Hi sorry for the weird question but a friend was suggesting to use an iron as dummy load
Actually a 1000W iron should have a resistance about 4.5 ohm We use 220 VAC
If you use 110 VAC a smaller wattage iron can be used to have a 8 or 4 ohm load
Used irons cost next to nothing and they are designed to bear heat of course
Actually a 1000W iron should have a resistance about 4.5 ohm We use 220 VAC
If you use 110 VAC a smaller wattage iron can be used to have a 8 or 4 ohm load
Used irons cost next to nothing and they are designed to bear heat of course
Some have used water heater elements (in water) for amplifier loads as well.
You'd have to electrically characterize the iron to see whether it would be suitable as an audio amplifier load.
Plot the current vs the applied voltage. Likely it would be nonlinear in resistance with variation in the applied voltage
You'd have to electrically characterize the iron to see whether it would be suitable as an audio amplifier load.
Plot the current vs the applied voltage. Likely it would be nonlinear in resistance with variation in the applied voltage
Hi ! yes My mistake Well i guess that this closes the question 48 ohms is too different from 8
the load will not mimic a real speaker load Case closed
Moreover looking around some used dummy load shows up The big one are not cheap but very helpful in testing
essential i would say
the load will not mimic a real speaker load Case closed
Moreover looking around some used dummy load shows up The big one are not cheap but very helpful in testing
essential i would say
I actually have a simulation of our mains electricity supply (don't ask 
) that shows all the resistive heating that can be on at one time. SH are storage heaters. CH convector heaters. IMH immersion heater and OFR is oil filled radiator.
This works out at about 2.56 ohms slapped across 240 volts. Scary.
(Mains is nominally 230 but measures as high as 245 at light loads)
) that shows all the resistive heating that can be on at one time. SH are storage heaters. CH convector heaters. IMH immersion heater and OFR is oil filled radiator.This works out at about 2.56 ohms slapped across 240 volts. Scary.
(Mains is nominally 230 but measures as high as 245 at light loads)
But if they are so cheap, you can put half a dozen in parallel
Make it a free ironing urban center.
Get an old electric shower element. The great thing with these is you can put them in a bucket of water for cooling and most have two elements that can be used separately or in series or parallel. An 8.5kW 230v one is just over 6 ohm for example.
This is a tried and true load.
https://audioxpress.com/article/you-can-diy-build-an-audio-dummy-load
Coffee machines, etc:
https://www.diyaudio.com/community/threads/the-franken-load.279747/
https://www.diyaudio.com/community/threads/the-franken-load.279747/
Probably the best test of a dummy load would be to apply enough power for rated load for a while, remove power and measure resistance as fast as reasonably possible.
Many resistive devices can have a positive temperature coefficient so it will have a higher resistance when hot.
This may lead to optimistic load tests for amplifiers in some cases.
Also light bulbs can have a somewhat larger resistance difference between cold and hot. Can be a useful feature as a speaker limiter or dim bulb tester.
Many resistive devices can have a positive temperature coefficient so it will have a higher resistance when hot.
This may lead to optimistic load tests for amplifiers in some cases.
Also light bulbs can have a somewhat larger resistance difference between cold and hot. Can be a useful feature as a speaker limiter or dim bulb tester.
Hi thank you very much I like the idea a lot
Considering the testing of 100Wrms amps max (but it could be much less I am going to high eff speakers) the output voltage would be around 25 Vrms max ? Good !
I remember we did the same 25 years ago with my friend to use it his repair shop. Purchased a few meters of resist wire from electric hardware store, hang it between two posts and fire up the amp. Then when the power goes up wire started to shine red and the wire grew longer softer and then touched the table surface and burned it
A while ago I read about a DIYS dummy load someone used for amp testing. He had a number of smaller resistors glued to a heat sink. The clever thing about it, he needed less than 1/5 of the rated power, because he dropped them into a bucket of water when testing.
Water takes up 14 times more heat than air, so he could even run long time adjustments at full power, which is requested by some amps.
So his 100W load could take 500W or more for a long time. Sure the water got warm, but it takes time. The resistance of water doesn't hurt in this case, so some glue for sealing them is enough. Nothing happens, even when there is full contact to the water.
So you can get away with a handfull of surplus load resistors, some epoxy glue and an old heatsink instead of a large, expensive air cooled construction . Also, the load doesn't change it's resistance that much, as the temperature change is quite low compared to air cooling.
Water takes up 14 times more heat than air, so he could even run long time adjustments at full power, which is requested by some amps.
So his 100W load could take 500W or more for a long time. Sure the water got warm, but it takes time. The resistance of water doesn't hurt in this case, so some glue for sealing them is enough. Nothing happens, even when there is full contact to the water.
So you can get away with a handfull of surplus load resistors, some epoxy glue and an old heatsink instead of a large, expensive air cooled construction . Also, the load doesn't change it's resistance that much, as the temperature change is quite low compared to air cooling.