I've just bought the K+K Double big twin..HELP!

You definitely need a preamp - this was pointed out on Bob Gollihur's site, where I bought mine from - Bob was very helpful with advice when I e-mailed him!

 

When the bridge is centered on the table, one leg should be directly over the bass bar (the long bar running the length of the top). The soundpost is the dowel that runs front to rear offset a little southerly of the other bridge leg (G-string, treble side). This relationship is important beyond any implications of how your instrument sounds amplified. Also, the position of the pick-ups is crititcal. The thickness and shape of the bridge also makde a difference. I don't have the Double Twin, but I have the Bassmax, and all transducer type pick-ups require some experimentation to get the best balanced sound. Currently I am able to use the Bassmax with no pre-amp and no EQ. But I had to experiment some with the placement to get that. Good luck.

 

JDM, first, if the bridge is positioned properly, I believe the bridge's centerline should be positioned so that it is in line with the inner notches in the middle of the f-holes.

On my bass, the soundpost is not directly underneath the foot of the bridge on the G string side like I think you described in your original post, but it is quite close. The soundpost on my bass is actually just a bit lower down than that, say about ¾” down (toward the endpin), like what Silversorcerer described.

So to answer your original question, I don't think you want the soundpost directly in line with the foot of the bridge. The soundpost should touch the table on the inside of the bass slightly lower than that I believe.

FYI, here’s an article that talks about the bridge, bassbar, and soundpost. I found the link to it on Bob Gollihur’s links page:

http://www.davidgage.com/z_david_archive3.htm

Hope some of this helps.

 

I think I'd trust David Gage and Bob...