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  Transistor headphones amplifier Musatoff HA-4  
The main this amplifier - an incredible accuracy of transmission of the musical material.
To achieve it required to apply a number of known and new techniques, among them:
  • Preventing transmission of the output signal via the power supply
  • Single-ended output stage with high-power germanium transistors
  • Capacitors exclusion from the signal path and DC amplification
  • Failure to use the integrator that affects on the transfer of virtual DC
  • Distortion minimizing of complex and stochastic signal, including the signal coming from the load 
  • The central signal ground connected to the input terminals 

  Amplifier sound so transparent and not colored that you can not notice it in the background of sources and headphones of higher price rate. Due to the high and frequency independent damping factor, amplifier controls any headphones perfectly.

Amplifier housing is made of steel and aluminum panels.

  The amplifier has a rich functionality that makes it convenient to use:
  • The volume control is based on potentiometer APLS RK-27
  • Output of the amplifier on the RCA terminals, it can be used as a pre-amplifier
  • When the power is off, the input signal is transmitted to the output terminals via a relay
  • Two level of signal gain for the convenience of the volume control
  • Output protection against DC voltage and phones damage
Amplifier specification:
Spectrogram measurements
  Headphones impedance range   from 8 Ohm to 600 Ohm
  Nominal output power    320 mW / 100 Ohm
100 mW / 32 Ohm
  Maximum output power with no clipping   500 mW / 100 Ohm
160 mW / 32 Ohm
  THD level at nominal output power level (0 dB)    0,001% 
  Output impedance   15-30 mOhm
  Amplification band   0 Hz - 800 kHz
  Amplification factor   1/3 (0/10 dB) Lo/Hi
  Input impedance   10 kOhm
  With, height, length   163х68х162
  Other photos
  With output cabel

  Power supply