Amp Meet Three - The Results

These are the results of the power and performance test conducted on the 6th June 2010 at the third Amplifier Meet in Bedford, Bedfordshire.

All power measurements are Maximum continuous output power in RMS watts* per channel, two channels driven to the threshold of clipping at 40 Hz, 1 kHz, and 10 kHz, and at loads of 8 ohm, 4 ohm and 2 ohm unless otherwise stated in the notes. Bridge power ratings are CALCULATED based on the amplifier's performance into 4R and 2R loads. 8R Bridge = 2 × 4R per channel; 4R Bridge = 2 × 2R Per channel. Inclusion of a calculated bridge rating does not necessarily mean the amp is bridgeable - PKN and Powersoft for example. "Continuous" means 5 seconds or greater - this ensured that the amplifiers were not damaged by the testing, and meant a sensible number of amplifiers could be tested in the alotted time. "Burst" (<100ms) ratings were not measured.

THD+N = Total Harmonic Distortion plus Noise and is a measure of the purity of the amplifier output as well as its noise level. It was measured at the maximum power output at various frequencies and load impedances. Anything below 1% is fine, below 0.1% is better. Obscure results sometimes appear because of distortion cancellation mechanisms.

Some amplifiers were not measured at 2R because they may have been damaged by the test. Exclusion of a 2R measurement does not mean the amplifier will not withstand 2R LOUDSPEAKER loading. Sine testing into a dummy load is considerably more demanding of an amplifier.

All tests were carried out using a Bruel & Kjaer 1023 Sine wave oscillator, HP8903A Audio distortion analyser, an HP3456A true-RMS digital voltmeter, a 8/4/2R Resistive dummy load, and a Tektronix TDS210 Digital Realtime Oscilloscope.

Distortion was not measured for the amplifiers in the bottom half of the list due to the enormous number of amplifiers on offer and the limited time available to get a reliable distortion measurement. We would welcome the opportunity to repeat these tests in a more tightly controlled environment, with more time, in our lab. Please get in touch with us if you would like to send us an amplifier to test.

Mains voltage WAS measured with a Fluke 233 true-RMS wireless display multimeter. All amplifiers were fed from the same supply, adapted according to the mains plug fitted. 32A, 16A and 13A was available, all wired into a fuse board with 16mm cable. The supply was extremely stiff, and did not sag below 238V all day. It fluctuated slightly throughout the day, but was never more than 246V.

In no particular order:

* "RMS Watts" is technically an incorrect term: see http://www.epanorama.net/documents/audio/amplifier_power.html

×