Planning stage for 8 string guitar. SS

[Dave Bagwill]

John, I'm just looking to extend the range to accommodate the most-used open tunings. I think the octave difference would be too drastic for the tone colors I'm looking for.
But I've had the idea for actual bass strings ever since I saw Michael Hedges using a bass E string on his 6 string guitar in place of the regular low E.

[Dave Bagwill]

Suppose a fella was wanting maximum sustain, and willing to put up with conflicting overtones and sacrifice projection and loudness to that end. How would affect the bracing/structure?

[Dave Bagwill]

A few online resources yielded this:

From Kent Chasson: "The short (24") scale guitars I recently built had more perceived sustain in the fundamental partly because the note wasn't as peaked to begin with. I'm not sure the actual duration was longer than a longer scale but it sounded better to hang out on a note longer because there was less fall off from the peak.
So I would start with a short scale, a stiff neck with a Brazilian (or other low-damping) fingerboard and then find out more about the rest of the sound you want."

From Steve Kinnaird: "My effort would center around stiffness in the neck/head.
My thinking runs along the lines of not squandering your available power by shaking the neck excessively. Reduce the dissipation of energy by not wasting it.
I'd laminate the neck w/ something that would be one of your trade-offs, creating a heavier neck, veneer both sides of the peghead, and possibly go for some heavier tuners. And, I've had success with African blackwood for bridges. Little internal damping, but enough mass than when once set in motion, they tend to stay in motion."

From Howard Klepper: " For starters I'd say you want a heavy back and side wood with low damping such as cocobolo, Honduras rosewood, or african blackwood, and one of the same woods for the bridge; a stiff, relatively heavy top wood such as Adirondack spruce, or possibly Alaskan yellow cedar (NOT western red cedar); you might want a heavy neck made from one of the tropical hardwoods (many choices). You would likely want a fairly shallow body with double sides and and a fairly thick, highly arched back. Bracing such as my own "Klepper" bracing pattern that emphasizes midrange, treble, and sustain. A 15-16" body width; not a dreadnought. One issue is that slow tunes tend to like good bass, and sustain tends to like good treble (but not quick treble; quick and bright are often confused), so some compromise is needed there."

From Elderly Instruments: "Solid brass bridge pin with cylindrical head, fits most acoustic guitar bridges, increases sustain and brightens the sound."

From AcousticMasters (?) website: "Any energy from the strings that vibrates the neck is really wasted and sustain is lost. Ideally the neck end of the strings shouldn’t vibrate at all and the neck shouldn’t adsorb any energy from the strings. In this case the neck wouldn’t affect or alter the sound of the guitar in any way and all the energy from the strings would go into driving the soundboard. Practically this isn’t possible, but a real neck (including the fretboard and frets) should be as stiff as possible and have a low internal damping factor. Modern materials such as carbon fibre, usually used as an insert, make it possible to make very stiff and strong necks, although currently only custom built and very high end production guitars feature this construction."

What do you think of those ideas?

[Dave Bagwill]

D'Addario has a nice way to determine which string to use if I want a couple of bass strings that will sound good at lower D and C. Has other uses too. From the chart it appears I would like a .060 for the D and a .066 for the C, if my base set is phosphor bronze with a .053 E string.

[John Parchem]

John, I'm just looking to extend the range to accommodate the most-used open tunings. I think the octave difference would be too drastic for the tone colors I'm looking for.
...

What open tuning has both a C and a D in the same tuning? The C and D are so close it would make more sense to build a seven string and tune up and down to C and D so you do not have a wrong bass string. I made a mistake in my recommendation. I was really thinking F# and B basically continue with the interval pattern of 4ths. If you separate the two bass strings by a 4th (half way around the circle) it will give you more flexibility to tune both of your non fretted bass notes to a good note in your open tuning. The two notes I am suggesting are within an octave of the low E.

[Dave Bagwill]

The D and C would not be 'fixed' notes - both could be tuned to any note within reason. I expect the C to be able to play a good A note, for instance.
I see what you are saying and I'm definitely thinking about it.

[John Parchem]

The D and C would not be 'fixed' notes - both could be tuned to any note within reason. I expect the C to be able to play a good A note, for instance.
I see what you are saying and I'm definitely thinking about it.

Yes, I understand that you can tune the note, I was looking at D and C as the ideal tuning or the design center of the note (you could tune up or down). If you spread the CDE range that you have, you can get all of the notes you want in an open tuning without pushing the string or detuning too far. To your example you would get a better A from detuning the B string I suggested and you can go the other way to get your C. In both cases you only have to tune 1 or 2 half steps instead of 4.
Also if you are in 4ths you can strum the open strings in the standard tuning and have the guitar sound OK.