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So I am making a Baritone Acoustic guitar and was wondering the type of wood I should use to brace the back and top as well as if it should be thicker than a normal guitar or vice versa. The top is cedar and the sides and back are walnut with a walnut, maple, and oak neck. I really want this guitar to have some bass. I read online that the harder the wood (Braces or top/side/back wood) the more high frequencies it will absorb and produce more low frequencies. Was wondering if anyone has ever done an accurate frequency analysis on different tone woods and that outcome. As we all know, as you thump the piece of wood your building with, it is producing sounds over the entire Hz range but the loudest ones are usually where the Tone comes from and knowing how to incorporate with right tones is really what I want to figure out. Really want to engineer this guitar right for my ear before I even play it.

What braces to use for a Baritone Guitar?

Potential further information on Tone wood analysis and its outcome frequency/Best suited woods for Baritone Instruments?

Appreciate it.

I would get a plan and build to that.
Unless you've built many guitars,
shooting for a particular sound is hard to do.
For me, not knowing what it will sound like is part of the fun.
I would use a spruce top,
and spruce bracing.
Good luck, have fun, and don't stress!
Alan

Plans good idea.
Tone wood analysis -
http://www.goreguitars.com.au/main/page_the_book_overview.html
Half price at Stewmac (also free shipping for everything) if you're a member https://www.stewmac.com/StewMAX/StewMAX_1-Year_Membership.html
Tonewood for bracing I'd stick to spruce, strength/weight ratios is so good.
Baritone I haven't built, but read the book, and stick to the suggested 2 degrees bridge rotation
I'd avoid a cedar top....spruce again for same reasons, or a least use a very large footprint bridge because of cedar's reputation for having bridges flying off.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I built a baritone (28" scale) about a year ago and am pleased with the results. Spruce over padauk. I used a slightly smaller soundhole to keep the air resonance down and slightly scalloped braces with the thought that this may enhance lower frequency resonances. Otherwise, my normal construction, including a live back. It sounds good -- resonant, good sustain, fairly loud. A baritone guitar.

My last baritone was 27” scale, Sitka over Padauk, and tuned to C. It runs a .060” on the bottom (requires a custom set. I can share the gauges if interested) and is based on my modified dreadnaught body. It is braced exactly the same as my mod-dread except that the bridge and x-brace are moved a bit closer to the tail block due to the longer scale. and the bridge is 1/16” deeper but the same width.

I took it to a guitar camp in august where it sold immediately (2hr, I never saw it again). I wouldn’t change a thing and it’s at the top of my new build hit list. Miss that thing...!!

Best, M

I've built a few baris. Keep in mind that you're looking at two things here; the actual stiffness needed in the top given the string load, and the relationship between the resonant pitches of the guitar itself ('main air', 'main top' resonance and so on) and the string tuning. All of this also has to be crammed into a package that somebody can actually play.

Structurally you're looking at the string tension and top stiffness. The tension may or may not be any greater than on a 'normal' guitar; it depends on the scale length and tuning. It's always a good idea to start with those.

Generally speaking, any guitar that is stiff enough to keep from folding up too soon will be strong enough to work. If you're making something in the 'normal' size range, then normal materials and scantlings will suffice. If you make it larger you'll need to beef things up a bit to retain the stiffness.

If you want to make an instrument that has the same sort of balance and timbre as a normal guitar in the new, lower tuning range, you'll need to enlarge it to lower the pitches of the modes. The scaling rules they developed for the very successful (acoustically, as least) 'violin octet' suggest that scaling the box length to the wave lengths of the lowest note makes sense. The 'alto' of that set, tuned like a viola a fifth down from the violin, needed to have a box 21" long, and is just about impossible for a normal human to play under the chin. You might not need to make it that much wider as well, but that could come with a penalty in tone.

You could make it the same size as a 'normal' guitar, maybe with a deeper box (wedged?), and build it lighter. Using a smaller sound hole could drop the 'air' resonance into the right range. However, the relatively small (compared with the wavelength of the sound) top and small hole would cost in terms of power. Does this need to hold it's own acoustically, or can you use a pickup?

There's a reason why bass fiddles are as big as they are; it's the only way to get that sound. You'll have to think about how far in that direction you'll want to go, or be able to, in order to get the tone you want. If you can't enlarge things enough then compromises will be necessary. Every bari I've made has had some of those. They've all 'worked', more or less, in the sense that they've been'good enough', but none of them has sounded like a real baritone guitar.

Ecin, what scale, strings and tuning(s) have you chosen for your baritone? Have you done the tension calcs?

A friend has one of the 8 string Taylor bari's - I could look inside it and get some idea of the bracing but I think its on their web site or Wood and Steel.

I use red spruce bracing on all my guitars. Can’t beat the strength-to-weight ratio.

Here’s the great Darrell Scott playing (soon-to-be) his Mountain Song baritone a few months ago. From my experience, baritones are all about a long scale length and a great big body. This one is a 28.75” scale length with a jumbo-sized body in quilted maple and a Carter “Singing Tree” redwood top.

Also critical to live performance is the right pickup, and for big-bodied baritones, you can’t beat the feedback resistance and low-end mud cleanup of the James May Engineering Ultratonic pickup.


https://youtu.be/I-3IgrGooME


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Mountain Song Guitars www.mountainsongguitars.com

I plan on using a 29in scale length. Haven't decided on the best strings But I would guess that string tension would be similar if I was in a lower tuning with higher gauge strings to stop them from buzzing from the low tuning. A normal guitar has around 200-250 lbs of force being exerted throughout the neck and top i'm pretty sure. But Metal and Wood bracing? How is that done/how is the metal adhered to the wood? Very interested to find out how.

Wood and Steel is the name of Taylor's magazine about steel string guitars.

But you could do wood/metal composite bracing using epoxy. Aluminum would be a lot easier to carve than steel, though Carbon fiber works too. Sandwich a strip between two pieces of wood and then glue to the soundboard with epoxy and carve as usual (but probably quite a bit lower due to the much higher stiffness of carbon or metal). The center laminate takes all the load, the wood just keeps it standing up and spreads out the pressure on the soundboard. Theoretically it should result in slightly lighter weight and better resistance to long-term deformation. But you will have to resharpen your chisel a lot more often. And if you radius the braces using abrasives, treat carbon fiber dust like the plague.

You can also do all-wood laminated braces like this using hardwood for the center piece. Honduran rosewood and purpleheart both have good stiffness to weight ratio and very high strength. By my calculations the total weight should be slightly higher than solid spruce for the same stiffness, but strength will be higher, so maybe better long-term deformation resistance.

Solid spruce is already an amazingly good bracing material, though. Light, stiff, strong, low damping, good split resistance, easy to glue, easy to carve, generally grows straight, and cheap. Not much room for improvement.

Metal bracing?
I don't think so.
Most players I've known love a lightweight guitar.
I sure do!
I'm not a trained luthier,
but I think slightly taller spruce braces would be fine.
Alan

I built a dread sized baritone guitar (BG) with a 28 3/8” scale, tuned B – B, and a slightly deeper than usual body. I used carbon fiber/spruce laminate bracing but I think any stiff spruce would be as good, and in hindsight I think that bracing was the least challenging part of this project.

I can share some experience with scale, string gauges, and bridge compensation. Before I attached the bridge to my baritone, I put on a temporary bridge using a tailpiece. Testing different strings suggested to me that medium gauge strings (.016 -.070) would sound better than light (.014 -.060) , and made me aware that baritone strings need a lot of bridge compensation. I couldn’t see how a conventional single slanted saddle would make this possible, and I also realized that if I changed gauges the saddle locations would all move. To deal with this, I decided to use temporary individual saddles, with the idea that I’d route in a bridge saddle slot when I finalized the gauges I wanted to use.

After I built the guitar, the medium gauge strings sounded decent. The low B string didn’t sound as strong or deep as one would wish, which is pretty much a given considering the size of the body and the length of the scale. However, though the sound was good, the long scale and heavy strings made it tough to play. I normally play acoustics with light gauge strings. Playing the BG, I felt the way a lifelong electric guitarist feels trying to play an acoustic 12 string. I finally switched to light strings, and it sounds all right: not as loud as mediums, but better sustain. Changing the gauge really changed the compensation, so I’m glad I made provisions for that, though with the bridge as it is I can’t get the lowest string quite long enough.

The temporary movable saddles (photo below) turned out to be a royal PIA to make and use. After trying easier alternatives that didn’t work for one reason or another, I used pieces of bone epoxied onto little rectangles of carbon fiber composite. These are held onto the bridge by fish glue, which holds just well enough to keep them in place under tension. A drop of water releases them when they need to be moved, and doesn’t mess up the shellac finish on the bridge. I had to reinforce the saddle for the lowest string, using a little piece of carbon composite glued on at a right angle. I could give more details on making these things, but I’d suggest you find a better alternative. I think three 2-string saddles, routed at angles—something like the saddles on a semi-vintage Tele bridge—would work much better, and I will probably re-bridge using this approach if I get back to this guitar. As it is it works OK to accompany other guitarists and singers, which is the main thing I built it for.

I used a 28 3/8 scale. I think the sound would degrade if you used a much shorter scale, but the bridge compensation would be easier. One design consideration: to improve bass, you would want a “forward shifted” bracing pattern (according to conventional thinking), but the longer the scale the more you have to move the bridge backward, which means the X arms need to be back further to go under the bridge wings. You could address this by making a larger body, but that creates other problems, such as how are you going to hold it and where are you going to find a case. Also, the bracing required for a larger body seems to restrict bass, which is why most J-200 size guitars don’t have the bass you’d hope for (IMHO, YMMV, etc. etc).

In designing a BG are a lot of variables, and it’s hard to know what’s the best combination. I’d probably build a better BG after 5 or 10 prototypes, but there still are inherent problems. It’s nice to have one around, but I personally doubt that a BG can be as good a musical instrument as a conventional sized guitar. But they all laughed at Christopher Columbus when he said the world was round, they all laughed when Edison recorded sound.

_________________
Tim Allen
"Never hurry, never rest."

Nut compensation is a good thing. Not only does it improve intonation, it cuts saddle compensation almost in half, reducing these practical problems. So simply using a 3/16-1/4" wide saddle would likely give you enough adjustment room.

Plans or at least a detailed inspection of a successful acoustic baritone sounds like a good idea if you do not have a very good feel for the project at this point. We've seen two baritones built in the shop, as well as a few acoustic bass guitars, and all have been built on either the J-200 body shape or the Martin 0000/J/M format, at around 5 inch depth. None have employed the Smith-Manzer Wedge, but if the player is of smaller stature, that might be one way to address both adequate ergonomics and getting enough interior volume to support a B-B tuned instrument.

On brace materials - as the boss harps on with new students, guitars are stiffness-driven structures, so are nearly always significantly stronger than need be if just stiff enough to do the job. Spruces have some of the highest stiffness-to-weight ratios seen in available timbers, so they are often used for conventional guitar bracing. Stiffness-to-weight and strength-to-weight are two very different physical qualities, so it might be worth reviewing the Gore/Gilet Volume 1 on design as mentioned earlier in the thread for a guitar-focused treatment, or for a more general, nearly math-free exposition, the book we use in the shop as supplemental reading for students that lack a technical background: J.E. Gordon's excellent 'Structures: Or Why Things Don't Fall Down' ($12 from Amazon in soft-cover).

https://www.amazon.com/Structures-Thing ... 0306812835

I have to confess that Gordon stayed on my night stand for nearly a year while I fended off questions from Mr. Morelli, etc., tailored to determine just how much of the reading assignments on materials and structures I had completed. When I finally did complete the reading selections in Gordon - a total of about 35 pages - the author's clear, very cogent writing style and ready application to real life outside of the shop encouraged me to invest the time to complete the book.

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We have become a civilization that elevates idiots, prostitutes, and clowns. Am I still to defend it? Yes, for its principles. Yes, for what it was. Yes, for what it still may be.

-Mark Helprin, The Oceans and the Stars: A Sea Story, A War Story, A Love Story (A Novel)

There are no industry standards for baritones, so you're pretty much free to experiment -- and that's what most builders do. I use exactly the same top plate strength parameters as I do for all my SS guitars (ala Gore and Gillet), but increase the X-brace height only slightly.

Compensation is a bit tricky. There are some web-based tools. I ended up building my own spreadsheet using the physics explained by Elmendorp 2010 (Am. Luth. 104: 56-60). The hard part is getting the appropriate physical data for strings. I based my calculations on D'Addario EXP16-70, for which tension data are available. I ended up changing to Elixir 80/20 and like them better. The main message from my calculator is that you'll need a wide saddle to have any hope of compensating (I use 0.25"). The spreadsheet is found here:
https://www.mullinguitars.com/2015/10/compensation-calculator-for-steel-string-guitars.html

The spreadsheet was designed for multi-scale instruments, but can handle single-scale as easily.

Woddie G wrote:
"Spruces have some of the highest stiffness-to-weight ratios seen in available timbers, so they are often used for conventional guitar bracing. Stiffness-to-weight and strength-to-weight are two very different physical qualities..."

Stiffness to weight is a structural property, not a material one. As anybody knows, 2x4 standing on edge is a lot stiffer than it is laying down flat, but the weight is the same. The real material property to look at is Young's modulus to density (E/rho).

If you measure a lot of samples of woods of various sorts, you'll find that, in general, E/rho for softwoods is higher than for hardwoods. Often the E values will be similar, while the density of a hardwood will be double that of a softwood. That's why we tend to use softwoods for tops; they're stiffer at a given weight.

In all of the soft woods I've checked out so far the Young's modulus along the grain tracks the density pretty closely. They all follow the same rule, so a piece of Western red cedar that has the same density as a piece of Red spruce tends to have the same E value along the grain. WRC does tend to be less dense then most of the spruces, but all woods vary, and there's plenty of overlap. So why use spruce by preference?

One reason seems to be that it tends to be tougher, harder to split, than many other softwoods. WRC, redwood, and Douglas fir are all much more prone to splitting than most of the spruce samples I've seen. Other soft woods that tend to be low in density, and thus to make a light, stiff top, tend to have a soft surface. Again WRC comes up, as does White pine. The pines and firs also tend to have larger resin channels, which can make finishing harder.

The upshot is that the spruces as a whole have a suite of good properties that make them relatively easy to use and give good results on guitar tops.

Specific modulus - also know as the stiffness-to-weight ratio and specific stiffness - is a materials property expressed as the elastic modulus per (mass) unit density for that material. I do agree that measured deflection of a given component under a specific load would be a property of both the stiffness-to-weight ratio of the material and the structural design. To restate, the stiffness-to-weight ratio of the spruce in that 2 x 4 does not change, but the measured deflection due to a given applied load does change based on how the 2 x 4 is oriented, supported, and loaded.

_________________
We have become a civilization that elevates idiots, prostitutes, and clowns. Am I still to defend it? Yes, for its principles. Yes, for what it was. Yes, for what it still may be.

-Mark Helprin, The Oceans and the Stars: A Sea Story, A War Story, A Love Story (A Novel)

Baritones are more about scale length and less about body size. If you want it to sound more like a guitar than a baritone, go shorter on your scale -- 27.5" but you limit your tunings -- you're more in the C-C tuning range. If you want it to be a full on baritone it needs to be longer than 28", preferably 28.6 or longer for a B-B tuning. A grand auditorium/SJ body to Jumbo will work best rather than a dreadnaught because they both focus the sound for more articulation which you need for a baritone. As a wise one once said, what you need for good bass is good treble. A 28.6" baritone, B-B will need a saddle slope of .200" over 2.312" and a 1/4" saddle to spread the load with such fat strings.

dberkowitz, curious about the saddle being 1/4".
Is that for stopping the saddle from twisting toward the nut?
Or, downward pressure?
A

It’s about compensation — the same point made earlier in my post in this thread. A narrower saddle can’t accommodate the compensation differences over six strings. See my spreadsheet calculator.


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"a 1/4" saddle to spread the load with such fat strings."
I know about the compensation, Tim.
Load and compensation are 2 different things.