What makes a guitar have 'natural reverb', bloom, etc?

[Ken Carr]

I always thought that natural acoustic "reverb" sound was due to a quality cedar top. Do those of you who have guitars with both cedar tops and spruce tops notice a tendency for one or the other tops to have more of that airy, beautiful reverbish sound? Or do you think it has more to do with the top thickness?

[jimi junior]

Originally Posted by Ken Carr

I always thought that natural acoustic "reverb" sound was due to a quality cedar top. Do those of you who have guitars with both cedar tops and spruce tops notice a tendency for one or the other tops to have more of that airy, beautiful reverbish sound? Or do you think it has more to do with the top thickness?

Good question, I'd also be interested to know the answer to this.

I have a Cedar and mahogany Lowden, which does display a surprising amount of this quality for a hog guitar, which I'd normally consider more dry sounding. But then it is a Lowden, and they're known for their overtones and prettiness.

I've also heard the quality i speak of in spruce topped guitars

[donlyn]

What makes a guitar have 'natural reverb', bloom, etc?

Wood, construction, and love.

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Edit => I re-read this thread including what was added after this post, and noticed that a lot of posters mentioned specific guitar examples, so here are my examples. Solid-wood X-braced spruce-topped rosewood B&S guitars do the magic for me (I have 4, including a 12 string; see signature). And I will add Jumbo shaped and/or large body guitars also lend a hand for this. The original Jumbo was a Gibson J-200,and I find that shape and size to be ideal for balance and a unique guitar sound experience. And Taylor's Grand Orchestra is their re-design of the Jumbo shape, and doesn't stint on size or depth either. And the new Epiphone solid wood J-200 Jumbo has a nice take on it too.

I fingerpick all my instruments using my nails on Elixir strings.
*

Don
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[Alan Carruth]

I think jimi nailed it when he asked the question, and mentioned a 'complex' tone. From my perspective as a maker it all comes down to how complex the instrument is as a vibrating object.

From what I can tell through experiments over the years the guitar is designed to be complex. Some of the features that have persisted through the centuries even though they're hard to justify structurally end up making the sound more complex. An example of that, I believe, is the combination of the waist above the center of length of the box, and the hole in the top just above that. The interaction of those parts acting on the air flow/sound pressure inside the box, along with the way the top vibrates, produces 'extra' resonances in a useful frequency range, adding to the 'tone color' of the instrument. This seems to be one of the things that makes the sound 'guitar like', as opposed to, say, an Irish bouzouki.

Starting from the 'standard' designs it's possible to add complexity to the sound by adding features. I built a harp guitar a few years back, designed to fold into a package that could go into the overhead on an airliner. It necessarily used a small guitar body (pretty much like a Martin 12-fret size 1), and had an extended 'arm' that was also a box with it's own soundboard for the sub-bases. It ended up sounding like a pocket cathedral. The small box 'talking' with an only slightly smaller 'annex' through a somewhat restricted arm gave rise to all sorts of feedback; much more than I'd seen on guitars of a similar concept but with larger main bodies.

One thing that probably helps is to minimize built-in losses. That starts with using low-loss woods, such as rosewoods and WRC. These don't insure success: IMO the wood can help to set a limit to how low you can keep the losses, but you can still blow it. It's distressingly easy to make a poor guitar from good wood; factories do it all the time. On the other hand, good design and good work can make a very 'interesting' guitar from any wood: that little folding harp guitar is walnut and Sitka spruce.

This is especially the case in the higher frequency ranges, up around 2000-4000 Hz. That's where hearing is in some sense the most acute. It's the range where a lot of speech recognition happens, for example. High damping tends to 'eat' high frequencies. Along with using low damping wood you have to pay particular attention to getting the details right. Much depends, for example, on getting the top and it's bracing working together, so that the top can be as light and easy to drive as possible without too-heavy bracing 'quenching' the high frequency resonant modes. Given the variability of wood this is hard to get right in production settings.

A good guitar is much more than the simple sum of it's parts. Much of what makes a 'great' one is in the way the maker balanced things out, without over emphasizing anything at the expense of squashing something else. Every part contributes something to the sound. The 'bloom' or 'reverb' you hear is all of the parts trading energy back and forth.

[ssstewart]

out of all the guitars I own or have ever owned. my 29 archtop has the greatest sustain and "natural reverb" of any of them by far. although it is birds eye maple top/back and sides I think the greatest influences on its great reverb/sustain is the fact that it only has 2 braces entirely on the top 1 horizontal upper bout brace and one on lower bout, thats it. meaning there is nothing to impede or interrupt the vibration of the top.,, with exception...the bridge which is the primary origin of the vibration. as well as the age (93 yrs) of the solid wood, to say it has "opened up" would be an understatement.

the shape of the archtops top also probably has a big influence on its natural reverb and sustain, especially early archtops, robert godin and ken parker have both spoken volumes on it so ill leave that to them the masters.

Most builders seem to stay away from Maple for tops as a rule but thats what drew me to this one in the first place was the beauty of it, and i feel this build was an exception to it, just like any guitar, each one can be special or a dud. just my thoughts

[jimi junior]

Originally Posted by Alan Carruth

I think jimi nailed it when he asked the question, and mentioned a 'complex' tone. From my perspective as a maker it all comes down to how complex the instrument is as a vibrating object.

From what I can tell through experiments over the years the guitar is designed to be complex. Some of the features that have persisted through the centuries even though they're hard to justify structurally end up making the sound more complex. An example of that, I believe, is the combination of the waist above the center of length of the box, and the hole in the top just above that. The interaction of those parts acting on the air flow/sound pressure inside the box, along with the way the top vibrates, produces 'extra' resonances in a useful frequency range, adding to the 'tone color' of the instrument. This seems to be one of the things that makes the sound 'guitar like', as opposed to, say, an Irish bouzouki.

Starting from the 'standard' designs it's possible to add complexity to the sound by adding features. I built a harp guitar a few years back, designed to fold into a package that could go into the overhead on an airliner. It necessarily used a small guitar body (pretty much like a Martin 12-fret size 1), and had an extended 'arm' that was also a box with it's own soundboard for the sub-bases. It ended up sounding like a pocket cathedral. The small box 'talking' with an only slightly smaller 'annex' through a somewhat restricted arm gave rise to all sorts of feedback; much more than I'd seen on guitars of a similar concept but with larger main bodies.

One thing that probably helps is to minimize built-in losses. That starts with using low-loss woods, such as rosewoods and WRC. These don't insure success: IMO the wood can help to set a limit to how low you can keep the losses, but you can still blow it. It's distressingly easy to make a poor guitar from good wood; factories do it all the time. On the other hand, good design and good work can make a very 'interesting' guitar from any wood: that little folding harp guitar is walnut and Sitka spruce.

This is especially the case in the higher frequency ranges, up around 2000-4000 Hz. That's where hearing is in some sense the most acute. It's the range where a lot of speech recognition happens, for example. High damping tends to 'eat' high frequencies. Along with using low damping wood you have to pay particular attention to getting the details right. Much depends, for example, on getting the top and it's bracing working together, so that the top can be as light and easy to drive as possible without too-heavy bracing 'quenching' the high frequency resonant modes. Given the variability of wood this is hard to get right in production settings.

A good guitar is much more than the simple sum of it's parts. Much of what makes a 'great' one is in the way the maker balanced things out, without over emphasizing anything at the expense of squashing something else. Every part contributes something to the sound. The 'bloom' or 'reverb' you hear is all of the parts trading energy back and forth.

Thanks for your insights Alan,

Couple things you said definitely resonate (pun intended) with my interpretation:

- the harp you describe sounds like you added a Helmholtz resonator which would almost be like attaching a reverb chamber to the instrument so I'm not surprised that sounded pretty cool! It's sometimes quite fun to rest the headstock of a guitar against a wooden door or cupboard while playing, to excite vibrations in that too. Adds very noticeably to the sound which just goes to show how much difference all these connected parts make! Though not the most convenient playing position...
- agree on minimising the losses (damping) and indeed that'll be more noticeable at high frequencies. But I suspect it's not just about minimising damping, as the effect I'm describing is different to just extended sustain, although that might be part of it. It's more about the dynamic tonal nature of the sustain. Almost like there are some interactions going on, perhaps even some aliasing between different resonances in the guitar
- which takes us to your final point - it must surely be a quality of the overall acoustic system, rather than any sole contribing element.

[Mandobart]

Originally Posted by Ken Carr

I always thought that natural acoustic "reverb" sound was due to a quality cedar top. Do those of you who have guitars with both cedar tops and spruce tops notice a tendency for one or the other tops to have more of that airy, beautiful reverbish sound? Or do you think it has more to do with the top thickness?

I have 5 cedar topped instruments built by 3 different builders. One is my recently bought Eastman E2OM-CD guitar. Two are carved top mandolins (a hybrid F4 from a local builder and an F5 from another custom builder in MN). One is a carved top F4 octave mandolin by the MN builder, and one is a custom carved top 10 string Hardanger viola also from MN.

My other guitars are spruce topped (except for my resonator, which outrings them all). Sure my Altamira gypsy jazz guitar doesn't bloom like my Eastman OM, and neither does my Eastman arch top, but those guitars aren't supposed to. Can I make any meaningful comparison between my Sitka topped HD-28, Ovation 12 string, ancient Applause with thick plastic finish and my cedar top OM attributable only to the top wood? I doubt it.

I can't say if the sustain/bloom of my cedar topped instruments is due most to the top wood, the thickness, the bracing, the builder's technique.....the arch topped mando's and fiddle are way thicker than the flat topped Eastman, but that's a real stretch to try to make any correlation from that.

We all like to boil things down to a repeatable, consistent recipe, but I don't personally believe the real, natural world works like that most of the time.

[Mandobart]

Originally Posted by jimi junior

Good question, I'd also be interested to know the answer to this.

I have a Cedar and mahogany Lowden, which does display a surprising amount of this quality for a hog guitar, which I'd normally consider more dry sounding. But then it is a Lowden, and they're known for their overtones and prettiness.

I've also heard the quality i speak of in spruce topped guitars

Your mention of Lowden prompted this recent memory - I played several cedar top Lowden and Sheeran (by Lowden) guitars plus a few Collings OM's on my last trip to Dusty Strings.

The Lowden's and lower end Sheeran's sounded like they were stuffed with socks compared to the spruce topped Collings's I played. I take this as only a personal anecdote, not as proof of one type of wood being superior to another regarding natural reverb. This experience did help me decide to give the cedar top Eastman OM a try.