Converting an Acoustic Guitar to a Bass, and String Selection

[CTGull]

Have a seat, this is long.

I’m not a bass player, I’m barely an acoustic guitar player (mostly fingerpicking and light strumming). I mostly collect and fix acoustic guitars for fun. Mostly vintage Yamaha FG’s, but I like Seagull’s also. I just finished mating a wide Seagull neck with a vintage Yamaha FG body and replacing the bridge with a wider string spacing. Making a guitar that is the best of both worlds, open and resonant, with a wide neck and string spacing. A vintage Yamaha that is much easier to fingerpick. I call it the YamaGull. YAMAGULL v1.0 | Yamaha Vintage FG Acoustic Guitars

I do have a bass though, even though I’ve never really used it much. A couple of years ago I found a guy on CraigsList selling a Hofner “Beatle” bass for $129. He had no idea if it was vintage/modern/copy. So I drove over an hour to check it out. It looked old so I bought it. The neck angle was horrible. It had come off in the case 15 years ago and he had someone reglue it and never played it again. When I got it home I took out the controls to check the pot dates and research the various characteristics. It’s an early 1967 Hofner 500/1!!! Vintage!! An authentic “Beatle” bass, although I think by that time McCartney was playing the Rickenbacker. I took the neck off, made a fixture, and reset the neck. It’s mentioned at the end of the page and continues on the next page. Also not acoustic, but... | AcousticGuitarCabin

BUT!!! Let me get to the point. I had a thought to convert a vintage Yamaha FG acoustic guitar to a 25” scale micro bass. The YamaBass! Why??? Why not??!! YamaBass!!! | Yamaha Vintage FG Acoustic Guitars

So I started researching micro basses and found the Gold Tone Mbass-25. And I found a lot of negative comments about the stretchy sticky Thunderguts. I’m not going to put rubber bands on my YamaBass!! Then I found the LaBella Silverback strings. It seemed like the way to go. I found the strings first mentioned on page 45 but the talk of them quickly died out. Gold Tone MicroBass Talk I’m guessing they’re too metallic??

Not being a bass player, I have no idea what sound I’m looking for. I have liked Geddy Lee and Rush for many decades, but I certainly have no hopes of being 1% of the bass player he is!! He’s had many basses and sounds over the 40+ years. I’m assuming I’d want a sound somewhere between the thuddy Thunderguts and the metallic Silverbacks. I’m not planning on amplifying, but that would be easy enough to add in the future.

I’m not finding any other options that don’t involve weeks of stretching strings and constant retuning. I assume I’m going to have to go with the Silverbacks, even though they will require some stretching time due to the nylon cores.

Any better string suggestions??

I haven’t seen anyone mention trying the GS Mini 23.5” scale strings on a Gold Tone Mbass-25. The construction is similar to the LaBells’s, but PB as the wrap. I’d guess they’d be slightly too short. Is this possible?? The GS Mini strings are .090”, .062”, .050” & .037” vs. .115”, .090”, .065” & .049” for the LaBella’s. That’s a huge difference in size!!

There will be some challenges in building the YamaBass, the biggest being finding the proper location for the fixed bridge & saddle to get proper intonation. This would be affected by the string choice, although as long as I make sure the scale length is a little longer vs. shorter it shouldn’t be very noticeable. I’ll be taking the neck off, doing a neck reset (based on an assumed saddle height and action) and refretting it with jumbo’s before getting too far into this.

There’s also the question of body size. I was originally going to use a smaller 000 size, but I’m also considering using a dreadnaught size to get some extra depth and volume. But it would be cool if the YamaGull and the YamaBass are both the same body size. Would the body size really make much difference with this short scale length??

Any suggestions to feed my madness is welcome.

 

[Ed Fuqua]

Not that I know anything about this, but is the internal bracing on a guitar top sufficient to stand up to increased tension of bass strings?

 

[CTGull]

Not that I know anything about this, but is the internal bracing on a guitar top sufficient to stand up to increased tension of bass strings?

The tension of the rubber and nylon core strings is less (possibly half) than the steel strings that the guitar has experienced for the last 40+ years.

 

[Matt Liebenau]

I don't have any advice on new strings. I did something similar years ago with an old, beat up Harmony archtop and used Fender acoustic bass guitar strings. It worked pretty well. I still know the guy who has it. If he lived closer, I'd get it back and try some of these new strings. Looking forward to seeing what you come up with. Post a thread here.

I like the Seagull / Yamaha concept to.

 

[CTGull]

I don't have any advice on new strings. I did something similar years ago with an old, beat up Harmony archtop and used Fender acoustic bass guitar strings. It worked pretty well. I still know the guy who has it. If he lived closer, I'd get it back and try some of these new strings. Looking forward to seeing what you come up with. Post a thread here.

I like the Seagull / Yamaha concept to.

Thanks! I was afraid I might get flamed in the Luthiers section for doing something like this. I've got nothing to lose, except a little money. The most expensive part of this project is I need the large nut files, I only have them for the smaller 6 string slots.

I enjoy oddball projects. If you look at any of the links I posted, and my YamahaVintageFG forum, you'll see a bunch of crazy repairs. And I like to share it in case someone else is looking to do the same or something similar.

 

[Matt Liebenau]

Thanks! I was afraid I might get flamed in the Luthiers section for doing something like this. I've got nothing to lose, except a little money. The most expensive part of this project is I need the large nut files, I only have them for the smaller 6 string slots.

I enjoy oddball projects. If you look at any of the links I posted, and my YamahaVintageFG forum, you'll see a bunch of crazy repairs. And I like to share it in case someone else is looking to do the same or something similar.

No worries. There's plenty of crazy goings on here. Those are more in my skill set then pretty stuff anyway.

 

[Will_White]

La Bella CB60s

 

[Jisch]

Here's mine. It's a bit of a hack job, but it plays fine. I used regular bass strings, just because I had a set here and I looked at this like an afternoon of messing around.

I added a tailpiece so I wouldn't have to worry about the strength of the top. I didn't want to change the tuners so I had to have the tapered part of the winding on the E and A strings in the small guitar string hole. That meant on the other end I had to cut off the ball end. I bought some electrical butt joints and fastened them to the string instead of the ball ends. I need to make a new bridge and make the string slots deeper, if I play aggressively the G string can jump out.

Generally it's not super loud, but I can play along with my wife when she plays ukulele, so it's working perfectly for my intention. I added an undersaddle piezo as well, but without a buffer it's kinda clacky. Maybe down the road I'll add a buffer.

 

[CTGull]

Cool! I'm in Connecticut also. I'll add that to my profile.

 

[Arie X]

fwiw,
-the string length issue has already been solved. it involves cutting down the ball end and re-wrapping it back together at the required length. i posted a procedure about this some time ago. apparently mandolin and banjo players have been doing this for some time.

String Winding Length

-in general, acoustic guitars of quality aren't built for the tension imparted by bass string forces, but that has never stopped people from trying. a pinned bridge will fail with bass strings on a six string guitar so a trapeze is the option. will the top crush in? maybe not with the shallow string break angle imparted by the trapeze setup. strength points can be gained by using a cheapo guitar with an over-braced laminate top. i've seen failure at the tailblock, headblock, the neck/body joint, and the neck scarf joint and headstock on acoustic guitar to bass conversions.

 

[CTGull]

La Bella CB60s

That's basically the same gages as the GS Mini strings with the same wrap as the Silverbacks.

I emailed LaBella asking for the individual string tensions for this set and the Silverback set. I haven't been able to find those numbers anywhere.

 

[CTGull]

fwiw,
-the string length issue has already been solved. it involves cutting down the ball end and re-wrapping it back together at the required length. i posted a procedure about this some time ago. apparently mandolin and banjo players have been doing this for some time.

String Winding Length

-in general, acoustic guitars of quality aren't built for the tension imparted by bass string forces, but that has never stopped people from trying. a pinned bridge will fail with bass strings on a six string guitar so a trapeze is the option. will the top crush in? maybe not with the shallow string break angle imparted by the trapeze setup. strength points can be gained by using a cheapo guitar with an over-braced laminate top. i've seen failure at the tailblock, headblock, the neck/body joint, and the neck scarf joint and headstock on acoustic guitar to bass conversions.

Thanks. I hope I don't have to go to the extreme of rewrapping strings.

I'm assuming the nylon core strings have a much lower tension than the steel string an acoustic guitar is designed for. I'll know more if LaBella gets back to me.

 

[Arie X]

middle of the road acoustic steel 6 string guitars can handle 180 to 200 pounds of string tension.

 

[CTGull]

middle of the road acoustic steel 6 string guitars can handle 180 to 200 pounds of string tension.

And what do you think the tension of 4 nylon strings will be? I'm guessing half that. If you put steel strings on a classical guitar they implode.

LaBella said they haven't measured tensions of those strings. I then asked what the sizes of the nylon cores are so I can guess what the tensions are. If they don't get back to me I can buy the strings and measure them myself.

 

[AndyPanda]

I've thought about converting my old Yamaha acoustic into a Mando-cello.

 

[Will_White]

And what do you think the tension of 4 nylon strings will be? I'm guessing half that. If you put steel strings on a classical guitar they implode.

LaBella said they haven't measured tensions of those strings. I then asked what the sizes of the nylon cores are so I can guess what the tensions are. If they don't get back to me I can buy the strings and measure them myself.

It's under 100 lbs, there's a guitar scale acoustic bass thread with info on other round wound nylon core strings.

 

[CTGull]

It's under 100 lbs, there's a guitar scale acoustic bass thread with info on other round wound nylon core strings.

I found that thread. Guitar Scale Acoustic Basses Now all I need is a few hours to read all 27 pages...

 

[SBassman]

I found that thread. Guitar Scale Acoustic Basses Now all I need is a few hours to read all 27 pages...

You're welcome.

 

[-Asdfgh-]

Have a seat, this is long.

I’m not a bass player, I’m barely an acoustic guitar player (mostly fingerpicking and light strumming). I mostly collect and fix acoustic guitars for fun. Mostly vintage Yamaha FG’s, but I like Seagull’s also. I just finished mating a wide Seagull neck with a vintage Yamaha FG body and replacing the bridge with a wider string spacing. Making a guitar that is the best of both worlds, open and resonant, with a wide neck and string spacing. A vintage Yamaha that is much easier to fingerpick. I call it the YamaGull. YAMAGULL v1.0 | Yamaha Vintage FG Acoustic Guitars

I do have a bass though, even though I’ve never really used it much. A couple of years ago I found a guy on CraigsList selling a Hofner “Beatle” bass for $129. He had no idea if it was vintage/modern/copy. So I drove over an hour to check it out. It looked old so I bought it. The neck angle was horrible. It had come off in the case 15 years ago and he had someone reglue it and never played it again. When I got it home I took out the controls to check the pot dates and research the various characteristics. It’s an early 1967 Hofner 500/1!!! Vintage!! An authentic “Beatle” bass, although I think by that time McCartney was playing the Rickenbacker. I took the neck off, made a fixture, and reset the neck. It’s mentioned at the end of the page and continues on the next page. Also not acoustic, but... | AcousticGuitarCabin

BUT!!! Let me get to the point. I had a thought to convert a vintage Yamaha FG acoustic guitar to a 25” scale micro bass. The YamaBass! Why??? Why not??!! YamaBass!!! | Yamaha Vintage FG Acoustic Guitars

So I started researching micro basses and found the Gold Tone Mbass-25. And I found a lot of negative comments about the stretchy sticky Thunderguts. I’m not going to put rubber bands on my YamaBass!! Then I found the LaBella Silverback strings. It seemed like the way to go. I found the strings first mentioned on page 45 but the talk of them quickly died out. Gold Tone MicroBass Talk I’m guessing they’re too metallic??

Not being a bass player, I have no idea what sound I’m looking for. I have liked Geddy Lee and Rush for many decades, but I certainly have no hopes of being 1% of the bass player he is!! He’s had many basses and sounds over the 40+ years. I’m assuming I’d want a sound somewhere between the thuddy Thunderguts and the metallic Silverbacks. I’m not planning on amplifying, but that would be easy enough to add in the future.

I’m not finding any other options that don’t involve weeks of stretching strings and constant retuning. I assume I’m going to have to go with the Silverbacks, even though they will require some stretching time due to the nylon cores.

Any better string suggestions??

I haven’t seen anyone mention trying the GS Mini 23.5” scale strings on a Gold Tone Mbass-25. The construction is similar to the LaBells’s, but PB as the wrap. I’d guess they’d be slightly too short. Is this possible?? The GS Mini strings are .090”, .062”, .050” & .037” vs. .115”, .090”, .065” & .049” for the LaBella’s. That’s a huge difference in size!!

There will be some challenges in building the YamaBass, the biggest being finding the proper location for the fixed bridge & saddle to get proper intonation. This would be affected by the string choice, although as long as I make sure the scale length is a little longer vs. shorter it shouldn’t be very noticeable. I’ll be taking the neck off, doing a neck reset (based on an assumed saddle height and action) and refretting it with jumbo’s before getting too far into this.

There’s also the question of body size. I was originally going to use a smaller 000 size, but I’m also considering using a dreadnaught size to get some extra depth and volume. But it would be cool if the YamaGull and the YamaBass are both the same body size. Would the body size really make much difference with this short scale length??

Any suggestions to feed my madness is welcome.

I have a 12 string that needs repair. Maybe I can turn it into a 12 string super short scale bass...

 

[CTGull]

I have a 12 string that needs repair. Maybe I can turn it into a 12 string super short scale bass...

I'm not sure if you're serious about 12 string bass... A 1-11/16" wide 6 string guitar neck is the same width as the typical 25" scale micro basses. A 12 string neck is at least 1/8" wider. Possibly a bit too much space between the strings.