JLT's "Tenor Acoustic Bass"

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JLT
Posts: 228
Joined: Wed Nov 02, 2011 9:13 pm

JLT's "Tenor Acoustic Bass"

Post by JLT »

Yeah, that's an oxymoron, but I can't think of anything else to call it. The prototype is a converted home-made Dreadnaught, with a 25-1/2" scale length. The idea came from this page:

http://www.instructables.com/id/Acousti ... onversion/

I'd been thinking about building an acoustic bass anyway, and talked it over with a friend of mine who's a professional luthier named Arnie Gamble. He said that it would be better to use a pin bridge rather than a tailpiece, so that's what I did. I removed the bridge, back, and bridge plate. Then I made a new bridge plate that was about 50% thicker and 20% larger in area than the old one (which, curiously, was made of plywood). Arnie slotted a new blank bridge for a 3/32" saddle and I bored the four holes for the strings. Since I had the back off anyway, and I knew that a box that small wouldn't give me much volume, I put a couple of piezo pickups on in case I ever used the instrument in a jam.

As for the tuning, I realized that with the short scale, a conventional set of acoustic bass strings would have far too low a tension for efficient sound production. But If I tuned the strings up a fourth (i.e., five frets) to A-D-G-C, that would give me the same tension as if the strings were on a conventional 34" scale length but capoed up five frets. (The tension, by the way, is about 210#, which is about a third greater than a standard guitar ... hence the reinforced bridge plate.) Hence the "tenor bass" designation. Since the string tension is higher than on conventional tuners, I bought a set of electric bass tuners. It also occurred to me that if I used a really, really thick string for the lowest string, I could use the other strings and get a conventional E-A-D-G tuning, but it seems that nobody makes a string that thick.

The result of all this will be a small acoustic bass that would fit into a dreadnaught case, and that might actually be loud enough for small group jams.

The reason that there aren't any pictures yet is because I haven't finished it. The reason I haven't finished it is that, before I close the box, you all might have something to add that I wish I'd known about before I closed the box. Your comments are welcome!
JLT
Posts: 228
Joined: Wed Nov 02, 2011 9:13 pm

Re: JLT's "Tenor Acoustic Bass"

Post by JLT »

An update:

It looks like it won't be a "tenor bass" after all. I found that D'Addario does make a string that would work for the low "E" on a 25.5" scale guitar. It's the string they use for the B below E on the five-string acoustic bass set for 34" scale lengths. So I ordered one, and I'll use the existing low three strings on the set I bought for the remaining three strings, leaving me with an .045" wound string that I'm sure to find some use for somewhere.
JLT
Posts: 228
Joined: Wed Nov 02, 2011 9:13 pm

Re: JLT's "Tenor Acoustic Bass"

Post by JLT »

Well, the bass is finished, and I've experimented with different strings on it. I consider the experiment a partial success, in that I do indeed have a bass that fits comfortably into a Dreadnaught case, but it isn't as loud as I hoped it would be. I guess that you can only get so much oomph from a Dreadnaught body.

I installed some JJB piezo pickups (virtually the same as a K&K pure mini set-up) with two elements, just in case the sound wouldn't be loud enough for jams. Good thing, too. If there's more than one guitar in the mix, you can't hear the bass without amplification.

The strings I'm using are actually sets for a 5-string long-scale bass tuned to low B, as I'd described earlier. I use the four fat strings and toss the G string. The tuning machine on the lowest string needed a bit of rework ... drilling out the interior for the fatter string and making the winding slot wider ... but there was enough metal in the Allparts machines for that.

The phosphor- bronze strings sounded best acoustically, but they were very sensitive to finger noise when I plugged in. I switched to half-rounds, which cut the finger noise by quite a bit, but I noticed that the loudness of the instrument had taken another hit ... not a problem when plugged into an amp, but definitely noticeable when playing unplugged.

FWIW, I'm using a Kustom 30 watt bass amp that I picked up for about $50 on Craigslist. Seems to work fine.

At this point, I'm kicking around the idea of building a version with a larger body, but the stumbling block is getting sides for it. A Dread top and back would work, but the standard Dread sides are a few inches too short. If there's somebody on the list that mills their own lumber for sides, maybe we can talk.
Last edited by JLT on Wed Nov 19, 2014 8:19 pm, edited 1 time in total.
tippie53
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Re: JLT's "Tenor Acoustic Bass"

Post by tippie53 »

interesting
thanks for sharing.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
JLT
Posts: 228
Joined: Wed Nov 02, 2011 9:13 pm

Re: JLT's "Tenor Acoustic Bass"

Post by JLT »

acoustic bass.jpg
]I just realized that I never posted pictures of the finished article. Here goes:


And there's a shot of the inside, with the new bridge plate and pickups installed:

One thing I've reconsidered was enlarging the sound hole. It was originally 4", I expanded it to 5" but now I think that that was a mistake. I've just made a plug to reduce the size to 3" but haven't played it. I'll let you know how it works out.

UPDATE: The soundhole plug worked fine. Another thing I forgot to note in the write-up was that there was a sound port on the top bout of the guitar which makes a huge difference in what the player is hearing.
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Last edited by JLT on Sat May 07, 2022 6:34 pm, edited 4 times in total.
JLT
Posts: 228
Joined: Wed Nov 02, 2011 9:13 pm

Re: JLT's "Tenor Acoustic Bass"

Post by JLT »

And the pictures are back! Thanks to John Read for making it happen and guiding me through the process.
Last edited by JLT on Sat May 07, 2022 6:38 pm, edited 1 time in total.
JLT
Posts: 228
Joined: Wed Nov 02, 2011 9:13 pm

Re: JLT's "Tenor Acoustic Bass"

Post by JLT »

Another update:

t's odd how well it turned out. A friend of mine from England was visiting and, since he's a bassist with a band in Bristol, I showed him the acoustic bass and also an OLP MM2 I'd just bought. He liked both basses, and even wanted to buy the OLP from me but couldn't figure out a way to get it back to England cheaply. (That sucker is heavy!) But as it turned out, he always returned to the acoustic bass when he was just putzing around. He said he loved the "woodiness" of the sound. I hope I get even a small portion of that with the Hofner-esque bass I'm building now.
jread
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Re: JLT's "Tenor Acoustic Bass"

Post by jread »

My neighbor was just inquiring about an acoustic bass. I may end up with one on my list. Yours is really gorgeous! I’m encouraged that you guys liked the sound. You don’t see these very often.
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