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knausz 19th January 2010 12:14 PM

Configurable Dummy Resistor Load Box for Amp design/repair
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What do you guys think of this dummy load I built for testing my amps? It's configurable for 4/8/16/32 ohms using just switches and has all the connectors. It's in an instrument box that should be easy to cool if I add a fan. It's about time I built one, it's making my life much easier. Any other ones out there?


Conrad Hoffman 20th January 2010 12:39 AM

Nice! I've thought about making one for decades, but it always seems to come down to hot resistors on the bench, hooked up with clip leads that fall off every now and then. Years ago I even had a set of four gigantic Dale 4-ohm resistors, but decided to sell them on my flea market table at a hamfest, since I could never get around to building the box.


knausz 20th January 2010 01:52 AM

Yeah, I was putting off building it for years too. I'm so glad I took the time out and did it - It saves me a lot of time now. Not to mention the time I spent an hour debugging a problem that turned out to be a clip lead that fell off my dummy load! I think we all have stories like that...


knausz 20th January 2010 01:55 AM

I forgot! to post a link to the complete documentation on my website including the schematic:

Dummy Load for Amp Testing |


funkytek 2nd February 2010 11:53 PM

Really sweet Knausz! Nice job man.

Count me in the dead beats that has a box set aside with all the parts to make one, just never got around to it.

I do have a wood board with a bunch of big Dales screwed to it and pigtails soldered to them with stackable banana plugs on the ends. That way I just connect them up to make the desired power/resistance.

Not anywhere as nice as your setup. I like the fine tuning too, though I can't think of a case where I would need it...

Unfortunately my setup works just well enough to keep me from building a better solution, like yours. :o

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