Welnick started playing keyboards as a teenager. He joined a band, the Beans, which eventually morphed into the Tubes, a San Francisco-based theater rock band popular in the late 1970s and early 1980s and noted for early live performances that combined lewd quasi-pornography with wild satires of media, consumerism and politics.
The Tubes in the 1980s were a major commercial rock act with substantial MTV success. Videos for rock classics “Talk To Ya Later” and “She’s A Beauty” played in heavy rotation on the MTV network for years in the mid-1980s. While playing in the Tubes, he also played and recorded with Todd Rundgren.