New home theatre speaker layout question

[dmccallie]

Hello Everyone,

We are building a new home with a small “home theatre” which will serve for both movies and audio listening (50/50). I have some basic questions about which Atmos speakers matter and where to place them.

The room is approx 14’ x 18’ x 9’, so on the small side. It will have sound treatment as necessary.

I already have mains, center speaker, and two subs from our existing (non-theatre) house (Martin Logan Summit X, SVS Ultra center, SVS 12” subs) and my question is about which other speakers are necessary for a good Atmos experience. The AVR will (probably) be a Denon 6800H. I would start by using the Audyssey built-in room EQ, and considering Dirac as a a future upgrade.

Our installer recommended using dual-5.25” angled side wall (surround) speakers (JBL Synthesis SCL-7) and two pair of 5.25” 2-way in-ceiling speakers (JBL Synthesis SCL-8) for the Atmos height (and rear?) channels. He recommended against adding any speakers to the rear wall, due to the small size of the room (too close to anyone sitting in back.)

Does this make sense? Or would one pair of ceiling (height) speakers and one pair of rear speakers be better? Or some other combination?

(Any comments on the JBL Speakers in particular would also be welcome.)

Thanks in advance,

—david

 

[dmccallie]

To clarify my question - in a smallish room, ~18' long, is it worth having a 9.2.4 system, where both height-1 and height-2 channels are active on the ceiling along with a rear-wall (surround-back) pair, or would it be adequate (or even better?) to have a 9.2.2 system where there is no rear-wall (surround-back) speaker?

And if the 9.2.2 is adequate, should the surround-back channels be routed to the rear ceiling speakers, or should height-2 be routed to those speakers? In other words, is there more information in the surround-back or in the height-2 channels?

I hope that makes sense.

 

[Chrispy]

Not sure how you're coming up with your speaker designations, but as far as rear surrounds go just where is your seating compared to back wall? If you don't use the rear surrounds your avr will take care of re-routing. The rear surrounds and atmos information would just be different.

 

[Bugal1998]

Hello Everyone,

We are building a new home with a small “home theatre” which will serve for both movies and audio listening (50/50). I have some basic questions about which Atmos speakers matter and where to place them.

The room is approx 14’ x 18’ x 9’, so on the small side. It will have sound treatment as necessary.

I already have mains, center speaker, and two subs from our existing (non-theatre) house (Martin Logan Summit X, SVS Ultra center, SVS 12” subs) and my question is about which other speakers are necessary for a good Atmos experience. The AVR will (probably) be a Denon 6800H. I would start by using the Audyssey built-in room EQ, and considering Dirac as a a future upgrade.

Our installer recommended using dual-5.25” angled side wall (surround) speakers (JBL Synthesis SCL-7) and two pair of 5.25” 2-way in-ceiling speakers (JBL Synthesis SCL-8) for the Atmos height (and rear?) channels. He recommended against adding any speakers to the rear wall, due to the small size of the room (too close to anyone sitting in back.)

Does this make sense? Or would one pair of ceiling (height) speakers and one pair of rear speakers be better? Or some other combination?

(Any comments on the JBL Speakers in particular would also be welcome.)

Thanks in advance,

—david

Hello and welcome!

A few things...

1) I would recommend checking out the Dolby Atmos installation guides (both the home and studio guides) as well as the Home Theater Gurus YouTube channel for placement guidelines. If the installer is not following (or won't follow) the guidelines as closely as possible within the confines of your space, you should probably fire them or very likely risk wasting your money on a dissapointing setup.

2) If your room can't accommodate the dolby atmos installation guidelines, give serious thought to whether it makes sense to spend money on the atmos speakers at all.

3) No matter what anybody says, even a larger home theater can only be optimized for one listening position. If there's enough distance between the main seat and the rear wall you may want to install the rear speakers to maximize the MLP (main listening position) experience and let the rear seats just be what they are anyway--compromised. Which do you care about more, accommodating the already compromised seats by also compromising the MLP, or maximizing the MLP experience? No wrong answer as long as you're planning for what matters most to you. [The wording of your post seemed to imply that not all seats are too close to the rear wall; disregard the comments above if that's not true]

Acoustically, for surround and ceiling speaker purposes, my room is ~19'x24'x8.5', and the speaker distances are 3-4 meters for the ceiling and surrounds.

I'm running scl-7s for surrounds and scl-5s (larger version of the SCL-8) in the ceiling. From an engineering perspective, the output of the scl-7s are on the edge of what I consider acceptable for my listening space (79db reference level with - 20db pink noise) since I prefer lots of headroom (output capability would likely be perfect for your space), but in practice they sound excellent and I haven't encountered their limits.

The measured performance of the scl 5/7s doesn't look great (see https://www.audiosciencereview.com/...ds/jbl-scl-5-in-ceiling-speaker-review.41763/ and https://www.audiosciencereview.com/forum/index.php?threads/jbl-scl-7-review-in-wall-speaker.32602/), but in practice they are a perfect timber match for the JBL M2 s in the front with EQ.

My room has the best atmos experience I've personally heard across the dozen or more dealer demos (and few home installations) I've heard, including two different theaters running the top of the line SCL speakers (one with JBL 4367s up front) and both with SDP-75s.

I don't say that to imply that the SCL 5/7s are the best atmos speakers, rather, that the design, implementation, and system tuning is far more important and these speakers are not a barrier to an excellent atmos hometheater and music experience.

That said, the SCL line may be overkill compared to the rest of your system; however, the angled horn configuration offers a lot of installation flexibility and real-world performance, which is why I went with them despite seeing the results linked above.

Note: I'm running a JBL SDP-75 with factory anechoic EQ corrections applied to the SCL 5/7; I can't comment on how they would sound with standard room correction without the factory anechoic EQ.

If you decide it's worth doing atmos, then do it right. Good luck with your room!

 

[dmccallie]

Thanks all for the helpful replies!

To clarify - the MLP location is in a good location, but the second row could get as close as 1 foot away from the back wall, depending on how big the chairs are. Probably more like 2-3 feet away. (The speaker terminology was taken from the Denon spec sheet. I guess the Dolby names are preferable.)

Anyway, the closeness to the back wall suggests that back wall speakers maybe not be a good idea (unless I just decide to ignore the poor family member who has to sit back there

If I didn't use back-surround speakers, would a 5.1.4 system be OK?
Would there be enough to gain from a 5.1.6 system (3 pair in the ceiling) to justify the extra cost?

Other suggestions?

--david

 

[Bugal1998]

The only way anyone can answer your question is to layout the speakers to ensure compliance with Dolby guidelines.

Your installer should be designing the speaker layout to comply with Dolby's guidelines. If they aren't, see my first post.

I pressume Dolby is only suggesting layouts that offer an engaging experience, so look through the various layout guides and see which are suitable in your space. The relative angles between the speakers as well as being on-axis at the MLP with all speakers (or using angled driver like the JBLs you have in mind) is what enables the envelopment.

I was an Atmos skeptic, but the technology when properly implemented can smoothly and seamlessly steer sounds up/down/around/and across the room at different perceived heights and distances (vertical panning is surprisingly good but not perfect due to the way we process the location of vertical sounds). The key is to have all of the angles between speaker pairs within the recommended range of each of the neighboring speaker pairs (horizontally and vertically).

Dolby home theater setups can be found here: https://www.dolby.com/about/support/guide/speaker-setup-guides/

See this post for the dolby studio layout guide as well as a link to Trinnov's guide: https://www.audiosciencereview.com/...olby-atmos-layouts-differ.39601/#post-1395033

(Apologies for not hyperlinking, as the mobile browser hasn't been allowing any font or link functionality for a while now).

Edit: hyperlinks were added automatically

 

[Audio Science Pal]

He recommended against adding any speakers to the rear wall, due to the small size of the room (too close to anyone sitting in back.)

That is helpful to consider.

 

[Bugal1998]

That is helpful to consider.

Agreed. The wild card is the knowledge, diligence, and professionalism of the installer.

The other considerations in my mind would be 1) how often the rear seats closest to the speakers would truly be in use, 2) how much the occupants of those seats would care, and 3) whether the Denon allows for multiple calibrations, one of which wouldn't use the rear speakers when the rear seats are in use. I optimized my room to deliver a reference/screening room level experience for the 70% use case, and accepted the trade-off in the 30% scenario, others may rightly make a different choice depending on the usage scenarios and just how significant the tradeoff would be. Sitting 1 foot from a speaker is a pretty big tradeoff.

 

[dmccallie]

Thanks to all for the great advice.

I have certainly been studying the Dolby layout sheets! Dolby shows a 5.x.4 layout (which is what my installer had suggested) and they also have a 7.x.6 layout, but they don't show a 5.x.6 arrangement. So that was my subjective question - would the two additional rear ceiling (height) speakers be useful to compensate for the lack of rear wall (surround) speakers.

Presumably the rear speakers on the ceiling would not be as bothersome to the back row as rear speakers that are only 1-2 feet away on the wall behind you.

I wonder what would happen if I routed the rear wall (surround) channels to the rear ceiling speakers?

 

[DVDdoug]

If I didn't use back-surround speakers, would a 5.1.4 system be OK?

If I was building a custom room I'd at-least run wires for any future possibilities. I'd probably also run power (or wiring for future-power) for the possibility of active speakers.

...Personally, I have 5.1 in my multi-purpose living room and I have no desire to add more channels.

 

[Bugal1998]

Thanks to all for the great advice.

I have certainly been studying the Dolby layout sheets! Dolby shows a 5.x.4 layout (which is what my installer had suggested) and they also have a 7.x.6 layout, but they don't show a 5.x.6 arrangement. So that was my subjective question - would the two additional rear ceiling (height) speakers be useful to compensate for the lack of rear wall (surround) speakers.

Presumably the rear speakers on the ceiling would not be as bothersome to the back row as rear speakers that are only 1-2 feet away on the wall behind you.

I wonder what would happen if I routed the rear wall (surround) channels to the rear ceiling speakers?

I honestly don’t know if there's benefit to 6 ceiling speakers--functioning as atmos ceiling speakers--in your space. However, if I was after reproduction of the atmos experience I would not try to route rear surround signals to the ceiling as that will distort the panning and placement of sounds in the rear of the room. That said, it's possible you would be happier with rear surrounds in the ceiling, or you may not be--you'd be running an experiment.

For what it's worth, humans have some of the least accurate spatial sensitivity for sounds originating from behind, so as long as there isn't a perceived gap in the soundscape I don't think you'll notice a particular lack of precision without rear surrounds (on-wall or otherwise).