ohm dummy load

[jonbearsmt 919]

of course i have 2 8ohm speakers that are less then 150 watts... and i need to run them 4 ohm stereo on the amp, i remember seeing somthing befor that you run inline to propose a ohm load to the amp,

so im guessing i will need, two 4 ohm dummy loads,=4 ohm at the amp, or two 6 ohm dummy loads =2 ohms at the amp

i can run this amp at 4 ohm stereo or 2 ohm stereo,.

i have seen a few things on parts express... but not too sure what exacty i need... so someone that has used these be for would be great!

thanks

[altoncustomtech 773]

The high wattage dummy loads that PE sells are about as good as you can get. It depends on the testing that you're doing though as the dummy loads are not like a speaker, they're non inductive. The inductance of the voice coil on a speaker, it's movement through the motor structure and many other properties changes the impedance the amplifier sees. Depending on the type of testing you're trying to do you may not get the results you're looking/hoping for.

EDIT: I read a little closer on what you wrote and I think I understand what you're trying to do. However, there's really no need to worry about the 8ohm load on the amp AND the power will be split between the speaker and the dummy load anyway so it's not going to get you any closer to what you're wanting to do. If your amp puts out 150wrms at 4 ohms, putting a resistor in with the speakers to get a 4 ohm load will not net you any extra power to the speaker. With the 4 ohm load the resistor and the driver will each see half the power given the impedance's are the same.

[95Honda 486]

You'll actually see less power at the speakers if you add some resistance in parallel due to the amplifier power output not increasing linearly as the load drops...

The only way to lower the the impedance to the amp with the same driver load is with a matching transformer. But these get expensive over 100 watts or so, have loss (5%+ at best) and increase distortion.....

You can add resistance in series to increase th eimpednace to the amp, but this will also net you less power to the actual drivers...

John, I might have some matching transformers laying around that have the primary/secondary impedances you need, If I do, I could send them to you to try. Let me see when I get home.

-Mike