Auction link. Head from a legendary company. Seller doesn't ID tubes ... 6L6s? Very little public domain information on the model but by the later '60s, Standel was making amps with transistor-based preamps and tube output ... a format later adopted by MusicMan.
Another Standel Imperial with original 2X15" speaker cabinet from TDPRI:
Another Standel Imperial with original 2X15" speaker cabinet from TDPRI:
