So You Think Your Room’s Bad, Pt. 4
In Part 3 of this series, I discussed how we arrived at a speaker system for the Kaleidescape booth by solving the riddle of the back of the room and working forward. I also hinted that Trinnov’s Altitude 16 home theater preamp/optimizer was key to making those speakers sound their best.
How did I get from “I need something to power these speakers and process all of the audio” to “Gimme one of the most advanced and luxurious audio/video preamplifiers on the planet,” you ask? It was a bit of a winding road, so let’s start at the beginning of it.
When we were first understanding what this room would look like and how we wanted it to sound, someone in our design group (I forget who) asked a simple question: “Can we do this with an AV receiver?”
It’s a reasonable question, since we wanted the space to evoke a living room environment, and AV receivers—in which all of the digital signal processing and amplification reside in one box—generally power the sound systems in such rooms. But in this case, my back-of-the-napkin calculations told me we needed 160 watts of clean power for every speaker, which is way more than most receivers can deliver.
I also knew we needed really amazing digital room correction to compensate for all of the acoustical shortcomings of this space. (If you’re not familiar with digital room correction and how it works, check out my article “Room Correction Revisited” at Home Theater Review.) The long and short of it is that the room optimization software built into most AV receivers wouldn’t be sophisticated enough.
So, given that we needed a separate AV preamp to handle the processing and standalone amplifiers to power the speakers, I started thinking long and hard about what was out there. I wasn’t picking between equipment manufacturers; I was picking between room correction systems—two in particular: Dirac and Trinnov. (Lyngdorf Audio’s RoomPerfect probably would have been a great option, too, but I don’t have hands-on experience with it, and given our time constraints I had to go with what I knew.)
The advantages of Dirac are that it’s available in much more affordable equipment, and its filters would have made this particular room sound really good with only a little effort. But I was informed that “really good” wasn’t good enough. We needed the best.
So, I turned to Trinnov, whose Altitude 16 (shown above) delivers the most advanced and customizable room correction I know of. What’s more, the Altitude 16 can sonically relocate speakers through some deft processing that I don’t even understand. This was handy because, as I said in the last post, sometimes we had to position speakers in such a way as to accommodate multiple standing-room-only attendees.
I reached out to Jon Herron, Trinnov’s International Sales Manager, and asked if I could take him on a 3D tour of my latest revision of the booth design via Google Hangouts. Here’s Jon with his own first impressions of the 3D renderings, along with some thoughts on the specific room correction challenges this demo space posed.
So, the challenge was to get sound that is as lifelike as possible in a space that (by itself) would be about as far from lifelike as you can get. The background noise would be high (since it was a trade show). The construction would be temporary and necessarily focused on speed of assembly rather than quality. The shape of the space was also driven to some degree by architectural features not normally found in a home.
Imagine trying to get a concert-hall experience in a baseball stadium.
Success in any endeavor involves first understanding the nature of the problem. In this case, the problem was largely based on psycho-acoustics—understanding how we humans hear and understand the world around us based on what we hear.
A key to understanding how we perceive sound is to understand that we always, without thinking about it, hear three different things:
Direct Sound: This is the sound that goes straight from the source (in this case, a speaker) to your ears. Our brains will “hear” this first arrival as the true source and nature of the sound itself.
First Reflections: The very next versions of the sound are the first reflections from the surroundings. In a room, these reflections are typically the first bounces from the floor, ceilings, and walls. These tell you quite a bit about the environment you’re in—outdoors (few reflections), or in a larger or smaller room, for example.
Subsequent Reverberation: Unless steps are taken to absorb or scatter the sound away from you, sound usually will bounce around for a while. These multiple, later, and smaller versions of the direct sound tell you even more about the environment you’re in. You’d have little or no reverberation outdoors; you’d have quite a lot in a cave; you’d probably hear something in between in your living room or a concert hall.
Unfortunately, it’s really easy to mess up what Dennis describes as “room correction” by trying to address all these disparate problems with a single solution. The problems are different; therefore, the best solutions are also different and need to be determined and layered together.
If you badly break a leg, you must first realign things, stabilize the leg with a splint, and then put it in a cast for long-term healing. Doing just one of those things, or doing all the things out of order, simply won’t work. It’s the same with using digital signal processing to fix a “broken” acoustical environment.
In our diagnosis of how we hear, the second and third items above are “soft” in the high frequencies (imagine turning down the Treble control) for the simple reason that higher frequencies are far easier to absorb or scatter than are lower frequencies. If you don’t make an allowance for the reflected energy sounding different than the direct, you’ll mistakenly ruin the direct sound in a vain effort to fix the environment of the room itself. They are different problems.
This, by the way, is why we at Trinnov refer to our system as a Speaker/Room Optimizer. We’re trying to optimize all these different problems with appropriate digital processing solutions, rather than trying to simply “correct” the room with a one-size-fits-all solution.
In the trade show demo room, the No. 1 priority was to focus on getting the direct sound as natural as possible. Mitigating first reflections (where we could) was also important, but not if it compromised the direct sound.
Similarly, we wanted to provide a more natural reverberant decay (the rate at which sound dies away) that didn’t allow one range of frequencies to stick out like a sore thumb or otherwise call attention to itself. In a good concert hall, when the symphony suddenly stops playing, the entire, rich tapestry of sound should
die away together. If the flute section reverberated after the other sounds had faded, even for a moment, it would sound extremely unnatural, even unpleasant.
Addressing all these varying challenges in a way that truly lets you enjoy the music or movie you choose without the heavy-handed overlay of the sound of the room you’re in requires (ideally) a combination of passive acoustics and what we at Trinnov have come to call “digital acoustics.”
And that’s the perfect segue into the next post in this series. I knew that physical acoustical treatments, working in conjunction with Trinnov’s digital acoustics, would make this demo room sound its best. But I also didn’t want to make the room look like a recording studio. We’ll dig more deeply into those concerns in Pt. 5.
Jon Herron has been in the audio & video business since he was a teenager. The
combination of music and technology was simply too seductive for him to do anything
else—that and the fact that no one would likely hire him to do anything else. He has
worked in both large and small retail organizations, as a manufacturers’ representative,
and (mostly) for a series of audio manufacturers, including Snell Acoustics, Madrigal
Audio Laboratories, Wisdom Audio, and Trinnov Audio. He lives in Connecticut with his
wife and two terribly spoiled cats.
Dennis Burger is an avid Star Wars scholar, Tolkien fanatic, and Corvette enthusiast
who somehow also manages to find time for technological passions including high-
end audio, home automation, and video gaming. He lives in the armpit of Alabama with
his wife Bethany and their four-legged child Bruno, a 75-pound American Staffordshire
Terrier who thinks he’s a Pomeranian.