Sub proximity to wall and couch - AVS Forum
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post #1 of 7 Old 07-15-2014, 11:56 AM - Thread Starter
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Sub proximity to wall and couch

So currently I have (2) 18 SI D4 at the front L and R under my screen. They are positioned about 10-12 feet from the listener. They are sealed and pretty darn good overall. I also have my first DIY sub - 15" HF in sealed enclosure behind my couch. but it's more to the side of the couch and firing out to the open room. It is corner loaded though.

I've been bitten by the DIY bug and I want more. Not that I probably need it, but what the hell I'd like to order (2) more SI 18's D4 and have all four corners covered for good room response and even more tactile feel.

Long story short, what I'm curious about is the space considerations for (2) MiniMarty enclosures and the spacing between the wall and couch. There's about 36" between the couch and the rear wall right now. So That leaves me about 10-12 inches between the MiniMarty and the wall or couch. So my question is, should I have the subs on the back wall firing into the back of the couch/listener? Should I place them against the back of the couch and subs firing back at the wall? Or should I have them against the back and firing towards the left and right side of the walls?

Any suggestions or opinions? Is this a bad idea for such near field?
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post #2 of 7 Old 07-15-2014, 12:01 PM
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Near field is nice, your couch will shake with the bass
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post #3 of 7 Old 07-15-2014, 01:41 PM
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Originally Posted by likelinus View Post
So currently I have (2) 18 SI D4 at the front L and R under my screen. They are positioned about 10-12 feet from the listener. They are sealed and pretty darn good overall. I also have my first DIY sub - 15" HF in sealed enclosure behind my couch. but it's more to the side of the couch and firing out to the open room. It is corner loaded though.

I've been bitten by the DIY bug and I want more. Not that I probably need it, but what the hell I'd like to order (2) more SI 18's D4 and have all four corners covered for good room response and even more tactile feel.

Long story short, what I'm curious about is the space considerations for (2) MiniMarty enclosures and the spacing between the wall and couch. There's about 36" between the couch and the rear wall right now. So That leaves me about 10-12 inches between the MiniMarty and the wall or couch. So my question is, should I have the subs on the back wall firing into the back of the couch/listener? Should I place them against the back of the couch and subs firing back at the wall? Or should I have them against the back and firing towards the left and right side of the walls?

Any suggestions or opinions? Is this a bad idea for such near field?
Ported will give you about another 12db at tune but ported and sealed might not mix so well since ported is also out of phase 180 degrees at port tune.

Is this problematic?


You could upgrade your current sealed boxed to marty cubes and do 4 marty cubes, which would be a significant improvement from what you have now. You are doubling your woofage and you are increasing the area near tune (usually 17hz-20hz) quite a bit in output too.

Other option would be stick with all sealed.

Or final option would be mix the ported and sealed an grab something like a cheap mini DSP to integrate the two systems.

You'll probably reject some of this just because it's me saying it though Just pretend it's another poster

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"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
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post #4 of 7 Old 07-15-2014, 01:52 PM - Thread Starter
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Originally Posted by Mfusick View Post
Ported will give you about another 12db at tune but ported and sealed might not mix so well since ported is also out of phase 180 degrees at port tune.

Is this problematic?


You could upgrade your current sealed boxed to marty cubes and do 4 marty cubes, which would be a significant improvement from what you have now. You are doubling your woofage and you are increasing the area near tune (usually 17hz-20hz) quite a bit in output too.

Other option would be stick with all sealed.

Or final option would be mix the ported and sealed an grab something like a cheap mini DSP to integrate the two systems.

You'll probably reject some of this just because it's me saying it though Just pretend it's another poster
I've already considered switching over the sealed 18s to a Martycube design - which is tuned to 20hz if I remember correctly. I just need to double check I have the depth and may need to tinker with the design to make it fit. I know I have the 24" height and width at this point, but that's another discussion and my primary concern is having subs so near field to the rear of the couch. Wasn't sure if this could potentially cause any issues with limited space and firing into the couch.

Horse before cart. Want to make sure this is a good setup and I can adjust accordingly...sealed or ported. I'm open to all options and opinions.

I'd rather not get a DSP unit since I'm using 3000 DSP amps and would like to stick with them.

Also, I have no problem with you responding to my thread. Just glad to see you aren't telling everyone what they have isn't as good as yours and how your brand is better than all.
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post #5 of 7 Old 07-15-2014, 02:53 PM
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Ported will be more impressive IRL IMO, the extra output at the lower range of hearing (and feeling) is more appreciated than chasing single digits at the expense of output. I had to learn this the hard way of coarse. My research has basically shown me that the majority of the tactile feel is actually in the 10hz-40hz range anways, and not below 10hz like many try to claim; It's often a futile endevour (or very expensive) to chase single digit bass at a level loud enough to appreciate. For this reason a ported sub at 17hz would be my top choice if you were looking for more excitement. Otherwise you'll need an army of subs and amps, which can work too.

I think you'd like the change to ported from an output perspective, the bass will seem to hit you harder. I've ported and sealed up the same drivers before and the ported is more impressive because of the extra output. My ports were tuned 20hz. I know there was more output from 15hz and down with the sealed, but in real life the ported just crapped in it's mouth. If you want SPL and output and impact ported wins for sure. Moving or placing near field only exaggerates and enhances the ass kicking. If you want to get kicked in the ass, port low and place it close. You won't be disappointed.

If you were starting fresh that would be my advice anyways. But since you already have investiture towards sealed (owning 2+1 operating subs now) then adding two more sealed near field might give you exactly what you want without the need for a bigger cab or complex construction. Sealed is certainly easier to build and can be smaller in size. If this is important, that's a solid reason to stick with sealed. Near field and additional drivers are still going to get you more of what you want, but how much you want would determine if changing over to ported would make sense or not.

If you do it, do it all the way IMO. It's easier. There is economies of scale that will play out to your benefit. It's way harder to build a couple marty cubes, then circle back and build a couple more later. If you do 4 sub boxes at once, it's not much harder than 1. Cut all your wood at the same time, and run all the pieces through your table saw fence on the same setting so all your pieces are identical. Don't adjust the fence until all the same parts and dimensions have been done, that way you get very exact pieces and cuts. If you need to go back and trim 1/8" off and run all the pieces you already cut through a second time to ensure they are all identical that works too. It's slightly more work, but not really. It takes only a few minutes to cut 3 more, once you already set the fence and measure and figure out the cut you need making additional identical cuts isn't too hard.

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post #6 of 7 Old 07-15-2014, 03:09 PM - Thread Starter
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Originally Posted by Mfusick View Post
Ported will be more impressive IRL IMO, the extra output at the lower range of hearing (and feeling) is more appreciated than chasing single digits at the expense of output. I had to learn this the hard way of coarse. My research has basically shown me that the majority of the tactile feel is actually in the 10hz-40hz range anways, and not below 10hz like many try to claim; It's often a futile endevour (or very expensive) to chase single digit bass at a level loud enough to appreciate. For this reason a ported sub at 17hz would be my top choice if you were looking for more excitement. Otherwise you'll need an army of subs and amps, which can work too.

I think you'd like the change to ported from an output perspective, the bass will seem to hit you harder. I've ported and sealed up the same drivers before and the ported is more impressive because of the extra output. My ports were tuned 20hz. I know there was more output from 15hz and down with the sealed, but in real life the ported just crapped in it's mouth. If you want SPL and output and impact ported wins for sure. Moving or placing near field only exaggerates and enhances the ass kicking. If you want to get kicked in the ass, port low and place it close. You won't be disappointed.

If you were starting fresh that would be my advice anyways. But since you already have investiture towards sealed (owning 2+1 operating subs now) then adding two more sealed near field might give you exactly what you want without the need for a bigger cab or complex construction. Sealed is certainly easier to build and can be smaller in size. If this is important, that's a solid reason to stick with sealed. Near field and additional drivers are still going to get you more of what you want, but how much you want would determine if changing over to ported would make sense or not.

If you do it, do it all the way IMO. It's easier. There is economies of scale that will play out to your benefit. It's way harder to build a couple marty cubes, then circle back and build a couple more later. If you do 4 sub boxes at once, it's not much harder than 1. Cut all your wood at the same time, and run all the pieces through your table saw fence on the same setting so all your pieces are identical. Don't adjust the fence until all the same parts and dimensions have been done, that way you get very exact pieces and cuts. If you need to go back and trim 1/8" off and run all the pieces you already cut through a second time to ensure they are all identical that works too. It's slightly more work, but not really. It takes only a few minutes to cut 3 more, once you already set the fence and measure and figure out the cut you need making additional identical cuts isn't too hard.
The woodworking part is nothing. I have a full on shop and can knock these out easily. I have a 1099 and (2) Fusion Pure speakers waiting for me to build this weekend. I figured if I'm going to be doing all this work, might as well round everything out and throw in a couple of MiniMarty subs. What I will probably do is pull my two from the front and build the rear MiniMarty. Then wait for the 18 SI D4 to return and then build the MartyCube to replace the fronts. That will give me all 4 corners and 2 of them near field.

The room size is about 25' x 20', but the issue is that it opens up to larger area on one size. So you don't get the full impact of a pressurized room, but it does shake and rumble nicely. That rear 15 HF seems to help and that's what got me thinking about throwing two Martys behind us. So I'm just looking for a bit more impact. I'm not one of those that looks for sub 15hz output. I would like to keep it around 16/17hz from the data I've seen.
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post #7 of 7 Old 07-15-2014, 03:22 PM
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17hz seems like a good compromise. If you have good wood working skills I'd say go for it! I like these kind of projects, they are strangely fun to me. If you are in the same camp as me then you should find satisfaction. I think you'll like it. Nice speaker choice BTW.. let me know what you think about them. Is that the 10" Fusion ?

That combined with 4 marty cubes is more than a weekend worth of work, and more than a case of beer project. At least if you want to take your time and enjoy the process. Big project but very cool. I look forward to seeing your results. Good luck!

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