Power Amplifiers

Earthquake Sound Cinenova 7 Multi-Channel Power Amplifier


On the Bench

Distortion measurements were made within an 80 kHz bandwidth. One of my Carver Mark IV speakers was used as the load, except where indicated. I ran the tests using a single module, since each module is independent.

At 10 volts output, THD+N was 0.02%. Even-ordered harmonics predominated.


Using 19 kHz and 20 kHz sine waves, the B-A peak at 1 kHz was 70 dB below the fundamentals.


IMD was 0.03%, using 60 Hz and 7 kHz sine waves as the test signals.


THD+N vs. Frequency was flat out to about 4 kHz, then rose to a bit more than 0.1% at 8 kHz to 50 kHz.


Here is an impedance/phase plot for the Carver Mark IV speaker that I used as a load for some of the bench tests.


The measured frequency response was 10 Hz - 20 kHz, - 0.1 dB, and was down 5 dB at 100 kHz.


Output into 8 ohms indicated the sharp knee at 150 watts, with clipping (1% THD+N) at 170 watts.


Using a 4 ohm load, output showed the sharp knee at 230 watts, and clipping at 280 watts. I did not test the amplifier into a 2 ohm load.