MIMF

Occasionally I build an instrument just for myself to keep and play. This is the one for this decade. It was built to facilitate my learning a new tuning scheme (alternating thirds) which required an 8 string format to match the range of a standard guitar. The tuning from low to high is E, G, B, D, F#, A, C#, E which is a full Em13 chord. The string gauges have had to be adjusted to accommodate the tuning. Since my goal was to be able to work on chord melody arranging, I couldn't see doing this instrument as anything other than an arch top. I thought I'd share it here.
The body is a scaled down (to 16" lower bout and 24.5" scale) D'Angelico shape with a yellow cedar top and curly soft maple back and sides. The thicknesses are basic Benedetto except that the arch is slightly flatter on top and the thinnest part of the graduation is on the curve, not the recurve. I was influenced in that by examining an early Gibson round hole arch top from the early 1900s, which surprised me by the steeply curved, but flat on top arch of the top, overall lightness and big sound. I stuck with an X brace and the thicker graduations due to paranoia of using 8 strings.

The neck is built with Cuban Mahogany (much heavier and stiffer than Honduran) grown and harvested in Florida, so it is legal. The fretboard, peghead veneer and tailpiece string holder is Mun Ebony, which has an almost Brazilian RW look. The bridge is two piece E.I. Rosewood. I gave the lower two strings an extra two frets and use a screw in capo to even the tuning out where desired. The inspiration for this came from an old lute and from a guitar shown in Louzao's book "La guitarra ma'gica". The odd peghead on the bass side facilitates that arrangement. The tuning facilitates easy playing for the key of D, so the extended fretboard allows that without changing the overall fretting scheme. Unfortunately, it is easy to get lost when trying to tune the bottom 4 strings due to the odd position of the tuners.
I'll post other photos in a reply post since it's not letting me add enough without stalling and loosing everything.

The back and neck/cutaway...
the neck attachment is a single bolt. I normally do a pivoting adjustable neck, but that is with a different setup all together (bolts not visible). On this I wasn't too picky. The fit is close enough that one bolt is enough to hold without glue.

Very cool! How are you making out playing it?

It's very interesting. There are several minor 7 and major 7 chords on every Barre and variants are quite easy to figure out. The challenge is figuring out where things are. Once you get over that it's pretty easy. For example, it's possible to play the 1, 6 and 2 chords as partial barres all on the same fret. The 5 chord is there too with just one note a fret higher. And so most do-wop songs played on one fret.

A couple of years ago I was asked to build an 8 fret archtop (fanned frets, no less!). I simply refused. It seemed like a project that was way more trouble than it could possibly be good. You are definitely more creative, talented, and courageous than me! Nice job.

Every so often I encounter someone so obviously talented at what they do that I'm momentarily dicouraged from even bothering to continue on my own journey. Not only is Chuck displaying a level of musical knowledge and skill that is probably forever beyond me, he then builds an absolutely stunningly beautiful instrument that also displays a jaw-dropping level of craftsmanship.

The guitar itself sounds quite nice. The treble notes chime nicely and the bass is growly, almost piano like. The tuning allows for more piano like chord voicings, so maybe that's influencing my perception.

I usually play finger style, which doesn't challenge this instrument much. I did take a pick to it the other day just to see if I could get it to bark a bit. Pushing it activated the back a lot more than I'm used to on an arch top. It definitely has dynamic room and doesn't appear to distort when pushed. If I was going to play it that way I'd consider using slightly beefier strings. The neck, with a double action truss rod barely tight, doesn't appear to have moved under tension, but it's really only been a week or so. I used strings that would equate to a light gauge (.0115" high E, .054" Low E), not knowing how much damage the 2 extra strings would do. It looks good so far.

I have not done any testing on it other than playing it. I'll get around to that some day.

That is a very interesting instrument, with some equally interesting solutions.
Beautiful job!

Cool instrument, Chuck! How is the extension for the two bass strings attached to the neck? And what does your neck block look like inside the guitar?

The extension for the two bass strings is actually a piece of Katalox about 1/2" thick that is rabbited into the bass side of the neck. It runs the full length plus the extension and is as wide as the extension for the full length of the neck. The bottom of the little peghead for the two bass strings is connected to the main peghead with a small piece of mahogany sandwiched between the two pegheads, so the main peghead supports the smaller extension. I don't know if it is necessary, but I did notice that the Katalox was more flexible than I'd expected, so I wanted to make sure it wouldn't rise and mess up the action.