Dummy - load

Hi all,

What sort of dummyload is best for testing amps ?

I have a ohmic load that can be used for amps up to 200 W (both 4 and 8 ohm). But is it enough to just use an ohmic load, or do I need to add a capacitor or inductor ?

What do you all use when testing ?

How about modelling a speaker with crossover, how is that done ?

thanks

\Jens
 
That's my dummy load.;)
 

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Hi,
for testing amps i made a box with some switches, to test different loads:
1. 8 ohm
2. 8 ohm
3. 0.33 ohm + 1u (MKP) series
4. 3 ohm + 22u (MKS) + 0.6 mH series

with 1/2 test: no load, 8, 4 real
with 1/2/3/4 test complex load;

with sine/triangle/square wave testing you see all problems, a amp can have... i youse this for about 15 years with success...

regards
alf
 
Another kind of load I have seen more than twenty years ago, was at the quality control of Studer (Revox).

They clamped 4.7uF capacitors, that were soldered to a specially made adaptor plate, directly to the output clamps of some receivers and fed the amps with a signal in the 10 to15 kHz range.

You can of course not use this test to figure out the maximum power an amp can deliver but you can test it for robustness and reliability (thermal stress and stability). They were run this way for about one hour as I can remember. You could even hear sound emerging from the amps !

Please be aware if you want to try this yourself !

Regards

Charles