Amp Meet Two - The Results

These are the results of the power and performance test conducted on the 7th April 2010 at the second Amplifier Meet.

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. "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.

Mains voltage was not measured. All amplifiers were fed from the same supply, adapted according to the mains plug fitted. 32A, 16A and 13A was available.

In no particular order:

Manufacturer	Model	Freq	8 Ohm Performance		4 Ohm Performance		2 Ohm Performance		8R Bridge Watts (Calc)	4R Bridge Watts (Calc)	Notes
Manufacturer	Model	Freq	Watts	THD+N	Watts	THD+N	Watts	THD+N	8R Bridge Watts (Calc)	4R Bridge Watts (Calc)	Notes
Labgruppen COPY	FP10000Q	40 Hz	1282	0.18%	1968	0.25%	880		3937	1761	Severe oscillation on top half of waveform at 2R. Amplifier buggered at 2R 40Hz. Inadequate protection. 4 channel amp, two channels driven
		1 kHz
		10 kHz
Crown	IT8000	40 Hz	1006	0.90%	492	1.00%			984		Thermal Limit at 40Hz 4R. Amplifier protecting itself against too much mains current draw. 1kHz 4R power should be considered a burst rating.
		1 kHz	2026	0.12%	3930	0.15%			7860
		10 kHz	2411	0.70%	2467	0.90%			4934
QSC	PL236	40 Hz	737	0.07%	1133	0.13%			2266		Filters Disabled, remained cold
		1 kHz	744	0.16%	1239	0.40%			2479
		10 kHz	755	0.60%	1172	0.90%			2345
QSC	MX3000A	40 Hz	820	0.07%	1273	0.10%			2547		Amp remained cold throughout
		1 kHz	788	0.07%	1263	0.30%			2526
		10 kHz	726	0.07%	1172	0.09%			2345
MC2	E25	40 Hz	603		1075				2151		One channel Faulty, ONE CHANNEL DRIVEN. Severe crossover distortion at 10K. Unable to measure THD because of floating grounded output
		1 kHz	603		1001				2002
		10 kHz	586		1013				2026
MC2	E45	40 Hz	900		1511		2912		3022	5824	ONE CHANNEL DRIVEN at 2R. Unable to measure THD because of floating grounded output
		1 kHz	921		1515		2772		3029	5544
		10 kHz	744		1308		2469		2616	4937
Void	Inf 7 Mk 1	40 Hz	952	0.30%	1451	0.50%			2903		Not tested at 10kHz because the amp probably wouldn't have survived it.
		1 kHz	952	0.50%	1526	0.80%			3052
		10 kHz
Void	Inf 8 Mk 2	40 Hz	1234	0.10%	2099	0.14%			4198		Powered from 32A Cee-Form. Peak draw according to front panel ammeter was 47A
		1 kHz	1234	0.13%	2099	0.28%	2608		4198	5215
		10 kHz	1234	0.30%
Labgruppen	LAB4000	40 Hz	1140	0.10%	1273	0.08%			2547		9 years old - csg asked me to note this
		1 kHz	1186	0.40%	1172	0.05%	824	0.06%	2345	1648
		10 kHz	1094	0.40%	1169	0.40%			2338
MC2	Turbosound 1250	40 Hz	668	0.11%	1169	0.10%	1148	0.18%	2338	2296	Bad high frequency artefacts when clipping at 10kHz.
		1 kHz	599	0.05%	1085	0.08%	1139	0.22%	2170	2277
		10 kHz	611	0.05%	1104	0.20%	1034	0.50%	2208	2068
Peavey	PV2600	40 Hz	586	0.05%	923	0.80%			1846		Excellent clipping and limiting behaviour
		1 kHz	558	0.04%	923	0.60%	1263	0.70%	1846	2526
		10 kHz	563	0.09%	818	0.09%			1636
Matrix	2U Matrix Short (Unlabeled)	40 Hz	213	0.10%	269	0.20%			538		Amp remained cold throughout
		1 kHz	205	0.09%	285	0.25%			570
		10 kHz	195	0.20%	283	0.50%			567
Matrix	2U Matrix Long (Unlabeled)	40 Hz	433	0.10%	772	0.20%			1543		Amp remained cold throughout
		1 kHz	476	0.50%	782	0.60%			1565
		10 kHz	433	0.20%	703	0.30%			1407
Matrix	1U Short (Unlabeled)	40 Hz	230	0.20%	318	0.30%			637
		1 kHz	221	0.20%	312	0.30%			623
		10 kHz	211	0.10%	295	0.19%			589
Matrix	XP3000 Toroidal	40 Hz	824	0.11%	1159	0.23%	1205	0.60%	2318	2410
		1 kHz	763	0.10%	1120	0.22%	1333	0.60%	2240	2665
		10 kHz	755	0.80%	944	1.60%			1887
Matrix	Vector 350 Toroidal	40 Hz	101	0.10%	107	0.20%			213
		1 kHz	89	0.13%	113	0.22%			225
		10 kHz	89	0.50%	95	0.70%			190
Matrix	XP5000 Switched Mode	40 Hz	915	0.80%	1069	1.60%			2138		One channel driven at 2R due to power supply over-temperature issues. Limited power due to limiter action, which, even though disengaged, caused limiting at 4R
		1 kHz	888	0.70%	1140	2.00%	1547	1.10%	2279	3094
		10 kHz	860	1.20%	1082	2.70%			2163
Matrix	XP5000 Switched Mode, sample 2	40 Hz	946	1.20%	1393	2.10%			2786		Both Channels Driven 2R - earlier version without power supply over temperature protection. Compare 2R figure above
		1 kHz	820	1.20%	1354	2.00%	1097	3.00%	2708	2194
		10 kHz	854	1.20%	1219	2.10%			2438
Crown	XTI4000	40 Hz	680	0.30%	1019	0.30%			2038		DSP system disabled. 180 degree phase shift between input and output at 10kHz due to ADC/DAC anti-aliasing filters
		1 kHz	689	0.12%	854	0.24%			1708
		10 kHz	594	0.50%	914	0.26%			1829
QSC	PLX3402	40 Hz	757	0.10%	1156	0.50%			2312		Good clipping and limiting behaviour
		1 kHz	748	0.13%	1222	0.20%			2445
		10 kHz	707	0.05%	1216	0.20%			2431
Labgruppen	LAB1000	40 Hz	430	0.50%	686	1.00%			1371		Not switched-mode
		1 kHz	403	0.30%	656	0.30%			1311
		10 kHz	399	0.30%	651	0.50%			1302
Labgruppen	LAB1200C	40 Hz	339	0.05%	641	0.50%			1282		Excellent clipping and limiting behaviour
		1 kHz	340	0.04%	617	0.06%			1234
		10 kHz	338	0.06%	617	0.30%			1234
Labgruppen	LAB1600	40 Hz	412	0.40%	756	0.17%			1511		Excellent clipping and limiting behaviour
		1 kHz	405	0.60%	756	0.40%			1511
		10 kHz	413	1.10%	703	0.14%			1407

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