I was on the Warwick website & you could see the switch but it didn't say anything about a switch.
<img src="http://www.warwickbass.com/images/streamerjazsm.gif">
<u>From the Warwick site:</u>
<font size=2><i>The Streamer "Jazzman" combines the Streamer bolt-on design with our extremely popular "Jazzman" pick-up configuration. Just like all our other "Jazzman" basses, the Streamer "Jazzman" has a large-pole, humbucking pick-up in the bridge position and a J-style pick-up in the neck position. The body is made of swamp ash back with a 5mm flamed-maple cap on top, which gives the bass a very warm sound.
The Streamer "Jazzman" is armed with a Basslines 3-band active preamp, with the "slap" contour that is activated when you pull on the volume knob. If you are looking for a bass that can give you a wide variety of tones in a very attractive package, then the Streamer "Jazzman" is for you.</i></font>