Official Luthiers Forum!

For your viewing pleasure, I have just published a profile on an experimental guitar by OLF's own Dennis Leahy. Called Angelina, it features an unsual bracing system as well as some clever bits of lutherie.

I can't link pics directly to here so do pop by to: http://guitarbench.com/index.php/2009/0 ... nis-leahy/ for the full audio/Visual presentation. As always, I present the text portion of the profile for your consideration- although I do highly recommend popping by to see the pics!
Warmest regards,
Terence
www.guitarbench.com


Guitar Database| Angelina by Dennis Leahy

Guitar Database

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Luthier Facts :
Name: Dennis Leahy
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Taking Orders?: Contact

* Model: Angelina
* Type: 6 string acoustic
* Year: 2006
* Serial #: 001
* Back/Sides Wood: figured Bubinga
* Top Wood: Lutz Spruce
* Neck Wood: curly Cherry (laminated, with Walnut/Maple/Walnut veneer center stripe)
* Fingerboard: Katalox (including sapwood stripe)
* Fret Markers: abalone dots
* Bridge: Katalox (rotated 4°)
* Body Bindings: Katalox, with birdseye Maple/black dyed veneer/birdseye Maple purflings
* Top Trim: none
* Backstrip: none
* Rosette: soundhole bound in Katalox
* Condition: See description below
* Body Length: in. 19-5/16″
* Upper Bout: in. 12-5/16″
* Lower Bout: in. 16-1/8″
* Body Depth @ Heel: in. 4″
* Body Depth @ Tail: in. 4-7/8″
* Scale Length: in. 25.34″
* Nut Width: in. 1-25/32″
* String spacing in. 2-1/16″

I came to know Dennis after he very kindly contacted me about the interview I had done with Adrian Lucas (see the interview here). I was intrigued to learn about the guitar he had built as it was an amalgam of various novel ideas in lutherie. I asked him to let us in on his project and I received an amazing amount of resources: pics, MP3s and videos. But most important, Dennis wrote up his thoughts on this guitar & it's construction. Published below are Dennis' take on his guitar:"

When I saw that you had interviewed Adrian Lucas (and, I suspect that many American luthiers did not know who he is) I got excited and wanted to thank you for your efforts.

Adrian Lucas is one of my mentors, though he doesn’t know it. I designed a “pivoting radial” bracing system, then, as I was in the process of building it, I became aware of Lucas’ radial X design. I was very pleased to hear his results, because my own experiment was not yet finished - and it gave me confidence that I was on the right track.This is one of those times where someone re-invents something without knowing it. When my Angelina guitar was designed, I had never heard of Adrian Lucas, had never seen the Ned Steinberger patent for a bridge system kind of similar to mine, and was unaware that suspended bracing had been used before - notably by Tilton, I think in about the 1850’s. So, I blindly reinvented several concepts to engineer Angelina.

Angelina was a proof of concept guitar even more than a prototype. And, it was my first guitar. And, so far it is my only guitar.

Angelina was a pile of experiments, very far from the “scientific method” of starting from a known guitar’s engineering, and then modifying one element at a time. So, by all rights, it should have ended up as “guitar-shaped, wall hanging artwork.”

Surprisingly, it is one of the best sounding steelstring guitars I have ever heard, and a dozen luthiers and players confirm what I’m hearing. Most noticeable to me is the articulation and clarity of bass and mid-bass notes, and the guitar shines in dropped tunings (I play mostly in DADGAD, and a few songs in CADGAD and BADGAD, or dropping the low E to C or B and then partial capoing the other 5 strings on the 2nd through 5th fret.) Surprisingly, even dropping a standard .053″ D’Addario Phosphor Bronze down to a B works pretty well, without a huge drop-off in bass volume.

The engineering of Angelina was a first attempt at breaking free from an X-braced soundboard. With deep respect for Martin engineering and all of the wonderful guitars that have been built using an X brace strategy, I had an idea that the X brace is first and foremost a structural element (to keep the guitar from imploding from 160 to 200 pounds of force from string pull.) The idea began with, “What if I could eliminate the X brace, and design soundboard bracing simply from a sonic standpoint, rather than structural…?”

Angelina has suspended bracing (a pair of triangles - a nod to architect Buckminster Fuller) from neck block to tail block. Using a “Tunnel Bridge” and a tailpiece, all of the shear force of the strings is removed from the soundboard, although the low exit holes on the backside of the bridge do create a fulcrum, and so the soundboard does experience torque forces. I figured an offset soundhole would allow more of the soundboard to be active, especially for bass notes, and made a large (4″ dia.) soundhole to enhance trebles.

The “Pivoting Radial” soundboard bracing consists of just a single, unbroken “pivot” brace, glued laterally in line with and beneath the saddle, and rotated 4° as is the bridge and saddle. There are a pair of bridge plates, echoing the canoe-shaped bridge, and ten sonic braces slightly overlapping and radiating out from the bridge plates (a nod to Adrian Lucas.) The bridge is canoe-shaped, purposely to destabilize it, to permit unfettered longitudinal rocking.

Angelina also sports a compound Florentine cutaway, a Grant Goltz-inspired adjustable 24 fret neck (floating above the soundboard), a uniquely shaped, Katalox-capped, Bubinga-backed headstock with straight string paths, and a built-in Katalox tailpiece in the unique butt of the guitar. The feminine shape of the guitar was part whimsy, and partially to ensure that the longest string would be long enough to go from tailpiece to tuner.

Immediately, on the first strum on Angelina, I knew I had hit on something special. I’m convinced that the concept will also make a very good baritone guitar, and probably a good acoustic bass guitar as well. In fact, I am also working on a concert/parlor-sized guitar, which are usually a bit sparse in bass, to see how well the engineering transfers over to small-bodied instruments.

I should mention that Angelina sounds like a steelstring guitar - not like a piano or some other instrument. I see the success of the engineering in expanding the breadth of articulate bass capability, and without the soundboard-distorting string shear force (and, with further reduction in torque in future versions of the tunnel bridge) the soundboard should last longer than other lightly braced guitars. It even opens a pathway for luthiers that like X-bracing, in that they could shave and scallop beyond what they would normally dare, in their quest for their sonic signature or Holy Grail timbre.

I also have a big hunch that the suspended bracing, tunnel bridge, and tailpiece system provides a larger target or larger “sweet spot” that may allow a wide variety of sonic bracing styles and patterns to produce pleasant sounding and balanced instruments - if the luthier braces lightly - because then the soundboard is freed to do its sonic job without being forced to perform both structurally and sonically. Again, that’s just my hunch, and it will take quite a few guitars to prove or disprove that idea.

I was fortunate that Todd Lunneborg, who has written a couple of Fretboard Journal articles and is himself both a luthier and a player, stopped by my house recently and played Angelina. I did not get anything approaching broadcast quality, but I got some casual living room playing of Angelina by Todd. And, Todd graciously allowed me to broadcast clips from the living room sessions. I really appreciated Todd’s comment on the Luthier Community forum: “Dennis’ 1st guitar is killer, crazy bass but not overpowering and even mids and trebles. The mids and trebs are right where I like em but he figured how to crank the bass “to 11″ and it’s still sounds even. Supremo work for guitar number 1, I’d say!!!”)

Guitar Database

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©2009

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Well, can't say I like how it looks much, but that is always a distant second to me compared to sound which is pretty _____ incredible! Harp guitar like tone. I feel like I know exactly what it would feel like to play it just by hearing it. Uber cool.

Terrence,

Thank you for putting this together for our listening enjoyment. Dennis, all I can say is that Angelina is a beautiful sounding guitar, she is quite simply outstanding. You have every right to be extremely proud of your remarkable efforts, truly delightful.

Cheers

Kim

I want to thank Terence for the honor of being included in his GuitarBench articles, alongside real luthiers that truly humble this beginner.

Dennis

_________________
Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

I have to say that I cannot accept the kind words because it all Dennis. 90% of the content on that article and the multimedia provided was from Dennis, so all the credit should do to him (and building that great guitar in the first instance!)

Terence
www,guitarbench.com

Dennis…Angelina sounds great!!!

How much does dampening the strings between the bridge and end-block affect the sound?

_________________
Rich S

"The inconvenience of poor quality will linger long after the thrill of a bargain has been forgotten"

Thanks, Rich!

My first, quick answer would be not at all. I had envisioned that I might have to shove a felt pad beneath the strings to kill any dissonant sound they make, because it is impossible to tune both lengths of string (unless you had the strings clamped at the saddle, and extra tuners at the tail.) But, they either make no audible sound or make almost no audible sound.

Every so often when I'm playing, there is a sound that I hear, coming from somewhere... I would not call it a "wolf note" because I cannot predict when it will happen nor duplicate it (and I have tried), and because it is more complex than a "note" and sounds more like a "chord." There are no parallel walls within the guitar box to create a standing wave, but the suspended bracing presents some surfaces that may be propagating certain sound waves. Or, maybe I am occasionally hearing some chord formed by "upper partials" coming from those short lengths of string from saddle to tail. That's why I have to say those strings may be producing some audible sound.

I know that I read some well-known luthier that mentioned this phenomenon - I think it may have been Steve Klein. When it occurs on Angelina, it is always a surprise, not unpleasant because it is not dissonant nor loud, but it makes me look around the room wondering where it is coming from. I laugh and say it is the choir of angels that I wanted Angelina to emulate.

Dennis

_________________
Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

That is a very interesting design. I love the name Angelina (big Jolie fan). Is there any connection? I mean it does have a very feminine look to it!

BTW, in the article, it says Angelina also sports a compound Florentine cutaway, a Grant Goltz-inspired adjustable 24 fret neck (floating above the soundboard), a uniquely shaped, Katalox-capped, Bubinga-backed headstock with straight string paths, and a built-in Katalox tailpiece in the unique butt of the guitar.

Is that not a Venetian cutaway?

Mike

Hi Mike,
Indeed that is Venetian cutaway. It is a typo that was originally caught in the published article Guitar Bench article on Angelina, but was still in the copy that Terence posted at the beginning of this thread. Looks like it made it back into the Guitar Bench article, so Terence must have used an older blurb when modifying some other text. Good catch! Thanks, I'll let Terence know.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

Dennis,

Could you please talk a bit about the inner structure in your guitar. Not the top bracing but the brace going from the heel to the tail block. i.e. why did you use the shapes etc. that you used.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Hi Andy,

I'll try to answer your question as asked, but then I'll tell you what I'm doing on the next one...

My concerns were:

• that since there is only a single brace holding a dome or cylinder in the soundboard, that I would need a secondary lateral method near the waist to help hold the soundboard dome. I achieved that with the suspended lateral brace, that swoops up and contacts the top by just the same width as the lining width. Even with an adjustable neck, I found it unnerving not to have a pretty good idea where the top of the soundboard would be.
• I was sure that I would install a soundboard transducer pickup (AST type), and the splayed out suspended bracing was to give me unfettered access to the bridge plate area. In reality, the suspended bracing, which crosses near the soundhole, makes it quite difficult to have unfettered access to anything inside the guitar. And, I have not yet put a pickup in it.
• I didn't want the tips of the triangles that are under compression to be all the way out to the ends of the suspended lateral brace, knowing that the redirected string shear force would then be pushing the sides apart, yet I wanted them splayed enough to keep the zone beneath the bridge clear so I could easily mount the AST pickup. So the spot where the tips of the triangles meet was a compromise between those criteria

So, my plan for suspended bracing for my next guitar (in progress) is to use 4 straight rods, from the neck block to the tail block. In this next one they are Oak dowel rods all the same diameter, but in the future they will probably be carbon fiber tubes or rods, with the upper pair (in compression) being larger diameter, and the lower pair (in tension) being a smaller diameter. I decided I would not let the need to get a hand inside the guitar dictate the size or shape or position of the soundhole or sound ports. Instead, I have decided to install an access panel in each guitar I build. (Oh, I know, archtop builders and violin family makers have been working through F-holes for centuries, but I don't wanna.) I'm putting an access panel in the lower bout near the tail, which gives great access to the innards, even with the suspended bracing. Oh, and the risk of the soundboard relaxing towards flat at the waist and upper bout? Well, first, it shouldn't matter too much. I'll still know where the bridge/saddle height is because that area is braced. And just testing the soundboard sitting in a dish with finger pressure where the linings will make contact show that the dome will be held (at least partially) in that waist/upper bout area. The rims really cannot relax outward, due to the head to tail rods, so once it is glued as a dome, it should stay as a dome. And those 3 little pads on the K&K Western Mini - even with the two upper suspended bracing rods, I should have no (physical) trouble placing those anywhere I want.

I will fully document the "build" on the Luthier Community, (as my "Basia" Concert/Parlor), but for those that don't like traveling to foreign territory, I'll post the results, good or bad, over here at the OLF.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

I like that Idea. What you did in #1 looked suspiciously like a solution looking for a problem.

I use a couple sticks in my banduras to counteract string pull as well. One thought I had was to put a cable with a turn buckle at the 'far end'. The idea being to counter act the torque acting on the tail block and heel block. In case it's not clear yet, you'd use an oak dowel or two between the heel and tail and have a cable with a turn buckle at the "back side" (i.e. near the back of the guitar) to counter act torque on the neck and tail block from the strings. The turnbuckle would allow you to tune the amount of tension.

I haven't thought that idea worthy enough to try but thought I might just through it out there for you.

_________________
http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com