mixed mono amp , passive crossover

I have been out of the loop for a while so forgive my question. I have a PPI PCX280 (80w x 2) amp that I want to run in mixed mono. Currently the amp is running a MB Quart 3-way component (Tweeter, 4"mid, 5.25"woofer) with a passive crossover. I'm assuming the amp is seeing a 4ohm load. I want to add a subwoofer and I need to get a low pass passive crossover but I'm a little confused. Running mixed mono is going to give me 80w x 2 and 320w x 1. That 320w is way too much power. I have searched all over the internet and couldn't find a premade low-pass crossover so I willing to custom build one but I'm not quite certain what kind of passive crossover is going to lower the frequency to 100mhz but also reduce the watts to the woofer so it's not over powering the system?

Well the amp will not put out 80 watts per channel AND 320 watts bridged and split that power between all of the speakers It will put out the rated rms power at 4 ohms bridged. refer to the "passive crossovers" link on the left of the site to find out what milli-henry coil you want for the desired low pass crossover point.

If I understand you correctly I'll be getting a total of 320w not 480w (80w x 2 and 320w x 1). So I will be getting 80w x 2 and 160w x 1? I read the crossover section and know what type of coil I need but how do I limit the watts/power/volume to the sub with the crossover? From what I gathered, all the passive crossover does is limit the frequency not the watts/power/volume. So if the sub is over-powering the components how do you adjust for that with a passive crossover network?

grozanc wrote: From what I gathered, all the passive crossover does is limit the frequency not the watts/power/volume. So if the sub is over-powering the components how do you adjust for that with a passive crossover network?

You can't.  And you will need more than just a low-pass crossover for the sub, you need to match the frequency and create a high-pass for the mains.  Running in tri-mode like this is generally only recommended as a stop-gap measure until a dedicated subwoofer amp can be installed, and only recommended with amps designed for tri-mode operation.

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