Ampeg SVT-VR 300 Watt Tube Bass HeadTubes, tubes, and more tubes! The new Ampeg SVT VR is a vintage reissue of an early 1970s Blue Line SVT head. The preamp stage, power section, and even rocker switches emulate the exact signal path, tone, and vibe of the original rock n roll workhorse. Authentic from its input jack all the way to its six 6550 output tubes, the SVT VR is a must have for rockers seeking that in your face Ampeg bass tone.