Now that 3D audio is arriving with the introduction of Dolby Atmos enabled gear and software in the fall of 2014, it's time to address the challenge of how to implement this innovation using our favorite speaker brand.
Since the big deal in Atmos is mostly about the introduction of the height channels, we'll focus the discussion on options for ways of reproducing those.
Atmos builds on existing 5.1 and 7.1 home theater layouts with the addition of two or four height channels (as a minimum, many more speakers will be supported by advanced processors). So you will see descriptions like 5.1.2, which means a standard surround setup + two height channels centered over the listening area, and 5.1.4, which is std surround + four overheads, two slightly ahead of the listeners, two slightly behind.
But before we dive into specifics about speakers, let's understand that there are two ways to achieve 'sound coming from above': One is to use reflection bounced off the ceiling towards the listeners, the other is to have ceiling-mounted (surface or in-ceiling) directly radiate down onto the listening area.
Let's tackle the reflected sound topic first, as that's what many will wind up doing due to WAF, effort, etc.
Now, before anyone goes all snooty on how reflected sound is not cool, please remember that every ESL speaker is radiating 100% of the same information towards the wall behind them and that reflected energy is deemed to add to the ESL 'ambiance' many of you cherish
Reflecting off the ceiling does entail a few constraints:
- The ceiling must be reasonably flat (no vaulted rooms need apply)
- Height of the ceiling should be between 8’ and 15’
So reflecting sound from a low-mounted speaker aimed at the ceiling using the right angles can result in pretty decent ‘height speaker’ image being received at the listening positions. The challenge is to ensure the unit does not have too wide a dispersion characteristic nor tries to reproduce too wide a range of sound (lest it be localized before the bounce from the ceiling).
An ideal Atmos-ready ceiling reflection speaker would meet the narrow dispersion characteristic, so I expect ML to engineer a specific add-on speaker tailored for this use based on one of the existing models. If it were me, I’d start with something like the ElectroMotion-IC which thanks to placing the tweeter inside the mid-range driver and angling it, is already pretty close to what we want. I’d add a wave-guide to limit dispersion if necessary, then put it in a box sized to support the intended frequency range (since that’s limited, the box would be pretty small), then design the slope of the baffle such that when the base is flat, the angle would work well in most normal-sized rooms and with ceiling in the height range mentioned above.
That would result in a box that could even be styled to look appropriate when sitting on top of a Motion 40.
These speakers (or even existing small Motion-series units) could be placed in the room such that their bounce covered the target area. So height at 45” to say 6’ (depending on ceiling and other considerations).
The minimum would be two for basic height information, which will add dramatically to the experience. I’d place them to the sides of the listeners and above the seated heads so any direct sound from them would appear ‘above’ the listeners.
If using four reflected speakers, then I’d place them in-line with the fronts and rear-backs, aiming the bounce into the listening area.
There’s much more to discuss about reflected speaker setups, so I’m pretty sure we’ll have lots of Q&A about this in this thread.
So on to direct radiators mounted overhead. Again, there are two approaches, use existing box speakers and attach to the ceiling or install flush in-celling models. The cleanest looking options would be to use models like the EM-IC or EM-R and mount them in-ceiling. That would be the ideal from a visual standpoint and still deliver very good ‘overhead channel’ performance.
For higher-performance dedicated spaces (like my HT with its flat-black 10’ ceilings), bracket-mounted box speakers would work well, especially when using four or more units. If picking from the ML line, a set of Motion 15’s would be my choice.
Now, for the tricky part, using ESL’s for height channels. Here, I’d suggest that only one center-channel model would do, and that your ceiling must be >10’ tall before these might work. The dispersion characteristics here are a bit of challenge, but two Motif X’s mounted parallel to the seating positions (long part running down the sides, narrow ends pointed at front/back) and slightly outboard of the seats but aimed at them could work well enough.
BTW- only the Motif X might work, as it absorbs the majority of its panel’s rear wave.
So there you have it, some approaches on dealing with this new dimension in home theater and surround sound. Let’s hear what questions you have about this interesting topic.
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