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Old 06-01-2019, 07:29 AM
Silly Moustache Silly Moustache is offline
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Default Question for luthiers: The differnce between the dreadnought and the jumbo?

Hi, I'm speaking about the 14 fret Martin dreadnought and the Gibson Jumbo - both introduced in 1934 on. (i.e I'm not referring to the original 12 fret dread, or the super jumbo).

I'm not sure which was introduced first but it would seem that both companies saw a market for a larger body flat top rhythm guitar.

I'm asking mainly about the differences in the strutting, and other internal structural variances.

I'd be most grateful for any advice and observations.

Thanks in advance.
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Old 06-01-2019, 09:26 AM
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Bruce Sexauer Bruce Sexauer is offline
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A very big difference is scale length. Except for the relatively Martin-esque Advance Jumbo, the Gibson’s string length is nearly 3/4” shorter than the Martin Dread.

People often speak about Martins and Gibson’s as if they were two brands of the same quality, but the craftsmanship and attention to structural detail in older Gibson’s is abysmal compared to older Martins. I think this is true in every era.
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Old 06-01-2019, 10:38 AM
charles Tauber charles Tauber is offline
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Quote:
Originally Posted by Silly Moustache View Post
I'm asking mainly about the differences in the strutting, and other internal structural variances.
I'm just curious, why do you want to know? What will you do with the information?

Not trying to give you a hard time, I'm just curious.
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Old 06-01-2019, 02:37 PM
Silly Moustache Silly Moustache is offline
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Quote:
Originally Posted by charles Tauber View Post
I'm just curious, why do you want to know? What will you do with the information?

Not trying to give you a hard time, I'm just curious.
Hi Charles,

I once met Bill Collings on a brief trip to the UK and he was quite excited by a strutting arrangement he was using on his "CJ" models, which I failed to understand.

Also, I'm slightly irritated when people refer to the Gibson jumbo style as "slope dreads" (even some makers!)

But really it is because I am a guitar nerd, know a fair amount about Martin history and designs, but less informed about Gibson, and I have a thirst for knowledge, esp. when I realise my ignorance.
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Old 06-01-2019, 02:43 PM
Silly Moustache Silly Moustache is offline
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Originally Posted by Bruce Sexauer View Post
A very big difference is scale length. Except for the relatively Martin-esque Advance Jumbo, the Gibson’s string length is nearly 3/4” shorter than the Martin Dread.

People often speak about Martins and Gibson’s as if they were two brands of the same quality, but the craftsmanship and attention to structural detail in older Gibson’s is abysmal compared to older Martins. I think this is true in every era.
Hi Bruce, I was aware of the difference in the scale lengths, and that Matin also had the shorter (24.9") scale on all models but the 000, until '29(OM) and '31(original dread).

I'm seeking to understand the differences in neck joints, and body construction etc.
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Old 06-01-2019, 02:56 PM
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murrmac123 murrmac123 is offline
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Andy, would it be too much to ask that you refer to "bracing " rather than "strutting " ?

You can edit your previous posts if you wish, and I will then delete this one.
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Old 06-01-2019, 09:38 PM
tadol tadol is offline
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Awww - I thought “strutting” sounded quite continental -

In fact, I’d ask what other alternate names might be in common use elsewhere - probably better as a new thread -
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Old 06-02-2019, 10:11 AM
Silly Moustache Silly Moustache is offline
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Originally Posted by murrmac123 View Post
Andy, would it be too much to ask that you refer to "bracing " rather than "strutting " ?

You can edit your previous posts if you wish, and I will then delete this one.
Ok, my error, to all, for "strutting" please read "bracing"

and while I'm at it for "differnce" please read "difference" and for Matin, please read "Martin".

It's not me - my keyboard is dyslexic.

(Never anthropomorphise inanimate objects - they hate that!)
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Old 06-02-2019, 10:30 AM
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The 3/4” I mentioned is actually a VERY BIG difference. And “attention to detail” refers to far more than how the corners come together. Gibson’s trusses are often rough sawn and do not appear to be sanded, let alone shaped. For instance. I’ve never been sure what people mean by “tuning” the top but it is a certainty than more of “it” happened on Martins than Gibsons I’ve looked at.

None of this makes Gibson’s “bad”, but Martins of all eras are more sophisticated IMO.
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Old 06-03-2019, 05:28 AM
Silly Moustache Silly Moustache is offline
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Quote:
Originally Posted by Bruce Sexauer View Post
The 3/4” I mentioned is actually a VERY BIG difference. And “attention to detail” refers to far more than how the corners come together. Gibson’s trusses are often rough sawn and do not appear to be sanded, let alone shaped. For instance. I’ve never been sure what people mean by “tuning” the top but it is a certainty than more of “it” happened on Martins than Gibsons I’ve looked at.

None of this makes Gibson’s “bad”, but Martins of all eras are more sophisticated IMO.
Hi Bruce, I do not for a moment dismiss the choice made by Martin and Gibson about their scale length.

I play Original Dreadnoughts made by Collings with a specified 25.5" scale, and I've just been playing in new strings on my Santa Cruz "RS" with a 24 & 3/4" scale, both wear medium P/B strings.

I know that I prefer the longer scale when I perform because I feel that I get more projection and "personal feedback" (I can over play on a short scale).

I also fully understand the differing approaches as far as wood choice/quality and "fit & finish" -which is why I only own one Gibson (a '34 Archtop)

Whilst flattops by both makers were built with "X-Bracing" (first developed by Martin I believe), I am wondering if there was a noticeable difference in the bracing (OK?) pattern or neck joints from the outset (i.e. from 1934 on).

I believe it would be pretty obvious to most guitar nerd to tell aurally the difference between a , say D-18 and a J-45. WhatI'm trying to understand is what is it, that makes that tonal difference, (apart from the scale length).

Thanks in advance.
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Old 06-03-2019, 08:04 AM
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"Struts" seems to be the more Euro way of talking about bracing, especially in the classical guitar community. Strutting does sound like a word they might use in dressage community

Gibson's are famous for their 'tone snot' which is essentially the complete lack of care about glue dripping all over the inside of the guitar. They also put the darn bridges on backwards too.
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Old 06-03-2019, 09:01 AM
charles Tauber charles Tauber is offline
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Quote:
Originally Posted by Silly Moustache View Post
I believe it would be pretty obvious to most guitar nerd to tell aurally the difference between a , say D-18 and a J-45. WhatI'm trying to understand is what is it, that makes that tonal difference, (apart from the scale length).
As would every guitar maker. The short answer is that there isn't a short answer.

There are a "1000" variables that go into the making of a guitar. Things like the air volume contained in the guitar - made up of the depth of the guitar at heel, depth of the guitar at butt, curvature of tops and backs, width of the guitar - at upper bout, at waist, at lower bout - length of guitar - the stiffness of the top - related to thickness of wood, inherent stiffness of the top material that varies from one top to the next - the stiffness of the top bracing - locations of braces, dimensions of braces - height, width, profile, scalloped or not - whether quarter sawn or not, inherent stiffness of the bracing material ... And, that barely scratches the surface of the variables involved.

What you are asking is what values for all of those variables produces sound "X"? No one knows. There are too many things all changing at the same time to isolate one of them and say, "Do this and it will sound like that". There are generalities that are known, but generalities are, well, generalities: sometimes apply, sometimes not.

For example, if we make the sound hole smaller in diameter, all things being equal, it will produce a sound change of "X". Problem is that all things are never equal: changing the sound hole diameter occurred at the same time we changed 100 other things while making the new guitar with the smaller sound hole. (One option, perhaps, is to make a guitar with the desired hole diameter, measure the sound qualities of that guitar with that sound hole size, then enlarge the sound hole of the same guitar, progressively, taking measurement with each enlargement. Doing so would isolate that one variable of sound hole size.)

Last edited by charles Tauber; 06-03-2019 at 09:07 AM.
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Old 06-03-2019, 09:17 AM
Howard Klepper Howard Klepper is offline
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A strut is a two force member, usually in compression. A truss is an assembly of two force members. Bracing glued to a guitar top is neither of those. Yes, Bruce, I know you were joking.

A Martin D has a 15-5/8" lower bout. Gibson Jumbos are 16"--noticeably wider. The Jumbos were not consistent in body depth (Gibson was not bothered by any need for consistency). But early Jumbos (1934-35) had bodies that were considerably deeper at the neck block than were Martin Dreads. Some of the Jumbos did not taper in depth at all. This gives them a lower frequency air resonance than a D, with a greater tendency to boominess.

Locations of braces vary a lot in Jumbos. So does the location of the bridge plate. Often the plates do not touch the arms of the X; and they often are not under the entire bridge. The neck blocks are bigger than Martin's, and usually don't have beveled corners.

AJs (introduced 1936) had the X arms spread out wider, and more taper in body depth than the first Jumbos, along with a longer scale. This was kind of like having a bored and stroked engine in your hot rod.
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