Vintage Armstrong 521 Stereo Amplifier for disc/tape/MP3/CD*
Very nice example of this highly acclaimed Hi-Fi stereo amplifier from the late 60's. Unmodified - with original AL102 germanium power transistors and two pin speaker plugs. Has been cleaned and all functions checked after a long period of storage (Bias, main caps checked and switches cleaned). Teak sleeve case is in very good condition. Collectors item. £75 ono. Carefully packed and posts for £ by courier to UK, insured and signed for. * Note that MP3 players will need a 3.5 mm stereo jack to male phono plugs cable to connect the earphone output to the amplifier 'tape' inputs, and a low volume setting from the MP3 player. Modern CD players with 2V level 'line' outputs will need a resistive attenuator to drop the level from 2V to 0.4V (or less), so a divide by 5 (-14db) or divide by db) in-line device will be required between the CD player line out and the amplifier 'tape' inputs. Specifications: Output power (RMS): 2 x 20 W into 4 to 8 Ohms, 2 x 15 W into 15 Ohms Frequency response: 22 Hz to 20 kHz (-1 db) Distortion: Less than 0.5 % at 2 x 15 W output Inputs: 2 x 3.5 mV / 60 mV (switch selectable magnetic/ceramic cartridge), 2 x 0.4 V (tape), 2 x 0.1 V (radio), both at 100 k Ohm input impedance Noise level (RMS): -55 db (magnetic cartridge), -60 db (radio), -70 db (tape) Line output: 2 x 0.4 V (via adjustable tone controls) Headphone out: 1 x 6.3 mm stereo (low impedance, mutes main speaker outputs) Rotary controls: Volume, balance, treble, bass Push button controls: Power on/off, rumble filter (-5 db at 30Hz), treble cut 1 (-3 db at 6.5 kHz & -25 db at 10 kHz), treble cut 2 (-3 db at 4.5 kHz & -40 db at 9.0 kHz), loudness (-20 db at 1 kHz produces +10 db at 70 Hz & +5db at 10 kHz), tape input, tape output, radio input, magnetic cartridge input, ceramic cartridge input Power supply: , Vac (selectable), Hz, transformer isolated, internal linear voltage regulated, ~ 20 W (idling) ~ 70 W (max) Cooling: Passive - air cooled