Buzz finding tools & techniques?

[gp_bass]

Despite all the many posts on buzzing in this forum, there's little mention of tools or techniques for diagnosis.

Here are a few that I've found so far:

• the knock test: knock with your knuckle on the top/back above the rib seam to see whether it makes a solid thunk or a papery "thwap". A thwap means a potentially open seam.
• the rubber tube test (from CarTalk): use a rubber tube with one end held near your ear and the other end focusing on different parts of the bass while a friend plays the bass. Helps determine where the buzz is coming from, as buzzing can be hard to locate.

Have people used or made other tools or techniques? Here are some I was thinking of:

• a bendable, pointy poker: put this through the FF hole to press on cleats, etc that might be loose. Have a friend play the bass at the same time to see whether holding a cleat stops the buzzing
• a stethescope: basically an upgrade to the rubber tube, helps pinpoint the buzz

What else? My bass has a million cleats and patches, and short of opening it up, I'm curious to find an efficient way to chase down these summer buzzes.

Thanks!

[JtheJazzMan]

For starters youll want to keep some lithium carbonate to stave off the inevitable decline into insanity from trying to find an elusive buzz......

Instead of your using your knuckle, try using a lightly padded drum stick/mallet. You can hit the bass harder without causing damage, to help isolate open seams or buzzes better.

I have a stethoscope but its not a lot of use. Its meant to listen to heartbeats and breathing which are very quiet. Putting it on a vibrating bass is like having someone shout in your ear.

I lay the bass down on the floor and using a bow with my left hand to bow the open strings hard. That way I can keep my ear down near the lower bouts and the block to listen for buzzes.

[gp_bass]

yeah, i figured a stethoscope would be too loud. thanks for saving me the $ there!

[bejoyous]

At one time, my bass had a weird buzz only on certain notes, whenever I took it to my luthier, it suddenly wouldn't be there. It was very frustrating.

We were testing it with the endpin all the way in or with it out of it's socket (since I use a wheel, when I pack it up, the endpin goes in the case).

Turns out the buzz was the sympathetic vibration of the inside part of the endpin when it was at the playing position.

I sawed off the unneeded part and the buzz magically disappeared!

So, be sure to test for a buzz with the endpin in the proper position.