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Archtop bass - Input requested

Discussion in 'Luthier's Corner' started by Geoff St. Germaine, Oct 6, 2013.

  1. Geoff St. Germaine

    Geoff St. Germaine Commercial User

    Hi everyone at LC,

    I've been on a bit of a hiatus again from bass building. It started with working on a few archtop guitars and now I'm away from home for the rest of the year for work in far off lands. I'm on a two week break in Spain and have been doing some thinking about upcoming bass projects. I have a couple of solid bodies that I have all of the woods and parts for to get started on when I get home, but what I'm quite a bit more interested in (from a design standpoint) is an archtop bass. I have two archtop guitars in the final stages of work and one completed and I'd like to build a bass using similar design principles. Here are the guitars:



    My thoughts on the bass are something like this:
    -obviously a bass should require a larger body owing to the lower frequency tuning
    -all acoustic basses I've played have been lacking in both acoustic volume and bass response
    -upright basses attain the volume, projection and bass response that is desired, but have a body size and volume that prohibit them being played in the way a bass guitar is played

    The massive body of an upright bass is realistically out of the question. IME with the 17" acoustic guitar I've built, a 17 or 18" body is about as large as is reasonable to be played in a comfortable manner seated. A deeper body is, of course, possible, but even that starts moving away from being ergonomic at some point.

    Obviously some sort of hybrid acoustic/electric function such as magnetic and/or piezo pickups may offer some amount of offset to the problem of body size.

    The other issue I have come across is the bridge placement on the body; generally to maintain an aesthetic and ergonomic quality, the bridge on an acoustic bass guitar is moved closed to the tail end of the body relative to where it is on an acoustic guitar.

    Since LC Has a wealth of knowledge and experience, not to mention the new ideas that anyone may have on the topic.

    My ideas so far for such an instrument are something like this:
    -17 or 18" lower bout with a cutaway
    -4.5" sides, possibly tapered between the heel and tail and possibly between the bass and treble side as well possible tapering between the bass and treble sides of the body
    -arm bevel to improve ergonomics of the instrument
    -16 fret neck, which moves the bridge about 1.25" toward the tail of the body
    -fanned frets, with the treble scale length going as short as 32"

    The issue becomes that many of the changes massively increase the complexity of building the instrument.

    If anyone has any ideas to share, I'd greatly appreciate them.
  2. This seems like a cool project! I like the look of your guitars you made.
    Unfortuneately I can{t give first hand advice, but I am gonna subscribe to this thread to read the advice of others.

    I{ll give a (purely) personal opinion on what I would find cool in an archtop bass if I were to build one.
    -19 frets, no more, no less. I think 19 is a good minimum and gets the job done. Any more might be a bit much on a bass like this. (My hofner has 22 for some reason, total overkill IMO, the longer board does look nice though).
    Naturally I want to suggest 30" scale because I prefer it, but I know that{s not for everyone.
    -Symmetry: most likely a mirrored double cutaway to allow access to the higher frets. (I{m kind of obsessed with symmetry a tad bit as well)
    -F-holes: I{m torn between the classic style F hole or maybe something more modern and individual.

    I wouldn{t go with fanned frets personally though.
    The archtop is somewhat "traditional" and it seems like it would kind of gum things up and also only cater to a smallish market.

    Once again, I{m just saying this from an aethetic and players viewpoint .

    One more thing...on my hofner (most archtopish bass I have) intonation is a real pain, so if you could get a bass with perfect intonation, that would be awesome.
    (Maybe the fanned frets help with intonation, I don{t really know)

    I{d really love to see this bass (whichever design you choose) come to fruition!
  3. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    Beautiful work on that guitar, Geoff!

    For the bass, would you be looking to have a trapeze tailpiece like the guitar, or do a hard mount like an Epi Jack Cassidy? If you're doing a trapeze and floating bridge, I imagine you need to keep the bridge on the maximum of the the face plate curve, which would make for an unusual curve if the bridge is towards the tail of the body.

    Although then again, maybe that's not a necessity. Hmmmm.
  4. pnchad


    Nov 3, 2005
    on the upper right - I think Vinny's only made the 2

    his work is great and this is a piece of art - wonderful thin J style neck - beautiful inlays, binding, etc.

    it is an awesome piece and I am always after the holy grail of AEBs


    your work looks wonderful too
  5. klyph

    klyph Supporting Member

    Mar 28, 2009
    If you are really serious about acoustic volume, I would go as deep as possible with the body, and compensate ergonomically by going shortscale. The Guilds do this pretty successfully. You would then also be able to use regular length strings and still have plenty of afterlength, for an archtop configuration. You may want to angle the neck back a little more than on a guitar, too, for more downward pressure on the bridge. It seems that the holes on the top of alot of good abg designs are proportionally smaller than the holes on your guitars, also good for lower tuning. Whatever you do, I'm psyched to see what you build!

    P.S. the loudest abgs i've played have been fretless. just a thought.
  6. Geoff St. Germaine

    Geoff St. Germaine Commercial User

    Thanks for the replies!

    Ivan - I think that fewer frets is probably a good idea. The shorter scale length is something I'll look into. I have seen a few multiscale archtop guitars and with a subtle fan and some tweaks to the body shape I think they maintained their archtop look without appearing strange.

    PJ - it'd be a trapeze style bridge and you're exactly right, the carve of the top plate will need to be modified such that the bridge sits at the top of the curve. Obviously this will alter the way the body will respond with comparison to the guitars I've built.

    pnchad - Vinny's instruments look great, thanks for the link.

    klyph - down pressure at the bridge will be one of the concerns. I'll be looking at the change in string tension between the guitars and this bass to see how much the break angle of the strings over the bridge needs to be modified. It'll likely become a combination of a change in neck angle and bridge height.

  7. abarson


    Nov 6, 2003
    Santa Cruz
  8. Jeff Bonny

    Jeff Bonny Supporting Member

    Nov 20, 2000
    Vancouver, BC
    Your guitars are quite beautiful and I'm exited to see what bass you build.

    After ten years playing an archtop Azola Deco I have a few observations. I played with very high action and occasionally did gigs with no amp. Ultimately though in any practical situation involving drums or an audience beyond a very attentive 25 a bass of this size is an amplified instrument. What was vastly more important to me was the quality of the acoustic sound and how well it amplified rather than raw acoustic volume. No matter how loud you make an ABG not many people are going to play with the extremely high action it takes to allow the powerful double bass type technique required compete acoustically with a piano, a couple of guitars or loud audience.

    Sonic quality over quantity and a smaller, more comfortable body size is something I'd consider. I've had several ABGs and played just about everything else and there's a point where reaching around a tall, deep body becomes a physical impediment. If acoustic volume really is the main consideration I guess it's something you'd learn to play around but it's not something I would want to deal with. A medium deep 16" - 17" body is as big as I'd want in my lap. If you have to extend too much from the shoulders to get around a big body it impedes your technique.

    I think sound of the the body is the key component and any scale length will give a useable voice. Back again to the acoustic volume thing though a shorter scale will have a softer feel and might not accommodate the most powerful touch to draw out the most acoustic volume. You can play with the tailpiece and bridge height to counter this I guess but it's something to consider. I did talk to Tom Ribbecke a couple of years ago about building a 30" scale Hafling bass and he was quite keen on the idea.

    Amplification is something I experimented with a lot and I'd want any design to accommodate different pickups. The cello-like bridge of the Deco was tall enough to have a pseudo wingslot cut into it that you could use K&K, Underwood and other wingslot pickups. I ended up with an under the foot Gage Realist. I also had Kent Armstrong build a magnetic that had some advantages but didn't project enough of the acoustic sound for my taste. A really great sounding mag is something I've always wanted though and would probably still be thinking about if I still played that bass.
  9. Rebop


    Jul 9, 2008
    La Honda, CA

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