Another experiment might be to stuff something like upholstery foam inside the body to see what that does, if anything!
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Fixing resonance dead spots on an ABG.
- Thread starter Rockin John
- Start date
I found deadspots to be much more noticable on the fretless than fretted basses. On one fretless, taking the roundwound strings off and fitting slightly higher tension flatwound strings susbstantial reduced the dead spots. On another bass, the dead spots were on the B string. In that case, changing from flatwounds over to roundounds made a huge difference.
I think @Bruce Johnson is right though (as per usual, lol). The top is the problem. Some of the bracing attached to the top is allowing it to move around too much on the notes you're mentioning.
I think @Bruce Johnson is right though (as per usual, lol). The top is the problem. Some of the bracing attached to the top is allowing it to move around too much on the notes you're mentioning.
Ok Rev, and thanks. I guess there's not really much I can do, working inside the body of an acoustic bass. I'll see how we go with this. I'm planning to buy another EABG so this one might just have to go in as a part exchange. But still, it's an interesting issue and is worth persuing just for the increase in knowledge.
Tks. J
Ps. String change makes little difference. The bass came new with D'Addario nickel rounds. They came off straight away, anyway, and using flats hasn't really changed anything. Retensioning the truss rod makes little / no difference from rounds to flats. And using different brands of flats has little effect, too.
Tks. J
Ps. String change makes little difference. The bass came new with D'Addario nickel rounds. They came off straight away, anyway, and using flats hasn't really changed anything. Retensioning the truss rod makes little / no difference from rounds to flats. And using different brands of flats has little effect, too.
If you are trying to find where the top vibrates the most, maybe you could try bouncing a laser beam off the top at an angle at different spots and see how much the reflection moves on a wall a few meters away. It's in no way precise, but it may be easier than moving a brace by trial and error.
Well, that's not a bad idea. Thanks. I've got some laser diodes somewhere. Due to construction work inside the house I'm not able to do much more with this for a few days, but I did try testing with the finger end for vibration. Now, though I don't have a calibrated finger, the vibration is centred around the bridge as far as I can tell, and that strength of vibration isn't found elsewhere on the body. So, again, at this point, I'm a bit unsure what to think.
Dead spots can effect any string instrument, including violins, cellos, mandolins, guitars... any thing with strings.. and has to do with the resonance of the wood. If the instrument resonates or "rings" at a certain frequency, the vibration interferes with the vibration of the string via something called phase cancellation. The phenomenon can be addressed. Increasing the mass of the instrument will change the resonance. The device known as the bass finger does just that. A qualified luthier is probably your best bet to deal with although with an inexpensive ABG, maybe not the best use of your hard earned money. I have seen some solutions that include in inlaying weights in the head stock and attaching weight in different ways. Here is an article from Johnny K about how to fix this issue http://johnkvintageguitars.homestead.com/Bass-Deadspot-Removal.html This all requires experimentation to find the right amount of weight in the right places to address the issue.
The dead spots or wolftones are issues that would absolutely make me walk away from an instrument. While they can be fixed, its can be a lot of time, effort and expense. If bass has dead spots, walk and find one that does not.
The dead spots or wolftones are issues that would absolutely make me walk away from an instrument. While they can be fixed, its can be a lot of time, effort and expense. If bass has dead spots, walk and find one that does not.
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Hello and thanks. Yes, I'm fairly clued-up on the 'theory' of dead spots but, because it's an ABG / EABG I wanted guidance. Nothing I've tried so far helps, including adding headstock mass (6" Carpenters' G clamp!).
The reason I have this bass is a convoluted story. In fact I'm looking to replace it. However, as someone who has a 'thirst' for knowledge and understanding, trying to sort it has become more of an academic exercise than anything else. If the spots can be fixed or partially fixed I might keep it. As you rightly say, I won't invest money on it with a luthier.
The C clamp is not enough mass apparently... this bass may be better suited as decorative wall art 
The C clamp is not enough mass apparently... this bass may be better suited as decorative wall art
Yes. Possibly so. A previous contributor to the thread felt extra headstock mass was most unlikely to work, and that checking for - and hopefully curing - vibration problems on the body might be best. Unfortunately neither has been good so far!
