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Chambering for less weight

Discussion in 'Luthier's Corner' started by Frank Martin, Apr 20, 2005.


  1. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Hello everyone!

    I thought I'll repost my thread here, as I didn't get many responses so far in Basses...

    Should I use acoustic dampening material in the chamber to avoid unwanted resonances?
    The chamber will most probably be a little less than 3" radius, roughly a half-circle, 3/4"-1" deep, and closed. (A bit bigger than an electronics cavity, just empty and used only for weight reduction)

    How much can this little chamber affect the tone, and how will it change?

    Thank you in advance!
     

  2. I do complete "chambering' on 2 of my designs and I've never heard any unwanted resonancese. Besides, if it's a new build, you would know it's an "unwanted" resonance until you've finished and got it all buttoned up to hear when it's plugged up. Then it's gonna be hard to put something in there when it's sealed. :meh:
     
  3. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    That's why I asked first ;)

    But do you think there is a chance that this size cavity will be causing problems?
     
  4. JP Basses

    JP Basses

    Mar 22, 2002
    Paris FRANCE
    few chances the cavity causes a problem. Few chances than you save more than 200 grams with one cavity only ;)

    Peace,
    JP
     
  5. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Well, there's a saying here: who does not appreciate the small is not worthy of the big ;)
    It's good for a start.
    A big electronics compartment, a deep battery shaft and this chamber, which is a bit bigger than the electronics cavity. With the back being swamp ash, this will work out to less weight. Hopefully ;)
     
  6. tjclem

    tjclem Supporting Member Commercial User

    Jun 6, 2004
    Central Florida
    Owner and builder Clementbass
    Just be careful of getting too light a body watch for neck dive....t
     
  7. JP Basses

    JP Basses

    Mar 22, 2002
    Paris FRANCE
    that's true frank. don't forget to use aluminium for the bridge and ultralite tuners...


    Peace,
    JP
     
  8. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Too light a body? Don't worry, it will have a thick (3/4") piece of figured bubinga as the top half of the body :D That's why I'm using swamp ash as the back, and even chamber that.
    The neck will be wenge/bubinga; but there will be a longer upper horn - it is right halfway between the 13th and 12th frets.
     
  9. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    I'm not really sure about the aluminium bridge... It is hard to find, especially for a 6. The ABM 3566 is available at Musik-produktiv, and it would also work as a counterweight to the wenge neck.
    As for the tuners, I think I will use Gotoh Res-o-lites... when they will finally be available at Musik-produktiv. If not, then the GB7s are not so bad after all (64 gramms).
    As for the Hipshot Ultralites, I can't get it anywhere here unless I order online.
     
  10. teej

    teej

    Aug 19, 2004
    Sheffield, AL 35660
    I may have misread this, but an aluminum bridge wont help with neck dive. In fact, I think it would only make things worse but decreasing the weight of the body, which is what causes neck dive in the first place. However, the lightweight tuners WILL help dramatically (from what I'm told).
     
  11. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    That's why i wrote I'm not sure about the aluminium bridge idea.
    But I assume JP only posted this as another weight-reducing method, before I wrote that it will have a wenge neck.
     
  12. teej

    teej

    Aug 19, 2004
    Sheffield, AL 35660
    To combat neck dive, a steel or brass bridge would be best. However, I think it was said that the upper horn would go to the 12th or 13th fret. Chambering wont make a HUGE difference in weight, compared to a hollowbody. There may be some neck dive, but I don't think it will be too bad.
     
  13. I would make sure the horn goes completely to the 12th fret to begin. That little bit would make a difference. Then if you need it, raise the rear strap button just a little to fine tune the setup.
     
  14. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    The ABM 3566B is a big brass bridge
    Like this, but in 6 and black:
    [​IMG]

    I'm not expecting a huge difference in weight, but even a little matters.

    The Corvette is solid bubinga. Bubinga is 4,8 lbs per bd ft.
    This project will have a swamp ash (3 lbs/bdft) back half -> 1/2 * (1 - 3/4,8) = 18,75% weight reduction. Then there are the chambers, so that should work out to a body about 25-30% lighter.
     
  15. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Well, it's about 1 cm (7/16 ") short of the 12th fret line now ;)

    As I like playing chest-height, the bass should not be too body-heavy, either.

    I'll post pics of the plans tomorrow, it's a bit dark now to take photos.
     
  16. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    So then here are two not-so-good pics...

    [​IMG]

    [​IMG]

    Though it's not really visible on these pics, but there is a line indicating the 12th fret, and the upper horn is just 1,1 cm from it.
    The outlines of the Corvette's upper & lower horns (dotted) are still visible.

    So, what do you think? :)
     
  17. Here's where I part company with Warwick's approach to pup location. I fail to see the wisdom in locating two similar pups so close together. Of course there will be some tonal difference but from my "builders" POV, I would try to achieve more tonal range with some more spacing between the pups.

    But that's just me... :meh:
     
  18. teej

    teej

    Aug 19, 2004
    Sheffield, AL 35660
    Yeah, I've seen some vintage hollowbodies with a pup hugging the neck heel, and another about 1/2" from the bridge. That's some space!
     
  19. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    :meh:

    Yes, maybe I'll move the front p-up a bit closer to the neck.
    However, this configuration has worked very well so far for me.
    When soloing the "neck" p-up, I get that P-bass-like tone with an agressive, growly edge to it. Also, it leaves me ample space for slap - with a p-up right at the neck, it would be a bit harder to manage ;)

    This p-up placement is probably not the final one. It also depends on what kind of p-ups I can get. Now it's a P4 shape drawn in, but if I can't get P4 DCs, or if I'll have to shell out $500+ for them (seems possible :mad: ), I'll go with something else.

    Thanks again for your responses!