With a 6" port, the velocity at 16Hz would be 40 m/s, peaking at 52 m/s. This seems to exceed what most people consider acceptable. Two 6" ports might work, but they'd each have to be 45" long (I'm going to have to buy so many of those 12" extensions, lol, but it will be worth it). With this design, the port resonance drops down to 154Hz, but I'm hoping this won't be an issue because these subs will be crossed over at around 40Hz.
Downfiring the port is a great idea. Thanks for that idea. But now that you've made me want to use PSP ports (I've used these on my car subwoofers too), I might have to put them on the front because they look so good, haha.
I also toyed around with the idea of using two 18" passive radiators but the rolloff is just too steep. It would be useless at 10Hz, a frequency of value to me.
Wow, 6 subs in different locations. I'd like to hear something like that someday. In my home theater, I put all 6 of my subs in front, side-by-side, right under the TV, partly because I like the way it looks but there are some nulls in the listening position I wish I could get rid of. Maybe I can add additional subs in other locations. How did you go about selecting the locations for your subs? Did you put a sub at the listening position and crawl around?
The reason I'm not worried about driver damage is because I've seen so many people feed high voltages to their drivers in free air, and I've tried this myself too on my Alpine Type R 15" subwoofer (70mm peak-to-peak). But here's a recipe for permanent damage. 7000 watt amp on a UM10, lol.
https://www.youtube.com/watch?v=06Rjk1IaJ-s
Also, if I put a subsonic filter in the signal path, I'm concerned that there's a chance it could subtract bass at frequencies I want to keep because as I understand it, if you set the filter at a certain setting, that means it's a certain dB down at the selected filter frequency. Subsonic filters might be necessary for protecting relatively fragile drivers, but I don't really consider the UM18 to be fragile. But you might be right, and if I somehow accidentally damage it, I'll consider incorporating some type of protection.
Now I'm wondering if I should make the enclosure 20 cubic feet instead.
You've given me many good things to think about. I appreciate that!
Downfiring the port is a great idea. Thanks for that idea. But now that you've made me want to use PSP ports (I've used these on my car subwoofers too), I might have to put them on the front because they look so good, haha.
I also toyed around with the idea of using two 18" passive radiators but the rolloff is just too steep. It would be useless at 10Hz, a frequency of value to me.
Wow, 6 subs in different locations. I'd like to hear something like that someday. In my home theater, I put all 6 of my subs in front, side-by-side, right under the TV, partly because I like the way it looks but there are some nulls in the listening position I wish I could get rid of. Maybe I can add additional subs in other locations. How did you go about selecting the locations for your subs? Did you put a sub at the listening position and crawl around?
The reason I'm not worried about driver damage is because I've seen so many people feed high voltages to their drivers in free air, and I've tried this myself too on my Alpine Type R 15" subwoofer (70mm peak-to-peak). But here's a recipe for permanent damage. 7000 watt amp on a UM10, lol.
https://www.youtube.com/watch?v=06Rjk1IaJ-s
Also, if I put a subsonic filter in the signal path, I'm concerned that there's a chance it could subtract bass at frequencies I want to keep because as I understand it, if you set the filter at a certain setting, that means it's a certain dB down at the selected filter frequency. Subsonic filters might be necessary for protecting relatively fragile drivers, but I don't really consider the UM18 to be fragile. But you might be right, and if I somehow accidentally damage it, I'll consider incorporating some type of protection.
Now I'm wondering if I should make the enclosure 20 cubic feet instead.
You've given me many good things to think about. I appreciate that!
Originally posted by Adam_M
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