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What might be wrong?

Discussion in 'Luthier's Corner' started by Frank Martin, Feb 5, 2006.


  1. Frank Martin

    Frank Martin Bitten by the luthiery bug...

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

    Unfortunately, my new bass is giving me some problems...
    After a few weeks of being put together, and after a few days of intensive use (rehearsals), the acoustic tone of the bass, especially when slapped, lost some lows and a lot of highs. It's not just the strings - the same type of strings, DR Lo Riders, are on my Corvette, too, and they still have those slap highs even though they are much older.

    I have some ideas what may be causing this.
    The prime suspect is the polyurethane hardcoat being too thick.
    The other one is the not-so-perfect neck joint. The neck is a bit "loose" in the neck pocket (by which I mean I don't have to force it to take it out, it comes out more or less easily; also, the neck's end and the pocket have only a few contact points). The five neck bolts are tight, though.
    Maybe the weight-reducing cavity?

    For more info, check the link in my sig

    Thanks in advance!
     
  2. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Thanks for the reply, Hambone!

    It still sounded good for fingerstyle, but the slap was a bit different even in the beginning. Now I see it's not just a bit different, but something is wrong...

    The change came by as the strings were getting broken in, filling in with sweat and dirt, etc.
    However, in this case, this process was quicker and more drastic. The strings sound more muted than some other, even older strings on my Corvette.
    After I first encountered the problem, I took the bass apart again and checked all the things that come in contact with string vibration; and for that time I put the strings in pure alcohol (it's hard to get these strings here, I have to order from abroad). Putting it back together, some zing and high-end came back, but the E and B still sound a bit hollow, and there's still some high-end missing. Even my Dad, who is half deaf, heard the difference between this and my Corvette, with 1-2 month old strings...

    The finish is thick, that's for sure. We are just amateurs with lousy tools, but we are glad we could come this far. I'm still wondering whether the finish can cause all this... :meh:
     
  3. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    It is a bit frustrating, but not that much - for me, anyway.
    I'll put on the spare set if it comes to worse... but three quality strings being bad is too much of a coincidence...
     
  4. I believe the problem may be that it's backwards...:ninja: :D

    I'd guess the neck joint, only because you mentioned acoustic sound. Humidity perhaps?
     
  5. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Humidity has been more or less constant @ 45-50%.
    The sound persists even when plugged in, I wrote acoustic tone to say that it isn't the electronics.

    Anyway, this weekend I'll try to finish the bass, sand it down again to polish and buff, we'll see what happens.
     
  6. I wouldn't think it's the finish.
    If your getting this unpluged I would be looking for something loose or poor setup. have you checked the neck angle, it might need shimming, can you get any play in the neck/pocket join when all the screws are tight, did you use threaded inserts or just screw into the wood, check the releif, it might need re-setting, a bad set up can cause something like this as it can alter the string tension and take away some of the brightness away.
    is your bridge firmly fixed.
    really go through the bass, check everything!
    and I agree with mr Hambone you'll be amazed what a naff set of strings can do!
     
  7. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    At first it did sound like something was dampening the strings or was loose, but even though I checked everything I could think of, it didn't work.
    Neck angle looks ok. It's got medium-low action now.
    Neck is held in place by the five bolts, it doesn't move. The luthier who made the neck just screwed into the wood.
    Relief is good.
    The strings were a new set, they were on it during the test runs for 2-3 weeks (with not too much use), then some days of more intense use (2 rehearsals), and after that it spent some time in alcohol. Should be quite zingy and bright, but it sounds a bit hollow on the lower strings on this bass.

    Maybe the lacquer in the neck pocket and on the back of the neck?

    Anyway, the finish was far from perfect, it needed evening and polishing/buffing, so I'll try that this weekend.
     
  8. as hambone said...it's most likely NOT your finish...

    if you want to perfect your finish, fine...but that's not going to change your tone...

    you've taken your strings on and off how many times now? I don't care how new they are, if you continue to do that there WILL be a change in quality of your sound...it may be slight, but it will change.

    Check your bridge saddles (move them around slightly to make sure that everything is seated well)

    Check your setup, especially the amount of compression your trussrod is putting on your neck...aka relief (that will change your sound a bit).

    Also, check the break point over the saddle for your strings...especially the E and A strings...push them down just in front of the bridge to make sure that the string has a good witness point..

    worst case, get new strings...but I seriously doubt that your problem has ANYTHING to do with your finish.
     
  9. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    That's why I asked, for possible problem sources.

    String changes:
    1 for initial electronics test
    1 for first assembly
    1 for problem check
    1 for different strings (take 1 off, put 1 new on method)
    that is 3 complete removals in a period of 2,5 months. I don't think that's many.

    Bridge saddles are ok.
    This doesn't seem like a case of witness point - I got some harmonic buzz for the open E on the nut-tuner part of the strings.

    I put on some old TI Powerbass strings, and the slap tone improved. Not just the highs (these are quite bright strings by default), but also the lows. Unfortunately, thought, the D string seems to be cracked (has a duller tone with less highs, but when plucked with more force, the entire string starts buzzing - and it's not fretbuzz...). I'll try to order some more, but it looks like they got quite expensive in the meantime :eek:
    What I noticed is that these strings are higher tension, and the action is now higher - and has more pull on the neck.

    Now I'm thinking about the neck angle, as HeathW pointed out. With the LRs, the neck had just a bit bigger angle than my other basses. Now the TI pulled it back, and it seems good.

    It's ironic that there are two things that I left to a professional, these constitute about 40% of all expenses, the rest was done by two complete amateurs; yet I had and have the most problems with the neck and the neck joint :rolleyes: :smug: (ok, and with the finish, but that due to lack of availability of high-grit papers and polishing compounds...)
     
  10. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Back to phase n-1.
    Something is still robbing me of highs.
    I checked the same sring on my Corvette then put it on this one, and the difference is night and day. I get stronger fundamentals, but the slap tone is much duller, with highs lacking.
    Neck is screwed in tight
    Bridge screwed in tight, saddles in place
    Break angles ok
    yet still...

    Might it be because of lacquer in the neck pocket?
    The grain direction?
    The recess for the electronics compartment?
    I'm running out of ideas...

    Advice is very welcome. Thanks.
     

  11. My guess is that it has something to do with the electronics.
     
  12. Hey Frank, aren't old Fenders masked off in the neck pocket? I don't imagine that alone is the problem, but maybe one of several 'little' factors involved. You tried different strings, resulting in a slight improvement, correct? Perhaps you've gotten some bad strings, the finish neck pocket/joint dampens things & the chambering takes a bit of definition away. A little bit here, a little bit there...
     
  13. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Thanks for the replies!

    This was just the acoustic tone, so the electronics don't come into question here.
    Most probably a bit of this, a bit of that... but the difference is still striking even with the very same string.
     
  14. Greenman

    Greenman

    Dec 17, 2005
    Ontario Canada
    How about trying resetting the neck with something like Acraglass. A cheap process of elimination maybe? :meh:

    [​IMG]
     
  15. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Hm... looks interesting.
    What exactly is this acraglass?
    I presume it's some kind of acrilate, right?
    Does it have better resonant properties than poliurethane-alkide?
    Thanks!
     
  16. Greenman

    Greenman

    Dec 17, 2005
    Ontario Canada
    Beets me. I use it for bedding rifle receivers into the stock for more uniform vibration when the gun is fired, and better contact area.
     
  17. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Googling a bit this Acraglas turns out to be a nylon-epoxy compound. I guess epoxy should work, as well (this acraglas doesn't seem to be available here).
     
  18. Greenman

    Greenman

    Dec 17, 2005
    Ontario Canada
    I would imagine similar materials would work just as well as long as you remember to use soom sort of release agent on the neck.:bassist:
     
  19. Sounds to me like the wood in the neck and neck pocket is settling in. You may need to tweek your truss rod. If its the neck pocket that's moving, then you may need to do a glue-in modification on it....but even that may not help.
     
  20. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Quite possible. The neck is a bit loose compared to the other instruments I have.
    The action is quite low, so setting the truss-rod again is not necessary imo.
    As for gluing-in, I think I'll rather try that epoxy bedding first - as it's easier to reverse than gluing in the neck...