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Discussion Starter #1
Hi All,

So I have been researching a ton on a DIY Sub build for my HT. I am 80% movies, 20% other.

The room is dedicated DD+GG+Clips. rough dimensions 19' long, 15' wide, 8.6' H at soffits all the way around.

I have a Dayton UM15-22 woofer and Xli-1500 with mini-dsp. Denon x4500h avr.

I am handy (doing the room build myself) but I am just learning sub box building in real time.

I want the sub to deliver strong low end but I dont need to break everything in the house. BTW the room is on a concrete slab. Also I plan on using MDF and Plywood for the second front plate. I have been studying the devastator, marty etc..

I have been playing with WinISD and subbox.pro.

I am not sure what I should tune the box at, too many variables. Im looking for a safe number for my first box. I can always build another in the future. I was just going to do a front facing slot with the woofer. I can go upto 42" long x 28" tall x 24 D. It will be in the front of the room under my AT screen 12' from MLP.

Any advice is welcome.
 

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I thought I would have the same listening habits as you. I ended up going with a mini Marty because I wanted to focus on the low end. I went with the 18" version of the one you have. I like it a lot but I wish I would have known more about the devastator at the time, I can definitely tell it lacks in the mid bass and I find myself listening to more music than I thought I would. Not super familiar with how well that 15" pairs with any of the devastator designs, but if any fit your constraints I'd pick that or marty variant.
 

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The condensed answer is:
20hz gets you like 90% of movie frequency coverage.
15hz gets you like 95%, 25-30hz gets you 80-85%
1-15hz is the last 1%, and will require a 1%er budget

Plan accordingly...

The lower you tune, the less efficient the mid-bass will become. Make it have less chest-kick (which is like 40-300hz.)
Due to that effect, a 1hz tuned box is basically a sealed box, they practically measure the same SPL in most cases.

The total power (watts) is spread evenly across all frequencies i.e. more thinly.

If you want 180db @ 90hz in a cement truck, then a narrow 6th order ported or horned box will get you near the world-record.

If you want all the frequencies, then you'll have low efficiency like a sealed box.
There is no free lunch.
Every design has different advantages and disadvantages, it's just a matter of know what you can/can't live with/without.

IB and Sealed has good 1-10hz performance and phase response, while keeping the box small.
Ported is more efficient near tuning, and a steep rolloff, port noise and requires a HPF.
Horned is comparable, but roughly ~6db louder than ported or sealed at all frequencies above tuning, larger, MUCH more complicated, and an even steeper rolloff, often limited bandwidth and uneven FR and bad phase/group delay figures.
Many subwoofer horns struggle going much higher than 120hz, where as all the other box-types go up to 200-300hz or whatever.
 

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Discussion Starter #4
I thought I would have the same listening habits as you. I ended up going with a mini Marty because I wanted to focus on the low end. I went with the 18" version of the one you have. I like it a lot but I wish I would have known more about the devastator at the time, I can definitely tell it lacks in the mid bass and I find myself listening to more music than I thought I would. Not super familiar with how well that 15" pairs with any of the devastator designs, but if any fit your constraints I'd pick that or marty variant.

Ok interesting. I have seent eh Devastator and I think there is a Micro Dev I can look into.
 

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Discussion Starter #5
The condensed answer is:
20hz gets you like 90% of movie frequency coverage.
15hz gets you like 95%, 25-30hz gets you 80-85%
1-15hz is the last 1%, and will require a 1%er budget

Plan accordingly...

The lower you tune, the less efficient the mid-bass will become. Make it have less chest-kick (which is like 40-300hz.)
Due to that effect, a 1hz tuned box is basically a sealed box, they practically measure the same SPL in most cases.

The total power (watts) is spread evenly across all frequencies i.e. more thinly.

If you want 180db @ 90hz in a cement truck, then a narrow 6th order ported or horned box will get you near the world-record.

If you want all the frequencies, then you'll have low efficiency like a sealed box.
There is no free lunch.
Every design has different advantages and disadvantages, it's just a matter of know what you can/can't live with/without.

IB and Sealed has good 1-10hz performance and phase response, while keeping the box small.
Ported is more efficient near tuning, and a steep rolloff, port noise and requires a HPF.
Horned is comparable, but roughly ~6db louder than ported or sealed at all frequencies above tuning, larger, MUCH more complicated, and an even steeper rolloff, often limited bandwidth and uneven FR and bad phase/group delay figures.
Many subwoofer horns struggle going much higher than 120hz, where as all the other box-types go up to 200-300hz or whatever.


This is a awesome summary. Since I already have a UM15-22 and I have a Crown XLi1500 I want to work within those boundaries. So I have been working in WinISD trying out different combos. I dont care if it is round verse rectangle vent.

I am looking at the Johnny vs Mini Marty as examples. I was thinking of tuning in the 18-20 range. I will have around 24" deep if I don't want it sticking out too far into the room from under the screen.
Under the screen I will have roughly 30" to play with. Length is where I can make up for the extra space, so I can probably go upto ~10cuft.

So if I run these through WInISD with the following settings: UM15-22 Driver, 450W Signal, 1 Vent @ 2.5x24x38.2. The biggest thing I am wondering about is the port velocity looks like it might be too high start at 23Hz. Since I am new to this, not sure if I need to control this better.

Also based on my specs any recommendations if there is a box I should mimic more.

Thanks.
 

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So if I run these through WInISD with the following settings: UM15-22 Driver, 450W Signal, 1 Vent @ 2.5x24x38.2. The biggest thing I am wondering about is the port velocity looks like it might be too high start at 23Hz. Since I am new to this, not sure if I need to control this better.
Don't forget to add the HPF in WinISD. That will tame the port velocity as well as the excursion.
 
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