valveamps.com Collector and restorer of old valve guitar amplifiers describes his collection. http://www.valveamps.com

Acme Sound Bass Speaker Cabinets Andy Lewis' flat-response extended-range "Low B" line of 3-way bass speakers. Direct sales. http://www.acmebass.com/

Harmony Central Amp Database Large database of guitar and bass amplifier and speaker user reviews. http://www.harmony-central.com/Guitar/Data/

ESP Projects Audio projects including amps and preamps suitable for musical instruments amps, effects, and some neat subwoofer/processor plans for bassists. http://www.sound.au.com/projects.htm

Bass Gear Review Page Huge archive of bass-related user reviews including preamps, power amps, amp heads, speaker cabinets, combo amps, and effects. http://www-eksl.cs.umass.edu/~schmill/bass-rev.html

Compact Bass Guitar Speaker Bottom Len Moskowitz' famous compact bass cab plans. Gonzo sound for the do-it-yourselfer. http://www.core-sound.com/bottom-article.html

Jörg Schmitz Analog Synthesizer DIY Information about analog synthesizers, including schematics, links and how-to tutorials. Also features a section on microcontrollers and audio music technology. http://www.analog-synth.de/