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.
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.
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..
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..
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?
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?
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.
7 channel test load now that would be very useful peace of equipment to have on the test bench or under it and like you say very good for soak testing plus the fact that you don't disturb any one during evening testing.
There's a valve tech in the uk that build a 1000w per side test load unit with added fans plus different type connections plus power meter read outs for ac readings...
his site is called champ electronics... He used a old army box plus a little revamping here and there,it look's very good.
good luck with that built...
There's a valve tech in the uk that build a 1000w per side test load unit with added fans plus different type connections plus power meter read outs for ac readings...
his site is called champ electronics... He used a old army box plus a little revamping here and there,it look's very good.
good luck with that built...
I think the best value for price is from Huntington Electric with part number FVE300-8.0.
They are 8 Ohm 300 W and you can buy them from Digi-Key in Australia for around 15 AUD.
Their connections are sturdy enough that you can screw binding posts directly on them.
All you need to do after that is mount them on pieces of angled metal with the help of threaded rods and you are ready to make them get warm, if you can...
I can post a picture if you want, we use a lot of those at work.
Digi-Key - FVE300-8.0-ND (Manufacturer - FVE300-8.0)
They are 8 Ohm 300 W and you can buy them from Digi-Key in Australia for around 15 AUD.
Their connections are sturdy enough that you can screw binding posts directly on them.
All you need to do after that is mount them on pieces of angled metal with the help of threaded rods and you are ready to make them get warm, if you can...
I can post a picture if you want, we use a lot of those at work.
Digi-Key - FVE300-8.0-ND (Manufacturer - FVE300-8.0)
That's one beast of a power resistor on that link Michel, the loads I used are metal clad types bolted to a large heavy duty heatsink and fan cooled all tucked in a 3u rack case plus different speaker/meter/scope in put connections.. It's been going strong for over 10+years now and get's a darn good beating on soak tests..
These peace's of equipment are a must when servicing such high powered amps and you just sit back and relax with out disturbing any one...
These peace's of equipment are a must when servicing such high powered amps and you just sit back and relax with out disturbing any one...
Pictures of my dummy load that uses 4 ohm 600 watt resistors. There is a little one that is setup for 4 or 8 ohm at the flip of the switch and there is my mega load that has 3) 5 1/4" fans that cool it.
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