[mtg90]

Port would go to the back and up ~5" (for 20hz tune).

 

[kalakasan]

I worked more on my dual VBSS couch table idea, but had to reduce the height of the slot port to 1" because of excessive length at 1.5." I think I can make it work with 4" round ports, might reduce the "chuffing" I'm sure would be present at the 1 inch height. As is it, you might feel air movement at your heels with the ports at carpet level. I kept speakers in separate chambers for rigidity/strength. Still, this thing will be very heavy and I'd probably put casters on to allow for easier movement. I included DVD storage at the ends.

EDIT: If you could only have 2 subs, what would you do?
1) build two subs for the best wall placement, or
2) build two subs for behind the couch?

 

[mixma]

View attachment 3078206

Port would go to the back and up ~5" (for 20hz tune).

That is awesome, thank you!!!!!

Would 20hz be the best to stay matched my fronts or would 15hz be better for right behind the couch?

 

[kalakasan]

min

View attachment 3078206

Port would go to the back and up ~5" (for 20hz tune).

I have been building out my 1600 sq ft basement over the last 4 yours and have finally focused attention on my modest theater room. I've read some of the MBM threads here and "chest thump" is an experience I want in my theater room. However, some here advise that to reach the lowest registers, one should add sealed subs to the mix.

Am I correct in this observation? The main advantage I see with sealed subs is reduced cab size - they wouldn't dominate the room like the full Martys, etc.

For the MBM, I've leaning towards the economy of the VBSS. My idea is a build a couch-table style enclosure. Some questions in my mind about this build are:

1) In the current plan, the drivers are isolated from each in separate sections of the box. Is there a good reason to have them both in the same enclosed space instead?
2) The current tuning is 20hz. Are there good reasons for me to switch to the 31hz tuning? I know the port length would be reduced. Am I right that with the box up against the back of my couch, it would be more about the "chest thump" which is located above 40hz?

My plan below includes end shelving - am I right I expecting any shelf items (DVD's etc) would move and rattle around from the speaker vibrations?

My basic idea at the moment is dual VBSS's behind the couch (first build) then 2 additional subs up front - leaving time to research whether to go ported or sealed.

 

[qguy]

1. Personally, I would build individual boxes, moving would be much easier.
2. 20hz tuning is effective if you have 3 or more VBSS, a single VBSS would not produce enough usable output at 20hz. 31 hz allow the sub to play louder vs 20 hz tuning.

1) In the current plan, the drivers are isolated from each in separate sections of the box. Is there a good reason to have them both in the same enclosed space instead?
2) The current tuning is 20hz. Are there good reasons for me to switch to the 31hz tuning? I know the port length would be reduced. Am I right that with the box up against the back of my couch, it would be more about the "chest thump" which is located above 40hz?

 

[kalakasan]

1. Personally, I would build individual boxes, moving would be much easier.
2. 20hz tuning is effective if you have 3 or more VBSS, a single VBSS would not produce enough usable output at 20hz. 31 hz allow the sub to play louder vs 20 hz tuning.

Yes, I see the practicality of building 2 separate boxes. So does 31hz tune make sense behind a couch, given the increased loudness? Or should I just commit to 4 VBSS units (2 in front) at 20hz tune? Here's my concept for a front VBSS - it's down-firing with the vent vertical at the rear. Should I consider front-facing instead because of my concrete floor? I'd have to give up on the "furniture" approach...

 

[qguy]

You can have 2 tunings in a single subwoofer, by adding a divider along the slot port You can lower the tuning by blocking one side of the port.

For maximum chest thump, the driver and port should be directed towards the listener.

Yes, I see the practicality of building 2 separate boxes. So does 31hz tune make sense behind a couch, given the increased loudness? Or should I just commit to 4 VBSS units (2 in front) at 20hz tune? Here's my concept for a front VBSS - it's down-firing with the vent vertical at the rear. Should I consider front-facing instead because of my concrete floor? I'd have to give up on the "furniture" approach...

 

[mixma]

I tried to find it but could not, there is a video of a guy who made a VBSS coffee table and he has a cup of water on it and there are slight ripples, very minor. Walls in your room and pictures will rattle but the sub box, given bracing, doesn't flex much.

As Qguy said you want ports directed to you, ported will give you more bass you can feel over sealed, behind the couch or close is the way to go. My 4 are 8ft in front of me and they sound great and my couch trembles....I just want more couch trembling and lower volumes so hoping I can add 2 more right behind the couch!

Someone correct me if I am wrong but sealed 'should' play lower and have a quicker response but you will not feel the bass as much and it will not be as loud. Your slope wont have a peak in a sealed box like a ported box would and ported has way more output at the tune (given your room)

Your room will also be the biggest factor in how much bass you get at what frequency, spikes and nulls!

You box designs look amazing, can't wait to see your builds!

 

[kalakasan]

I tried to find it but could not, there is a video of a guy who made a VBSS coffee table and he has a cup of water on it and there are slight ripples, very minor. Walls in your room and pictures will rattle but the sub box, given bracing, doesn't flex much.

As Qguy said you want ports directed to you, ported will give you more bass you can feel over sealed, behind the couch or close is the way to go. My 4 are 8ft in front of me and they sound great and my couch trembles....I just want more couch trembling and lower volumes so hoping I can add 2 more right behind the couch!

Someone correct me if I am wrong but sealed 'should' play lower and have a quicker response but you will not feel the bass as much and it will not be as loud. Your slope wont have a peak in a sealed box like a ported box would and ported has way more output at the tune (given your room)

Your room will also be the biggest factor in how much bass you get at what frequency, spikes and nulls!

You box designs look amazing, can't wait to see your builds!

Thanks for the compliments. Designing is one of the things I most enjoy doing. However, the design of course must follow function, and I'll admit my technical knowledge of speaker design is not what it should be to be confident in my design choices. I am a decent designer and woodworker, but I don't pretend to "grok" the mathematics of acoustics. The other factor nagging at me throughout this process of discovery is "guessing" at how the finished sub will actually sound, not to mention the amplification, speaker wiring, dsp and crossover magic that has to properly applied. So many variables! So I'm definitely one who will spend hours and hours on research until I'm pretty confident I'll get the outcome I expect.

Perhaps I need to join a local audiophile group so I can hear the different varieties of subs in an actual home use setting...

So here's another stab at a single VBSS design, using the same dimensions of the couch table idea, but separating them for ease of movement...

 

[kgull85]

I tried to find it but could not, there is a video of a guy who made a VBSS coffee table and he has a cup of water on it and there are slight ripples, very minor. Walls in your room and pictures will rattle but the sub box, given bracing, doesn't flex much.

This one?

 

[kalakasan]

This one?

Ha! Yes I watched all the videos on this build. Still, much less YouTube content on the VBSS than other subs. The Martys seen immensely popular...

 

[mixma]

Thanks for the compliments. Designing is one of the things I most enjoy doing. However, the design of course must follow function, and I'll admit my technical knowledge of speaker design is not what it should be to be confident in my design choices. I am a decent designer and woodworker, but I don't pretend to "grok" the mathematics of acoustics. The other factor nagging at me throughout this process of discovery is "guessing" at how the finished sub will actually sound, not to mention the amplification, speaker wiring, dsp and crossover magic that has to properly applied. So many variables! So I'm definitely one who will spend hours and hours on research until I'm pretty confident I'll get the outcome I expect.

Perhaps I need to join a local audiophile group so I can hear the different varieties of subs in an actual home use setting...

I know with these Matt got it down to a science so you need to keep internal volume within 10% so you can mess around with any box as long as the volume is the kept the same but port length and tuning I don't quite understand.

I've built car audio boxes before but always someone else's design!

 

[petethekiller]

I just thought I would share my current and future VBSS builds

 

[kalakasan]

I just thought I would share my current and future VBSS builds

View attachment 3079553 View attachment 3079554 View attachment 3079555

Those look great! Where in the room are you putting them?

 

[kalakasan]

SO another idea I had is to build a "box bench" version of a dual VBSS design. I went looking for design examples of said benches and stumbled across this unique L-shaped "entry way" bench that would reside in the back corner of the room. I'm sure I could make it work (I'd have to extend it and put fabric over fake door frames), the question is, where to place the 460's? How much is bass loading going to be an issue? Is this even feasible? I'm on a concrete floor, so that's a consideration: