Is it a set up problem?

[Ken Smith]

I think that the sound is in the wood. With a string length of 104cm (40.94") you have a small 3/4 sized bass. The pizz boom you talk about might be lacking from the thickness of the wood and just the overall size of the bass. I would assume at this point that the bass is factory made (pictures might help to guess better) and that the wood is fairly thick in both the top and back. Bowing the Evahs which have lower tension but a bigger diameter makes sense as the Spiros have greater tension and might be choking the sound a bit.

I have one bass that is on the smaller side like yours and it too lacks that depth that sounds deep and shakes the floor. It's loud and carries and has a nice boom but the size of the bass prevents itself from sounding like a larger bass that could be deeper sounding. Actually, I have 2 such basses at the moment. Both are fantastic sounding but that deep dark floor shaking boom you are looking for usually comes from a larger sized bass. Both of my basses I speak of are handmade and much older than yours. Still, they can only be what they are and they are just fine sounding like themselves. If I want a deeper bigger 'boom' sounding bass, I just go to a bigger bass. Problem solved.

[Arnold Schnitzer]

Please check the soundpost position. It should be about the same distance in from the g-side f-hole as the bass bar is from the e-side f-hole. It should be about 12-20mm down from the bridge. It should fit really well and be just a tad snug with the strings off. A larger diameter post will likely make the bass response worse, not better. If you want to boost the bottom, move the post out toward the f-hole a bit. I fear that Ken is probably right, though you state that the arco tone is deep. How high are the strings? Is the nut cut nice and low?

[Ken Smith]

Originally Posted by Arnold Schnitzer

Please check the soundpost position. It should be about the same distance in from the g-side f-hole as the bass bar is from the e-side f-hole. It should be about 12-20mm down from the bridge. It should fit really well and be just a tad snug with the strings off. A larger diameter post will likely make the bass response worse, not better. If you want to boost the bottom, move the post out toward the f-hole a bit. I fear that Ken is probably right, though you state that the arco tone is deep. How high are the strings? Is the nut cut nice and low?

I think it's great to be feared.. lol

[Mike Mandelas]

At first let me state that i consider myself lucky to be a member in our forum, since the treasure of information i gather is invaluable. I tried the new soundpost, making a nice fitting and moving it around the ideal spot. Nothing changed and in fact the bass, as Arnold pointed, has lost some depth. I tried a soundpost with the same old diameter, but with more density in the grain. Moving it and trying it i found a place, 20 mm behind the bridge's G foot and closer towards the f hole, that seems to be the best one. The bass now gives a better piz sound and the E and A strings seem to be more resonant. Obviously, as Arnold stated in another thread, the bass bar responds better with the soundpost closer to the f hole. I think that the instrument now has reached its potential since the arco sound remains unaffected. The strings' height is 5 mm, 6 mm, 7 mm and 9 mm (G,D,A,E). Probably a larger instrument will deliver a more "booming" sound, so dear Ken, i take is as a fact.
Thank you all for your time.
Mike