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  #16  
Old 04-30-2017, 07:44 AM
runamuck runamuck is offline
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I don't understand quite what it is you're wanting.

Is it simply a flat top sound in an archtop form?
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  #17  
Old 04-30-2017, 07:47 AM
pmatolcsy pmatolcsy is offline
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Thank for all the excellent ideas. I have already contacted Ken Parker and Ervin Somogyi(hopefully he'll recognize me as a fellow hungarian) but I hadn't thought of trying other archtop builders, and I wasn't holding my breath for them expecting them to contact me. I only recently discovered this site, but on the ANZLF I've gotten 46 views with no replies from a post that I later cut and pasted here in desperation.
phil
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  #18  
Old 04-30-2017, 08:01 AM
pmatolcsy pmatolcsy is offline
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To Runamuck,
yes thats just about it.I love the aesthetics of the archtop form although I have my owh unique shape planned. My current body form and volume (which is relatively small in archtop terms for playability) should approach the body volume and port size of a Martin OO thin 14 fret which is a guitar size I do not own(and plan to build one day) but think has a sweet sound. I think that sound is approachable with my design.
phil
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  #19  
Old 04-30-2017, 08:22 AM
pmatolcsy pmatolcsy is offline
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I have thought of adding an upper transverse brace ,bridge plate and tone bars to my design (as well as my X brace) already . I plan on making the plates quite thin and reinforcing the active back as well . I build for me and give away (or materials only) for freinds and family, so I'm not too worried about failures. But It would be nice to get it right the first time.
Phil
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  #20  
Old 04-30-2017, 09:00 AM
Richard Mott Richard Mott is offline
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Bob, just listened again to that Comins as played by Jimmy Bruno. Tremendous clarity! Very impressive instrument.
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  #21  
Old 04-30-2017, 09:20 AM
SJ VanSandt SJ VanSandt is offline
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I don't know if this will be any help at all, but the only archtop I've ever played that sounded like a flattop was built by Bayard Blain (but I have very limited experience since I don't like the sound of an archtop in my hands). He doesn't hang out on AGF as far a I know, but you could contact him through his website, http://www.bayardguitars.com/ and he might offer some useful tips. Good luck with this project.
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  #22  
Old 04-30-2017, 09:47 AM
runamuck runamuck is offline
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Quote:
Originally Posted by pmatolcsy View Post
To Runamuck,
yes thats just about it.I love the aesthetics of the archtop form although I have my owh unique shape planned. My current body form and volume (which is relatively small in archtop terms for playability) should approach the body volume and port size of a Martin OO thin 14 fret which is a guitar size I do not own(and plan to build one day) but think has a sweet sound. I think that sound is approachable with my design.
phil
If you could choose only one, what's most important to you aesthetically : F-holes, the look of a carved top or the look of the bridge and tailpiece?
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  #23  
Old 04-30-2017, 10:10 AM
printer2 printer2 is offline
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Quote:
Originally Posted by runamuck View Post
If you could choose only one, what's most important to you aesthetically : F-holes, the look of a carved top or the look of the bridge and tailpiece?
My thoughts also. I would start with a flat top design and work my way toward an archtop look if I was after a flat top sound. For one I would make the back and sides the same I would if I were making a flattop. Elevated fretboards are also finding their way into flattops. There was a builder here that made sort of repo's of Gibson's L1 (I think).

Found the link.
http://www.acousticguitarforum.com/f...d.php?t=428115

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Last edited by printer2; 04-30-2017 at 10:16 AM.
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  #24  
Old 04-30-2017, 11:25 AM
M Hayden M Hayden is offline
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Talk to Bruce Sexauer, who posts regularly on these forums. Some years ago he made a series of archtop/flattop hybrids called, IIRC, "Coostik Dominators," which had the warmth of a flattop and the projection of an archtop. I found them quite good.

http://www.sexauerluthier.com/abtcdom.html
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  #25  
Old 04-30-2017, 01:11 PM
pmatolcsy pmatolcsy is offline
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Its the arch of the top and back and hence the reduced depth of the sides I'm after. The shape will also be fairly untraditional for an arch top , closer to many semi hollow electrics but bigger and deeper
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  #26  
Old 04-30-2017, 01:16 PM
pmatolcsy pmatolcsy is offline
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And the soundhole will not be traditional F holes . It will be towards the neck from the upper transverse brace in the upper bout
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  #27  
Old 04-30-2017, 01:33 PM
Howard Klepper Howard Klepper is offline
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Quote:
Originally Posted by pmatolcsy View Post
I'm looking for steel string acoustic sound out of an arch top. But I want it to work in intimate groups as well as with my band. In the band setting it will be plugged in. I'm planning on using a transducer, and an LRBaggs Session DI to tone shape and suppress feedback. I have talked with them extensively and their product seems ideal for my "plugged in" needs. So I guess what I'm after is the unplugged sound in an intimate setting.

phil
If you are looking for a steel-string acoustic sound, there is already a guitar design that gets that.
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  #28  
Old 04-30-2017, 02:05 PM
Alan Carruth Alan Carruth is offline
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I've made a few arch top Classical guitars; trying for a tone that was usable for the normal repertoire, but with more power. It took a few tries to get it reasonably close, and I'm hoping to make another at some point to improve it further. Here's what I think I've learned so far.

It's normal to think that you'd scale the arch height to the length of the box, but that doesn't work. You scale the height to the thickness of the top. So what you want to do is figure out how thick you want to make the top, and go from there. Most archtops use a somewhat thicker top than flat tops, and thus a higher arch.

On my arch Classicals I started out with thin tops, to keep the weight down, and a high arch to get the stiffness The first two ended up sounding 'tinny'. When I read about that scaling rule I decided to use a 3mm thick top, and since that's about what a violin uses, I went to the same overall arch height of 15mm above the rib edge. Those worked much better.

The first unsuccessful arch top Classical that I made used a padauk back, which is a decent BRW substitute (except for the way it cracks!): it was too 'lively', with a 'peaky' spectrum, and that contributed to the tinny sound IMO. With Thomastic 'S' series steel wire core Classical strings it made a pretty good Blues box. Stick with the usual arch top woods.

All the arch tops I've made to date, both 'normal' steel string and nylon string, have used X bracing. I'm now working on one (for steel strings) that has 'parallel' bracing. That's supposed to give a punchier sound. We'll see.

Use a round or oval hole. The F-holes move the 'main air' resonance up too much, even if you keep them very narrow. A round hole arch top tends to sound somewhere between an arch top and a flat top. There's also a benefit to having the main hole in the 'normal' spot: again, it's complicated, but it's part of what makes things sound like a guitar instead of a cittern.

From what I can find in the experiments I've done, side ports are best looked at as 'monitors'. They can direct a useful amount of high frequency sound out toward the player if you can look into the port as you play. Normally the player only gets most of the high from room reflections, so that in a large, dead, or noisy room (the 'restaurant gig') it can be hard to hear a guitar acoustically without a port. Some folks with high frequency hearing loss report that they're beneficial in normal playing, which fits. You don't need a big one: a 1" or 1-1/2" hole in the upper bout near the wide point on the right side works well for most people. If you want to use only a port and do away with the normal hole then the port should go on the side at the same height as the hole would have; just above the waist.

Another instrument with a 'tween sound is a flat top with an arched back. I made one of those years ago and a student made one some time after that. The arching makes a wood like maple or walnut act more like a rosewood on the guitar: it has higher mass and lower damping than a flat braced back of the same material.

Flat top guitars with the strings tied or pinned to the bridge get a small amount of energy from the twice-per-cycle tension change as the string vibrates, which rocks the bridge fore and aft. This is not the major driver on a flat top, contrary to an opinion that is widely held on these groups, but nowhere within the guitar acoustics research community. Bridge rocking contributes just enough to the signal to color the sound a bit, so that a fairly large change in string height off the top with that system makes an audible difference. I've done that experiment.

At any rate, that small bit of signal is missing on arch top guitars with tail pieces. You'll note that they don't sound an octave lower than flat tops with the same strings.

Changing the string height off the top of an arch top also changes the break angle , and thus the down bearing force on the top. Again, from experiments I've done, more break angle does not equate with more sound. In fact, too much break angle kills it. I don't know what the limits are for this. Benedetto seems to recommend about 5-6 degrees of break angle, which is barely enough to stop the string vibration at the saddle top, assuming there are notches in it to stop sideways motion. I tend to keep it about there on the theory that I know that too much angle hurts the tone, and since I don't know how to say that 'too much' is, I'll go with less. It's possible that there is some 'ideal' amount of down bearing, but short of a lot of experimenting with each guitar I don't know how to find it.

The tailpiece can have quite an effect. It's got at least one resonant frequency that can push on the bridge, and tuning that relative to the other resonant modes of the top and air can effect those. This gets complicated, and a lot depends on what you want to do with the sound. The actual string tension used is one variable, along with the mass and length of the tail piece, so it can be hard to know exactly until you get the thing strung up. In a general way, all else equal, the longer the tail piece (shorter back strings) the more effect it will have. I saw Jim D'Aquisto in one talk where he said that he could move the guitar sound around a lot with a different tailpiece.

That's a start. As always, these things get complicated. It would help if I knew just exactly what sound you're after.
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  #29  
Old 04-30-2017, 02:15 PM
jessupe jessupe is offline
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I have spent my entire guitar making energy at making instruments the way you describe...my guitars are built using Italian violin making methods and therefore have hand carved arched tops and backs. But instead of a "jazz style tailpeice / bridge" I make custom fitted to the top radius bridges that conform to the top.

Now of all the people in the world to have heard this guitar, Bruce Sexauer has heard it, he did not play it much as it had real high nut action....he helped me quite a bit that day with our short visit. All is his critique was spot on and very helpful.

Pertinent to your query also was that Bruce had an archtop there that he let me play, with the traditional tailpiece, to paraphrase the snipet of conversation , something like "

"Wow Bruce what a great archtop for Jazz" "Ya but yours sounds much better" "well ya but thats just because of the different bridge styles"

Of course I was blown away to hear Bruce say that, maybe he was blowing smoke up my skirt, but still it was nice.

Really I could blather for days about this topic and why I build arched flatops, but well

Here is a video of me playing one...

1. the guitar is less than a week old, not set up and with softish uncured varnish, and no final rub out so it is not 100% accurate tonal representation
2. At the time, the recorder/video cam was brand new , and therefore not optimized as far as volume, distance and all that , so that also effects the representation.
3. I'm not a pro player...and it is a Maple/cedar guitar built with "high register overtones in mind"



Edit...

Here is Carlo Bartolini {2x latin grammy winner, player/ producer/engineer for guys like Keith Urban} playing his harp guitar I made for him....he is playing dropped BFLAT!!! so that tells how this style of building conserves energy and allows for even super way low tuning to be playable....again like the above video, the recording quality is low


Last edited by jessupe; 04-30-2017 at 02:34 PM.
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  #30  
Old 04-30-2017, 03:29 PM
pmatolcsy pmatolcsy is offline
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Thank you all for your excellent input.
The body volume of my design I believe is whats going to limit my possibilities for volume and type of sound. As I said the body volume is similar to a Martin OO 14 fret thin. There specs list the body as
00 Thin Body
Body Length 18 7/8"
Body Width 14 5/16"
Body Depth 3 1/4"
I plan on building one in sitka/ovangkol ,another in redwood/birdseye maple and another in engleman /mahogany
I cant really afford to build in archtop dimensions with rosewood(my favorite tone wood).
I have heard several small guitars that I like the sound of from Taylor and Martin. All of the steel string acoustics I own and have built are dreadnaught or larger.
So I think the most I can hope for is the sound of a smallish steel string
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