Thoughts on Arch Top Bass Guitar

[Edison Gebhard]

I found this good looking little instrument at http://www.sonntag-guitars.com/english/ ... c-Bass.php it has given me some ideas that I thought I would run by all the gifted and experienced builders here. First off, would a more drastic arched top allow for a slightly thinner more comfortable body without sacrificing volume? Could a larger neck angle, similar to an upright bass, allow for a taller bridge and thus louder, as well as a longer fingerboard OVER the soundboard and extending from the neck (i.e. as an upright bass)?

I guess what I am describing seems kind of like a cello with a guitar shaped body. Really all I am trying to do is figure out how to make an acoustic bass instrument that is more portable than a doghouse bass and louder than the typical flat top acoustic bass guitar (no electronics). That is also not a guitaron.

Ideas?

[Michael Lewis]

The depth of the sides reminds me of the Ernie Ball Earthwood basses. The reasoning is a larger air chamber can support a lower frequency than a smaller one. Sorry but so far I haven't seen a bass guitar that can really carry it's weight in an acoustic jam. I'm not saying it's impossible, but I have yet to see one.

[Stephen Neal Saqui]

I converted a gitaron to four strings for a friend who plays in a bluegrass band. It's the only small acoustic bass I've heard that could hold its own and blend with the band. It was a long time ago, but I believe we excluded the low "E" and added a "B" on the treble side. He's still using it.

This pretty instrument has a pickup for good reason!

[Edison Gebhard]

Those were my thoughts also. Thank you.

[Joshua Levin-Epstein]

I played a few notes on a Ribeckke Halfling bass and it was pretty loud (and sounded good, too). I saw some footage on an archtop bass he is building for Jack Casady and I suspect it will be pretty loud as well. But nothing is going to make it as loud as a decent double bass. None of the "violin" family instruments are large enough to produce the fundamental of their lowest string (or so I've heard) so a guitar sized object is already at a disadvantage.

Which is not to say it wouldn't be fun to have.

[Edison Gebhard]

So we have to figure out how to defy physics and get this done!!! I will do more research, just because it hasn't been done yet, doesn't mean it can't ever be done!

[Bob Gramann]

I built a very successful (in my opinion) acoustic bass guitar. Since the body couldn't possibly be big enough to carry the low notes, I built it to accentuate the second harmonic and counted on the ear to fill in the missing fundamental. It pretty well worked. When we did an FFT on my upright bass, the fundamental on the low E string was maybe a third of the height of the second harmonic on the graph. The FFT of the acoustic bass guitar showed almost no fundamental but a second harmonic twice as tall as that of the upright bass. To the ear, both notes sounded very much the same. But, that note was quite loud in the room no matter where you stood in reference to the upright. With the bass guitar, the note was loud when you were in front of the bass, not so loud when behind. To get the strong second harmonic, I made sure the bridge was above the center of the lower bout and made sure the saddle was at least 1/2 inch tall. It required a pin bridge to get ghe rocking bridge motion that would drive the second harmonic on the top. I don't think it can be done with a floating bridge and a tailpiece.

Later on, I did some work on the upright bass that greatly increased its volume. Now, the acoustic bass guitar doesn't sound as loud as the upright, but it is still loud for an acoustic bass guitar.

[Patrick Hanna]

I've never built a bass guitar and I don't anticipate doing so. Still, I am pretty interested in this sort of problem solving and I must say I like Edison's "can do" attitude about the challenge of building a good acoustic bass guitar! I can't even contribute a meaningful suggestion. I just like Edison's attitude. Press on, man! Everyone here benefits from everyone else's experimentation.

[David King]

How about breaking some "acoustic" rules and including a little amp and transmission line style driver on the inside. A T-class amp is incredibly efficient and it will do bass like nobody's business. Pair it with a 4" driver and tune the thing to 80Hz with a lot of internal baffles and a sound port towards the floor. No one will be the wiser.

[Edison Gebhard]

Some fresh thoughts... sound=energy so tighter string=more stored energy=more volume? also... longer scale length would mean a tighter string.
physical volume=sound volume so make the body as large as possible without being uncomfortable and it will be as loud as possible

now about a bridge... what kind of differences in sound do we find between floaters and fixed?

also... thoughts on neck angle?

in regards to the internal amp and speaker... how would that fare around the campfire? I can see at as being a huge benefit indoors with lots of surfaces to bounce the sound around, but outside?

[Bob Gramann]

Tighter strings mean the top has to be stiffer to support it. A stiffer top can mean less vibration. Lengthening the scale may decrease the loudness, not increase it. For an acoustic bass, more volume in the body will help with the perceived fullness of the lower notes. In this case, as big as is ergonomically possible is probably right. But, again, you reach a point where the stiffness of the top required to support the pull of the strings over the longer span of the bigger top starts to work against the loudness.

[Mark Swanson]

Moving the bridge nearer the center will certainly produce a difference, but the trade-off is that you then need to move the neck outward and with a scale length of a bass this makes a really long instrument and a long reach to the first frets, bad balance.

[David King]

Some of the loudest acoustic bass bass guitars I've heard were very inexpensive plywood instruments from China. The sound is anything but refined and the sustain was rather uneven but the notes really kicked. I'd argue that less sustain is where you might pick up some more volume at the front of your notes. The action needs to be higher and these things are a bear to play but the volume is there.

[Edison Gebhard]

I will cut to the chase... I have a neck through electric bass under construction for the last 12 years. I realized that it is still under construction forever because I don't WANT a solid body instrumfent anymore. I am trying to figure out something to do with the neck... it is a beautiful neck, perhaps the only thing an impatient teenager did well on his first build. Obviously, I thought to cut the body wings off and try for an acoustic bass, but then there's the volume problem. I am thinking I may just try this T-amp idea that David King mentioned. Playability is more important to me than pioneering a design for a big, ugly, uncomfortable, but loud acoustic bass guitar.

Tell me more about this class T-amp setup, and baffles and such.

Thank you for all your input. This novice appreciates it very much.

[David King]

Sonic Impact sold them for a while. You can search for them on ebay or search for Tripath 15W or 20W stereo amp. They ran on 8 AA cells but I'd buy a LiPo 11V 1300ma battery pack at the hobby store and a LiPo charger and be done with that.

[Edison Gebhard]

I have been mulling this over, and it may have left the realm of archtops and entering the world of electronics Would putting one of these newer battery powered hi-fi systems (i.e. the pill, some bose units, iLoud, etc) inside the instrument be feasible as opposed to t-amp, power source, and driver? I would probable want it removable because they are pretty nice little units, so I am thinking a removable back. Any experience with removable backs? More importantly, how can you make a removable back look nice? I am almost starting to feel stupid for thinking up this contraption. It will be a sit down and play instrument, since its doomed to be a heavy ol' heifer!

[Edison Gebhard]

Nevermind... These are just creative, naive, and idealistic novice luthier thoughts. I went to investigate and compare stereos that would work and then thought of all sorts of troubles like feedback and how to connect it all together. I did, however, discover a little gem called Acoustic Stream, a device that transmits guitar and instrument signals via Bluetooth (check it out it is pretty cool). Finally I just think it will be easier to make a good looking acoustic electric and get an Acoustic Stream to put on board, so I can fool people into thinking its acoustic because there will be no jacks! Ha! I am clever after all! Sometimes you just have to write it all down. Thanks guys! I am still interested in an archtop style bass if anyone has anything to say about that?

[Michael Lewis]

As long as it is amplified an archtop bass can be a great bass. I made an 8 string archtop with 3 bass strings and 5 guitar strings. It works ok acoustically but is much better amplified.

[Beate Ritzert]

12 years ago id did a neck through bass. It is not a solid body, but actually semi hollow, and it is equipped with a wooden bridge (with a bone inlay). It is fretless. Equipped with TI flats i get a full, warm tone which is competitive in attack with most solid bodies (it is actually more powerful than most solid bodies), but the higher You play the more the sound reminds to a double bass.

Maybe something like this might be a useful approach for Your unfinished solidbody bass?

As for archtop style basses: there a re a few treads discussing some basics, relatively recently one started by me (i must buy a new house before i can start new instruments...).