Acoustic guitar repair London: Gibson 1966 LG-0 (Hot Rod)





Here is an interesting project recently taken in by the workshop: a Gibson LG-O made in 1966

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This is an all Mahogany guitar: Mahogany soundboard, back, ribs and neck. This guitar was a budget instrument at the time of manufacture and sold at an affordable price as an entry-level model. The guitar has a slim neck which measures 1 9/16’’ at the nut and joins the body at the 14th fret.

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The Bridge

In 1962 with many thousands of the LG-O sold Gibson decided to exchange the standard rectangular Rosewood bridge for a plastic “belly above” type. This plastic moulded version was held in place by 4 screws that attached from under the soundboard up into the base of the bridge. This was done for ease of removal when dealing with replacements. This was upgraded in 1968 with a Rosewood replacement which included an adjustable saddle.

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 The Soundboard

The soundboard is ladder-braced with 5 lateral braces across its width. This type of bracing gives a distinctive tone that is indicative of the old acoustic Blues sounds of the 1930s. However, this system lacks structural strength and over time the soundboard can become bulged and distorted with string tension. The over large bridge-plate can exasperate the problem as these where generally made of softwood which also offered little structural strength. The LG-O was discontinued in 1974.



The Brief

Our Brief in this instance was to remove the internal ladder bracing, replace with a scalloped X brace system to give the guitar a more balanced tone and to accentuate the bass tone.

To upgrade the bridge-plate and to make and fit a Rosewood replacement bridge.



Removing the Back

In order to gain easy access to the internal bracing it will be necessary to remove the back.

This LG-O does not have an edge binding around its back outline. Therefore, a thin pallet knife is slipped between the back and the end block to start the separation. Once started a Japanese saw is used to precisely cut through the inner lining. Because of the saw’s thin blade and unique cutting motion very little material is lost during this process.

 

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Once the back is removed the simplistic ladder-brace system is revealed. You will notice that a brace and the bridge-plate are missing. I believe these became loose and subsequently lost years before. Their footprints are still visible.

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Rosewood Bridge-Plate

The remaining braces are easily removed and the internal face of the soundboard is prepped in readiness for its upgrade. An Indian Rosewood bridge-plate is made up and fitted. Rosewood is the workshop’s prefered material for bridge-plate replacement because of its strength to thickness ratio.

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Go-bars are a very handy and simple way to fit bridge-plates and braces. They are made from flexible timbers that allows pressure to be applied where needed whilst glue is drying.

The Bracing System

The bracing system is made up and glued into place piece by piece.

Each brace is made from 1/4 sawn straight-grained spruce individually scalloped.

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 Gluing the Back

Once the bracing system is completed the back is cleaned up and glued into place

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A replica of the plastic bridge is made up out of Brazilian Rosewood and fitted

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The Set-Up

The frets are showing some wear. They are honed and re-profiled and the truss-rod is adjusted.

The guitar is strung up and tested.

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 Conclusion

I’m happy to report that the finished upgrade turned out very well. The guitar has a sweet sound with a good balance. It has a warmth and depth to the bass with sweet mids and trebles. It likes to be picked as well as strummed and I suspect that it will record very nicely and with a small body guitar that’s all you can really ask for.

Full size photos available here on Flickr





Gibson Guitar Repair : 1969 Southern Jumbo





The owner of this lovely old Gibson SJ thinks it doesn’t have the sound projection that it should have.

My suggestion is to fit a GPL Saddle Insert to replace the existing adjustable bridge saddle.

Adjustable bridge saddles of this type were used by Gibson and Epiphone on their acoustic guitars during the 1960s. This adjustment gives the player the opportunity to set the action to the required height to suit the player’s style. However, when the saddle is set to a good playing action the saddle makes no contact with the soundboard; this is the down side to this system. This lack of contact is due to the saddle being suspended on two adjusting posts. These posts are screwed into two threaded inserts that are housed into the soundboard. Therefore the transmission of sound vibration from the strings to the soundboard is via two metal adjusting posts. This is not an ideal situation for producing good volume or tone. Simple logic would dictate that the more contact the saddle has with the bridge or soundboard the more transmission of sound, therefore producing more volume and more tone.

View Forum discussion here...


What is a GPL Saddle Insert ? A GPL Saddle Insert replaces the existing adjustable bridge saddle found on vintage Gibson and Epiphone guitars. It’s a non-invasive modification and can be removed if necessary. It’s an idea that I’ve used on several vintage guitars in the past which has enhanced the volume and tone and brought out the true voice of the guitar.

The Process

  1. The adjustable saddle is removed
  2. A GPL Saddle Insert is custom-made from matching woods to fit the slot
  3. The insert is glued into place
  4. The saddle position is marked out
  5. A saddle slot is routed into the insert
  6. A bone saddle is custom-made
  7. The string height is set for optimum playability

The GPL Saddle Insert is glued into place using high quality Hide glue. The remarkable thing about Hide glue is that it’s reversible. With most synthetic glues when it’s stuck it stays stuck. Not the case with Hide glue because it’s an organic material that softens with heat and moisture.  Therefore, by using a little heat and moisture the insert can be released and removed. Consequently, if the old saddle system needs to be put back into place it’s a simple job to reverse the above process and re-install the adjustable bridge saddle.


The Dilemma

Meanwhile the debate still rages on about the rights and wrongs of upgrading any aspects of a “vintage” guitar. Many owners of instruments that are of a certain age are reluctant to change any element of that instrument because it would no longer be origin. In a nutshell, if you have a guitar that’s 30 plus years old, making upgrades or changes to it could make it worth less than if it remained unchanged.

View a recent poll discussing the pros and cons of vintage guitar upgrades here…

The GPL Saddle Insert cuts across this issue because it is a non-invasive change that can be removed when required. If you have an old vintage acoustic that’s not living up to its potential contact this workshop and ask about the GPL Saddle Insert.

Update 23.01.11

An email from the SJ owner, shortly after collecting from the workshop

…………………………… it doesn’t show a lot of play wear and this might have been because it didn’t respond well and as a result, it never got the play for it to break-in and open-up since there was no vibration getting to the soundboard.   Now that the vibration is connected to the soundboard for the first time in its life, it might open up and get much better than it has ever been; wishful thinking or rational reasoning?  Even playing it last night warmed it up and as the evening wore on it seemed to sound better. I do have to say that it now does have a mystical kind of sound that is quite beguiling when one becomes familiar with it. As you can see, my enthusiasm has returned for the old SJ.