Sealed Infinity Kappa Perfect VQ

[WmAx]

How far away from my tube TV will I have to keep these subs? I don't need an excuse to buy a new TV just yet.

Miner detail...

To be safe: 5 feet. The flux field of the magnet varies with angle, etc.; so particular distance may be dependent on angle as well as distance. I have them about 3 feet from my high end CRT computer monitor and it's fine, with the subs angled in a bit.

-Chris

 

[annunaki]

Thought I'd mention that I saw 3/4" Birch and Oak hardwood plywood at Home Depot for just under $50. However there did seem to be some voids in the plys that could be seen from the edge.

I keep seeing hardwood plywood recommended. Is there a void free hardwood plywood? Maybe a cabinet grade void free hardwood plywood?

One thing that I'm not getting about all this is why the veneer on the plywood matters. Once you run screws into your bracing, the veneer is shot. I can't imagine doing all that fastening from the inside of the box.

Cabinet grade should be void free. Usually, for the best stuff, go to a cabinet manufacturer/custom cabinet maker.

 

[Guiria]

In my attachment you'll see my speakers on end tables as stands. My wife likes the idea of the subs becoming the speaker stands and the end tables going back to the ends of the sofa.

Are their known issues with pointing subwoofers opposite of each other? One would be pointed left and the other right, away from the entertainment center.

I'd rather position them like that than firing forward, the footprint 'appears' smaller.

My alternative is to just build two sub boxes and place them in the optimal position for performance The design would be different however if I was using them as speaker stands.

 

[Guiria]

Just realized that the speaker stand method would be too close to the TV.

Hmm...

 

[Alex2507]

Just realized that the speaker stand method would be too close to the TV.

Hmm...

With all the money you save by DIY subs....PLASMA!!!!!!

 

[Guiria]

Well when I was really getting serious about doing this my wife brought up the fact that I need to build a closet behind the bonus room wall (attic space over garage) for storage, etc, before attempting a sub build.

The sub build will have to wait, although I do plan on going through with this provided I can get my hands on some kappa perfects when it is time...

Hopefully it's not more than a month or so.

House upgrades...

 

[Guiria]

I've got attic space behind my walls of my HT room. If I built ported enclosures I could put them into my walls that would take up 0.00 floor space. What specific acoustical issues do I run into if I do this???
Obviously I would port the boxes out the front.

hmm...the possibilities

 

[Guiria]

One thing I forgot. The studs are 24" on center so the sub box size shouldn't be a problem.

 

[Alex2507]

One thing I forgot. The studs are 24" on center.

You sure they're not 16" on center?

 

[Guiria]

Yes absolutely sure, just measured this week. This is a bonus room over my garage and the studs are different than your typical room.

In fact this is the same wall I was going behind to build a closet, come to find out from a respected home contractor that the 2x4 I was hoping to cut out is under compression and is part of the flooring truss system. If I take out that 2x4 I would need to re-support the bonus room floor with a glue-lam-beam?? and pour an additional footing in my garage to support the beam and on and on and on.

Needless to say I'm not building the closet anymore, which means there is plenty of room for a couple of boxes should I decide to go that route.

 

[Guiria]

Passive Radiators?

Would the box size of a kappa perfect 12 vq be considerably smaller than the slot ported counterpart if you used one or two Passive Radiators instead of a slot port? I'm not sure if this is possible to get to the right tuning but it would be interesting to try! Albeit a little more expensive than the slot port build.

 

[jaxvon]

Would the box size of a kappa perfect 12 vq be considerably smaller than the slot ported counterpart if you used one or two Passive Radiators instead of a slot port? I'm not sure if this is possible to get to the right tuning but it would be interesting to try! Albeit a little more expensive than the slot port build.

You would lose 25%-30% of size from the elimination of the long port. The advantage to using a PR system is the elimination of the port construction. A long slot port is difficult to construct, but essentially adding more holes really isn't. The downside is the added cost of quality radiators. You just need to make sure that your passive radiator(s) have enough excursion capability to not limit SPL.

 

[TLS Guy]

You would lose 25%-30% of size from the elimination of the long port. The advantage to using a PR system is the elimination of the port construction. A long slot port is difficult to construct, but essentially adding more holes really isn't. The downside is the added cost of quality radiators. You just need to make sure that your passive radiator(s) have enough excursion capability to not limit SPL.

You also have to find a passive radiator with the correct weight and VAS. Passive radiator designs are a severe problem for DIY designs, as there are so few to choose from. You can construct a port to any specification you desire. A speaker manufacturer can design a passive radiator to the specs required.

The passive radiator is replacing the port, and has to be built for the design just like a port. There is way more to this than excursion of the passive radiator.

 

[Guiria]

But don't most passive radiators have some way of adding or subtracting mass? I've designed and help build an 8inch sub with an 8inch passive and we had to add a little weight to the PR to get to the desired weight for the proper tuning but it worked and it sounded good.

I need to just accept the sealed alignment and get to it. I have no idea what 20 hz at 120 db is like anyways

 

[TLS Guy]

But don't most passive radiators have some way of adding or subtracting mass? I've designed and help build an 8inch sub with an 8inch passive and we had to add a little weight to the PR to get to the desired weight for the proper tuning but it worked and it sounded good.

I need to just accept the sealed alignment and get to it. I have no idea what 20 hz at 120 db is like anyways

Yes, you can add mass, but that changes only one parameter. You have to think of the equivalent weight on a spring. You can change the weight, but you also need to control the compliance of the spring in the design. As Chris pointed out the only volume it would save you would be the volume of the port minus the displacement volume of the passive radiator.

This would be the characteristics of a passive radiator for the kappa perfect 12 VQ with mid Qt insert.

Fs = 11.45 Hz
Qms = 15.03
Vas = 349.5 liters
Cms = 0.462 mm/N
Mms = 417.8 g
Rms = 2 kg/s
Sd = 729.7 sq.cm

I don't think there is one that comes close.

 

[Guiria]

The first parameter alone seems daunting That would be one PR if there was one!

 

[annunaki]

Yes, you can add mass, but that changes only one parameter. You have to think of the equivalent weight on a spring. You can change the weight, but you also need to control the compliance of the spring in the design. As Chris pointed out the only volume it would save you would be the volume of the port minus the displacement volume of the passive radiator.

This would be the characteristics of a passive radiator for the kappa perfect 12 VQ with mid Qt insert.

Fs = 11.45 Hz
Qms = 15.03
Vas = 349.5 liters
Cms = 0.462 mm/N
Mms = 417.8 g
Rms = 2 kg/s
Sd = 729.7 sq.cm

I don't think there is one that comes close.

The surface area of said passive would be quite large to boot!

 

[Guiria]

So in a 16" cubed box using 3/4 MDF or Ply with a double thick baffle and bracing I come out to 1.48 net cubic feet.

As for stuffing I planned on following the rule of 1 lb poly-fill per 1 cubic foot. Anyone else have a ratio they like?

I'm hoping Monday is cutting day

 

[jaxvon]

So in a 16" cubed box using 3/4 MDF or Ply with a double thick baffle and bracing I come out to 1.48 net cubic feet.

As for stuffing I planned on following the rule of 1 lb poly-fill per 1 cubic foot. Anyone else have a ratio they like?

I'm hoping Monday is cutting day

Poly fill is basically useless at these frequencies. Use some higher density mineral wool or fiberglass (6-8lbs/cu foot) if you want an actual effect.

 

[TLS Guy]

Poly fill is basically useless at these frequencies. Use some higher density mineral wool or fiberglass (6-8lbs/cu foot) if you want an actual effect.

You might want to put Rockwool on the enclosure sides, and fill the cavity with Polyfill. Polyfill has excellent damping properties just like acousta stuff, but it won't control internal reflections. Do not use housing insulation, that really is sub par.

What ever you do make sure you fill the cavity completely without compressing the fill.