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This is a continuation from my partial hijacking of this thread, about a crazy newbie idea I've been thinking about.

I made up the name "piano harp guitar", because the idea was to take a harp guitar, and make it longer, similar to the way grand pianos get longer to increase volume and bass clarity. The current design has 20 strings; 6 bass, 6 standard, and 8 treble, and adds about 12 inches of body length to the lower bout, as well as a third soundhole down there. I could post my current mouse-drawn doodle, but I would probably be laughed at for how terribly drawn it is

Anyway, continuing from this post by Mike:

Yeah, I'm pretty sure I'll need longer and higher tension bass strings to drive the larger top. Not going to 40K lbs, but I can most likely get a fair bit higher than an acoustic bass guitar, since the strings don't need to be fretted. I'll have to run some experiments to figure out what's the most tension I can pull on different gauges of string before it gets uncomfortable to pluck. Definitely will need some CF rods inside the box, so I don't have to brace the top so heavily that it can't vibrate at all.

I do need to read up on existing harp guitar designs though, as well as guitarron. One thing I'm worried about is that the larger air volume and total mass will make the standard and treble strings sound bad. Maybe a larger harp arm would be a better approach, to keep the added mass more isolated from the standard strings. Or maybe that wouldn't make any difference.

From this site HERE

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So it would look like this?



Christian

On a more serious note:

Rather than increasing the box size, you could try to increase the active soundboard area by moving the soundhole, cantilevered fretboard, lattice bracing, etc. such as some luthiers have tried with 'regular' steel-string (and classical) designs.

An example would be this:
http://theneoteric.us/lattice_bracing_system.htm

Just a thought...
Christian

I just finished making a 'true' harp-guitar: the sub-bases pull upward on their soundboard as harp strings do, rather than being parallel. The Dyer style shown in the picture is a 'zither guitar' organologically, since the strings are parallel to the soundboard.

The basic problem with harp guitars is simply physical, and, as Scotty said: "Ye canna brreak the laws o' physics, capt'n!" The low G bass string on my harp guitar is tuned to about 49 Hz, and sound from it has a wave length in air of about 23 feet. To make that sound with any sort of efficiency, you need a speaker/soundboard 5 feet or so in diameter. The instrument is just too small to do it.

When you can't have 'efficient', you can go for 'effective': driving a Hummer a half block to the store for a quart of milk is not efficient, but it is effective. Using a really fat, long string, with lots of tension, gives you enough power that some of it is bound to come out as sound. On my beast, the harp-type soundboard is reasonably effective, even though it's only 16" or so long, by 8" wide. You can actually hear that low string as a pitch, rather than simply as a 'thunk'.

Concert grand pianos are, in fact, large enough to be reasonably effective radiators of sound at their lowest frequencies. They are not very efficient, though: very little of the energy that the player puts into the string actually comes out as sound. Again, they use brute force to make the sound that they do: pianists work hard enough that they suffer from bad backs from pounding on the things.

It's interesting that the guitar seems to be one of the _most_ efficient of the musical instruments. It has to be: we're dealing with such small amounts of power that if it was not there would be no hope of hearing it at all.

Anyway, I have not had any luck posting photos here, but you can see my harp-guitar on the MIMF forum, under 'Other Stringed Instruments', in the $100 Challenge. There is a pretty good build log, too, if you've a mind to make a copy.

I just went over and looked at the REAL harp guitar Alan .. BRAVO .. that is really a work of art and engineering ... If anyone hasnt been to see it, go NOW .. your head will spin ...

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

That is the absolute truth, Tony. It is a head spinning, and unbelievable instrument idea, that works. It's the reason he wears the term Luthier after his name! He's truly earned it.

_________________
Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

I wholeheartedly agree with Tony and Waddy. It's really incredible. What a great piece of Art!

I hope this link to the build thread works. If you haven't seen it yet, best go now:
http://www.mimf.com/cgi-bin/WebX?128@80.JsOKal6aFUC.36@.2cb6b96b

Christian

Alan, I wondered when you would chime in. Reduce the pixel count of your images to about 20% and they should post here. Use Gimp, Photoshop-like and is free! I have to admit ur harp is ingenious. I always wondered what you meant until I saw ur current design. Pics here please!

Thanks to everyone who has chimed in so far.

Alan: Wow, I just happened to stumble across your thread over there about a week ago. Indeed it is a wonderful idea, and an inspiration to creative instrument building. Certainly one of the most 3 dimensional instruments I've seen. I can only imagine the difficulty of getting it in your mind how to shape and bend all those pieces of wood to fit together that way

That is interesting that such a small soundbox can still produce very low frequencies. Do you think the direct upward pull makes a big improvement to the energy transfer from string to box? Oddly enough, mine is pretty close to 5 feet in its longest continuous run of soundboard, so maybe it can produce those low notes with some degree of efficiency.

I drew a better picture of the current design:

I decided to bump it up to 8 bass strings. I figure if you're going to build a bass monster you might as well have more strings to use it, even if it does mean more tension to deal with. I also removed the third soundhole for now (it was down past the bass bridge, on the tail area), since I'm not entirely sure it would improve things, and it obstructs the continuous soundboard run from bass tuners to tail. I may also move the harp arm soundhole to the edge, to increase the width of that run.


Christian: That lattice bracing is pretty cool. It looks like an awful lot of wood, but I guess it could be less than normal since they're all so thin. Definitely looks like it would produce a more evenly vibrating surface. I wonder how the bridge patch/string holes fit into that though? Maybe the guitar in that picture uses a floating bridge with tailpiece.
But if each of those lattice intersections uses notches in both pieces like a normal X brace... I think I would like a CNC machine.


And Andy, that picture you posted looks hard to play. Perhaps like a piano with all white keys

I do not understand. I thought the reason for the "extension" was to increase the string length (significantly).

Mike

PS: Christian, that pic of yours is a hoot!

It's a pretty strong bracing design. So you may be able to have the top a bit thinner and save weight.



There is no bridge patch/string hole. The lattice assumes one of the functions of the bridge patch (resisting the torque from the string pull). A bracing design like this implies the use of a pinless bridge. You can enter 'pinless bridge' into google image search for some examples.



It's really easy to make a lattice without CNC. See here:

http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=23892&p=325447&hilit=lattice#p325447

I'm not really that knowledgeable to talk about any acoustic properties of your design, but my main concern would be playing comfort. I couldn't rest my right arm where I'd like it to be...

cheers, Christian

Looking at your drawing, something I don't like is that the lowest strings are so close to the edge of the top near the rims. My lowest string on my banduras are also close to the rim and they sound rather thin. On my next couple of builds I'm making the soundboard a little wider to get it away from there. You may consider ditching the arm bevel and adding some real estate on the top near the bass end of the bass bridge.

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http://banduramaker.blogspot.com

Yes, the idea with the harp was that the strings pulling upward on the soundboard does seem to be more effective.

Another aspect of it was to get the stress of the sub-basses off the guitar soundboard. The extra torque load would require heavier bracing, which pushes it toward a 'treble' sound, just the opposite of what you're trying to do. It also cuts down on the power, of course. With this setup the stress of the harp strings is pretty much off the guitar soundboard, which can then be optimized to work as a guitar.

The drawbacks of the harp-guitar setup are that there is less opportunity for 'cross talk' between the two, and more chance that there will be an unacceptible difference in timbre. The question that the prototype was built to answer was whether there would be enough of an improvement (if any) in the sub-bass output to be worth it. So far, I'm happy, but the real jury is still out.

U know, the original Dyer is quite a real estate beast. Modern makers have trended to smaller bodies. My first harp is faithful in size (though not the neck joint). It has no trouble putting the sound out. And sympathetic resonance is amazing.

Mike: The main goal was to increase the longest continuous run of soundboard, on the theory that it could produce longer wavelengths more clearly. I may increase the length of the bass strings as well. That depends on the results of the tension-comfort tests, as well as whether I can find a source of strings that long.

I've never actually played a harp guitar, but a lot of recordings, the lowest strings sound muddy or "metallic", like a big heavy steel string vibrating, not so much a smooth wood vibration sound. Sort of like the low keys on a small piano, or most acoustic bass guitars unplugged.

Increasing the soundboard length may be entirely ineffective though, without also increasing the width of that area significantly, which is not really practical. It could be that a Dyer has plenty of soundboard area, but just too much bracing keeping it from vibrating freely at the longer wavelengths. So maybe before trying the giant one, I should try a lattice braced Dyer-sized instrument.


Christian: Ah yes, pinless bridge. And how sad, that I couldn't think of such a simple method to cut the notches for a lattice...

As for playability, I think I'd be ok. I have long gangly arms that have no trouble reaching around a jumbo. But, with the guitar's neck angled upward a bit so your arm isn't held up too high, the harp arm might end up in your face, not unlike that somewhat ridiculous looking harp-guitarron picture...


Andy: Good point about the strings near the edge. I think I would rather lose a bass string than the bevel though. Playing comfort will be one of the main challenges, without a rounded lower bout to rest your arm over. Might ditch the top one or two trebles too. They would be pretty hard to reach anyway, and I do think too many strings can be a bad thing.

You think 26 strings are too many?

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I too have wondered about Michael Hedge's metalic sound. My harp does not sound like that, but I have no pickups yet. Maybe you should try listening to some Stephen Bennett songs.

I do realize that this is an old, old thread, but may I suggest that you do a search for a theorbo or an archlute? For example: http://richardsweeney.com/an-18th-century-theorbo/

Old indeed! I'd just started on my first guitar when I came up with this thing

I've never been particularly fond of the theorbo design. That neck is way too long. Heavy and cumbersome. Plus it puts the plucking point proportionally closer to the tail on the longer strings, which is the opposite of what I'd want for bass strings. And I like the extra resonance of the hollow arm on harp guitars. Although Michael Thames has had good results with a more lute-like neck extension rather than the hollow arm https://www.youtube.com/watch?v=ir9Ur-K06TI

One thing I've pondered for the piano harp guitar is to extend the bass strings so they attach farther and farther toward the tail. Lengthening the strings for the lower notes, spreading out the force, and putting the plucking position closer to the center for the low notes. With clever design of the bracing to incorporate the long, curved bridge as a brace, it might work reasonably well. Especially using a relatively lightweight wood like walnut for the bridge.

If I do ever build it, I'll probably rearrange the overall design to be more like my regular harp guitar. 7 bass strings, no super trebles, 12 fret neck join, planetary gear pegs for the harp headstock so it doesn't have to stick out so far. Not quite as piano-like without the trebles, but since the primary goal is to get some decent power in the 40-80Hz range, being able to lighten up the bracing would be a good thing.

That tube link , eventually I ended up with Pat Metheny playing a 42 string guitar . Thanks!

An ANCIENT thread, by 'net standards!

I've made two other harp guitars since this thread started; one just shipped today. They're really the usual 'zither guitar', but with some differences from the Dyer style that seem to help.

The basic issue with any harp guitar is that a soundboard smaller than that of a double bass just won't be efficient in producing those low notes. Since it's impossible to reach around a double bass, you're sort of stuck.

My hope was that the 'real' harp soundboard for the sub-basses would be effective, even if it wasn't efficient. It turned out to be better than the usual Dyer style, but not by all that much. It also came with a couple of drawbacks.

One was the issue of a case. That's bad enough for the Dyer style instruments, but that thing was much trickier. Another was that the sub-basses were backward relative to the usual harp guitars, with the lowest string nearest the fingerboard, rather than furthest away. Most players found it counter intuitive. It's also harder to record. We never tried to put in any pickups, but I imagine those would be harder too.

One thing that did work out well was the idea of a separate sound board and sound box for the sub basses, linked to the main box by a narrow neck. The two that I've built since have both had that feature. You can see one on Ken Bonfield's web site. The added resonating chamber and soundboard make for a more complex tone, and even the small additional soundboard area that can be put up top helps with the bass output. With some careful construction you can take the stress off the upper soundboard, which allows for making it quite thin. The low resonance of it helps make up for the fact that you have to leave the main soundboard so thick, due to the added string load.

The one I shipped today is 20-string: six guitar strings, six sub-basses, and eight super trebles. It's based broadly on the Sullivan/Elliot/Doan harp guitar that Jeff Elliot detailed in 'American Lutherie' a while back. It seems to work pretty well: we'll see what the customer thinks in a few days, assuming it gets there...

Just to throw out another idea, here's a snapshot of a harp guitar I made about 15 years back. Sorry for the blurry photo. This was before cheap digital cameras. It's basically a folk harp with a 4 string tenor guitar built into it. The pillar doubles as a fretboard and neck. It took a some tricky carving to get it to work. Strings that pull up from a soundboard like a harp definitely make a different sound than the parallel strings of a zither. It makes the trebles more 'angelic' sounding. For bass strings, I don't think it would be worth the bother.

I've also made a giant super zither thing with a baritone guitar and autoharp on one soundbox. Bass was well supported down to the fundamentals. I have a better picture somewhere if anyone is interested.

That's cool! I've considered making something more or less along those lines too.

Harp makers avoid using steel strings, which don't sound nearly as good on a harp as nylon or brass/bronze. I think it's because the longitudinal compression wave in steel strings is at a much higher frequency than in the other materials, and is stronger. It drives the soundboard pretty effectively, and, since it tends to be dissonant (usually between the 7th and 8th partials) it's not very pleasant.

I tried steel sub-basses on my 'beast', and took them off pretty quickly. Overspun nylon strings sounded much nicer, but didn't sound a lot like the guitar. That was another drawback of the thing.

And then there is the Edward Light Harp Lute of the early 19 th century:

https://www.youtube.com/watch?v=txHodAb59VU

And the Dital Harp, which most certainly is more of a harp:

https://www.youtube.com/watch?v=PxgD90mRP-A

That 19 th century was full of folk making all sorts of odd things.