Audio Research writes: “It’s Throwback Thursday. It is gratifying when products like this D-90 come in for service. It is in such beautiful condition for an amplifier that is over 42 years old, built in January, 1982. Except for some new parts like the Nichicon capacitors in the power supply, this one is completely stock. Output tubes are Sovtek 5881/6L6, producing 90 WPC.
Like all Audio Research components offered at the time, this D-90 has rack mount cutouts in its front panel. Bill Johnson loved rack-mounting his equipment.
The matching preamp for the D-90 was the SP-6B, which was a great sounding combo. Interestingly, you can see there is no power switch on the D-90. In the late ’70s and early ’80s, preamps had power outlets on their rear panels and many owners would plug their amplifiers into the switched power outlets. It worked best if the preamp (like the SP-6) had an auto-mute warmup cycle, which prevented spurious noises from being passed to the amplifier and speakers. We have learned a great deal since then and we do not recommend plugging amplifiers into preamps!
