Stereo Amplifier 521

Armstrong Audio / Wireless & Television / Manufacturing; London

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  • Year
  • 1968 ??
  • Category
  • Audio Amplifier or -mixer
  • Radiomuseum.org ID
  • 283408

Click on the schematic thumbnail to request the schematic as a free document.

 Technical Specifications

  • Number of Transistors
  • 21
  • Main principle
  • Audio-Amplification
  • Wave bands
  • - without
  • Details
  • Hi-Fi equipment
  • Power type and voltage
  • Alternating Current supply (AC) / 110; 120; 220; 240 Volt
  • Loudspeaker
  • - This model requires external speaker(s).
  • Power out
  • 50 W (undistorted)
  • Material
  • Wooden case
  • from Radiomuseum.org
  • Model: Stereo Amplifier 521 - Armstrong Audio / Wireless &
  • Shape
  • Book-shelf unit.
  • Dimensions (WHD)
  • 292 x 117 x 280 mm / 11.5 x 4.6 x 11 inch
  • Notes

  • 2 x 25 watts output at 0.5% harmonic distortion
    Frequency responce 20 to 25,000 Hz
    Bass Control; ± 10dB @ 70Hz, Treble Control ± 10dB @ 10kHz.
    Rumble filter; -5dB @ 30Hz increasing at lower frequencies
    Treble filters 1;  6.5kHz -3dB, 10kHz -25dB
                       2;  4.5kHz -3dB,  9kHz -40dB
    Loudness control; at 1kHz reference (-20dB), 70Hz +10dB, 10kHz +5dB

    Outputs for Tape Recording and headphones

    Inputs for;
    1 Tape, 2 Radio, 3 Ceramic cartridge & 4 Magnetic Cartridge.

    An later example of this amp, which appeared to be all original, was fitted with the following transistors.
    C16 preamp board; BC384L BC1586 BC1586
    A15 power amp board; XK1112 BSV44A BSV44A BSV44A AL102 AL102
    Z17 power supply board AC139 AC139 AL102

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