Hybrid Acoustic/electric Idea

[avengers63]

I had a thought today. We all know that's dangerous enough as-is, but hear me out anyway. Some ground info needs to be established. If I'm off on any of this, please LMK so we can get on the right track.

For a semi-acoustic, there needs to be a solid block for the pups & bridge to mount on. This is because of feedback. To the best of my knowledge, this applies to chambered solid-bodies as well.

Acoustics have very thin wood which vibrates, this amplifying & shaping the sound. It requires bracing due to the lack of thickness.

Chambered electrics have thicker sides & tops, and therefore do not require bracing. From a topic I posted some months ago, the thinnedt you should go with a chambered electric is about 1/4". Beyond that and the wood might be too thin.

So...

Let's take a solid body electric, and chamber it. Nothing new. Let's only leave a small block inside at the neck pocket, just big enough to have a neck pup as well. We'll also leave a small block for the bridge. EVERYTHING else is hollowed out to aboy 1/4"-3/8". We'll have a 1/4" cap, or maybe a 1/2" that has been carved. Instead of f-holes, let's put a big round acoustic hole between the neck pup & the bridge.

How would you predict this would sound acoustically? Clearly it wouldn't be anywhere as loud as a real acoustic, but with some heavier gauge strings, it could be OK. At minimum, it'd be a pretty sweet jazz guitar.

Let's take it a little further. Let's say it's 2 1/2" thick. That'd leave you just under 2" for the sound box. Then let's put in a true acoustic pup system. NOW what happens when it's plugged in?

Since we've gone that far, let's NOT leave the solid block under the bridge. Instead, let's put in a TOM bridge mounted on a piece of rosewood/ebony like an archtop. NOW what happens?

[Geo]

How would you predict this would sound acoustically?

Probably boxy and not very loud. The wood is so thick, I doubt it will be able to produce a satisfying acoustic sound. But I'm sure it would sound beautiful with electric pickups through an amp.

Since we've gone that far, let's NOT leave the solid block under the bridge. Instead, let's put in a TOM bridge mounted on a piece of rosewood/ebony like an archtop. NOW what happens?

I would be worried about the top collapsing without some sort of bracing or arching like an archtop. Remember with a separate archtop-style tailpiece, the bridge experiences a straight downward force (it wants to go through the top).

My guess is it would sound like an archtop acoustic with an electric pickup.

There's a thread about this over in the acoustic board. Might be interesting to you.

[Mickguard]

I've been tempted to make a guitar like this: Acoustic Klein sort of......

And doesn't Godin make an acoustic-type electric guitar as well?

Also, there are plenty of full hollowbody electrics out there. I had an Epiphone Sorrento for example. And I just sold a hollowbody longhorn body from the sixties that had only a small block of wood beneath where the bridge was supposed to be. Both were more of an archtop type of construction. Which are often full hollow. And usually laminated to get past the problem of getting thin enough to be acoustically responsive, but strong enough to handle the downward pressure of the bridge.

But as you point out, these are very prone to feedback at loud volumes and high distortion levels. (Although with the Sorrento, that was part of its charm...the damn thing literally quivered in my hands...sounded great too...kind of wish I hadn't sold it now...ah well...). But for jazz or blues, where the volume stays reasonable, I don't think it's a problem.

[RestorationAD]

I would suspect any combination that you mentioned will make for a nice Jazz or a BeBop type guitar.

Here are some ideas.

Gibson ES330 is one of my favorite hollow bodies.

rick turner 79-003

However Benedetto suggests anything under 3 inches deep sounds bad.

[avengers63]

ResoAD: Benedetto's opinion should probably be taken without question. However, we're not looking at a true semi-acoustic, like a 335-ish, or an archtop, like a... well... archtop. We're talking about a solid-body that has been hogged almost completely hollow with a sound hole and both an electric & acoustic pup.

MICK: IIRC, those longhorns were a Dano product. If so, those were a wood frame with a melamie top & back. I'd equate those more closely with a semi- than a hollow solid-body.

GEO/MICK: Please explain exactly what you mean by "downward pressure of the bridge".

GEO: The intent wouldn't be to have it loud acoustically. Because of the construction, that'd be impossible. I'm wondering about acoustic tone rather than volume. If THAT was OK, then perhaps the pup system would be OK too.

I'm picturing a fancy rosette and all of the binding/decoration that an acoustic would have, and then a mini-humbucker in the neck. To emphasize the look, maybe only a 20-fret f/b and a shallow acoustic-like cutaway. Maybe a florentine cutaway.

[Geo]

GEO/MICK: Please explain exactly what you mean by "downward pressure of the bridge".

GEO: The intent wouldn't be to have it loud acoustically. Because of the construction, that'd be impossible. I'm wondering about acoustic tone rather than volume. If THAT was OK, then perhaps the pup system would be OK too.

I don't think there's any torque like you have with an acoustic bridge or a combo bridge/tailpiece on a solidbody.

Er... I don't see how an "acoustic" with very little acoustic volume could have good tone. Or do you mean the strictly electronic "tone" from the "acoustic" pickup etc?

[erikbojerik]

Acoustic guitars derive their sound from the string vibration driving the top via the bridge - so if you fix the bridge to a solid block that is also attached to the back, then any acoustic connection between the strings and the top is entirely sympathetic.

Not all that different from a hollowbody (cf. ES335) except you might get a little more of that hollowbody warmth. You won't get hardly any acoustic sound out of that soundhole.

[Mickguard]

MICK: IIRC, those longhorns were a Dano product. If so, those were a wood frame with a melamie top & back. I'd equate those more closely with a semi- than a hollow solid-body.

No, sorry, I wasn't clear. It was actually a Coral longhorn (made in Japan, but sold by Dano?) --it was a true archtop construction, not at all like the Danos. Quite nice construction too, but I just didn't feel like carrying through on the project, so I sold it on.

[avengers63]

Acoustic guitars derive their sound from the string vibration driving the top via the bridge - so if you fix the bridge to a solid block that is also attached to the back, then any acoustic connection between the strings and the top is entirely sympathetic.

Not all that different from a hollowbody (cf. ES335) except you might get a little more of that hollowbody warmth. You won't get hardly any acoustic sound out of that soundhole.

SO...

I can have 3/8"-1/2" sides & back, and it wouldn't effect the overall sound because the acoustic part is driven by the vibrations of the top.

The sides/back of an acoustic are braced because of the thickness (or lack thereof) of the wood.

Therefore I can have an 1/8" top and not have to worry about bracing, right? The only caveat is that I cannot have a block under the bridge because it'd dampen the vibrations.

If I have thicker back & sides and a thin top WITHOUT a block under the bridge, what does that do in regards to the security of the bridge? Say there's a screwed-on tailpiece. Would there be enough transfer of energy? What about an archtop style? I couldn't see there being enough wood to securely hold a TOM, so whatever is used, it might have to be secured somehow other than posts/bushings.

[guitar101]

Acoustic guitars derive their sound from the string vibration driving the top via the bridge - so if you fix the bridge to a solid block that is also attached to the back, then any acoustic connection between the strings and the top is entirely sympathetic.

Not all that different from a hollowbody (cf. ES335) except you might get a little more of that hollowbody warmth. You won't get hardly any acoustic sound out of that soundhole.

SO...

I can have 3/8"-1/2" sides & back, and it wouldn't effect the overall sound because the acoustic part is driven by the vibrations of the top.

The sides/back of an acoustic are braced because of the thickness (or lack thereof) of the wood.

Therefore I can have an 1/8" top and not have to worry about bracing, right? The only caveat is that I cannot have a block under the bridge because it'd dampen the vibrations.

If I have thicker back & sides and a thin top WITHOUT a block under the bridge, what does that do in regards to the security of the bridge? Say there's a screwed-on tailpiece. Would there be enough transfer of energy? What about an archtop style? I couldn't see there being enough wood to securely hold a TOM, so whatever is used, it might have to be secured somehow other than posts/bushings.

I just measured my semi acoustic electric guitar. The top is .128 of an inch. .125 is 1/8th. I haven't had any problems with it. The top is the same thickness as my acoustic. Mine appears to have a solid block running from top to bottom of the body holding the pickups and the bridge. I think you will get feedback problems with no center block but i am no expert.

[fryovanni]

Kinda confusing topic with all the variations out there. I think you have to look at the function of different designs and of course the major performance difference. To break down the four general designs; Flat top acoustic, Hollow body(archtop), semi-hollow(speaking to the 335-ish style), and the chambered. Without trying to nit-pick the definition of semi-hollow v.s. chambered, lets assume the chambered is simply routed pockets introduced into a basic solid bodies design.

Flat top acoustic. The concept is to transfer as efficiently as possible energy from the strings to the vibrating soundboard. The transfer is through a bridge is attached to the soundboard with the bridge being the anchor point for the strings. The size and structure of the box are critical to the performance. The air in the box is also a critical part of the performance as it effects the way the surfaces of the box vibrate. Key concept though is to transfer the energy from the strings to set the box in motion, thus moving the air about the box(move air=sound waves).

Hollow body(archtop). Similar concept to the flat top acoustic, you use the box to move air about the box. The archtop uses a different style of bridge/string anchor(strings are not fixed to the bridge, instead the tail of the body) to transfer the energy. This design uses more downward pressure as opposed to the rotating motion of a flat top bridge. Because of this the structural design differs from the flat top. Both a flat top and Hollow use plates that are similar in thickness(close to 1/8"). Bracing, F-holes, recurve, depth, width of the lower bout and so forth are very different than a flat-top. Of course the sound is very different, and there are many factors that contribute to that difference.

FWIW; The sides of an acoustic instrument are generally a strength and support element(although weight may motivate pushing the minimalism). A banjo uses vibrating surfaces and very rigid sides for example. You could certainly route away material to use as sides as is sometimes done with chambered solid bodies, although it would be a huge waste of wood and would likely need to be on the heavy side because of all the grain runout.

Semi-hollow(335-ish). Introduced to allow for the use of pickups without having major issues from the thin plates of an acoustic instrument sypathetically vibrating as much. The bridge design of course serves the purpose of anchoring and of course intonating, but is not primarily designed around the transfer of energy to a vibrating surface. Since an electrified instrument does not produce sound by moving air about the box, instead inducing current flow via the pickups. The transfer of string energy to the body serves only to modify string vibration(the body does not produce current flow per. sey). So you have a very different dynamic and set of goals with an electric. You can't deny the design of a semi-hollow does have an effect on the sound v.s. a solid body. It would seem that the body design when as structurally different and different in terms of density, you get a modification in the way the strings vibrate.

Chambered solid body. Generally lighter, but minimal difference in the size of the body or strength. Usually uses a typical style electric bridge.

So when you start to think about mixing some of these elements. Keep the function in mind, what are you using to generate the sound. If it is string to pickup, focus on what you are doing to the strings vibration. If you want acoustic volume, then focus on optimal efficiency of the transfer to and use of string energy by the box. Just because one style of bridge works well for say an acoustic flattop, that does not mean it will perform in a similar fasion on an electric(the functional goals are just different). Of course even if it doesn't perform in a similar fasion, you may like the way it does effect the performance(just depends). It is a good idea to get a realistic understanding of what will work structurally, so you know certain limits. Remeber an acoustic flatop generally is loaded with more string tension than electrics, and the strings are anchored on a lightly braced soundboard that is usually less than 1/8" thick Spruce. You shouldn't drive yourself nuts with overthinking some of this stuff though. Go with your concept, trust your gut, and see if you may a great sounding instrument.

[psw]

That's a great overview...fry'

I am a little confused about what is being tried to achieve here and in other recent posts. I suspect we are looking really at an acoustic instrument looks with electric performance. However, much of that can be achieved with a completely solid guitar to some extent. By this I mean, if you are looking at undersaddle piezo pickups...these take the signal directly from the bridge, if using electric strings this will create even less of an acoustic response...with magnetic pickups...well that's again electric. I doubt you'd get much of an acousitic sound at all...but perhaps that's not the intention...if not, a lot of it may well be cosmetic without a lot of "science" involved relying a lot on the pickups and preamp eq to get the primary sound.

A lot of the acoustic features (soundholes, reactive top) may even begin to work against or restrict it as an electric instrument (possibly feedback and such). It could work out ok, but with a lot of these things, it may be only ok and a master at neither acoustic, acoustic electric or straight acoustic...

but hey, never know if you don't have a go. There are a lot of variations out there to draw inspiration from...sounds a lot like the old gibson chet atkins concept in many ways...perhaps check them out. None of these things seem to have made a big commercial success...maybe the parker fly or something...JohnH at GN2 has recently done some great work on the electronics and a very convincing cheap piezo in a strat that sounds quite convincing...just showing it doesn't need the chambering necessarily at all.

I guess this begs the question as well...how would you intend to mix, control and manage the two pickup systems?

pete

[avengers63]

Excellent information Fry. Thank you very much.

I guess this begs the question as well...how would you intend to mix, control and manage the two pickup systems?

Either an on/on toggle switch or a blend pot.

I suppose the absolute bottom line of what I'm trying to find out is how close you can get a solid-body, or chambered as it bay me, to sound like an acoustic without going semi- like a 335.

Functionally, the end hope is twofold. 1) If it sounds nice enough, one could switch from electric to acoustic immediately. 2) This would, or at least should end up being a really sweet, mellow sounding guitar.

Let's make some design assumptions:

1) 2" - 2 1/2" hollowed out mahogany or sapele body with the back & sides 1/4" - 3/8" thick

2) solid block extending from the neck pocket for the meck pup - a mini hb or a jazz hb of some type

3) 1/8" spruce top with an acoustic soundhole in the center

4) no block under the bridge, or at maximum a small block attached to the top - no direct contact with the back

5) acoustic pup system

Questions:

1) What is the structural function of bracing on the top?

2) Does the top need bracing? If so, how thick can you go before you don't need it but still have it thin enough to vibrate?

3) What type of bridge do you use for this type of hybrid and how is it attached?

[Mickguard]

2) solid block extending from the neck pocket for the meck pup - a mini hb or a jazz hb of some type

How about a floating mini-humbucker, the type that attach to the neck. They're more for archtops (you need a lot of clearance for them, but it could be interesting-- you could position the sound hole at the end of the neck, for example, the mini would float over that. This way you'd be really close to an acoustic top.

From what I've read, bracing has a pretty important function in helping to balance the tone.

[avengers63]

That's not a bad idea at all. To help with the clearance issue, the pup could be basically hanging in the soundhole at the end of the neck. BUT... what would that do to the feedback issue?

[psw]

Hmmm...either I am not understanding the intention, or...I don't know...

A 335 has a very poor acoustic tone...it's not an acoustic guitar at all.

All the same...you may well like to check out JohnH's recent work in the $3 peizo thread over at GN2 LINK

There is a lot more to mixing mags and piezo systems that a simple switch as you might with similar mag pickups...active electronics are a must with peizos and a lot of the quality of sound is reliant on the circcuities compensation.

On johns strat with a cheap piezo on the metal tremolo block...you can see the work required to make this work and how effective it can be if done right without requiring chambering or typical acoustic appointments or concerns.

As so much relies on the pickups and electronics in these things...it shouldn't be treated lightly and preferably be the starting point in a design.

...

I should pull my finger out with the jazz strat project...I have a 4 band commercial eq and piezo thing for it, but combining the mags with it is still going to be tricky. I am sure though with it's true acoustic design, it will feedback at any major volume...but then I'm not attempting anything new in that department.

[Geo]

Questions:

1) What is the structural function of bracing on the top?

2) Does the top need bracing? If so, how thick can you go before you don't need it but still have it thin enough to vibrate?

3) What type of bridge do you use for this type of hybrid and how is it attached?

If you're asking what the function of bracing is... honestly, you may not be ready to design a guitar like this.

This connects to what Fryovanni said... the function of the bracing is dependent on the way the strings are attached. On a flat top, the bridge is being twisted by the strings so that its rear wants to rise and its front wants to break the plane of the soundboard. So the bracing's job is to keep the top from flexing in this way. On an archtop, the strings are anchored behind the bridge, so the bridge only experiences downward pressure. If I remember right, archtops usually have two braces on the top (like on a violin). Their job is not to counteract torque (there is none) but to strengthen the domed top and keep it from collapsing.

[fryovanni]

Excellent information Fry. Thank you very much.

I guess this begs the question as well...how would you intend to mix, control and manage the two pickup systems?

Either an on/on toggle switch or a blend pot.

I suppose the absolute bottom line of what I'm trying to find out is how close you can get a solid-body, or chambered as it bay me, to sound like an acoustic without going semi- like a 335.

Functionally, the end hope is twofold. 1) If it sounds nice enough, one could switch from electric to acoustic immediately. 2) This would, or at least should end up being a really sweet, mellow sounding guitar.

Let's make some design assumptions:

1) 2" - 2 1/2" hollowed out mahogany or sapele body with the back & sides 1/4" - 3/8" thick

2) solid block extending from the neck pocket for the meck pup - a mini hb or a jazz hb of some type

3) 1/8" spruce top with an acoustic soundhole in the center

4) no block under the bridge, or at maximum a small block attached to the top - no direct contact with the back

5) acoustic pup system

Questions:

1) What is the structural function of bracing on the top?

2) Does the top need bracing? If so, how thick can you go before you don't need it but still have it thin enough to vibrate?

3) What type of bridge do you use for this type of hybrid and how is it attached?

Maybe a good answer to the main question you are posing is to look at what has worked well so far. Much success has been had with piezo systems on solid bodies. It may be that the piezo lends itself to a better platform because of the way it generates the signal, or it may be that it provides a signal that is easier to work with on the pre-amp side. Kinda takes the fun out of toying with non electronic design elements. Some builders are finding they are really happy with the results they are getting from blending more acoustic design elements into pickup based electrics, but I don't think their main goal is to emulate an acoustic guitars responce as much as explore an appealing modified electrics responce. I think you just need to figure out what it is you honestly want. If you want to try to get a very convincing acoustic sound from a high quality electric at the flip of a switch. Then a well built pickup loaded solidbody with a discrete(does not harm the performance of the electric) and convincing piezo system would seem to be reasonable(pretty straight forward). If you want to explore new avenues and possibilities then experimenting with design elements may lead you to something appealing and different.

In your list of 5 assumptions, you have basically said you want to build a shallow bodied acoustic guitar(size/shape of the body/soundboard is not real clear), with a pickup attached in the neck position(this is much like a neck mouted pickup, which is done, so you can get a feel for the results), and you want to add an "acoustic pup system". There are a lot of options out there for acoustic pickup systems. Some use mics, some differnt types of piezo(mounting location varies), and some use accelerameters(SP?), and of course pre amps vary. It seems to me that if your goal is to make an acoustic that performs well and you want to capture as best you can that performance, you should build a good sounding acoustic and add a neck mounted pickup. If you create a cheap sounding acoustic and capture that sound, it seems counter productive. I think it really comes down to the electronics system you choose to develop the acoustic sound(like I mentioned some systems really kick butt on solid body guitars).

With regards to your questions;

1. To keep the soundboard from distorting and collapsing under string tension, and still allow the soundboard to utalize the string energy as efficiently as possible.

2. Yes, because bracing provides significantly more strength per. weight added to the soundboard vs simply using a thicker soundboard(it is extreamly efficient). If you were to use a solid plate it would likely need to be between 3/16" and 1/4" thick(depends on the Spruce that is used, size of the box, and gauge of strings). It would be very inefficient and likely would not sound very pleasing acoustically(even a solid body vibrates, just not enough to move a lot of air).

3. An acoustic guitar uses a glued on bridge generally, although mechanical assistance(pins, nut and bolt) are occasionally used, but these tend to add mass and reduce efficiency.

[dpm99]

I also think you can learn a lot by seeing what's been done.

Probably the most widely purchased is the Taylor T5. Building on the Taylor Expression system, it uses a single body sensor located an inch or two below the bridge, an acoustic mag pickup buried beneath the fretboard, and a stacked humbucker in the bridge position. (It looks like a lipstick pickup, but it really is a humbucker.) This is what I play most of the time, and in my humble opinion, it's better at electric tones than acoustic ones. Run it through Taylor's K4 equalizer (a $500 investment, unless you get a deal), and it gets better, but still not awesome.

An interesting variation is the Crafter SA. Crafter pretty much copied Taylor's design, but they put in an LR Baggs piezo pickup system. Reportedly, the acoustic sound is better than the Taylor guitar it copies, and it's much cheaper.

The thing about a piezo pickup that I find interesting is that it sounds pretty similar from one guitar to another. A cheap guitar and a high end guitar sound pretty much the same. That's why piezo bridge saddles sound good. As long as something's vibrating, you get a pretty good piezo sound. That brings me to my next example.

The Parker Fly is, I think, the best representative of a hybrid that uses a piezo pickup successfully. It's an electric guitar with piezo pickups build into the bridge saddles. Most of the big acoustic pickup builders are now making bridges just like this. Because these are typically six individual piezo pickups, you can run it hexaphonically into a synth.

A poorer attempt at the same thing, in my opinion, is the Ovation VXT. It also uses a piezo bridge, which is fine, but I guess I expect more from a company that's been making acoustic guitars for as long as they have.

Then there's the Anderson Crowdster Plus. To ears, this one actually sounds better as an acoustic than it does as an electric. A lot of that is probably because this is the only one mentioned so far that uses bronze strings. They built a humbucker designed for bronze strings that's unlike anything else I've heard of.

Finally, there's the Ibanez Montage, which is your basic acoustic guitar with a humbucker stuck right where you'd expect the soundhole to go.

I think it's helpful just to search for each of these on YouTube and see what they do. You can learn a lot that way. Obviously, there are a lot of hybrids out there I didn't mention. But that covers the major types of hybrids I know of. In the end, this is mostly experimental stuff. Like Rich says, you just have to have fun building something, and see what it sounds like when you're done. If you'd like me to point you toward some interesting reading I've found, let me know. Can't wait to see your build! Since you do build so much faster than me, I'm sure I'll learn a lot from it your build that I can apply toward mine.

-Dave

P.S. Oh yeah! Final example: Mikro's reso. From what I've gathered from him, a cone is a great substitute for a traditional soundboard.

[psw]

If you don't mind a post just generally addressing the "hybrid" idea...I can add a few random and more off the wall thoughts...

To me the hybrid concept is just that...neither and electric or an acoustic guitar. Once that is accepted, then there is a huge variety of options. If the pure acoustic sound is discounted as is implied here really...if you want an acoustic sound and response, there has been a huge amount of research and tradition in that none or which engaged in hollowed out solid bodies.

On the difference in flat and arched tops and their bracing. I think of an archtop as 'bouncing' and offering a lot of projection where as a flat top works by a complicated twisting of the plate. The bracing here is paramount for both strength and allowing and balancing this twisting motion. Neither are particularly good for something that is primarily and electric instrument.

Piezo's are electric pickups...they are an alternative to magnetic pickups...but they are still electric. A piezo creates a signal by mechanical means by the string vibrations sensing the pressure of the string on the bridge...or sometimes the vibrations in a top or even in the neck joint (something I have done a little work on)...while magnetic pickups sense the string vibration at some point along the string. The characteristics are different, and important piezo thing it the typically high harmonic content that needs to be toned down to be natural. Typically a bridge piezo is sensing very little if any of the guitar's wood...as an electric, this kind of thing only encourages things like feedback and not add very much to the acoustic response.

Once you discount the acoustic sound and treat all the pickups as electric or electronic in nature. Then the normal acoustic constructions kind of go out the window. You could go completely solid...but compared to an acoustic, the attack and sustain is often not really like that of an acoustic guitar. This is one reason why you might want to consider more a traditional construction...or perhaps a hollowed out body but with thin top and bracing and bridge type to edge it more towards an acoustic guitar.

Another 'off the wall' aproach would be something with an exoskeleton. In manyways this is what the fly has done...an extremely light guitar, some made out of spruce...with an outer hard shell of glass and epoxy. This could potentially give the fly a much more acoustic like attack and harmonic content like a chambered guitar. You could make such guitars out of almost anything...balsa cored for instance...as the strength is largely in the outer shell. Not being strictly hollow has some advantages while offering a lively guitar.

Here is a memory from my childhood. I used to make and design model aeroplanes. Once I made a wing from polystyrene with a very thin outer layer of balsa (1/16" perhaps) with no internal struts or anything. Not only was the thing incredibly light (and resonant as I recall)...it was strong enough to stand on!

Of course balsa is a little soft and fragile for an outer coating on a guitar and some parts would need reinforcement...but you could devise very similar constructions with veneers over a soft core of something like balsa or even foam (as long as heat doesnt melt it).

This kind of thing I would expect give a more acoustic attack and sustain characteristics but still have some feedback damping. Of course...you don't get an electric guitar out of it at the same time.

All in all though, everyone seems to be on the same page with this I think and there seems to be some interest of late with other projects and even questions to me about what little piezo stuff I have played around with.

While chambering would appear to be a lot easier than bending sides and everything...I am not sure about the incredible wood wastage for the perceived result. I am all for the idea of lightweight very resonant guitars though...I think a lot of shredders have enjoyed the response of light basswood guitars for instance for this very reason and the ability to easily get controlled feedback...even if they don't use a piezo system.

This is another aspect to...for all the perceived benefits...there are few 'hybrid' players. Even fly people seem to rarely use the 'acoustic' side of things to any great degree (correct me if I am wrong) and there are a wealth of hybrids to choose from. Adrian Legg one of the few truely hybrid specialists I can think of...light electric strings on an acoustic through mild effects...or more lately a custom piezo solid body. If you can get a hold of his first instructional video, he talks a bit about his approach to the 'hybrid' guitar.

It's kind of odd, cause the idea seems to hold a lot of promise. Personally though, if you want to make a hybrid it would be more convincing and acceptable if it didn't look like either one I think. Making it look acoustic with rosettes and sound holes might offer false promise...making it look like an electric but sound like an acoustic always seems to be odd, even if the performance is up there.

But, generally people like things to look like they sound. So, if you are looking for a jazz style thing, I'd be going for something that looks like a jazz guitar I guess...if it is something you are going to be strumming out c&w or bob dylan, then you are probably going to want it to look like a flat top.

One thing that isn't exploited but really sounds great...what I look for in hybrid ideas of mine...is something that combines the electric and acoustic sounds. This is something only a hybrid can do and is perhaps where some real magic lies. I had a neck piezo in a strat for a bit and I got a very acoustic fast attack full of complex harmonics that quickly gave way to a smooth electric tone. It also made the inbetween strat sounds even more delicate and complex as well. Mine was not quite as convincing as JohnH's...I don't know if he still has the earlier sound samples up...but the first ones sounded really bad...but a little tweaking of the eq really made it come to life for this guitar and integrated the electric and acoustic sounds really well.

Anyway...as I say, some random thoughts. I don't think that a guitar that looked kind of acoustic but was in fact a chambered electric would have a lot of appeal...but if the guitar is purely for yourself, maybe you could make a fine personal instrument for your personal sound and look.

I am still thinking about these kinds of things...my own presently stalled, jazz strat thing was intended to be an experiment along these lines and a bit of fun...it could even have a decent acoustic volume (if not a quality sound) for practicing. What I'd really like to develop though is a hybrid that is more electric in look and feel and treated the piezo as a different type of electric pickup in it's own right...not an 'acoustic' at all. Perhaps the closest thing like that is the modeling Variax that has no magnetic pickups at all.

pete

oh...ps...I forgot a technology that is never really talked about but went no where. There has been attempts (before piezos) to use magnetic pickups to pickup top vibration. How it worked was to put a thin metal sheet on part of the top and inside the guitar a magnetic pickup...this pickup would sense the movement of the top (not the strings) alone. Something like this does require an active acoustic top and would probably work well it the motion of an archtop. Ancient technology, but maybe it's potential was never really explored.

Edited November 26, 2008 by psw

[Southbound]

I've been following this one cos I really like the idea of a nice hybrid guitar myself.

It seems to me the aim of a hybrid is is to get 2 sounds that are traditionally produced in fundiemntally different ways.

So either the instrument works in 2 totally different ways (which is presumably what Avenger is wanting to acheive)

OR you get one sound the traditional way and "simulate" the other (like the electric guitar with the piezo)

It's seems like the later is the infinitely more simple way to go about it.

HOWEVER the thing that grates on me somewhat is that the concept of "simulation" brings to mind thoughts of synths and digital effects...I know yuk! RIGHT!

Most guitarists seem to be traditionalists at heart (why do you think we'd rather have a guitar build in the 50's rather than one built yesterday with the same materials and techniques)

So shouldn't we all get over ourselves and start using whatever technology creates the sound we want instead of trying to cling to the traditional ways (I'm totally guilty of this myself...I'd give my right nut for a '52 Tele instead I'm settling for spending a fortune on a '52 reissue)?

In a nutshell you'll never get both the sounds without compromise..somethings gotta give. That begin the caseyou might as well simulate.

So...to simulate you need to know:

1) what you want it to sound like

2) what you can produce with existing technology

3) and what the difference between the 2 is

Only then can you even start to get the sound you're looking for.

So my question would be:

What acoustic guitar do you want to simulate (give yourself a ball park to start in)?

How close can you get to it with existing technology?

and what is the difference between the what you're getting from you're existing technology and the Acoustic sound you want?

Then you can start to think about how to do it.

(I've got my own ideas about these questions..but this ain't my thread)

Sorry i haven't given you any answers with this post (I hate it when people do that to me) but I hope I've posed some new questions that might help you get where you wanna go.

[erikbojerik]

In a nutshell, the idea behind a flattop acoustic guitar top is to thin it and brace it so that it is very responsive to string vibration yet still holds the string tension - basically designing it almost to the point of collapse, and then keeping it there. Getting a top like that to sound good, and stay stable over time, is the holy grail of acoustic guitar building and is what all acoustic builders are striving for every time they build one. It is a continually evolving art.

IMO it is much easier to try to get the best acoustic tone you can out of a solidbody or chambered/semihollow instrument. There is a LOT of experimenation you can do with piezos - you will (for example) hear a distinct difference between a transducer piezo mounted directly on a Strat trem block, and one mounted on a 1/8" thick sliver of spruce mounted onto a Strat trem block - now substitute different woods, etc. Now move the piezo transducer to difference places on the guitar - use multiple transducers - you see where I'm going.

Then there are undersaddle piezos or individual-saddle piezos (like Graphtech/Ghost) - on any acoustic guitar with an undersaddle piezo, you will (for example) hear big differences in tones if you replace a plastic saddle with a bone saddle with an ebony saddle. You could also mix/blend piezos (undersaddle + transducers).

Finally, you could just transplant the saddles and electronics from a Variax acoustic into a solidbody and get a digitally-modeled acoustic tone. Many ways to go here.

[avengers63]

My original theory is to see how close you can get a solid-body to react & sound like an acoustic. In my mind, if you can get a middle-of-the-road acoustic sound from a hollowed-out solid-body, then the rest can be shaped up with the EQ. This is the type of "acoustic pup system" I've had in mind. Not necessarily this system, but this type of system - the side mounted acoustic preamp box.

http://www.fishman.com/products/details.asp?id=91

I already have the Boss Acoustic Simulator pedal. It actuallt works VERY well. Via technology, I CAN make my electric sound like an acoustic. That's not what I'm thinking about.

What's going on in my mind is: A chambered solid body with a mellow pup in the neck sounds really sweet. We already have the hollow chamber, so let's see what we can do with it. If a sound hole was introduced, how much of a true acoustic quality would it have? This leads into thinning the top, putting in an acoustic preamp, etc.

The thought of useing a piezo-TOM is 100% not the way I'd go with this one. That's immitating an acoustic tone. I'm thinking that with a hollowed out body, there will be some there already, so let's see what we can to to enhance it without going full on semi-.

Where I'm at right now:

I know virutally nothing about bracing. Geo pointed out this reality. Honestly, while I'd like to learn about it, I'm not in that place right now, so if it involves bracing, it's gotta go. I still like the idea of the acoustic preamp though. With that ni mind, let's make some more design assumptions:

1) 2 1/2" - 3" thick solid body that has been hollowed out with 1/4" - 3/8" back & sides.

2) 1/4" top w/ soundhole

3) acoustic preamp system, neck pup

With these in mind, what would be the anticipated result and/or pitfalls?

[psw]

Personally...I think there are too many things that are not understood or taken on board yet...and that there's some fundamental misunderstandings of what a peizo system is and works and it's limitations and requirements.

A chambered guitar...especially with something like a 1/4-3/4" top held rigid all around by a chambered body is really just a light electric and has no real value as an acoustic guitar. It might have some more complex harmonics than a very solid guitar...but you can get similar effects with different woods (the quick attack of a tele vs the smooth tone of an LP vs the hollowed out sound of a strat (really a chambered guitar when you think about it with all that wood removed in the spring cavity and somtimes a huge pickup and control route or a 355 (really a solid body with hollowed wings))).

That's ok since you are proposing something like that fishman with a computer controlled eq (image settings) or something similar with extensive eq for instance...in this way it is like any other electric guitar and you get into how much of an electric guitars tone is in the wood and shape and such, and how much is in the pickup design, placement and quality.

Generally this debate falls significantly on the side of the pickups having the larger size of the "tone equation"...a piezo system is no different, some sound good, some sound bad...and a lot rely on mounting and placement and eq.

As far as the chambered guitars are concerned, there is a lot of mojo involved and making it look like an acoustic guitar could be adding even more...don't swallow all the hype about it. A real acoustic that might sound great with a bad piezo system will sound worse than a solid body with a well designed and properly compensated system.

There is a similar thing with these neck mounted "jazz" pickups...a lot of it is a factor of history. In order to add an electric pickup to the old jazz boxes without cutting into them, they came up with these kinds of things and they became a bit of the jazz sound. However, a lot of this smooth jazz tone really comes from the technical fact that they wanted a clean tone and had space restrictions on the design and so often they used small coils and magnet structures resulting in very low powered, low impedance pickups...very clean and accurate and mounted to get that typical fundamental dominant sound typical of mounting the thing way up at the 20th fret.

...

The other important thing with piezo and hybrid use is the type of amplification being used. A typical guitar amplifier is designed for using magnetic pickups and not active piezo systems...certainly not ideal for both at the same time and a compromise at best if used alternatively without channel switching as well. To really get a convincing "hybrid acoustic/electric sound" you really need to use two completely specialized amplification systems. Not many really do have this capacity and there is nothing much or anything on the market that could do both well.

...

So...what I am trying to advocate for people is to look at a peizo system as a different kind of electric guitar pickup...not an "acoustic" pickup. Just like a magnetic pickup, it is picking up primarily the string vibrations and turning them into an electric signal. Typically, and to a large extent in the way they are typically mounted directly to the bridge or picking up the signal transmitted from the bridge into nearby wood (as with a bug style) and as a result have a very fast attack, extreme high end and extremely high and complex (not necessarily good) high order harmonic content...to our ears this sounds "acousticy" but only good or more "realistic" after some modification to tone these characteristics down (removing the out of tuneness of over accentuated high order harmonics and things like 'quack'). Often a solid, or more solid bodied guitar will aid in toning this down over a true "acoustic guitar".

...

Now...if that can be accepted as 'true'...then it really doesn't matter a whole lot if it is solid or hollowed or a braced traditional top...a TOM bridge, a trem or an acoustic style bridge. So much relies on the marriage between the pickup mounting and tone shaping and the amp, that a lot of these guitar design ideas are secondary really...IMHO.

That's not to say you shouldn't build an electric guitar that looks like an acoustic with all the rosettes, fuller body and chambering that you want...but it will still be an electric guitar and a peizo another form of electric guitar pickup.

...

There is some ergonomic things about playing an acoustic guitar that is neat though. Light weight and a body that better puts the guitar into a playing position when sitting down, something that extends away from your body instead of almost a plane to it...often thais can feel a lot more comfortable to play and possibly inspire you to play in a different way...perhaps a more 'acoustic' style.

A long time ago (1983 to be exact) while studying music...I played an LP exclusively...but I found myself in a jazz band (bass, drums, acoustic piano, sax, trumpet sometimes...and me on electric guitar). Now, the LP can work as a great jazz guitar sound, but it's heavy and small and not so good if sitting down a lot in rehearsals or on a bandstand. I took the LP and enlarged the shape, attached a bolt on neck to some hardwood and built up the shape around it in light red cedar and put a bit of a 2d carve in it...then I covered it with teak veneer...and put a single neck HB I had around in it. The result was a very light, responsive guitar that allowed me to sit comfortably and play tricky jazz chords without cramping up the hand. It was as rough as all get out, but it sounded ok, looked ok (at any distance) and worked fine for doing that. I have to admit, that in concert and in a standing situation, I still went back to the LP...but ergonomically it was a lot better and I neer had to worry about anyone wanting to steal it off the stage

...

Anyway...just a few more personal opinions for the number of people with an interest in this area and to consider with this project. My only "concern" is that the concept might "ape" an acoustic guitar and may well not be convincing as an electric or an acoustic...certainly if you are thinking of making these things to sell...there may not be any real market appeal in this even with a lot of "spin"...and to get people to consider the peizo as a very interesting and valid alternate form of electric guitar pickup from the magnet and wire version.

pete

P.S. The combination of the two systems also need very careful consideration...it is the same kind of problems you would encounter if you put an active EMG and a passive SD in the same guitar...problems...to do it properly you need to buffer the mags and provide a mix with the preamped piezo...I am thinking of variations...but generally this is necessary.

[Mickguard]

Now, I really don't like the sound of acoustic preamp systems. They just don't really sound like acoustic guitars anymore. I mean, sure, they're helpful live, but I still like the sound of a miked guitar better. Just more natural sounding.

Hmmm....I wonder if this exists? Instead of a pickup integrated into the guitar, some kind of removable rig that positions a mike (or mikes) to capture the guitar's sound. You'd want it not to interfere with strumming/picking, obviously. And it should be positionable to accommodate the individual guitar.