Kerfed Bracing on Gibson ES-175

[fritz jones]

So, I looked inside my early ES 175 and found that the tone bar bracing is kerfed. I thought this was a characteristic of Norlin era production.

does anyone know if and when Gibson stopped this practice?

[DC Ron]

My 1976 is not kerfed...

[Franz 1997]

...but my 76 is...

[rpguitar]

Kerfed braces have been used at Gibson since at least 1929, which is approximately when the L-5 was fitted with them instead of having the braces carved. My '33 L-12 has kerfed braces. My 1928 L-5 does not. I haven't bothered to look at the other archtops I own.

[KEOKI]

I tried to look up the definition and am still not sure what kerfed means. If someone would explain I would appreciate it. Also, is this of any significance as far as a manufacturing process?

[DC Ron]

I tried to look up the definition and am still not sure what kerfed means. If someone would explain I would appreciate it. Also, is this of any significance as far as a manufacturing process?

Here is a picture of a kerfed brace that has broken...

[Jabberwocky]

I tried to look up the definition and am still not sure what kerfed means. If someone would explain I would appreciate it. Also, is this of any significance as far as a manufacturing process?

This explains what it could be all about. FRETS.COM Field Trip

See those slots in the tone-bars. They are made by the thickness of the cutting blade. The thickness of the blade is known as a "kerf". Hence, the tone-bar is "kerfed".

[fritz jones]

anyone have a recent model they can look at inside?

[fritz jones]

I wonder if it is part of the Gibson sound.
It's amazing that they can sound so good with such deplorable time-saving measures. Or maybe they it's deliberate as part of the recipe for the sound they were after.

[oldane]

I wonder if it is part of the Gibson sound.
It's amazing that they can sound so good with such deplorable time-saving measures. Or maybe they it's deliberate as part of the recipe for the sound they were after.

I don't believe it's that. It's a time and labor cutting measure. The very purpose of fitting a brace is to strengthen the top and prevent sagging when under string pressure. (In acoustic instrumensts the braces also spreads the sound vibrations from under the bridge to the rest of the top, but that's not important with the 175 which is primarily an electric guitar.) Kerfing the braces severely weakens them and thus counteracts their purpose. That so many 175 tops with kerfed braces have after all not sagged must be attributed to the thickness of the tops - they will keep their arch with or without braces.

[JGL]

Kerfed braces - kind of defeats the purpose of any brace at all. Not only does the brace support the top, but it transmits vibration from the bridge area across the top. The mass of the brace help loosen or limit the plate (top) as well, contributing to the voice of the instrument. Except to allow a non-skilled worker to contour an otherwise flat strip of wood to a compound arch, in a concaved top, it doesn't make much sense. But, in the case of multi-ply tops, I would imagine them to be slightly more rigid than a carved top guitar.

I really like Gibson products, don't get me wrong, but one reference I have on Martin guitars states they have always crafted guitars. Gibson, according to the Martin reference, abandoned guitar making during the war to mass produce toys. Not saying that's a bad thing - just that they apparently keep a close watch on the bottom line.

[fritz jones]

spruce is very strong and hard to break if it is quarter sawn.

[Max405]

1997 es175 no kerf

[Max405]

2014 L5 no kerf

[Max405]

2001 es165 no kerf.

[Max405]

Sorry I got carried away..
I never tried taking a pic of inside a guitar before. Cool.
JD

[fritz jones]

thanks for posting those.
so they have stopped using kerfed bracing on ES 175's, but they don't even try to clean up the glue.
the L5 looks much cleaner inside, and the braces are rounded.

[mikeSF]

silly Gibson.

[fritz jones]

that sound though.

[Klatu]

What would be the benefits and drawbacks of kerfed braces?

[rpguitar]

The other disadvantage applies primarily to carved acoustic archtop guitars: Kerfed braces are essentially one-size-fits-all pieces of wood. They are glued to the top, and the kerfs allow the brace to be flexible in order to compensate for minor arch inconsistencies between individual guitars. The negative to this approach is that the luthier is not shaving/tuning each brace for tonal or resonance purposes on each individual guitar. Mind you, that could also be done with kerfed braces, but it would defeat the cost/time-saving purpose of using them in the first place.

It was Lloyd Loar's original design vision to hand-tune several individual components of the L-5 guitar's construction to specific pitches. The braces, or "tone bars," were naturally included. A few years after Loar left Gibson, this practice ceased at least in part, and kerfs began appearing on the tone bars. In the nutty vintage archtop market, it is esoterica such as this that can be responsible for a difference in value of several thousand dollars between two old L-5s literally a year or two apart.

[JGL]

A 5/16" piece of Spruce, Mahogany, Rosewood, only a few inches long makes a distinct musical note when dropped on a hard surface. A kerfed piece of anything has the musical quality of a Bic pen when dropped. I would honestly run from any purchase of an instrument made with kerfed bracing. Linings are a different story.

[Patrick2]

thanks for posting those.
so they have stopped using kerfed bracing on ES 175's, but they don't even try to clean up the glue.
the L5 looks much cleaner inside, and the braces are rounded.

Never thought I'd be quoting jabberwocky, but . . . "That's Gibson".

However, here's what I do believe is happening, and has been happening for a while now. Gibson has recognized that many people have become far more knowledgeable of the procedures of fine arch top building, as well as the results achievable from the differing or deviation of these procedures. We can all thank the rapid growth in numbers of fine, talented and knowledgeable boutique luthiers . . as well as the info shared on the inter net and forums such as these. Gibson also recognizes that despite its brand allure, some of the best players in the genre of music (ours) which most requires these arch tops, had abandoned the iconic arch top brand due to better alternatives being available. I believe that this has led Gibson to a review of its procedures and attention to quality and detail. They're not quite where many would like to see them yet. But, the current L5s, Super 400s, 175s . . are some of the best quality (generally speaking) that Gibson has produced in quite some time. IMO

During my discussions of the this subject (kerfed braces) with Jim and Marv at Heritage . . they'd make a face similar to the one we might make after an old bull dog farted in a small room.

[JGL]

Patrick2 - I would be inclined to agree. Fender has also had to readdress quality, post CBS ownership. I absolutely love Gibson electronics an pickups. I think they generally shine there. They seem to go thru all sorts of ups and downs in finish and build quality. I understand price point marketing - trying to have something for every buyer - but what I have not agreed with Gibson on is that they have historically increased their pricing, sometimes well ahead of maintaining quality, let alone improving quality. They are aggressive if you look to their company portfolio. It's been a while since I did that, but at last glance they owned Baldwin Piano, Steinberger guitars etc, etc... One thing I can say for Fender (albeit not a traditional choice of jazz instrument) they settled in on overall quality and have hovered around it fairly well for the US line. Gibson just has those darned sweet body profiles - like a Byrdland for instance. When they do the things that makes us scratch our heads, I regard it as putting a Ford Pinto engine in a Rolls Royce. Maybe it was the Benedetto /Guild line that shook things up, or maybe the combination of boutique builders and more informed buyers.

[DC Ron]

1997 es175 no kerf

Now this is an interesting shot since it shows a cross brace just below the bridge pickup that my '76 175 doesn't have. Am I seeing this right? Given the sunken top syndrome, seems like a potential design improvement. Can anyone confirm? Thx!