Blew my speaker dummy load

[J M Fahey]

Thanks a lot.

The 120V 2000W one looks like a killer 8 ohms load.
In fact, itīs better that itīs nominal 7 ohms, closer to a speaker minimum impedance.

[Mick Bailey]

The main heat dissipation path is through the mounting base and into the heatsink.

Before that there's the thermal resistance between the internal resistive element, which is insulated, and the extruded housing. Even with perfect heat transmission between the housing into the heatsink (which also has a thermal resistance) this is still a limitation with aluminium clad resistors.

Put enough current through the resistor and it will burn up before the housing even gets warm.

[tedmich]

Big Dummy Load Ŧ Synergetic Audio Concepts

I might use eco friendly antifreeze (PPG) instead of oil but its a good design

[Chuck H]

I've suggested the water heater elements a few times. I do some water heater repair here (the water here on Whidbey is VERY hard). I noticed the specs line up for our purposes. Anyone ever try it?

[Jazz P Bass]

Yes you have, Chuck.

So, that's where I got the idea?

I should have attached a 'copywrite, Chuck @ MEF' tag.

[Chuck H]

I don't think I worded my post in such a way as to claim proprietorship.?. Just seconding the suggestion and noting that, since the idea has passed around here before, I'd like to know if it ever worked out for anyone. But I'll take what I can get if you want to credit me for anything you know

I've never needed a dummy load for huge power so I've never tried it myself. I imagine a big, sealed tub of water. Perhaps some kind of anti microbial additive to prevent unpleasant odors. I wouldn't want to have to fill the tub whenever I needed a dummy load. Even then it would only be good to a point. Once the water boils you have pressure and once you have pressure you compromise the seals. If the pressure is significant you get temps beyond boiling and likely risk thermal limits for the elements. Ideally you'd have a circulation system and a pressure relief valve (just like a water heater). This is all overkill of course. It's not likely that anyone would ever have a problem with an element simply submerged in a pail. Just thinking about considerations for the PRO model.

[Jazz P Bass]

As an aside, there is really no reason to 'test' an amplifer very long at full power.
1/2 power will do for extended testing.

Now there are instances, such as certain QSC amp current limiting circuits, where you do need to run them flat out.
But even then, the time period is not that long.

[g1]

Hmm, around 1000W, water cooled, pressure relief, still sounds like an electric kettle full of water to me.
For real big stuff, maybe an electric water heater (small type for house trailer etc.) with a loop for circulation.

[Chuck H]

I think I looked into electric kettles once but couldn't find any that would provide a desirable load.

[S2udio]

As an aside, there is really no reason to 'test' an amplifer very long at full power.
1/2 power will do for extended testing.

100% there,

Half power for 1hr.....Well warmed by now,and cookin !
Blast at full for a further 3 mins.
Turn of,and let cool.
One more turn on , pass a bit of audio....job done.
No need to kill it again, .......the customer will do that soon enough