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Old 30th January 2009, 04:40 PM   #21
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try here

[URL=http://diyaudioprojects.com/Technical/DIY-Speaker-Dummy-Load//]DIY-Speaker-Dummy-Load[/UR]
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Old 9th April 2011, 11:53 PM   #22
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Default Radio Shack

Hey all,

Radio shack sells an 8 ohm, 20 watt, non-inductive resistor. Part number 271-0120 they sell for $2.49. Like Sy says if you don't need to put a lot of power across it these work well. And they're cheap!

Oh, and they sell phones too!

Kevin
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Old 10th April 2011, 07:11 AM   #23
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If you're needing an el-cheapo high-power dummy load, most home/kitchen appliances have heating elements around 16 to 10 ohms... stove elements, toasters, irons etc. I've used them as dummy loads for testing switching power supplies. Inductance varies with configuration, but oven heating elements are pretty much one loop.
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Old 10th April 2011, 08:54 AM   #24
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I used a few oven elements for high power amplifier testing with large fans cooling them down or use water cool them...
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Old 10th April 2011, 09:18 AM   #25
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Also via adding vu meter's you can see how much power the amp under test is pushing out.. there's many ways to set up needle type meters for this app..or a cheap meter set on ac volts..
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Old 18th April 2011, 02:39 PM   #26
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Via using heavy duty selector switching you can build a 2,4,8 and 16 ohm dummy load tester and add plenty of fan cooling if your going to push things real hard...
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Old 18th April 2011, 03:34 PM   #27
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I found a couple of 10 ohm, 100 W at surplus. In order to make 8 ohms, I paralleled each with 3 x 13 ohm 10W in series (so 10 // 39 ohm = 7.96 ohm). This makes it 2 x 8 ohms at 126 W each. I don't mind one bit that these loads are a little bit inductive, because we all know that speaker coils are ... um... coils! I'd rather have non-ideal load even if it doesn't match with the speakers precisely.
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Old 18th April 2011, 03:44 PM   #28
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Even using 10 ohms is plenty at low power say 30 or 60w if your resistors are 100w at 10 ohms..

I first used two 15 ohms at 100w each resistors paralleled that gave 7.5 ohm then added two 1 ohms paralleled to give half an ohm then wired the lot together and there you have it 8 ohms at 400w test load..
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Old 18th April 2011, 03:54 PM   #29
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I've seen 200w/300w types resistor at 1 0hm but there a bit high priced..

Some times you have to use what you can lay your hands on to make good test loads such as heating elements.. Also use large heat sinks that you can bolt the resistors to the larger the better..
Macboy, what type of amp testing are you connecting your test load to and is it two channel or mono block?
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Old 18th April 2011, 04:45 PM   #30
macboy is offline macboy  Canada
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Mine is a 2 channel dummy load. I use it for bench testing any amp I test (only solid state). Any amp that is built or repaired gets tested with this load before using speakers. I also use it as a dummy load when testing distortion, frequency response, etc. using my Agilent 8903B distortion analyzer. I really want to set up a 7 channel load bank so that I can test multi-channel home theatre amps with all channels driven.
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