5.1.4 Atmos System

[Brady]

Apologies if a thread on this already exists- please point me in the right direction if so.

I'm designing an addition to our home, and making sure its HT friendly. While my system will be 80% HT, I am a critical music listener/lover.

My plan is for Towers/Horizon across the front, all RAAL.

Surrounds: Lunas, on stands.

Atmos: Id like to ceiling mount speakers. Either 1 or 2 pair.

Subs: I'm leaning towards two in opposite corners.

Questions:
Would the LVX12 subs be "enough" for this application/room size? I'm not a bass-head, but do like full deep bass that you can just 'feel' in your chest from time to time. No need to shake the room.

Can I get away with CBM-170s mounted on the ceiling for Atmos highs? I know Lunas would be best, but that a LOT of dough to spend on Atmos speakers. I'm NOT a super critical listener when it comes to HT- I'm way more wrapped up in what's happening on the screen. But I'd like it to sound decent enough/plausible.

AVR: can I get away with JUST a Denon 4300 for this room, or should I seriously think about a 3 channel amp to handle the front three?

Ok...that's enough for now. Thanks guys.

-Brady

(drawing below 1 cell = 6", and IS to scale. Vaulted ceiling peak will run north-south)

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[Bruce Watson]

Look at this thread, post #32 by member N. Boros. This is an excellent way to figure out how much sub you need. It really comes down to how big a space you are playing into (cuft is more important than sqft, and BTW, 28x15=420, not 378, but that might be throwing off some of your calculations), and how loud you need the subs to play in that space. And you're the only one who can answer those questions. And for the record, I've got a pair of LVX12s that I love, but in a smaller sealed room (about 13.5 x 21 x 8, about 2250 cuft), and I mostly listen to HT at -20dB below reference, and no higher than -10 dB, so I don't need gobs of power from my subs.

For anyone who is building new space for HT and/or music, I typically recommend some level of acoustical consulting. Making a room sound nice is difficult and not at all obvious. I suspect that most consultants would look askance at your dimensions (28 is almost 2x15) and all that wall area covered in glass (doors/windows) for example. Also, construction details matter, especially if you're trying to sound proof (that is, keeping outside sounds from getting into the room, and HT sounds from getting outside the room). This will really matter if you like to play HT/music after young kids have gone to bed, or if you share a wall with a kitchen that includes a noisy appliance like a Vitamix, or if you share a wall/floor/ceiling with a laundry room (washing machines can produce a huge amount of midbass noise). For what it's worth, my problem is neighbors and their lawn crews using power tools in their yards (the howl of gasoline powered blowers can penetrate just about anything). So it doesn't have to be an attached wall.

Anyway, good luck with it, and enjoy your new room!

[natetg57]

Excellent suggestions from Bruce. My guess is that subs with 15" drivers would be needed in this room. I think the 170's would be fine but my suggestion would be to go with HTM-200s for on the ceiling. The rear atmos speakers could be mounted high on the rear wall. If you'll be putting in that many glass doors and windows then consider some heavy curtains to cut down on acoustic reflections.
You could certainly 'get away with' a Denon 4300 for all 9 channels as long as you don't try to crank it too much. Having all of your speakers crossed over at 80hz will take a lot of strain off of the receiver.

[Brady]

Thanks Bruce! Greatly appreciate the insight and recommendations.

- Sorry for the confusing dimensions- those are exterior. The room itself is 27 x 14, or 378sq ft.
- I currently have an Onkyo 805 that I turn up to between -20 and -10. But, more accurately, I like listening between 75-85dB with peaks up to low 90s. My current set-up is in an open great room with 17ft vaulted ceiling. Using a 3 channel Axiom ADA-1500 amp which I hope to sell as its overkill.
- All the windows and doors will have heavy black-out curtains to keep out light and absorb reflections.
- Room butts up against my bedroom, so no worries there.

Thanks again- I'll take at look at the N.Boros thread for sure- don't want to underpower the room when spending a few hundred more will reach the goal.

[Brady]

Thanks Nate- I'll check out the 15s. What's the advantage of the HTMs over the 170s besides size? The 170s certainly have a nice pedigree
I really don't crank it, but I find you don't have to to completely feel the music. Others may disagree with that tho! I once demoed a pair of Legacy Classics for someone that cranked them up north of 100dB. Insane loud- not enjoyable at all for me. Good point about the crossing over for HT- I forgot about that. I'll most likely be doing music in 'pure direct' mode, so no sub, just pure 100% towers!

[natetg57]

Thanks Nate- I'll check out the 15s. What's the advantage of the HTMs over the 170s besides size? The 170s certainly have a nice pedigree
I really don't crank it, but I find you don't have to to completely feel the music. Others may disagree with that tho! I once demoed a pair of Legacy Classics for someone that cranked them up north of 100dB. Insane loud- not enjoyable at all for me. Good point about the crossing over for HT- I forgot about that. I'll most likely be doing music in 'pure direct' mode, so no sub, just pure 100% towers!

The 200s are sealed and smaller (and 4lbs lighter) than the 170s so easier to mount on a wall or ceiling. They both use the same tweeter and should have a similar overall sound. The disadvantage is that they don't produce as much bass as the 170s but that wouldn't be an issue for Atmos.

[Brady]

yup- didn't think about the sealed thing. Nice call.

Actually, was thinking last night about just doing 5.2.2, and use just two Atmos heights. Could possibly afford Lunas if I do that. Still seems like a task well beneath the abilities of the Luna though.

[N Boros]

I really don't crank it, but I find you don't have to to completely feel the music. Others may disagree with that tho! I once demoed a pair of Legacy Classics for someone that cranked them up north of 100dB. Insane loud- not enjoyable at all for me.

I agree with natetg57 that in this room size, with HT as the priority, you probably want a Rythmik sub with a 15" driver. I would lean towards the ported models. Since it doesn't sound like you like peaks more than 100 dB or so, you might actually be able to get away with a ported 12" Rythmik, but it is starting to get really close with that room size, where you might want to error on the side of the ported 15" Rythmik. The LVX12 and FVX15 are pretty close in price that you might as well just step up the larger one to be safe.

Good point about the crossing over for HT- I forgot about that. I'll most likely be doing music in 'pure direct' mode, so no sub, just pure 100% towers!

Man, if you are going to spend the money on two Rythmik subs, why not take advantage of them when using music. It not only will fill out the bottom two octaves much better than the tower speakers can, but with the subs placed as you indicate in the diagram, you should also be fixing some of the room modes. Room modes are either large peaks or dips in the bass, caused by the dimensions of your room, where a bass wave perfectly fits into the room and then reinforces itself. This causes some places where the bass can be inaudible and other places where it is way too loud. The difference in most rooms can be as large as 30 to 40 dB. The two subs can make the frequency response similar from one seat to the next and then the room EQ can similarly bring down the peaks, making it much closer to accurate than it was before across multiple seats. If you put the receiver in direct mode, then you are usually bypassing Room EQ and turning off your subs, which will likely make the bass much worse, in comparison.

[Brady]

well, I did say "most likely" I plan on long testing sessions, like we all love to do