Two crazy home theater epiphanies – could this elevate your home theater sound?

[High Power Dude]

Years ago while auditioning a friend’s home theater, his ceiling exploded. Literally. The 8 inch full-range Atmos mounted marine speakers (he got them cheap) had bass, and lots of it. This messed me up because the Atmos spec doesn’t call for sounds below 170Hz. So what was going on? Well, he changed the frequency on his AV receiver and wham! Bass from explosions in the sky. Who knew? Rocked my world. I did some homework and got Heco 44f speakers, mounted them on the ceiling and ka-blam – the sound donut is now the cone of sound and things blowing up in the sky ain’t no joke. Years have passed, and now I’m about to try something new with rear channels.

In my 18’ x 14’ x 7’ home theater, It’s time to ditch my floor standing rear channel speakers for a much better option. As most of you know in medium sized rooms, rear channel floor standing speakers can have unforeseen drawbacks. First, they are often too close to listeners, second, the bass can be wasted by the cone of dispersion blocked by seats or other obstacles. So I thought, what’s the purpose of rear channel speakers? Professional sound editors use rear channels for environmental ambience in world-building. Most of that is mid-bass frequencies and up. They create space and support a 360-degree soundfield. Although 80% of our sense of sound comes from the front and sides, rear channels come into play when something moves from the rear to the front or vice versa. From directional effects and flyovers to panning and acoustical reflections – such as gunshots in a warehouse, sound editors want you to feel like you are there. They employ off-screen sound cues and wrap-around music spatial metadata but never direct dialogue. They like to put creepy sounds from the darkness behind you while you watch in the dark because they want you to feel scared. When it comes to deep bass, they generally keep it up front but in movies it’s wherever it is. So what speaker is designed optimally for the mid-bass to vocal range and higher? The answer lies in the center of my question.

That’s right. I am about to buy 2 center channel speakers that reach down to 70 Hz, placed, as they should, horizontally at ear height in the corners of the room angled into the primary listening position. Do I add subs below for the full effect? Maybe. But not just yet. Think about it and let me know your thoughts. Cheers!

The equipment depicted in the bathroom signage has changed, but it's a great way to inform the uninitiated.

 

[90sNintendoKid]

I wouldn’t personally go for two center channels unless maybe a Kef centre speaker.

What’s your reason for centre speakers and not book shelves that go down to 70 hz?

Might I suggest nearfield and MLP measurements to investigate if your current rear speakers are being compromised?

 

[90sNintendoKid]

Do you have front wide speakers?

I would personally experiment with different positions for those rear speakers.

Also, I noticed you have high backed theater seats. Have you thought about using a coaxial speaker for the rear speakers, slightly higher than the height of the seats? Something with good vertical dispersion like a Kef or Ascilab?

 

[Oddball]

I am a bit lost in your post. There are centers that go down to 30hz in the room if your are looking for that. Two centers can't be done properly unless your processor has option to EQ two centers, which is few.

As to the bass management, it depends what you use. Rather than buying 2 new centers, you might want to buy gear compatible with Dirac ART that will brighten your day and manage the bass like nothing else available at that price.

Atmos specs are for full range BTW. What is in the mix is really up to the mix. Theoretically it should not matter if you are bass managing your Atmos.

 

[popej]

That’s right. I am about to buy 2 center channel speakers that reach down to 70 Hz, placed, as they should, horizontally at ear height in the corners of the room angled into the primary listening position

Many center speakers are MTM type, symmetric with tweeter in the middle. The better position for these speakers is vertical, because it gives better spatial characteristics.
Do you really need new speakers? Why not set the crossover to 70Hz for your rear floor standing?

 

[EJasonC]

They employ off-screen sound cues and wrap-around music spatial metadata but never direct dialogue.

One exception is Bane's dialog in the opening sequence of ‘The Dark Knight Rises’ - virtually all channels used for his dialog only no one else. In full range and to excellent effect by the way! One’s system needs to be very highly resolving to render the sound design in many of Christopher Nolan’s work.

 

[Soundmixer]

Atmos mounted marine speakers (he got them cheap) had bass, and lots of it. This messed me up because the Atmos spec doesn’t call for sounds below 170Hz.

There is no such limitation in the Atmos spec. The ceiling channels, much like all of the other channels, are spec'd from 20-20kHz.

 

[High Power Dude]

I wouldn’t personally go for two center channels unless maybe a Kef centre speaker.

What’s your reason for centre speakers and not book shelves that go down to 70 hz?

Might I suggest nearfield and MLP measurements to investigate if your current rear speakers are being compromised?

Good points. I've owned nearfields and as you know beyond a few feet they surprisingly lose coherence, so they don't cover the audience uniformly. Bookshelves are a great option too. The perspective I have is dual woofers horizontally placed provide a wider dispersion for the audience. It's very easy to go back to the bookshelf option. I do have measurements of my Induction Dynamics rear speakers and elevating them is an option. Thanks for your insight. Good stuff!

 

[High Power Dude]

Do you have front wide speakers?

I would personally experiment with different positions for those rear speakers.

Also, I noticed you have high backed theater seats. Have you thought about using a coaxial speaker for the rear speakers, slightly higher than the height of the seats? Something with good vertical dispersion like a Kef or Ascilab?

I don't have front wide although I have experimented with that in the past (photo). I've had every imaginable iteration out there and it's always fun. I even had dual center channels, one low, one above the TV. I always felt that was something I'd like to return to. Thanks for the coaxial tip. I overlooked that option.

 

[High Power Dude]

I am a bit lost in your post. There are centers that go down to 30hz in the room if your are looking for that. Two centers can't be done properly unless your processor has option to EQ two centers, which is few.

As to the bass management, it depends what you use. Rather than buying 2 new centers, you might want to buy gear compatible with Dirac ART that will brighten your day and manage the bass like nothing else available at that price.

Atmos specs are for full range BTW. What is in the mix is really up to the mix. Theoretically it should not matter if you are bass managing your Atmos.

Center channel speakers that go low invariably get larger or wider. So space is a factor. The Atmos upfiring or downfiring spec is 100Hz minimum, so many speaker manufacturers design them in that range. I thought that was the limit but you are correct, it is not and that's where one can be lulled into thinking "that's what they make so that's what Dolby wants," which is not the case. As for Dirac ART, I took the painfully expensive route of building a room from the ground up to be as acoustically neutral as I could. It is double-walled, green glued, employs mass-loaded vinyl between the walls, over a quarter ton of Roxull Safe-N-Sound, acoustic putty, etc. Nothing rattles or produces sound from bass, etc. The Dirac ART option I haven't explored. Thanks!

 

[High Power Dude]

One exception is Bane's dialog in the opening sequence of ‘The Dark Knight Rises’ - virtually all channels used for his dialog only no one else. In full range and to excellent effect by the way! One’s system needs to be very highly resolving to render the sound design in many of Christopher Nolan’s work.

True. I use the airplane sequence in 'The Dark Knight Rises' as a demo. Being a skydiver myself, that's an awesome scene.