Amplifier bench tests |
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Tonskulus
Registered User Joined: 15 September 2017 Location: Finland Status: Offline Points: 425 |
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Posted: 31 October 2017 at 4:07pm |
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Share your bench results here!
I have recently made couple of uncertified dyno runs for different amplifiers. Especially those cheaper ones, claimed power outputs are sometimes a bit optimistic. So let's see how they really perform. Setup: 40Hz sinewave signal, 8ohm resistive dummy load. Measurements taken just before clipping led lights, confirmed w/ oscillosope that there is no signal clipping. Alto mac 2.3 Claimed: 2x285Wrms / 8ohm or 1x1000Wrms / 8ohm Measured: 8ohm stereo: 48Vrms / 288Watts, single channel driven. 8ohm bridged: 82Vrms, 840Watts. Not quite 1kW, however input voltage dropped from 233V to 224V. T.amp TA-1400 mk2 Claimed: 2x450Wrms/8ohm, 1x1200Wrms/8ohm Measured: 8ohm stereo (one channel loaded), 61Vrms / 465Watts 8ohm bridged, 100Vrms / 1250Watts (223Volt input at full power) I will soon add more amplifiers and measure both channels loaded @ stereo as soon as I get another 8ohm dummy load :) Edited by Tonskulus - 31 October 2017 at 4:08pm |
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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I have done quite a few. However, time is not what I have at the moment to post multiple figures.
Here is one out of the bunch: Peavey CS 800X
Rated wattage: 400 watts per channel @ 4 ohms from 20 Hz – 20,000 kHz
Rated wattage before clipping @ 4 ohms
125,347 kHz: 37.4 volts: 349.69 watts
100,141 kHz: 41.0 volts: 420.25 watts
75,128 kHz: 42.0 volts: 441.00 watts
61,638 kHz: 42.9 volts: 460.10 watts
50,274 kHz: 42.6 volts: 453.69 watts
40,205 kHz: 42.9 volts: 460.10 watts
30,370 kHz: 42.8 volts: 457.96 watts
25,008 kHz: 42.9 volts: 460.10 watts
19,992 kHz: 42.8 volts: 457.96 watts
14,988 kHz: 42.8 volts: 457.96 watts
9,994 kHz: 42.9 volts: 460.10 watts
5,003 kHz: 42.9 volts: 460.10 watts
2,498 kHz: 43.3 volts: 468.72 watts
1,018 kHz: 43.4 volts: 470.89 watts
509.28 Hz: 43.3 volts: 468.72 watts
252.84 Hz: 43.5 volts: 473.06 watts
100.36 Hz: 43.4 volts: 470.89 watts
50.078 Hz: 42.8 volts: 457.96 watts
40.016 Hz: 43.1 volts: 464.40 watts
30.474 Hz: 42.0 volts: 441.00 watts
25.125 Hz: 42.0 volts: 441.00 watts
20.007 Hz: 41.5 volts: 430.56 watts
14.908 Hz: 42.0 volts: 441.00 watts
9.998 Hz: 31.4 volts: 246.49 watts (Amplifier ramps into DC Protect beyond 31.4 volts)
Completely Squared Wave Form: 100.47 Hz: 56.6 volts: 800.89 watts
2 Ohm Load
Rated wattage: 600 watts per channel @ 2 ohms from 20 Hz – 20,000 kHz
Rated wattage before clipping @ 2 ohms
100.765 Hz: 37.4 volts: 699.38 watts
50.336 Hz: 37.1 volts: 688.20 watts
40.101 Hz: 37.0 volts: 684.50 watts
29.946 Hz: 37.0 volts: 684.50 watts
20.674 Hz: 35.3 volts: 623.04 watts
15.161 Hz: 35.5 volts: 630.13 watts
Completely Squared Wave Form: 101.64 Hz: 49.7 volts: 1235.05 watts
Completely Squared Wave Form: 101.64 Hz: 49.9 volts: 1245.01 watts (Regulated) Best Regards, Edited by Elliot Thompson - 02 November 2017 at 10:02am |
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Elliot Thompson
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Tonskulus
Registered User Joined: 15 September 2017 Location: Finland Status: Offline Points: 425 |
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As can be seen, heavy distortion (squarewave compared to clean sine wave) almost doubles the output power..thus, power dissipated by driver. No wonder why heavy distortion can make voicecoils overheating quickly.
Edited by Tonskulus - 02 November 2017 at 11:15am |
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ReubGold
Registered User Joined: 09 April 2012 Location: Essex/JA Status: Offline Points: 271 |
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Some would argue, testing using load with inductive component, as opposed to purely resistive, is more realiststic..
E.g., segment of heating element. However, the mere hint of bench testing amplifiers with 40hz sine waves, will send shudder down spine of many lightweight amp manufacturers, and distributors on SP. |
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ReubGold
Registered User Joined: 09 April 2012 Location: Essex/JA Status: Offline Points: 271 |
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Also maybe tests, with both channels driven, are more reflective of real world use, PSU sturdiness !?
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If he turns me into a zombie, first person I'm coming after is you.
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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Older amplifiers have the capability of doubling their output power when pushed beyond clipping. You won't find that type of behaviour with amplifiers offering burst ratings for the power supply is not robust enough to offer such results. Best Regards, |
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Elliot Thompson
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Tonskulus
Registered User Joined: 15 September 2017 Location: Finland Status: Offline Points: 425 |
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True that. Many of those old "iron amps" had quite overrated transformers. I have some big old QSC amps which will be soon measured. |
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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Here is an old Crown lightweight Switch-Mode Design
Crown XS 900
Rated Power: 900 watts per channel @ 1 kHz, under a 4 ohm load
Measured Results before Clipping Takes Place
20.707 kHz, 72.1 volts, 4 ohm load: 1299.60 watts
14.991 kHz, 64.0 volts, 4 ohm load: 1024.00 watts
10.004 kHz, 64.0 volts, 4 ohm load: 1024.00 watts
5.003 kHz, 64.0 volts, 4 ohm load: 1024.00 watts
2.083 kHz, 64.0 volts, 4 ohm load: 1024.00 watts
999.282 Hz, 64.0 volts, 4 ohm load: 1024.00 watts
500.995 Hz, 64.0 volts, 4 ohm load: 1024.00 watts
200.939 Hz, 64.0 volts, 4 ohm load: 1024.00 watts
100.882 Hz, 62.9 volts, 4 ohm load: 989.10 watts
50.221 Hz, 62.5 volts, 4 ohm load: 976.56 watts
39.903 Hz, 62.0 volts, 4 ohm load: 961.00 watts
30.021 Hz, 62.9 volts, 4 ohm load: 989.10 watts
20.746 Hz, 62.2 volts, 4 ohm load: 967.21 watts
9.999 Hz, 62.2 volts, 4 ohm load: 967.21 watts
4.939 Hz, 60.0 volts, 4 ohm load: 900.00 watts (Amplifier goes into DC Protect beyond 60 volts)
NOTE: Amplifier received a constant sine wave signal at various cycles for a period of one hour. The amplifier did not overheat nor thermal during the testing.
Best Regards, |
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Elliot Thompson
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