I'm going to be using my amp in tri-channel mode for short-term and need to get a Low Pass Filter for the sub. Anyone know of a place online that I can purchase one of these?

Thanks in advance!

 

go here to find the crossover point you want

http://www.apicsllc.com/apics/Misc/filter1.html

Then go here and get your coil

http://www.partsexpress.com/webpage.cfm?&D...&WebPage_ID=309

Typical for a 4 ohm sub is to use a 6 or 7mH coil (around 120-90 Hz Fc)

 

Perfect! Thanks for the good info and links!

 

ok, I'll ask one more question, since I've never incoporated this into any of my previous systems. do i just splice/solder it inline to the positive and it can just hang there (meaning it doesn't need to be truly mounted or anything)? I would obviously "mount" it on my amp rack.

 

yeah... it goes inline on the + side of the sub's lead. and it's good. it will be too heavy to literally just hang , so go w/ your plan of mounting it on the amp rack.

it has been a long time since i used one of these, but as i recall it was pretty straight forward.

 

youse guys are the bestest!

 

 

Hmm the chart on that page is not accurate at all.

Assuming that For every -3db you will lose 50% of the signal. I ran some simulations with inductors of the size the reccomended and found that their cutoff frequencies were very wrong.

For example with a .25mH and 8 ohm load it says your cutoff frequncy is 5k but actually -3db occurs at 8.8k. And then it says a 1.27mH inductor with a 8 ohm load will give you cutoff at 1k but it actually give you half your input at 1.7k.

So unless im missing somthing that chart is completely wrong.