Balanced Audio Technology VK-6200 multichannel power amplifier Measurements
The BAT VK-6200's frequency response from its unbalanced inputs measured –0.42dB at 10Hz (–0.16dB, balanced in) and –0.16dB at 50kHz (–0.14dB, balanced in). The amp's gain measured 28.3dB unbalanced and 22.7dB balanced. THD+noise (balanced) at 1W into 8ohms measured 0.166% at 20Hz, 0.187% at 1kHz, and 0.004% at 20kHz. The corresponding results at 2W into 4ohms were 0.128% at 20Hz, 0.141% at 1kHz, and 0.002% at 20kHz.
With all five channels driven into an 8ohms load, the BAT clipped (1% THD+noise) at 220Wpc at 20Hz and 227Wpc at 1kHz. Into 4ohms, all channels driven, clipping occurred at 343Wpc at 20Hz and 351Wpc at 1kHz. With two channels driven into 8ohms, the BAT clipped at 267Wpc into 8ohms and 397Wpc into 4ohms, both at 1kHz.
The VK-6200 has an independent power supply for each channel, therefore the same output would normally be expected regardless of the number of channels operating. However, limitations in our 12V mains power supply (a limitation you may also share) and the variac we use to maintain 120V (which you likely will not) resulted in the differences obtained with two and five channels driven. The measurement results presented here were taken on the left channel, to the nearest watt, at a line voltage of 120V.—Thomas J. Norton