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I am building a J-45 style for the first time which are based on plans with no scalloping of the top braces.

My inclination is to scallop anyway based on the fact that most D******* sized instruments do scallop the braces.

If you have experience with non-scalloped braces, I would be interested in what sound you got.

What say ye?

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"Building guitars looks hard, but it's actually much harder than it looks." Tom Buck

Depends on whether or not you are looking for the classic J-45 "thunk" sound or not. If you are - then make sure you keep the closely spaced tone bars and tapered bracing. If you just want a "dread" with 1/2" wider body and J-45 shape - then go with scalloped or whatever suits your fancy.

I thought the J-45's had scalloped bracing?

I've been building mostly with tapered bracing and so far I like it better than any. IT just makes sense to me to weaken the tops structure as it approaches the rigid rim. I know the common belief is that a scalloped braced guitar will be more responsive but I don't find that to be true at all compared to my tapered once. They definitely will be a bit more boom-chucka bassy though. But the tapered bracing just seems to be an all round balanced sound. Some of the other Gibson style bracing is just straight braces and they tend to sound tighter but that's not necessarily a bad thing either.

The early ones were scalloped, Steve Smith has one that a relative handed him in a bag that he's since rebuilt. While it was apart I made a very detailed tracing for future reference.

Steve, I have some photos of the bracing somewhere if you would like me to post some.

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Steve Smith
"Music is what feelings sound like"

J45s changed a lot over the years, from the lightly built live back ones to the more heavily built ones with the massive adjustable ceramic saddles from the mid 50's onward.

To me, the "real" J45 sound is from the lightly built, live back models with a distinctive diagonal dipole mode of vibration that is forced by closely coupled, tapered (not scalloped) lower face braces. It is this diagonal dipole mode which contributes significantly to the "real" J45 sound. If you just want a slope dread, you don't have to bother with any of that, of course. However, the J45 is such an iconic model which ushered in the singer/songwriter era that we investigated it in detail for the book (mobility, modal analysis, modeling etc.) and because it is so interesting we used it to demonstrate X-bracing in the book (plans, building instructions etc.) rather than use the typical Martin dread patterns.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

How did they go about making a 'live back' or was that just a result of accident in design? Did they use low wide lower bout back braces?

Steve, it it's not too much trouble, I would like very much to see your photos.

Thanks all for the feedback Gents and the detailed comments Trevor.

My own (modest) research reinforces what I am reading here - which is Gibson changed things up a lot. The photos I see of J-45s with non-scalloped bracing look massively overbraced to me, with a huge bridge plate. I cannot imagine how, with those braces, it would be possible to get a balanced and open sound with good volume.

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"Building guitars looks hard, but it's actually much harder than it looks." Tom Buck

Happy to do it, I will dig them out tonight, they are on my home computer.

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Steve Smith
"Music is what feelings sound like"

The average J-45 built between the late '70's and mid 90's are way too stiff, heavy, and dead unless you string them up super heavy. Even then - the screwed on plastic bridges, ceramic saddles with metal adjustment mechanisms, huge massive bridge plates, and gigantic double-x lower bout bracing... Those are not good ones to use as a model.

You have to go back to the 50's and 60's before you find models worth copying.

I like the J-45 scalloped sound. I have one of John Arnolds very detailed tracings of his pristine 1937 Gibson Nick Lucas special, it has 1/4" almost dainty tapered triangular bracing. I built a 13 fret version that sounds heavenly. Good bass, clear ringing trebles and great sustain very responsive. I want to build two J-45's one with each style bracing I don't think you can go wrong with either properly done.

In my view the things that make a J45 sound so much different from a D18 are the use of a short scale 24.75" vs 25.34" and larger lower bout. But it is certainly true that the prized J45's are very lightly braced -- to the point of near implosion. I've seen the insides of some oldies but goodies that look like a bunch of rough sticks glued in a standard "X" pattern -- very messy but it worked. 1/4" wide, roughly triangular, no scallops, hardly any taper. Same with the back. Something like this drawing

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Ken Cierp

http://www.kennethmichaelguitars.com/

Here's some photos of the J45 I've been restoring.

Mahogany and Spruce 14 fret pinned bridge (showed up with a tailpiece and movable bridge)
Four ladder braces on back. Tall and about 1/4" wide.
Top is X-braced with a cloth reinforcement at the X
Top braces nominal 1/4" wide.
Neck is mahogany, 1.7" at the nut, 2" at 10th fret, 19 frets total.
Scale 24.75"
Upper bout: 11 1/2"
Waist: 10 3/4"
Lower bout: 16"
Body Length 20"; Depth tapers from 4 3/4" to 3 3/4".

Just so you know I have not been trying to destroy a pristine J45 As received with tailpiece, all original finish sanded off, seems to have been varnished and in general poor condition. FON indicates likely date of 1949.




Back off, inside bracing pattern. Convenient gap between top and sides for inserting the ruler.


Here's the back after I put it back together.


X brace on engineering paper. Major divisions are 1" with 5 minor divisions per inch.


Tone bars


Bridge plate

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Steve Smith
"Music is what feelings sound like"

More '49 J45 stuff
Finger braces with a bit of lining still attached


Upper transverse brace with a bit of finish from the factory.


Sound hole reinforcements with holes where someone had once added a pickup.


Interesting cross brace details


yep, the braces were tapered before they were notched

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Steve Smith
"Music is what feelings sound like"

Wow, you got your work cut out for ya on that one that's for sure.

Ha. Yes, it has been a lot of work but it is ready for finish now.

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Steve Smith
"Music is what feelings sound like"

Wow. A 1" bridge plate.... That's pretty narrow.

The live back was likely intentional design (the designers, I think, knew a lot more than they tend to get credited for) but certainly an accident of build. The ones I've worked on were thrown together pretty haphazardly. Remember that the guitar originally sold for $45; very much a budget model. The main reason it had a sunburst was to hide the runout and the general low quality of the top wood. One of the ones our take was modeled on had 1/4" wide top braces with rounded tops, no reinforcement over the X, and I'm pretty sure some of them didn't even have a box joint; just two half braces butted to a continuous one. In the book we do 1/4" gabled braces with tapers. There are 4 back braces. The guitars we liked had all braces 1/4" wide, so no wide/low ones. The backs were quite thin/light mahogany. That the "good" ones ended up with the right T(1,1)2 - T(1,1)3 separation was purely a matter of chance. The thing that matters in replicating a sound is to get the right modes at the right frequencies in a way that can be repeated. So our take is probably structurally unlike any version that Gibson ever produced, but certainly captures the essence of the sound of the ones we like. If you use high quality materials it is very easy to over-build these things, even if you stick with the narrow braces.

The short scale length is certainly a component of the sound, but Gibson used a variety of (short) scale lengths on this model. The fret spacings tended to be fairly random, too, some with a definite hand-cut vibe about them, with odd frets just wrong. We don't advocate that part!

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Steve: Amazing pics. You have a LOT to do to get that one playing again. Fun project!

Trevor: Thanks again for the beta. I am definitely doing 1/4" bracing except for the UTB, which will be pretty stout. I like to support the neck in that area of the top.

I will post up some pics of my solution (give me a week or so) when I get the top singing properly.

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"Building guitars looks hard, but it's actually much harder than it looks." Tom Buck

Trevor, is that plan part of your book?

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Pat

That plan is included with the book.

Wow! A lot of great information here.

I am just closing up the box on my first J-45- Lutz and curly koa.

I am using 1/4" non scalloped, tapered bracing-pretty light.

Can't wait to hear it!

The soft wood bridge plate is a nice touch. I've seen that before in an old 45.
Is it just me or does the neck in the pics look a little suspect? I've never seen a Gibson logo tacked on in that fashion. Plus, a truss rod cover with 3 screw holes is an Asian detail. AFAIK, Gibson has always used truss rod covers with 2 screw holes.

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Stay with the happy people.
--Reynolds Large

Did I mention that this guitar had been butchered by who knows how many previous owners after who knows how many beers? I got it after it had sat for many years in a storage shed in rural Alabama. All of the finish had been completely sanded off - everywhere. The top was sanded so thin it was ruined, probably why they stuck the tailpiece on there. The neck was sanded a bit thinner but it seemed to survive ok. The BRW fingerboard was not sanded but sure had some huge grooves in it. The headplate was sanded almost completely off. The bottom hole for the truss rod cover was there but was hogged out so big it wouldn't take a screw hence, perhaps, the replacement truss rod cover with 3 screws, although no telling where that came from. As best I can figure, the tacked on logo came off of a old Gibson case since the original logo was sanded off.

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Steve Smith
"Music is what feelings sound like"

That explains it! I'm impressed with your dedication to get this old Gibby back in playing condition.

_________________
Stay with the happy people.
--Reynolds Large