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Double Bass What's wrong?

M

Meddle771

Aug 9, 2010
141
2
Minneapolis/St Paul MN
#1
I play a Sam Eastman ply with Corelli Tungsten TX gauge 370's.

It's hard to explain without sound samples, but some notes are very uneven in volume and feel than others. My A on the D string (Octave of the open A) moves the open A a ridiculous amount to the point where I almost can't play it amplified because it gets so muddy. It seems like the bass sounds choked and rumbly when I play an A, any and everywhere on the bass. My Bb (once again, anywhere and everywhere) sounds really funny as well. The Bb right above the octave A on the D string is a wolf tone and completely unplayable. The other Bb's just sound rumbly and obtuse.

My question is, what is causing this? Soundpost? Tailpiece? I'm pretty sure it's not the strings. I would like to use this bass for a full album in early Jan/late December and need to get it fixed before then.
 
#2
Bb is often the main tone of the body of the bass so it creates a sympathetic resonance. This can often be subdued by altering the tension of your strings, increasing or decreasing the pressure of the of the bridge on the top.

I had to increase the string tension on my gigging bass to eliminate some pretty serious main body "feedback". I also had a movable wolf tone that would travel up or down slightly in relation to the pressure of the bridge on the top (on the D string between F and G#) The ultimate solution for me ended up being a shorter, lighter tailpiece - increasing the afterlengths (the portion of the string between the bridge and the tailpiece) slightly beyond recommended specs.

However, I should add that my bass has a carved top which is more sturdy than plywood.

You might want to google "wolf tone eliminator" if you haven't already. I've never used one, but I guess they work.

The best solution would probably be to take it to a luthier.
 
#3
You can also try a sound post adjustment. It's not as likely a fix as Mark's suggestions, but it's fairly cheap and easy to get a luthier to knock your post around a bit while you try the notes you are having issues with every few bumps. You might want to get this done anyway if you solve the problem another way, just to fine tune the sound to your liking.
 
#5
Wolf eliminators are usually 1 per instrument on the string creating the highest level of wolf tone.

Wolfs are fairly rare for basses. I don't even carry bass wolf eliminators in my shop. Most cellos will have one, some violas, and rarely violins.

On the cello and viola the wolf eliminator almost always goes on the 3rd string which for them is the G. The wolf pitch is typically anywhere from E to F sharp and most prominent approaching the octave up in position.
 
#9
Maxvla said:
Wolfs are fairly rare for basses. I don't even carry bass wolf eliminators in my shop. Most cellos will have one, some violas, and rarely violins.
Click to expand...
Are you serious? Theoretically, wolfs should be most common on basses given their size. Nearly every good bass I've ever played had at least a slight wolf. Both of my basses have severe ones.

They don't seem to be as common on cheaper instruments, for what ever reason.
 
#10
Meddle771 said:
i know of the wolf tone eliminators, but i don't want to put like 3 or 4 on, because each one only messes with one string, right? and my problems are across 3-4 strings.

is there a way i could change the tension of the strings without adjusting the string height?
Click to expand...

You can change the length of the tailpiece wire (tailgut) a bit, unless it's a coathanger - which should probably be done away with anyway. It will undoubtedly require a lot of experimentation to find the right level of tension.

3/32 steel cable and a couple of little cable clamps are all the rage. :) I buy mine by the foot at a ranch supply store. Should be about $5.
 
#11
A single wolf tone eliminator should reduce and shift all current wolf tones, depending on where it is put. Trial and error. The aim is to put them (wolf tones) somewhere they are not so noticable, without creating another in an obvious spot. It is simply altering the resonant frequency of the whole string / bass / bridge / afterlength etc combination to reduce feedback of the vibration energy back into the string and cancellation. Anthing that alters the afterlength / mass etc would do it. Personally I like the idea of the wire tailpieces, with the correct damping they are theoretically the best wolf tone eliminator.

I use my old trusty BP-100 pickup - the socket is reasonably heavy and clips over two strings and has dramatically reduced the wolf tone I had on my A string C. One day I'll make the effort to get a proper wolf tome eliminator!

Simon
 
#12
bigolbassguy said:
You can change the length of the tailpiece wire (tailgut) a bit, unless it's a coathanger - which should probably be done away with anyway. It will undoubtedly require a lot of experimentation to find the right level of tension.

3/32 steel cable and a couple of little cable clamps are all the rage. :) I buy mine by the foot at a ranch supply store. Should be about $5.
Click to expand...

How do i change the length of the tailpiece wire? ill probably end up bringing it to my luthier on Saturday.
 
#13
If your tailpiece is using a sacconi (black plastic looking) for a tailgut, you can adjust the length with the brass screws. If it is aircraft cable with blocks smashed to secure it, you might be out of luck. You can always put a new one on however that is shorter or longer.
 

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