pickguard (although this will advertise it is not original)

Workshop Pictures

Back removal- separation tools and japanese saws for the neck and tail block

Top thinning- notice body form is stable in foam outer form and internal rod braces.

Braces

Bridge- Obsess over the bridge since that is where the sound forms. Perfect fits are needed.

Kerf- added to cross brace ends

Assembly

Frets

The end