- Written by John E. Johnson, Jr.
- Published on 10 July 2013
On the Bench
All distortion measurements were made within an 80 kHz bandwidth. The load was 8 ohms unless otherwise specified. The XLR inputs were used for the test signals. The Volume setting was 50 unless otherwise specified.
At 1 kHz and 5 volts output, distortion was only 0.007%.
At 10 volts output, distortion rose just a bit.
At 20 volts output (50 watts into 8 ohms), distortion was 0.02%. The INT-150 does not use global negative feedback, so a rise in distortion is not unexpected. It was not audible in any case.
Using 19 kHz and 20 kHz sine waves, and 10 volts output, the B-A peak at 1 kHz was 87 dB below the fundamentals.
IMD at 10 volts output was 0.05%.
THD+N vs. Frequency is shown below. This was measured with the volume control set at its maximum value of 63. The lower lines are at 8 ohms, and the upper ones are with a 4 ohm load.
Maximum output at 8 ohms was 150 watts at 0.1% THD+N, and clipping (1% THD+N) at 175 watts.
With a 4 ohm load, maximum output was 225 watts at 0.1% THD+N and clipping at 260 watts (the wall AC voltage dropped to 113 volts, so if you have a power conditioner that regulates the voltage, and maintains 120 volts, the maximum output from the INT-150 with a 4 ohm load would be about 300 watts.
The measured frequency response was nearly the same at 8 ohms and 4 ohms, with the response being 10 Hz - 50 kHz, - 2 dB.