Dreadnoughts ??? or Jumbos??

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Silly Moustache
Posts: 103
Joined: Fri Oct 26, 2018 10:58 am

Dreadnoughts ??? or Jumbos??

Post: # 4176Post Silly Moustache
Tue May 25, 2021 1:25 pm

Help me, please!
Martin coined the term Dreadnought back in the Early part of the 20h century - we all know the story (if not the precise date).
We also know that there was the Ditson 111 (not a commercial success)!
We know about the ORIGINAL Martin branded Dreadnought from 1931-1933 (not a commercial success! - but the best IMHO!).
And I guess two or three of us will be familiar with the oft copied 14 fret "rhythm" dreadnought from 1934 until now.

We also know that in 1934 Gibson rapidly responded with the "Jumbo" which was probably influenced in body shape by the original dreadnought but in a 14 fret short scale thin necked configuration.
Martin prefixed all Dreadnoughts with a "D" Ok!
Gibson prefixed all theirs with a "J" Yup-logical.
The bigger guitars by Gibson were prefixed as "SJ" i.e. "Super Jumbo"

Q1. so why do so many refer to Gibsonesque style guitars as slope dreadnoughts?


Q2. and this probably should be in another area but can anyone advise me of the differences in bracing between the Gibson jumbo and the Martin dreadnought, or was it a close copy?

n.b. I remember Bill Collings talking excitedly to me about his ideas about tone bars in the CJ but I confess I didn't really understand.


Help me please - this constant misuse (even on Gibson, Collings, and Bourgeois websites) is making me tear my hair out (and I don't have much left!!)

Thanks in advance. old and confused (UK)

Frank Sanns
Posts: 147
Joined: Sun Oct 21, 2018 5:38 pm
Real Name: Frank Sanns
Location: Pittsburgh

Re: Dreadnoughts ??? or Jumbos??

Post: # 4179Post Frank Sanns
Tue May 25, 2021 4:02 pm

Some of you know that I have sonically examined and mapped an extensive number of different guitars for many people. My comments are based both on physics as well as personal measurements.

The conclusions that can be made.

1. The more a guitar approaches a rectangular box, the more one low frequency will dominate. Rounding off corners reduces that. Sloping the shoulders cuts down on the number of long sonic paths that are the same length and thus cuts down on a single fundamental resonance. This forces the energy to go into other more diverse wavelengths. This is one of the contributors to a more balanced sound with slopes compared to dreds.

2 Bigger boxes have the potential to give lower resonant frequencies. Bigger guitars typically have a much fatter low E string and add rumble. The box is stretched at the top bout with a dred giving more volume and a longer vibrating path.

3. All X braces are not created the same. Besides geometry and material, the length of the X brace is important. With a larger lower bout, the X brace is longer and that too adds to allowing lower frequencies.

4. Mid tones have little to do with the size of the box or the slope of the shoulders. They are contoured by the tone bars. These damp out lower frequencies and undesirable resonances. This is much of where the voice of the guitar is made.

With that information, it can be concluded that slope shoulder guitars be they Gibson or any other manufacture SHOULD if all things are equal, have a more balanced lower end. A dred on the other hand often has a more boxy sound because of the longer and more numerous long paths competing for rumble or drone.

All dreadnoughts are not called Martins and all slope shoulder guitars are not called Gibsons. I think the nomenclature and references all merged over time and the purity of the company that invented it was used by the entire industry.

Not sure that I answered your historical questions but let this be a start for others to comment on. It is a good question.

Red Oak
Posts: 433
Joined: Mon Jan 18, 2021 4:00 am

Re: Dreadnoughts ??? or Jumbos??

Post: # 4603Post Red Oak
Fri Sep 03, 2021 12:18 pm

Frank Sanns wrote: Tue May 25, 2021 4:02 pm Some of you know that I have sonically examined and mapped an extensive number of different guitars for many people. My comments are based both on physics as well as personal measurements.

The conclusions that can be made.

1. The more a guitar approaches a rectangular box, the more one low frequency will dominate. Rounding off corners reduces that. Sloping the shoulders cuts down on the number of long sonic paths that are the same length and thus cuts down on a single fundamental resonance. This forces the energy to go into other more diverse wavelengths. This is one of the contributors to a more balanced sound with slopes compared to dreds.

2 Bigger boxes have the potential to give lower resonant frequencies. Bigger guitars typically have a much fatter low E string and add rumble. The box is stretched at the top bout with a dred giving more volume and a longer vibrating path.

3. All X braces are not created the same. Besides geometry and material, the length of the X brace is important. With a larger lower bout, the X brace is longer and that too adds to allowing lower frequencies.

4. Mid tones have little to do with the size of the box or the slope of the shoulders. They are contoured by the tone bars. These damp out lower frequencies and undesirable resonances. This is much of where the voice of the guitar is made.

With that information, it can be concluded that slope shoulder guitars be they Gibson or any other manufacture SHOULD if all things are equal, have a more balanced lower end. A dred on the other hand often has a more boxy sound because of the longer and more numerous long paths competing for rumble or drone.

All dreadnoughts are not called Martins and all slope shoulder guitars are not called Gibsons. I think the nomenclature and references all merged over time and the purity of the company that invented it was used by the entire industry.

Not sure that I answered your historical questions but let this be a start for others to comment on. It is a good question.

Great lesson for many of us!! We appreciate your knowledge and ability to clearly explain the differences!!

doctorZ
Posts: 1
Joined: Wed Dec 06, 2023 2:59 pm
Real Name: Jim Zalewski

Re: Dreadnoughts ??? or Jumbos??

Post: # 6478Post doctorZ
Thu Jan 11, 2024 9:13 pm

Excellent breakdown on the differences. Thanks.

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