Show me your dummy load(s)!

[rottalpha]

I use whatever I have available. The last set of dummy loads I made out of 4 x 2R @100w resistors, per channel. A cheapo solution with fleabay resistors.

I am now looking for something with more "meet" to test some beasty amp that that wants to cook my 400w cheapo dummy loads.

I am not opposed to adding more resistors or a different combo to my cheapo solution, but I would like to see other ideas first.....

So would you please show me your dummy load(s)!

 

[whoaru99]

A fellow that was doing a bunch of pro amp testing on a different forum used water heater elements mounted in a bucket of water.

240V, 3500W elements should be ~16.5 ohms. Two in parallel would be darn close to 8 ohms.

 

[BinaryMike]

Here's a couple of Dummies from my collection. The big paralleled wirewound guys have been dunked in a bucket of water more than once:

 

[Son-of-Vere]

I just so happen to have one of those. Speakers are heavily padded and I'm still working on the line level out.

 

[rottalpha]

Here's a couple of Dummies from my collection. The big paralleled wirewound guys have been dunked in a bucket of water more than once:

View attachment 870797 View attachment 870799

that's lots of dummies : -)

the gold color ones is the kind I used. Are you placing a fan next to the greenies??

 

[rottalpha]

I just so happen to have one of those. Speakers are heavily padded and I'm still working on the line level out.View attachment 870800

how do you like this type of resistors? did you test the resistance while they were hot?? I was also looking at this type too.

A fellow that was doing a bunch of pro amp testing on a different forum used water heater elements mounted in a bucket of water.

240V, 3500W elements should be ~16.5 ohms. Two in parallel would be darn close to 8 ohms.

Ok, maybe I do not need something that extreme, but that is an interesting approach.

 

[Ray Gianelli]

A friend and I were testing a pro audio amp down to 2 ohms. We did the water heater element thing, submerged in a bucket of oil. Actually got the oil boiling! Here's someone who did it:

http://www.prosoundtraining.com/site/synaudcon-library/big-dummy-load/

For everyday amp testing I use the Parts Express 100 watt dummy loads. If you heat sink them you can use them above 100 watts for limited periods of time.



I had 4 of them mounted in a heat sink, but it was too cumbersome at over 2 feet in length, so I hacked one off the end for general testing.

 

[Son-of-Vere]

So far that load setup has tested a 4 watt flea amp. I'll have to space them off the wood if I test them at their limits.

 

[arts]

I sold my no longer needed, multi-kilowatt oil cooled monster some time ago,which freed up some space under the bench,and filled some space in my wallet.

Here's the little guy I constructed to replace it. The power ratings are more than adequate for the work I'm doing,and it will suffer considerable short duration overloads.

 

[rottalpha]

A friend and I were testing a pro audio amp down to 2 ohms. We did the water heater element thing, submerged in a bucket of oil. Actually got the oil boiling! Here's someone who did it:

http://www.prosoundtraining.com/site/synaudcon-library/big-dummy-load/

For everyday amp testing I use the Parts Express 100 watt dummy loads. If you heat sink them you can use them above 100 watts for limited periods of time.



I had 4 of them mounted in a heat sink, but it was too cumbersome at over 2 feet in length, so I hacked one off the end for general testing.

The oil barrel was wild!

 

[rottalpha]

I sold my no longer needed, multi-kilowatt oil cooled monster some time ago,which freed up some space under the bench,and filled some space in my wallet.

Here's the little guy I constructed to replace it. The power ratings are more than adequate for the work I'm doing,and it will suffer considerable short duration overloads.

View attachment 870972 View attachment 870974 View attachment 870975

this is really nice! I would only be worry about having a cover over those resistors durring testing

 

[rottalpha]

So far that load setup has tested a 4 watt flea amp. I'll have to space them off the wood if I test them at their limits.

 

[Alan0354]

I don't use it every day, only to bring up the amp, check for stability and run FFT to get THD measurement, I don't need a fancy one like you guys. Just 2 4ohm non inductive resistors on wood with banana connectors. If I need 2ohm, just one more speaker cable to join the two.

 

[avionic]

4Ω X 2 ,8Ω X 2 and 16Ω X 2 --- Arcol ,non-inductive, 300 watt.
http://www.mouser.com/ProductDetail/ARCOL-Ohmite/NHS300-4R0-1/?qs=sGAEpiMZZMtbXrIkmrvidKzXrWGN%2biMBe1URSpuqQRc=
http://www.mouser.com/ProductDetail/ARCOL-Ohmite/NHS300-8R0-1/?qs=sGAEpiMZZMtbXrIkmrvidKzXrWGN%2biMBr6yNOT91FTI=
http://www.mouser.com/ProductDetail/ARCOL-Ohmite/NHS300-16R-1/?qs=sGAEpiMZZMtbXrIkmrvidKzXrWGN%2biMB%2bjsmIutjzr0=

Large sink was cannabilized from a forklift batter charger.

 

[avionic]

Large sink can be wired for 600watt @ 8Ω per channel. -- 2 X16 parallel and 2 X 4 series
small sink is wired for 300watt @ 8Ω per channel.

 

[avionic]

Smaller Sink -- Cannibalized from and 3 phase VFD.

 

[Lavane]

I just so happen to have one of those. Speakers are heavily padded and I'm still working on the line level out.View attachment 870800

Those bricks are what I use. Two 4 ohm and two 8 ohm. I should mount them like you did.

 

[arts]

4Ω X 2 ,8Ω X 2 and 16Ω X 2 --- Arcol ,non-inductive, 300 watt.
http://www.mouser.com/ProductDetail/ARCOL-Ohmite/NHS300-4R0-1/?qs=sGAEpiMZZMtbXrIkmrvidKzXrWGN%2biMBe1URSpuqQRc=
http://www.mouser.com/ProductDetail/ARCOL-Ohmite/NHS300-8R0-1/?qs=sGAEpiMZZMtbXrIkmrvidKzXrWGN%2biMBr6yNOT91FTI=
http://www.mouser.com/ProductDetail/ARCOL-Ohmite/NHS300-16R-1/?qs=sGAEpiMZZMtbXrIkmrvidKzXrWGN%2biMB%2bjsmIutjzr0=

Large sink was cannabilized from a forklift batter charger.

The parts list for that load bank costs more than most of the amps I work on
I do like that speed drive heat sink,kinda on the ''hefty'' side.Mmmm....

One important point to make note of re load banks:

If you work on tube type amplifiers,you should ALWAYS have either paralleled load resistors or a supplementary higher value resistor in parallel with the primary (or both,as I do) load resistors.This will ensure that you will not lose an output transformer in the event that the primary load resistor goes open,especially during high power testing.

There are lots of these aluminum cased high wattage resistors around now,and unlike the ones specified by Avionic,most are really cheap (and inferior!) Chinese garbage.
Remember,you get what you pay for,and in this case,probably not even.Spend the bucks on quality,name brand parts,whether new or NOS.

 

[arts]

this is really nice! I would only be worry about having a cover over those resistors durring testing

Good point,and I will admit to the smell of scorched paint occasionally. Maybe some more ventilation holes in the future......

 

[avionic]

If you work on tube type amplifiers,you should ALWAYS have either paralleled load resistors or a supplementary higher value resistor in parallel with the primary (or both,as I do) load resistors.This will ensure that you will not lose an output transformer in the event that the primary load resistor goes open,especially during high power testing.

I do strictly SS.
Yamaha PC5002M in the photo.