- Written by John E. Johnson, Jr.
- Published on 06 May 2013
On the Bench
All distortion measurements were made within an 80 kHz bandwidth. I used the XLR input for the test signals generated by an Audio Precision 2722. Except where indicated, the output of the XPR-1 was connected to a Carver Mark IV speaker.
At 1 kHz, distortion was extremely low.
Using 19 kHz and 20 kHz test signals, the B-A peak at 1 kHz was 107 dB below the fundamentals.
IMD was also quite low, which means fine detail in the music will come through clearly.
The measured Frequency Response was 10 Hz - 80 kHz, - 3 dB, and 20 Hz - 20 kHz, - 0.1 dB
THD+N vs. Frequency showed that for most of the audible range, distortion stayed at about 0.002%.
Here is the Impedance/Phase plot for the Carver speaker.
THD+N vs. Power Ouput for an 8 Ohm load is shown below. The sharp knee was at 850 watts (the wall AC voltage dropped from 120 Volts to 111 Volts), and output reached 1,000 watts at 0.07% distortion, with clipping (1% THD+N) at just over 1,000 watts.
With a 4 ohm load, the sharp knee was at 1,400 volts (the wall AC voltage dropped to 109 volts), and clipping occurred at 1,700 watts output.