Acoustic bass guerilla build

[Thoragaverung]

A friend of mine told me he's been looking for an acoustic bass that's actually loud enough to go toe to toe with an acoustic guitar in a small venue. They exist but he can't afford one.

I got curious and decided to try to throw something together. It's going to be a challenge because the string tension on a bass is ferocious and all my builds treat the soundboard like the membrane on a reflex speaker. And if he's going to be gigging, it needs to be robust. How I'm going to reconcile these contradictory requirements will be a nice exercise in engineering.

I have decided to take a major shortcut; I got a generic neck from a Fender Jazz Bass. None of my guitar jigs are set up for the longer scale length of a bass, and I want to get this thing out the door. Also, I'd like the thing to feel familiar in his hands. If he picks it up and it plays like his amped bass, only acoustic, that would be a win. Everything else on the instrument, I'll build.

The back and ribs are cherry. The endblocks are hickory and walnut. I'm figuring out how to do a bolt-on neck on an acoustic. The kerfing (well, it's not kerfed, but you know) is also cherry, bent on the same form as the ribs. I find that adds a lot of rigidity to the carcass and I'm going to need all the rigidity I can get. I think I'm do a cedar top to warm it up. Top bracing will be spruce, with a couple of key points that carry load in Orange Osage.

Trying to figure out how to do a trapeze bridge.

[j. Kinnaird]

With all the tension you are describing, I'd be tempted to use Sitka for the top.

[Thoragaverung]

If I use a trapeze tailpiece/bridge I just have to cope with up/down compressive tension on the top. Longitudinal stress I'll deal with another way, I'll post pics when I get there.

[Steve DeRosa]

Have you approached your bud with the idea of a short (30-31") scale, along the lines of the old Guild B-50/B-30 - one of the very few all-acoustic basses that really could hang with an acoustic guitar in a small venue (I owned one, BTW)? To my way of thinking, it'll not only take most of the tension problems out of the equation (probably negating the need for a tailpiece) but shift some of the harmonic emphasis, toward more warmth and "bass" tonality rather than the "baritone guitar" response I find typical of most PB-strung ABG's; should be easy enough to find something suitable here:

http://www.warmoth.com/Pages/Classic...e=349&Path=SSB

Probably make it a whole lot easier to find an over-the-counter case for the finished product as well...

[Thoragaverung]

I just had my router bit 'climb' and screwed up the carcass -- badly.

I am so angry at myself I could spit out my own teeth. I've never had anything like this happen before.

At least I didn't get hurt.

[Halcyon/Tinker]

Glad for the last bit. Everything you build can be replaced.

[Thoragaverung]

OK, after a number of hours away from the shop I went back and looked at the damage. The damage is around the place where the neck enters the body. I think this might be patched with some nice, beautiful, ornate wood in a cowl or shroud.

In short, it's worth some effort to salvage. I have nothing to lose at this point.

Wabi sabi indeed...

[Thoragaverung]

Sigh.....

[rogthefrog]

Originally Posted by Thoragaverung

Sigh.....

OUCH

Good luck with the repair!

[Halcyon/Tinker]

Now I'm really curious as to what your neck attachment idea is...

[Jeff Scott]

Originally Posted by j. Kinnaird

With all the tension you are describing, I'd be tempted to use Sitka for the top.

String tension shouldn't be an issue. Comparing acoustic guitar strings to acoustic and electric bass strings:

Here are the tensions of some representative string sets, all D'Addarrio:

EJ-16 PB - 163.5 lbs.
EJ-17 PB - 188.8 lbs.
EPBB 170 - 191.1 lbs.
XL 165 - 182.8 lbs.

So it looks to me that string tension is only a small consideration. If the top is braced sufficiently a pin bridge may work just fine.

Once I played a Fender Kingman bass that looks to be essentially what you are making, a dred body with a Jazz Bass neck. It was very neck heavy, JFYI.

How large is the body on this bass? I hope it is significantly larger than a Dred to produce the bass and volume/projection you are seeking, and to minimize neck drop.

[LSemmens]

I am by no means a guitar builder so, please take this advice (from experience) with a huge grain of salt.

Background: Back in my youth I purchased a 12 string that badly needed a neck re-set. I tried all that I then knew how and could never make it playable. Being an enterprising young thing (NO internet in the 70's) and with a little cabinet making training under my belt, I thought that I could replace the neck. I was able to get a neck off an Eston that had seen better days so I thought I could convert this 12 to a bolt on. I did not have the body of the old eston to compare the bracing to, so I just removed the old dovetailed neck and went about replacing the neck block with something more substantial. All went well, and I ended up with a (somewhat) playable twelve string. For some months. The tension eventually started to pull the neck forward and push my brace out the back of the body.

Suggestion: Ensure that the neck block is appropriately braced. You might even need to look at bracing the sides either side of the neck to take some of the tension, too.

As I said, please treat this as experience from AN AMATUER luthier.

[Thoragaverung]

OK, I think I know how to address this mess. I'm calling the solution "picket-parquet."

We'll see...

[Thoragaverung]

This is going to take awhile....

[Thoragaverung]

This is takin a really long time