Guitar
Aguilar Amplifiers, Aiken Amplification, Amp Tone, Cornford Amplification, Crate Amps, Dave Hall, Demeter Amplification, Dr Z Amplifiers, Eden Electronics, Euphonic Audio
Repair and Modification
Amp Technician Registry, Angela Intruments, Nashville Amplifer Service, Plexi Palace, Time Electronics
Acme Sound Bass Speaker Cabinets
Andy Lewis' flat-response extended-range "Low B" line of 3-way bass speakers. Direct sales.
Bass Gear Review Page
Huge archive of bass-related user reviews including preamps, power amps, amp heads, speaker cabinets, combo amps, and effects.
Compact Bass Guitar Speaker Bottom
Len Moskowitz' famous compact bass cab plans. Gonzo sound for the do-it-yourselfer.
ESP Projects
Audio projects including amps and preamps suitable for musical instruments amps, effects, and some neat subwoofer/processor plans for bassists.
Harmony Central Amp Database
Large database of guitar and bass amplifier and speaker user reviews.
valveamps.com
Collector and restorer of old valve guitar amplifiers describes his collection.