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Discussion Starter #1 (Edited)
For my down stairs area I'm contemplating building a sub myself, scary thought I know.

I'm wanting to create a sub that I can place a TV on top of so minimising vibrations is a consideration. Something like the Seaton Submersive with its opposed 15" drivers would do the trick. But... to perhaps get a bit more out of the unit I was thinking of making it ported (slot port on the front).

When modelling this type of configuration would one just model a single 15" ported sub and then double everything to cater for the two drivers? Or is there something a bit more tricky involved?

Feel free to say its bad idea, I'm full of those :)
 

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For my down stairs area I'm contemplating building a sub myself, scary thought I know.

I'm wanting to create a sub that I can place a TV on top of so minimising vibrations is a consideration. Something like the Seaton Submersive with its opposed 15" drivers would do the trick. But... to perhaps get a bit more out of the unit I was thinking of making it ported (slot port on the front).
Opposed drivers will help remove most vibration, but strong physical coupling between them via bracing is needed for it to work best.

Here are a couple of serving suggestions, that IIRC, I got off Dave D (Planet 10).



This was used to describe an overkill design where the driver magnets were threaded to allow the rod in the middle: my old KEF 104/2 did something similar. See the bit labelled 'solid aluminium spacer'? If you were to build the box, then trial fit a spacer between the drivers in place of this one, made from aluminium or hardwood like Tas Oak, that would work well. The threaded rods are also overkill but it's the best sketch I have to explain otherwise.



This is much more conventional. The notches in the horizontal brace would be sized to fit tightly between the driver magnets as per the previous diagram and lock them solidly together when they bolt in finally.

A third alternative (but imagine the manifold horizontal, not angled).



This gives the vibration advantage of the two previous, but also allows a good deal of even order non-linearity cancellation from the driver motors and suspensions. Also makes it more kid resistant to cone damage. Can be sealed or ported and is a slightly more difficult design and build.

When modelling this type of configuration would one just model a single 15" ported sub and then double everything to cater for the two drivers? Or is there something a bit more tricky involved?
When you go into WinISD and select new project, about the second choice is driver configuration and number of drivers. Select as normal for the type of box you want and '2' for number of drivers. In Unibox it's a drop down menu just below the driver selection box on the RHS. Start modelling. Use the application suggestions for drivers eg the Exodus for a single driver and multiply volume by 2 roughly and port diameter up x1.41 or CSA by 2. Tweak to taste.

Give me some idea of the internal volume, power available and the size and shape of the box and I'll throw together a couple of quick models.
 

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Discussion Starter #3
Thanks again Brett, your a champ.

I was thinking somewhere around 250L (internal) or so (depending on min size requirements I could go bigger)

Power available would be whatever is required. Probably a yammy bridged to 2600W if need be. Or EP4000 bridged if I want to save some money.
 

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Thanks again Brett, your a champ.

I was thinking somewhere around 250L (internal) or so (depending on min size requirements I could go bigger)

Power available would be whatever is required. Probably a yammy bridged to 2600W if need be. Or EP4000 bridged if I want to save some money.
The EP2500 puts out 650W/ch into 4Ω or about 1300W into 4Ω bridged according to Chas' tests so I used that for the calcs. Using more power will increase the SPL proportionately and you'll need a larger port to get the same air speed which will also make it longer. I used 2x150mm ID round for these Q&D sims and they were 97cm long for the 250L and 90 for the 300L.

As usual, all volumes are net and don't factor in port volume, driver displacement or bracing.
 

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Thats some serious output :) Love it. Thanks heaps for the effort you have put in for me.

Brett, if I used a yammy P3500S bridged to 2000W what would you recommend ?

The EP2500 puts out 650W/ch into 4Ω or about 1300W into 4Ω bridged according to Chas' tests so I used that for the calcs. Using more power will increase the SPL proportionately and you'll need a larger port to get the same air speed which will also make it longer. I used 2x150mm ID round for these Q&D sims and they were 97cm long for the 250L and 90 for the 300L.

As usual, all volumes are net and don't factor in port volume, driver displacement or bracing.
 

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I'm wanting to create a sub that I can place a TV on top of so minimising vibrations is a consideration. Something like the Seaton Submersive with its opposed 15" drivers would do the trick. But... to perhaps get a bit more out of the unit I was thinking of making it ported (slot port on the front).

When modelling this type of configuration would one just model a single 15" ported sub and then double everything to cater for the two drivers? Or is there something a bit more tricky involved?

Feel free to say its bad idea, I'm full of those :)
IMO, 2 separate slot ported enclosures with plate amplifiers, namely the inexpensive O-Audio 500w.

Vented designs modulate air, they don't pressurise it, so by design cabinet movement should not be an issue, atleast in my experience. Place both subs together to become a TV stand, or as u have found with ur Mal-X, experiment with placement for best results in ur listening position.

This Tempest-X2 15" Slot Ported Design is a very good project to follow, and performs very well for a 150 liter cabinet. eg. 118db @ 30Hz with the cone only half way into it's full excursion.
 
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