- Written by John E. Johnson, Jr.
- Published on 11 May 2012
The Anthem P2 Power Amplifier On the Bench
All distortion measurements were made within an 80 kHz bandwidth, and using the XLR inputs on the P2, into 100 kOhms, except where noted.
At 1 kHz and 10 volts into my Carver Mark IV ribbon speaker, distortion was only 0.002%. The fact that the second and third ordered harmonics were about the same size was reflected in a very musical sound quality, with no harshness.
Using a combination of 19 kHz and 20 kHz sine waves, the B-A peak at 1 kHz was 82 dB below the fundamentals.
IMD, using 60 Hz and 7 kHz, was only 0.003%. This is very good performance, and means the sound will have plenty of detail, which is what I heard.
THD+N vs. Frequency showed a flat spectrum of 0.002% out to 2.5 kHz, then a rise to about 0.05% at 20 kHz.
Here is the impedance/phase plot for the Carver speaker.
The power output spectrum at 8 ohms load shows the soft knee at 20 watts, and the hard knee at 340 watts, with clipping (1% THD+N) at 380 watts.
The 4 ohm spectrum has the soft knee again at 20 watts, but the hard knee is at 540 watts (the hard knee is the "practical" limits of the amplifier), and clipping at 600 watts.
The measured frequency response was 10 Hz -200 kHz, -2.5 dB.