Double Bass Thoughts on K&K issue???

[Nate74]

My EUB build is done and I'm really enjoying it. However when playing through an amp, I noticed what I thought was static. But the noise I thought was static was only present when a string was vibrating.

I then realized I could recreat the sound by pushing down on a string, near the bridge. From this I deduced it was the sound of the K&K Big Twin pickups that I have under the bridge.

Here's a pic that should help better show the setup.

Link Removed

I'm guessing this isn't normal and am open to any thoughts on bridge/setup modifications that might help eliminate this.

Thanks.

 

[Bob Gollihur]

The piezos are sensitive, and since your photo isn't 3D like "Chuck" on NBC, I cannot be sure but it seems that your bass' body has a slight bit of contour to it.

The Big Twin transducers do not, so when you press down I think you're ever so slightly bending the transducers-- and that's what transducers do, react to ever-so-slightly vibrations. Especially when under pressure.

As you may have noticed, simply touching the wires coming from the transducers will create a signal (noise). They are that sensitive, and need to be to give us those string vibrations.

 

[Nate74]

Thanks Bob! I probably should have just emailed you directly huh?

At any rate, the top actually isn't contoured but I guess the flame maple looks that way. It did get me thinking though about the contact between all the mechanical parts of the bridge.

I got to thinking that maybe something else was compressing and that the vibration that compressing was causing was what I was hearing. I took the top part of the bridge off and wrapped the 1/4-20 screw posts with plumbers teflon tape. I then put the top portion of the bridge back on and the noise is gone!

It was your comment about transducers picking up "ever-so-slightly vibrations" that really helped me see what I was dealing with so yet another big thanks Bob!

 

[ToneRanger]

As you may have noticed, simply touching the wires coming from the transducers will create a signal (noise).

The first time I played my EUB in a loud band, I had a huge resonance whenever I hit a 'D'. It made the bass quite unplayable. Over the next week I tried all sorts of things to get rid of the problem - damping the tailpiece, replacing the endpin, clamping different weights on the body to try to change the resonant frequency. Then by chance, I bumped the arc of cable coming from the pickup and it produced a loud 'D'! A small scrap of foam on the leads and the problem was solved!