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Old 10-20-2018, 07:35 PM
Photojeep Photojeep is offline
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Default Body depth and bass projection

I tried looking this up using the search function but didn't really get what I was looking for...

I am a dreadnought lover and probably always will be but I was wondering how much the depth of these beautiful giants contributes to the wonderful bass sounds they make.

Is it possible for a smaller body guitar to have similar bass output if it were as deep as a dread?

I don't know the acoustic theory behind any of this so any info you could send my way would be appreciated.

Thanks,
PJ
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Old 10-20-2018, 08:42 PM
The Bard Rocks The Bard Rocks is offline
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The greater depth and the wider waist contribute to extra bass. It is more the internal volume than the depth.
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Old 10-20-2018, 10:02 PM
musicwu musicwu is offline
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I'm no expert but I've heard from a video from a luthier saying quite contrary to the popular belief that 'depth contributes to the bass' , in fact, it doesn't or does less so compared to the width of the lower bout of the guitar.

I'm sure someone will correct me this...but I'm not convinced that depth itself has much to do with bass.
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Old 10-20-2018, 10:37 PM
Brucebubs Brucebubs is offline
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Quote:
Originally Posted by musicwu View Post
I'm no expert but I've heard from a video from a luthier saying quite contrary to the popular belief that 'depth contributes to the bass' , in fact, it doesn't or does less so compared to the width of the lower bout of the guitar.

I'm sure someone will correct me this...but I'm not convinced that depth itself has much to do with bass.
Perhaps you should ask yourself why do so many builders offer a 'deep body' option on their OM guitars?

What made Chris Martin himself add an extra 3/4" in depth to the existing 0000/M body and create the Martin J-14 fret?
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Old 10-20-2018, 10:51 PM
ChalkLitIScream ChalkLitIScream is offline
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As was mentioned, its the total volume inside the body which contributes to bass, and probably overall volume too.

You can do that with a wider lower bout and/or a deeper body.

Deep body OMs give the comfort of a smaller waist while keeping the big bottom end.
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Old 10-20-2018, 11:20 PM
robj144 robj144 is offline
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Quote:
Originally Posted by ChalkLitIScream View Post
As was mentioned, its the total volume inside the body which contributes to bass, and probably overall volume too.

You can do that with a wider lower bout and/or a deeper body.

Deep body OMs give the comfort of a smaller waist while keeping the big bottom end.
The wider bout does this more I believe since the lowest normal of the top (which most colors the sound) is a function of the wider lower bout.
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Old 10-21-2018, 02:41 AM
AndyC AndyC is offline
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I have a deep bodied OM and I just love the extra oomph that the extra volume gives. For me, it is the perfect all round guitar.
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Old 10-21-2018, 03:06 AM
Wade Hampton Wade Hampton is offline
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Well, it's true that adding extra body depth to an OM will give you a more pronounced bass response. However, it actually has a bit of a negative impact on the acoustic projection of the instrument.

Projection and loudness are not the same thing. What sounds louder to the person playing the guitar and perhaps those sitting within six feet won't necessarily cut through when there are other instruments being played at the same time.

I'm one of the rare players who has for years favored 14 fret Triple O's and OM's as rhythm guitars (which is what the OM model was originally designed for back when it first came out.) When I first heard of deep-bodied OM's, I was very interested, only to discover once I'd gotten my hands on a few of them that they simply don't project as well as standard depth OM's.

So it's a trade-off. When you change something like body depth it affects more than just the tone.

Or, as my father used to say, "there ain't no free lunch." If you gain in one area, another aspect might shift at the same time.

Hope that makes sense.


Wade Hampton Miller
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Old 10-21-2018, 03:25 AM
AndyC AndyC is offline
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Well, that's an opinion of course - but my experience has been the exact opposite.

I've had many OM's and 000's over the years, and categorically I am getting more bass and more projection and clarity with the deeper bodied version I now own.

(Of course, this could also be influenced by the combination of tonewoods, the build and the mojo of this particular guitar)
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  #10  
Old 10-21-2018, 03:35 AM
silverspear silverspear is offline
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ooo, I love this topic.

I'm one of few who desires visceral bass response when I do fingerstyle.. nothing but a jumbo seems to get me what I need. or so I thought all jumbos were the same..

years ago I was looking to upgrade to a jumbo, and I found a great deal on a shallow bodied jumbo at that time. took it home with me, and after playing with it for a week I realized that though it had the bass I was looking for, it lacked the immersion that my previous mid sized jumbo had. And I realized from that point on that I needed not only good bass, but good immersion when I play alone in my room.

fast forward months of researching and info digging and trying various other guitars of different depths and lower bout widths, I realized exactly what I needed.. I needed a guitar with minimum 4.5 inch body depth.

And now my favourite guitar is an Avalon jumbo. part of the reason I chose an Irish guitar is because their dimensions are exactly what I wanted, and when I got my Avalon it didn't disappoint one bit.
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Old 10-21-2018, 04:35 AM
Silly Moustache Silly Moustache is offline
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Firstly I must register my agreement in every aspect with Wade.
Think about the way a guitar's sound box works:

1. You hit the strings (you brute!)
2. The top is agitated by the strings (literally)
3. The agitated top sends pulses of compressed air into the sound box which travel, the vast dark, dusty arid distances - mostly to the back.
4. the back, made of the strutted tone wood of your choice gets "punched" by these pulses of compressed air and absorbs some, (in varying amounts depending on it's strength and the pressure of your belly on the outside) and bounces back some which , hopefully finds its way our of the sound hole to sail across the uncharted space of the venue to hit your audience.

Now this blast of compressed air (that you started with your violent attack on the strings.. you brute) carries many frequencies, and they travel at slightly different speeds, and as Humans have a relatively dull and slow hearing mechanism compared to more advanced creatures, perceive a chord - i.e. many different frequencies speeding into their aural cavities at approximately the same time. I don't know (much) but I suspect that critters with more developed hearing may hear a struck chord more like an arpeggio than we do.

See what you did with all your violent actions?

Now, the distance between the agitated top and the punched back will of course affect the time, and therefore strength of the frequencies travelling back, bounce then forward.

Assuming that different frequencies travel and different speeds then one struck note might register through your earwax slightly quicker than others, and so it is possible that your brain might perceive that one is more dominant that others, so maybe you hear more or less bass... or treble.

Now I like a nice bass, but I'm more interested in balance which is why I tend towards Collings guitars than Martins

The bass heavy Martin sound came about in 1934 when they abandoned the balance principle and made their remodelled dreadnought guitars bassier. Collings decided not to follow that aspect and so make more balanced instruments. That was a design decision and offers us a choice.

Also the introduction of ever larger amplification with overly extended frequency responses have distorted our perceptions of true bass and treble, and to my (old) mind, the sound of a well balanced acoustic guitar is as far as it needs to go ... leave the heart thumping bass end to the double bass.

Big, deep guitar bodies really started for Hawaian instruments. Bass lines played with a slide on a guitar pointing upards diod not travel well so they buildt deeper bodies to distort the bass end - hence the first Martin dreadnoughts and the Gibson Roy Smecks jumbo.

The following video shows a comparison of two modern versions of the 1931 style dreadnought and the 1934 style Gibson Roy Smeck. Both are sitka over mahogany.

The Dread is 4 & 7/8" deep at the deepest part and the Jumbo is 5" at the butt end but also 4" at the heel end so a bit deeper all around.
Watch this and listen on cans or a good, balanced, stereo and see what your think.

However, I still say that balance is more important than just bass.

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Old 10-21-2018, 09:01 AM
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Here is John Thomas playing some guitars out of his collection, in this case a couple of early L-bodied guitars as compared to a Nick Lucas Special. The regular offerings are 3-7/8" thick if I recall, and the Nicks can be up to 5". My ears aren;t good enough to tell much, espicailly on my computer speakers, but maybe yours are.

https://www.youtube.com/watch?v=VOKsdAFCCIw

Ed
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Old 10-21-2018, 09:44 AM
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iim7V7IM7 iim7V7IM7 is offline
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In general, acoustic flat tops are about choices of what is important to a player. It is very unusual for a design change that favors a sonic aspect not to come at the expense of another attribute. For my playing style, I prefer guitars with moderate depth. My 16” SJ for example is 4-3/8” at the end block. In my opinion, it has a balanced, projective and articulate bass.

I have found bass response is driven by longer scale length as an energy source, flatter top dish, scalloped bracing, and added body volume. These choices come at the expense of other tonal targets. For example, in my experience, tapered bracing favors a quality to the mids and sustain at the expense of bass. Added depth in my experience adds to the perceived reverb in how the top and back interact and does as Wade suggested cut back on projection. I also feel that added depth can impact balance of an instrument.

My $.02
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Old 10-21-2018, 10:12 AM
donlyn donlyn is offline
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I think that depth plays a large part, but overall body size and shape does too. Here's why I believe that. Don't know the science of it all, but . . .

About 20 years a go, I happened to get a Taylor 355 12 string jumbo. Liking the Taylor a lot, this triggered a long search for a rosewood Taylor jumbo. Never found one that could come close to the sound of my rosewood Gibson J200. While the lower bouts are the same width (17"), the depths are different. The J200 has a 4 7/8" depth at its deepest point at the strap button, top to bottom, external edge. This is about a half inch deeper than a Taylor jumbo (4 7/16") at the same spot. Fast forward 15 years and I found what I was looking for; A Taylor Grand Orchestra 818e. It has a depth of 4 3/4", and its body shape is somewhat of a cross between a dreadnought and a jumbo.

For the record, here are some external measurements:

Guitar, length, upper bout, waist, lower bout, and depth.

818 is 20 1/2", 11 3/4", 10 7/16", 16 3/4", 4 3/4".
355 is 20 7/8", 12 1/8", 9 7/8", 17", 4 7/16".
J 200 is 20 15/16", 12 1/2", 10 1/4", 17", 4 7/8".

All measurements are from external surfaces. If I had to guess, it would appear that the J 200 has the largest internal volume. I don't have the capability to calculate that, however. One of my sons would be able to.

Don

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Old 10-21-2018, 11:24 AM
Steadfastly Steadfastly is offline
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We've all seen bass guitars; the ones we see in an orchestra. Why are they so large? Could it be to produce bass?
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