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Discussion Starter #1
I would say my listening is split 50/50 music to HT. Front speakers are Thiel MCS1s driven by Sony ES55s bridged. I currently have an old Vifa 30W in a 5 cu ft ported box. It's not really meant to match up with the MCS1s or do HT, just an old box that was available. I'm leaning towards a 500W BASH amp, seem to have good reviews and are flexible when it comes to subsonic filter and built in boost. My room will be (under construction) about 14' wide, 21' long, 8' average height (~2300 cu ft). The room will be very well sealed, isolated, and treated. This is a dedicated theater/music room.

I don't require vision blurring, heart stopping difficult to breath bass. I want something that blends well with the MCS1s (can do 55Hz flat in room without problems) and is VERY accurate to match them. For HT, the sub needs to hit 20Hz and not puke.

I've read some about the Shiva + 2 PR setup and it looks interesting. But, I'm also leaning towards a larger sealed box and then boost/filter/EQ to flatten.

This is far from my first build, I'm not afraid of complex boxes. The sub/subs will be hidden behind the false wall in front, they don't need to be pretty. I have tons of room to work with, I'd say up to 20" deep, 36" wide and 80" tall. Smaller will allow me to move them around a bit.

What to do?? I've mentioned the Shiva by name already, just because it fits well in the price range if I'm going to end up with 2 subs + 2 amps. I'm still planning here and no purchases made yet, so a change in sub is possible if there is something else out there that fits my needs better.
 

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Yep. The ported Shiva was nice and clean and had a good top end through the X-over area (70-120hz). Decent output power too.
 

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Discussion Starter #5
I'm leaning towards a single PR build. I don't know if I can fit 2 PRs with the shape box I'm going for (all drivers on the front of the box). Bare min H (15")xW(42") would leave me with a 9" deep box to get 3.25 cu ft internal.... And those aren't very good ratios for the box shape.
 

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Why not just port it? PR is essentially the same thing. Ported at 6 cu ft dual 4" ports is good with the Shiva.
 

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Discussion Starter #7
How long are the ports at that spec? I'm not much of a fan of multiple ports, I'd rather slot port it. Anyone ever slot ported a Shiva?
 

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As above, use a PR if space is an issue, or the box shape is nonconducive to a port. Ports are usually cheaper, but the DIY deal is on right now. It would be easier to use PR, but you can handle a ported build as you said. Try a search for slot ported Shiva:dumbcrazy: Sounds like a great project.
 

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Discussion Starter #9
I ran a few box sims today. 5.25 cu ft ported, tuned to 20Hz looks nice. Of course the ports (or slot) basically dictate the box shape. I'm leaning back towards a single PR. If I end up maxing the PR, I'll turn down the gain and build a second one... :daydream:
 

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Discussion Starter #10
OK, new wrinkle. I'm having a hard time figuring out box dimensions. Looks like the larger box (>5cu ft) isn't going to work with a single PR, it will max out. I've re-measured and I've got about 16" of depth to play with, and about 34" width. The screen is 22" off the floor, and I'd like to keep the drivers all below that, but the box can go all the way up to 70" or so behind it. I don't think I have the "surface area" for 2 15" PRs plus the Shiva. That is pushing me back towards a slot port, or dual flared ports. Any advice?
 

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The advantage of the PRs, is they can be tuned low and you can keep the box size small. With the BASH 500W amp, you can twiddle with the Q on the subsonic filter and pick up a couple dB on the bottom-end. That gives it basically the same bandwidth as the larger ported design.

The other advantage is that you get away from any possibility of port noise.

It mainly comes down to box size though. If you can live with a larger box the ported design works great. I wouldn't give either of them an edge in sound quality when built correctly.

PR box = 3.0-4.0 cubic feet
Ported Box = 6.5 cubic feet

As you play with the modeling, you quickly find that the port dictates the size of the box. You can choose undersize it and use a smaller box. Most commercial subwoofers do but just understand that you pay for it in port compression and possible chuffing that is audible at high SPL.

Kevin Haskins
Exodus Audio
 

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Discussion Starter #12
I think I could use the 18" PR, stay away from maxing it out and still fit everything where I want on the box. I'm looking at 3.5 cu ft with 1500g added to the PR. Does that sound right?? Thanks
 

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Yes you can do a slot port quite well with the Shiva just try to stay around at least 25 or 30sq inches of area. Like Kevin was saying 6.5cu ft with dual 4" x 26" ports (19hz) and the Bash 500w is a nice combo. You could even go with a single 6" port 28" long if you wanted. Just bend it in the enclosure.
 

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I think I could use the 18" PR, stay away from maxing it out and still fit everything where I want on the box. I'm looking at 3.5 cu ft with 1500g added to the PR. Does that sound right?? Thanks
I run a single Shiva-X and one PR-15 in my warehouse and it does fine. You really have to push it to overload the PR-15 and at that point, the system is complaining period. I think you will be fine with a single 15". If you have the space, the 18" will give you a little more cushion.

The specials I'm running are based upon the PR-15 though.

http://www.diycable.com/main/product_info.php?cPath=24_93_153&products_id=691

I think it is $295 for the dual PR-15 package. You get the shipping on the PR-15s paid for free (because my shopping cart isn't capable of figuring it out).

Kevin Haskins
Exodus Audio
 

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Discussion Starter #15
The dual 4" ports might be doable, I would need to bend it for sure. Looking at the nice flared ports he offers... Is it possible to just cut the center of that tube and use some PVC angle fittings to turn it in the box? Assuming 2 45 degree fittings would be preferable to a single 90?
 

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And those aren't very good ratios for the box shape.
Like it matters at <100 Hz frequencies in a such an acoustically small cab......... The first eigenmode will be above even the XO's pass-band, so is easily damped with insulation.

GM
 
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