String clearance over soapbar - How much?

[gapupten]

I had this in the pickup section.. probably goes here.

I can't make my string clearance over my soapbar pickup greater than 1/4 inch without increasing the action to way more than I want.
I have a bartolini soapbars and the screws are down as far as they can go. I normal like to play with very low action but that makes the clearance about 3/16th of an inch. At that low level, the sound is not clean. The best description I can give is that there is little decay in the sound levels from the first thump to the after strike vibrations. The output is much higher than a single coil Bartolini J pickup I have on another bass. The situation improves as the clearance increases. There is more definition in the sound.
Am I describing a situation that would occur as a result of the stings too close to the pickups? Somewhere I thought I read that the clearance needed to be more on a soapbar than a J. And for some reason I recall that 3/8" was proper for a soapbar setup.
Anyone have any ideas?