Dummy Loads: Wirewound VS Aluminum Shell?

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Looking to build a dummy load for bench testing with no sound. Right now I am using two 12" subs in a sealed enclosure wired out of phase to cancel each other out (for the most part). But it still has quite a bit of sound and vibration at high volumes, and they just cannot handle some of the amps Ive been testing at full power (or anywhere near on some).

So I was looking at load resistors. Would like to get around 2000W of dissipation. I was going to buy 16 x 16-ohm 120W wirewound resistors. Put them in batches of 4 in parallel (so 4 sets of 4-ohm @ 480W) that I could then wire to in series/parallel together for various loads.

These are the wirewound Wirewound Power Resistor 16 Ohm 120 Watt Audio and Power Supply Load | eBay

But I also saw these aluminum shell resistors that are rated at 1000W?!?! I could get 4 x 2-ohm versions of these for the same money and have over twice the power dissipation. 1000W 2 4 8 16 Ohm Aluminium Shell Braking Resistor Resistance Dummy Load Audio | eBay

Anyone have any negatives about doing the aluminum shell vs the wirewound? Do you think these ratings are accurate? I plan on sinking them and adding fans in either scenario.
 
Mouser and Digikey has a few that are around 20 bucks each and are 300watts.

Also recently saw some youtube videos about how to make your own 8ohm loads using heating elements and a little creativity.

I rather use the used wire wound that are available on ebay for pretty cheap or on mouser.
 
These shell resistors are a class on their own.
I made the mistake to buy one.
Although it is supposed to be "silent" that means with no sound,
this resistor "whistles" your test frequency.
Additionally, the leads are way too thin to handle high current.
 

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Most or maybe all of the aluminium clad power resistors are intended to be fitted to a large heatsink to reach their dissipation specification. The need for a heatsink makes them very expensive.

I prefer using arrays of ceramic cased 5W power resistors. Banks of 4r0 are very useful for many different test/dummy loads. I have 4 off 4r0, each at 225W (45off 20r 5W in series parallel)
4+4 = 8
4+4+4 =12
4+4+4+4 = 16
4||4 = 2
4||4||4 = 1r33
4||4||4||4 = 1r0

4||4 + 4||4 = 4r0
4||4||{4+4} = 1r6
4||{4+4} = 2r67
etc.....
 
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These shell resistors are a class on their own.
I made the mistake to buy one.
Although it is supposed to be "silent" that means with no sound,
this resistor "whistles" your test frequency.
Additionally, the leads are way too thin to handle high current.

Although when testing with the wire wound I could here higher fhz pretty good, that was without ANY hardware. Once I mounted them with proper hardware they are pretty silent.

There's a guy on youtube that compared a non inductive load with a large wire wound resistor and pretty much explain what to expect which wasn't much difference. There is like a 300 buck difference between the two, wire wound can be bought for around 25 bucks and an non inductive is around 300.00.

I would like to have a non inductive load to compare to a large wire wound resistor...to actually measure the differences for myself.
 
non inductive is not really necessary for dummy load testing, It should be done to prove DUT reliability and insure PS & heat sink device temps. (near clipping ) which is overkill for most DIY
you can use a smaller load for square wave and frequency flatness, IMD test maybe a variable.
 
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All i need this for is to run the amps at or near clipping for a period to ensure a good repair and make sure no hidden problems will arise once the amp warms up or is put through a workout. I also would like it to do some power tests via clamping and/or the new SMD AMM-1 when I finally getting around to buying one.

So the heaters will suffice. REALLY REALLY wish I could find some 120V 3500W water heater elements. Largest Ive seen is 3000W. I could use the 240V 3500W ones, but I would need twice as many of them to get a 4/2/1 ohm load than if they were 120V.
 
any junk yard/scrap yard is full of hot water heaters just asking for the elements to be taken out.

Then there are electric ovens...
Also old "rotisseries".

Wirewound is superior to the aluminum "Dale" type resistors for high power testing. Unless you ramp up the temp slowly there is the danger of blowing the ends out of the aluminum case type. I avoid them wherever possible. Too bad, because they *look* good.

You can make a wirewound GLOW red and it is ok usually.

As far as getting the extra 500watts out of the 3000watt element?
Put in a metal can water bath. Or oil if you pick the right type...

_-_-
 
I'd have thought an inductive load (like a speaker) would be the ONLY way to test real performance of an amplifier...

I mean really, who cares what a nice sine wave you have in a non-inductive load if it goes haywire when a speaker is connected?

Just my 2c.

I use cheap kettles (jugs) in parallel to give lower ohms. at only $5 a pop, you can't get much cheaper
 
A speaker load is indeterminate.

A simulated speaker load could be set as a standard. ESP and others discuss this.

But designers have an array of predictable test procedures using standard value components and techniques that can identify poor performance and lead the competent designer (without interference from the accountant) to adopt all the compensations that ensure exemplary performance into any simulated or actual speaker load.
 
All i need this for is to run the amps at or near clipping for a period to ensure a good repair and make sure no hidden problems will arise once the amp warms up or is put through a workout. I.

burn in testing for repairs use any value around 3 ohms ( for 4 ohm car stuff )
value not critical. dial in the power you want via input level. remember the heater resistance is somewhat variable depends on temp


depending on how long you burn in and tank size, the water can be boiling off. it would be ideal to re-use the heat of course. The rating without water is prolly 10-20%

three or four old 1500W space heaters in parallel ( coiled wire types with fan ) they have 2 way switches to adjust tap selection.
$40 new or less used . could be the easiest to modify IMO
 
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The extra 500W was not a dissipation concern. It was the fact that a 120V 3000W element would yield a 4.8 ohm load. At 3500W it would be a 4.1 ohm load. As close to multiples of 2 the better. (2.0, 4.0, 8.0)

rather irrelevant, imo.

Don't see why the exact value matters all that much...
1/2 power is only 3dB.

At that power level it either works or smokes pretty much, and the line voltage will probably cause more variation than that impedance difference.

Oh, right, this is a car amp, so unless the internal supply maintains the voltage precisely, the power out will vary a bit...

but also a little exercise, if you used say 4 x those elements (series parallel) to result in a load that at 3kw did not shift resistance very much if at all, how much *shunt* resistance would be required to pull it to 4.0 ohms, and what *power* resistor is needed for this job?

_-_-bear
 
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