WS-442 en

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The WS-442 is a stereo amplifier manufactured by Diora in the 1980s. It was produced in a black metal housing, the twin version of the WS432 was embedded in a silver housing. It has interesting functions, e.g. switching 2 sets of speakers, RIAA equalizer for a turntable with a magnetic insert.

WS 442 specification:

  • Rated output power at Rload = 2×8 Ω: 2×35 W.
  • Harmonic distortion at rated power: ≤0.2% at f = 1kHz
  • Maximum output power: 2x40W
  • Intermodulation distortion at rated power: ≤0.4%
  • Sensitivity of inputs:
  1. line input ≤200 mV
  2. RIAA correction input (turntable) 2 mV ± 2 dB
  • Maximum input voltage: 
  1. line input ≥2V
  2. RIAA correction input (turntable) ≥20 mV
  • Output voltage recording:
  1. 0.2 mV ± 2 dB DIN socket
  2. CINCH 200 mV ± 2 dB jack
  • Input impedance
  1. 220 kΩ line input
  2. RIAA correction input (turntable) 47 kΩ ± 20%
  • Headphone output voltage at R = 400 Ω: 5.0 V ± 2 dB
  • Power frequency response: 35 ÷ 20,000 Hz
  • Amplifier frequency response:
  • line input (with tolerance ± 1.5 dB) 20 ÷ 20,000 Hz
  • Correction (with a tolerance of ± 2 dB) according to the RIAA curve
  • Signal to noise ratio 90 dBA line input 85 dBA correction input
  • Tone adjustment range for f = 100 Hz and f = 10 kHz: ≥10 dB
  • Crosstalk attenuation for f = 1 kHz: ≥45 dB
  • Power supply:
  1. 220 V – 50 Hz network
  2. Permissible power consumption: 140 VA
  • Dimensions: 440x90x260 mm
  • Weight: 8 kg

I used WS442 from the beginning with the DST-102, once it was repaired, the transistors in the power amplifier of one channel were replaced and the resistor that caused damage to the transistors.

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