Well, I guess I asked for it... (1 Viewer)

[Owen Bartley]

I was showing my boss my new Tempest and in a sudden moment of sub envy he declared he wanted one! I knew this hobby was contagious! :wink:

Anyway, he's just starting out and has a box almost finished (that was originally for a cabinet, but never got finished, so for simplicity's sake I'm directing him towards a sealed Tempest. The box is in between Adire's Mid-Q and Low-Q designs at about 5.7 cu. ft. (internal). Should this be a good arrangement for a DIY newcomer? The box is made from 3/4" plywood, and will be sealed with silicone, I told him no leaks. It is: H 33" x W 20" D 18" and he wants it to be front firing as well.

It will be powered by an old 2 ch. amp with about 100w per/ch... I'm assuming he can just hook one chan. to each VC (the amp will be operating in mono from a split sub-out signal from his Marantz receiver).

Any input here would be great considering I just ordered the parts for him this afternoon. I'm just not too clear on how a sealed box is "tuned". It's easy with a port!

 

[Pete Mazz]

Make sure he adds some bracing. Adding a layer of MDF or ply in between braces (basically adding another wall thickness) would help too.

Amp should be fine.

Use about 6 lbs of polyfill to stuff it and he'll wind up with ~.6Q. Not too shabby. F3 ~35Hz / F10 ~18Hz.

Pete

 

[Chris Carswell]

I think you have a few options here. I was thinking sealed with PE #300-796 would be nice but then I re-read your post & saw that it would be powered by the Marantz receiver so there goes that one...

What I would do (for a # of reasons) would be to go ported. I know some won't agree with me (again for a # of reasons ). Biggest negative being no LF protection (rumble filter). I like ported for HT. This is going to be used for HT correct?

Get a 4" flared port from PE or 4" PVC pipe from Lowes or HD, 16" for flared, 14" for PVC. Go to Walmart & buy 4 bags of pollyfill (each bag is 20oz). I think you know the rest.

If you must go sealed you can tune the box by its size; 4.5 ft^3 = .72Q, 5ft^3 = .7Q, 5.5ft^3 = .68Q, & 6ft^3 = .66Q.

Hope this helps.

 

[Chris Carswell]

Looks like Pete can crunch #'s faster than me

 

[Brian Foley]

Is this void-free plywood? If not, the results are going to be disappointing. He's also going to need plenty of internal bracing for a box that big.

 

[Dave Poehlman]

Is this void-free plywood? If not, the results are going to be disappointing.

I agree.. if it's not too late to sway him towards MDF... or at least void-free plywood.

But it really depends on his level of "audio-geekness". If he's been living with a crappy system, even a plywood Tempest will make him happy.

 

[Owen Bartley]

Wow, thanks everybody. Let's see...

Pete: I'll tell him to add some bracing, and the polyfill is a defenite must.

Chris: actually, its going to be powered by an old Nikko or something 2 ch amp fed theough the sub out of the Marantz, but same thing. I'm a big fan of ported too (I LOVE mine) but I just want to give him something easy that will add a lot of boom.

Also: I'm not too sure about the plywood, it should be of decent quality because he was going to make cabinets out of it, which is why they're half built now. And I'm pretty sure he's not quite a sound quality afficionado, just looking to add some spectacle to the HT experience.