Steel String MKII

The Vertex Steel String MKII is an analog preamp, boost and overdrive based on serial #001 of the Dumble Steel String Singer, a rare 100-watt 6L6 amplifier. Designed to add D-style clean character to an existing amp, it emphasizes touch sensitivity, low-end fullness and glassy top-end response. Below halfway, the Gain control produces mostly clean boost and tonal coloration; higher settings introduce light-to-mid-gain overdrive suitable for standalone use or stacking with other drives. The Filter control shapes the overall response, while the Rock/Jazz switch provides additional low-frequency voicing options. It can also function as an EQ shaper to smooth harsher drive sounds. The MKII is over 33% smaller than the MKI, operates from 9–18V DC, with 18V providing increased clean headroom, and uses mechanical true bypass.