The restoration of the first Beomaster 1900 receiver is finished.

The final testing involved measuring the Total Harmonic Distortion (THD) and Frequency Response. Using a dummy 8Ω speaker load, the THD was measured at 1KHz with a 20-watt output. An image of the test setup with the dummy speaker load is provided below.

At the maximum rated power of 20 watts across the dummy speaker load, the THD measured 0.068% using a 1kHz sine wave input to the Beomaster 1900’s Tape input. This is significantly lower than the service manual’s specified maximum THD level of 0.2%.

The frequency response was then assessed from 20Hz to 20kHz with a 260mV input to the Tape input and a power level of 20 watts.

The outcome showed a ±1 dB variance across the 20Hz to 20kHz frequency range. This result aligns closely with previous measurements taken on a restored Beomaster 2400 receiver.

These measurements are highly satisfactory for an amplifier from this Bang & Olufsen series.

The Beomaster will now be placed in a listening room while the second Beomaster 1900 unit undergoes restoration.

A few final pictures from the workbench are included below. This Beomaster 1900 receiver should not require further workbench time for another five decades.