MIMF

ok saw on a forum somewhere where somebody had swapped the necks on an acoustic to make an acoustic bass.been thinking about it since. i have a guitar that the neck is so warped it would need to be replaced. just been hangin in the rafters in my brothers band room for a while. can find a neck pretty cheap online. what do you guys think? just for a campfire bass kinda thing ya know.

Sounds like a fun project. Plan it out completely though... your not just swapping out a neck, you will need to also address the bridge and how the strings are anchored.

yeah i've givin it minimal thought as of yet, but i'm not sure if i'm gonna do it yet. i'm just curious if it could sound halfway descent. wouldn't expect it to sound great or anything but...don't know. i'll post if i do it.

A friend was recently considering an acoustic bass to take to campouts and other places where a standup wasn't practical and asked my opinion. I didn't know enough to be helpful but I did find this tidbit from Cumpiano on the subject.

http://www.cumpiano.com/Home/Articles/S ... acbass.htm

There is a lot of things going on that you may not be considering. I can't imagine you will find a suitable bass neck without having to make a custom job. You don't even know what kind of neck joint you are dealing with yet, you will likely have to do a good deal of modification to even fit another neck. forgetting that for a second, you can't just put a longer neck on and expect the bridge/saddle to be in the correct location. You can't just move the bridge because it is designed to fit the bracing. . . Then as mentioned you will need to make a new bridge and hope the current bracing is up to the task.

If you want to proceed, I would recommend you learn to make a neck and make a custom neck to achieve your goals. You'll have to start at the saddle and determine what compromises you will need to make between scale length and what fret the body joins the neck. Without really doing any math, I would guess you are going to end up with a pretty long neck, then you have to decide how to get a truss rod to fit. It would be a shame to put in all that work and have the top fold up on you, so I would be tempted to make a new top with bass tension in mind (you could also then play with bridge location.

By the time you do all that design work you might as well just make an acoustic bass guitar from an available plan. The plan will probably be better suited for bass tone anyway. Then take the guitar with a bad neck and put a really tall nut and saddle on so you can learn to play slide.

Bryan Bear wrote:Without really doing any math, I would guess you are going to end up with a pretty long neck,

Not necessarily. If you leave the bridge where it is and just make a bass with a shorter scale length, there wouldn't be as much tension so the bracing could be okay too.
Not sure if it would make the strings TOO slack though. I've seen basses with shorter scales, but I don't know much about them. maybe use a little heavier gauge string? I don't know, but maybe it could be done. Maybe plug the holes for the pins and redrill for bass, just reuse the same bridge.

The shorter the scale the heavier the strings are needed to achieve the pitch. There is a reason basses have long scales. A rather short bass scale is 29", will that fit on your guitar?

I think Bryan has spelled out the situation pretty well.

IMHO, even 29" is too short. It seems like the typical 34" bass guitar scale is already a compromise. I haven't seen a ton of ABG and certainly no high end ABGs, but I have never heard one that impressed me. To be fair, a good deal of the blame probably belongs on the size of the soundboard not supporting bass more than scale length.

If I'm not mistaken Bob Graham recently made one that sounded good (I apologize if I have remembered the name wrong). Perhaps he will chime in with some info on ABGs.

Yeah, but the idea isn't to make a bass acoustic that will knock the socks off a client that is paying a few thousand dollars. The idea is to have some fun with a piece of guitar-shaped trash and see if it can be made to be fun and/or useful.

Robert, I have a spreadsheet that takes as input
frequency desired for the open string
scale length
string tension
and then lists the string gauge that comes closest. If you want to try some scale lengths out, let me know.

I tried many ABG and finally bought a Tacoma Thunderchief which is good, but not loud enough without amplification, hence I now own two Double Basses!!

I would suggest going with a 34" scale as strings are readily available, and going fretless. I know that sounds scary but if you persevere the lack of frets just stops being an issue and your brain will just let you play the note. Not having to worry about frets makes the conversion much easier, just plug and recut the holes in the bridge/bridgeplate. If the top lifts a bit that won't matter as you will need a higher action anyway.

I second the 34" scale. The more standard you build it the easier it will be to find components. I had a cheap Michael Kelley 34" A.B.G. that was too quiet, but amplified (with phosphor bronze strings) sounded like a grand piano.