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8 Hifonics Atlas ASX15s, 2 quadruples or 4 doubles?

3256 Views 17 Replies 3 Participants Last post by  nethien
Hi guys,
originally i intended to build 2 dual opposed 18" Dayton HO, but now i managed to score 8 Hifonics Atlas ASX 15s for half the price of 4 Dayton 18 HOs shipped to Europe.
I have installed my homecinema in the attic and have big problems to fill the L-shaped room with inclined walls with bass. In my boxshaped living room i get better bassresponse and subjectively more impact with my floorstanding B&W 804s without subwoofer, than in my homecinema with 4 11" in my mainspeakers, 2 active 12" BK Monolith DF + and 2 inceiling (as IB) Tempest 15" corrected by antimode AM8033.
The idea is to use 1 Inuke DSP 6000 to power the 8 new subwoofers and use the DSP for correction of delay/phase to combat cancellations/room modes.
If the DSP of the Inuke is not up to the task (it is only 90€ more than the non DSP Inuke) i might have to get more control in the form of a MiniDSP.

So much for the situation overview.

Now, for the 8 ASX15, i am considering 3 main options and i would like to get some advice/ input about the pros and cons.

1. Build 2 quadruple enclosures of 500 to 600 l each (LLT) (similar to those built by my brother described here http://www.hometheatershack.com/for...56-500l-llt-12hz-8x12-4x15.html#axzz2KEZQkZMV ), to be placed in the left and right corners next to the front tower speakers. I tried to simulate 18 Hz tune in WinISP alpha (old version from their website, because the newer version from their forum would not let me save the T/S parameters) and i simulate [email protected] Hz without roomgain with 2kW per channel with just one enclosure.
This should ensure more than enough headroom.

2. Build 4 dual enclosures of roughly half size LLT, same tune, 2 in front, 2 in back. Would there be any benefit of going double opposed?

3. Build 1 quad monster to be placed under the screen and 2 duals to be placed left and right of the front tower speakers, thus coming close to a line array.

The 2 existing (and much smaller) Monoliths could be used to fill in any FR gaps, since they are much easier to move around.

The enclosures will be built with 21 or 25 mm cabinet grade birch MPX sourced (and cut to size) from a befriended cabinet builder pro.
Once i have decided which of the above variants will be built, i will post some sketches, maybe even in sketchup (i am still cutting my teeth with it).
I will use 4 inch round ports (PVC drainage pipes already sitting in the garage).
Bracing and such will only be addressed once the final design is settled.

I am open to any critic and suggestion, but due to the size (and weight) of the beasts to be built , i' d rather get it right the first time around.
I will have to do all the woodwork in my garage, then test fit, carry all the stuff 3 levels up and do the final assembly and staining in the home cinema.
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Umm, yeah, subscribed! :hsd: I'm looking forward to seeing how this progresses. You will get expert advice here...just not from me on design with WinISD.
4 dual enclosures would give you the most options for sub placement if you have the room. Each pair in 300 liters tuned to 18 hz with 2000 watts and a HPF at 17 hz would produce an awesome amount of output.
Hi Mike, thanks for your input.
Realistically i cannot expect anything close to 4 times 2000 W from the Inuke, probably closer to 4 times 750 W. The DSP 6000 cannot be bridged, but even with that "limited" power, it should be cabable of insane output.
I am somehow drawn to double opposed pairs, with 1 sub on top and 1 on the bottom, with maybe 15 cm (6") clearance from the floor.
To get to the required net volume i'd need a 60*60 cm base with about 110 cm cabinet height.
The 60*60*110cm should leave me with ample room for the driver and the 2 10 cm ports.
Dual opposed should cancel out any vibrations caused by the drivers.
I am speculating on getting better in room response by exciting the air at 2 different heigths (correct me, if i am wrong).
Are there any other advantages or disadvantages going dual opposed, besides hiding half the speakers from direct view?

I might even build power ports top and bottom, the top one could even display a small piece of my HT decoration (Batmobile blu ray edition, Terminator skull or such)

Edit: not sure if i can program a 17 HZ highpass in the Inuke DSP, but then i will be using way less than the suggested 2000 W per box.
The T/S parameters supplied with the speaker somehow make it impossible for me to simulate in the curent WinISD, so i have no access to some important functions.
I did not manage to find "better" T/S parameters acceptable to WinISD.
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I forgot the Inuke DSP 6000 part. Since the DSP can't set a HPF lower than 20 hz then that's what I'd tune the cabinets to. You should consider 3 ports instead of 2, you may end up with more power in the future and 2 ports won't be enough. Something to consider since the drivers can handle so much more than what a single DSP 6000 can provide to 8 Atlas 15's.
Is there a high risk of damaging the speakers if i stay with the 18 Hz tune with the limited power i will have, without that 17 Hz HPF?
Anyway with 4 of these i should be around 120 [email protected] 18 Hz before room gain.
If it is safe, i' d rather go with the lower tune to start out and add better DSP , maybe even more power later on.
Already now, with my small IB, my neighbour (semidetached house) reports shaking rooftiles. With the additional SPL given by the 8 ASX 15, i should have a fun way to get rid of the snow covering my roof in winter:hsd:.
If necessary, i will get rid of my antimode and get a MiniDSP later, preferably the 4x10HD.
You are right with the 3 10 cm ports, i still had an old simulation with 2 14cm ports i made a couple days ago.
With 3 ports will the asymmetrical disposition of the ports (2+1 or 3+0) matter?
It depends what the Xmax is on the driver. I'm guessing it should be good for 20 mm, if so, with 650 watts to 2 drivers Xmax should be reached at 14 hz.

With 3 ports will the asymmetrical disposition of the ports (2+1 or 3+0) matter?
I'm not sure what you mean by asymmetrical disposition.

According to the manufacturer Xmax linear is +/- 16.4 mm, Xmax peak to peak +/- 35 mm.
By asymmetrical i meant, that for 2 ports and 2 speakers i would have aimed for 1 speaker and 1 port on top and on bottom : Oo + Oo, whereas for 3 ports i will have Oo + Ooo or O+oOoo, O being the outline of the speaker, o the port.
With the (what i call) symmetrical layout, both speakers would work under similar conditions, with the asymmetrical, that would not be the case.
But then one speaker would work with gravity, the other one against it, if i use a vertical dual opposed construction.
Maybe i am just worrying about things i don't need to worry about.
I understand now.. The ports can be anywhere as long as the drivers share a common space and aren't in separate chambers.
When i came home after work this was waiting for me:

Here are the T/S parameters as provided by the manufacturer.
Now i need to spend some time with WinISD alpha 0.7 and then try my hand on sketchup.
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I have been playing around with Win ISD and it seems that going to a 12 Hz tune in 400L seems to be a much safer proposition regarding cone excursion, with a little sacrifice in output.
If i take into account that i will be building 4 boxes, output should still be plentiful.
Port speed is high at maximum power below 15 Hz, but i doubt such signals will ever be seen.

One more question, can i subsitute a triangular port of equal surface for a square one?
If i go with 4 triangular ports in the corners, besides of having a pleasing design, the ports should give me a good amount of almost free bracing over almost the whole length of the cabinet.

Tomorrow i will try to figure out how to post the WinISD graphs for discussion.
I modeled 2 ASX 15 in 400 l with 4 8*8cm vents of 126.37 cm length.

If i get approval, the weekend will be spent on sketchup and by sunday evening i hope to have my cutsheet ready to be transferred to my friendly carpenter .
Depending on delivery time of the cut 25 mm MPX, i hope to have the first box up and running the weekend following reception of the wood.
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Here is what i came up with:
about 400 l net internal volume

My sketchup skills are not the best, so the drawings do not include all the details.
There will be 4 triangular ports, 2 each in diagonally opposed corners. To get to the necessary length, they will run full height and part of the side of each side panel, thus providing substantial bracing in all corners.
The top and bottom baffles are rotated 90 ° to each other so that the ports construction stay clear of each other.
The 5*5cm braces under the top and bottom baffles should eliminate the need for a double baffle, as well as provided sufficient meat for the T-nuts.
They will also provide more breathing room for the drivers and allow for a lighter construction ( i will have to carry 4 of them to the 3rd floor and i estimate them to be close to 200 lbs each, without the drivers:coocoo:).
Depending on necessity, i might add one crossbrace at half height of the speaker.
I will also put a 5 cm high section of 25 mm MDF between the ports at 25 mm below top , respectively bottom edge.
This will give me more surface for gluing the baffles, or give me the possibilty to screw the baffles in (this would actually be my 1st choice, rather than gluing, with the option of easy access inside the box or just switching the baffles if i needed or wanted to).
I did not represent any feet to the sketches, but i will have them about 15 cm off the ground, if i will use them in vertical position as drawn.

I will also buy a 2*8 MiniDSP and my brother will provide me temporarily with 2 Emotiva XPA 5 for testing purposes. 2 more heavy items to carry up 3 floors. I wish i was in the States with lower real estate prices and the possibility to have a basement theater.
Behringer websites says Nu 4-6000 now shipping, maybe that's what i will be shooting for (and a couple of silent fans of course).
My brother's 4 Atlas in a 500l LLT is currently in the process of testing. So far it is only running on 2 of 4 channels of 1 Emotiva XPA 5 and there are reports of substantial output already. Luckily he lives close to the airport so he can blame some ULF rumble on the aircrafts ;-))
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Depending on necessity, i might add one crossbrace at half height of the speaker.
I would actually suggest 2 cross braces evenly spaced, that's a tall cabinet.

I submitted the sketches to the carpenter . Having the big panels cut by him, especially the long cuts and the 45° cuts for the ports will ensure a nice and easy fit, since i do not have the equipment to do precise long cuts, especially not at 45°.
Now i'll have to play the waiting game...
On friday, i got my 24mm Birch MPX precut from the carpenter.

16 side panels 130*65 cm, 8 square panels for tops and bottoms and 16 130 cm long port boards cut at 45° on both sides.

Before starting the build, i slightly modified the plans. I will have no ports on top, but all 4 ports will exit through the bottom. I will extend the port boards 15 cm outside of the baffle, thus creating 4 feet that will keep the bottom subwoofer 15 cm clear off the ground.
Today i routered the openings for the subs in the tops and bottoms, then i started assembly of the first box.
First 2 sides glued and first port board in place:

3rd side glued, as well as 2nd port fitted (view from bottom end):

Top end view, 4 sides glued, 3 ports fitted:

You can also recognize additional bracing fitted between the ports.
The bracing is 25 mm from the top edge ( idem on the bottom part of the sub), allowing for a removable top and bottom. I plan to use a foam gasket on top of that bracing and screwing the top and bottoms into the bracing, giving me easy access to the interior of the box.

The top with the mounting hole for the sub is not glued, just fitted in to make sure the box stays true until the glue is set.
A couple clamps and tie downs make sure everything stays put overnight.

That's it for today, no more clamps available.
I still need to cut more braces and glue the 4th port board in.
I hope to find some time tomorrow or on tuesday for that, the next baffle will have to wait until the weekend.
After Easter i should have 4 fridge sized and very heavy subs. Already at this uncompleted stage the enclosures are really heavy. I had a hard time flipping the enclosure over to glue the 3rd port in:gulp:.
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Lot of progress here! I wish I had even half the number of clamps you have :(
I fit the 4th port and finished the bracing on the first enclosure after work tonight.
Due to bad weather (ice rain and a little bit of snow) i skipped my badminton practice , so i got a lot more work done than originally planned.
I borrowed 4 50" clamps from my neighbour and i managed to get the second enclosure to the same stage that i left the first one last night.
I took some more pics that i will post later this week.
I stood the first enclosure upright on its feet and that thing is huge:doh:.145 cm tall, with the finished feet it will stand over 5 feet and easily big enough to fit an adult person.
4 of these will take up a lot of real estate in my homecinema:eek:.
2 might have been enough, but the sale was too good not to go completely overboard:rofl2:.
I should have enough headroom once these behemoths will be finished. In a worst case scenario, i could always put more power into them:innocent:, as a single Inuke 6000 will not overpower them for sure.
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