[Licinius]

I'm going to start this with a couple questions... For the past several years I've been using a ported sonotube with an AA Atlas 15", previously powered by at 350w Rythmik amp. I've since built a little sub with the Rythmik amp (it was a plate amp after all)...

It came out well, nice for the living room... adorable huh?

So now I have no amp for my sonosub, so I find two QSC RMX850s on CL for $150 ea... killer deal. They should do ~850 watts bridged into 4 ohms. Overkill for the Atlas.

My question, will the QSC drive a sealed (22" cube, so ~5cf) Tempest X2 to acceptable levels safely? I'm going to assume just one of these will outperform the ported Atlas, and two would be even better... I'm pretty sure this plan would work great... Just looking for some confirmation that the Tempests will work well with the amps that I have. I'd rather stick with sealed, as I'm trying to have my HT area look tidy and put together... and my sonosub doesn't really fit in (6ft x 18"). If I'm going to lose performance I'll reevaluate however.

Thoughts?

 

[Kevin Haskins]

That is plenty of power for a single Tempest-X2 in a sealed enclosure. In general (and this is a big generalization) a ported 12" will equal the output in the 20-30Hz range of a sealed 15". You have to actually model both because as I said, it is a BIG generalization. Things are more complicated than that generalization so in order to get an accurate answer, you have to model both and project them both to maximum output based upon your best guess (published specs) of the available power, subsonice filter + enclosure, port tuning etc....

There is nothing wrong with building a slot ported box, which you may like better than the Sonotube. That way you don't have to give up any output, but you do have to plan for an appropriate subsonic filter.

Kevin Haskins
Exodus Audio

 

[Licinius]

Alright, so I can do 5cf ported (per your design in the other thread) and keep about the same size/footprint as my sealed plan, brilliant. As far as a subsonic filter... it seems that the Reckhorn B1 is pretty killer for the price ($75)? Or is there a better alternative? The eD? I don't really need EQ as I already have a BFD, but it can't do a SS filter as far as I can tell.

 

[Kevin Haskins]

Alright, so I can do 5cf ported (per your design in the other thread) and keep about the same size/footprint as my sealed plan, brilliant. As far as a subsonic filter... it seems that the Reckhorn B1 is pretty killer for the price ($75)? Or is there a better alternative? The eD? I don't really need EQ as I already have a BFD, but it can't do a SS filter as far as I can tell.

I don't use any of those devices so I don't have any first hand experience if their filter functions are well designed or not. I recommend the Velodyne SMS-1 if it is in any way within your budget. If it isn't now, save your pennies, mow the neighbors lawn, eat Mac & Cheese for a few months and save for it. Why? Because I sell them and make money when you buy one! Actually, it is more complicated than that.

I've said it so many times that I've worn out several keyboards typing it. The single biggest factor in your subwoofer design is how it measures in-room at the listening position. The only way to assure you are getting the best results is room measurement and equalization. The SMS-1 is the easiest tool, with everything you need to accomplish that included and it is fairly simple to use. It also has a subsonic filter that you can set in software so it has everything you need in terms of signal processing in one nice box.

So... anytime someone ask me for a recommendation for a subsonic filter, you are going to get the same response, SMS-1 because it provides that function and much more. For my own use, I wouldn't design a subwoofer system without one.

Kevin Haskins
Exodus Audio

 

[Licinius]

Gotcha, but I already have a measurement setup and a BFD. I think I'm going to build a 5cf sealed cube and see if I like it =) I already have the amps, so as far as for-the-hell-of-it project budgets go, the cost of the driver and MDF isn't all that bad. I'll pull this thread back up once I get started. Thanks Kevin.

 

[Mike P.]

Just curious what size volume and tuning the Atlas 15" is in.

 

[Licinius]

I thought I would have to go measure it, but I had the project on my computer still!

8.7 cf tuned to 22hz.

 

[Mike P.]

Thanks, mine are 10 cu.ft. tuned to 18hz and I love em!

 

[Licinius]

Well, got a bit of a bonus at work, so I've ordered 2 Tempest X2s =) We'll see where this goes... I'm sure it ends with things shaking off the walls though.

 

[Licinius]

Alrighty, two sheets of 3/4 MDF in the garage. Design finalized. Drivers waiting impatiently... I'm going to build two 5cf sealed boxes for these guys. They will be powered by a QSC RMX850 each. I'll eq the low end if needed, but with room gain, I think I'll be happy with the extension. Drivers, design (of course there will be holes in the brace...), and location I'm putting them below...

Hope to get some MDF cut this week/weekend. So... Heavy... :flex: