Altec Lansing 771B Electronic Crossover Biamplifier TESTED Amplifier 

Up for auction is a pair of Altec Lansing 771B Electronic Crossover Biamplifiers - serial #'s 6135 & 1087.  These little solidstate "monoblocks" contain a separate 60W LF amplifier and a 30W HF amplifier which drive an 8 ohm minimum load. The crossover network is placed ahead of the dual power amplifiers so the full biamplifier output is distributed to the speakers. Crossover points at 500, 800 and 1500 Hz (-12 dB/octave). Rated output power is 60W and 30W (RMS) at less than .5% THD into 8 ohms. Bass and gain control faders on the front panel are continuously variable +6 to -15 dB. Input sensitivity (for rated output with full boost) .5v RMS. Note - these units do not come with the optional line matching transformers and only have an unbalanced input.

Both units have been completely refurbished. Power transformers were tested for rated voltage output and grounded mains cables installed. All electrolytic capacitors were visually inspected, ESR checked and any defective components replaced. All components in the signal path (connectors, film caps, transistors, etc) were tested and replaced if not meeting specifications. Power semiconductors that were damaged/weak were replaced with NOS replacements and thermal pads used in lieu of mica and silicon grease. Faders were disassembled, cleaned and lubricated (DeoxIT F100L) to restore performance and "feel". System testing was done using an HP8903B to check frequency response and THD. Output levels were verified with an HP 54603B scope and 3312A signal generator with the amplifiers connected to an 8 ohm resistive load. Final listening tests and "burn in" was accomplished using two Altec 9846B loudspeakers (shown BUT NOT included in the auction) with gated sinusoids and test material (i.e. Crown Microphone Demonstration CD).

Flat rate FedEx ground shipping in the 48 states is $52 (each amp weighs over 16 lbs) - please no rural shipping destinations.