[gtpsuper24]

Well I'm new to DIY subs. I've had a RLP18 just sitting around for awhile, and decided to do something with it. Its almost 100% home theater, i'm still learning all the programs like winisd and have been playing around with the enclosure calculator. So I decide to make something about 13-13.5 FT3. Thinking about down firing with a 24x24x60 enclosure 1.5" mdf, I want it ported at the top so what kind of port length and diameter should I be looking at, when playing around with the calculator I put a 17" long and 8" diameter port, would that work, not looking for SPL more hard hitting low bass for movies. Going with the ED lt1300 amp. Going to use 3 0.75" 21x21in bracing with 8" holes. Is there anything I'm missing or not doing right or something I should change? Just making sure, I don't want to screw anything up, so if anyone has any options that would be great. Thanks. Oh current sub is a SVS 25-31 PCi, this shoud be a major upgrade right?

 

[Mike P.]

If you want low end extension you should tune around 16 hz. a 8 inch port 35 inches long would do the job.

 

[gtpsuper24]

I've read through some forums on DIY and I see alot of people use HPFs will I need one with the LT1300 amp? Or should I just let the driver naturally roll off? I'm still going to use the SVS for the upper bass freq to help blend with the L/R bookshelfs.

 

[Mike P.]

With a 16 hz tuning the sub won't exceed Xmax until about 13 hz, and that at full power. Build the sub and see how it works for you. If you notice it bottoming out then you can get a HPF.