The second coming… of two-channel
What does the resurgence of high-end two-channel means for home cinema? Anthony Grimani investigates.
If word around the halls of audio conventions is true, there’s a full-blown revival of high-end two-channel music in progress.
It may stem from vinyl’s resurgence in popularity, or perhaps there were simply a large number of surround sound ‘experimenters’ who are returning to their two-channel roots?
Regardless, our industry is once again faced with the age-old question: are high-quality two-channel and home cinema compatible? Is there some inherent difference in requirements for gear and room environment that make the two mutually exclusive? After all, home cinema is still popular. If there is a way to kill two birds with one stone, it’s that much better for everyone.
Let’s not forget that L/R speakers are vitally important for home cinema. In fact, a good portion of music and effects are two-channel stereo at their core. They are carried by the L/R speakers, with reinforcement provided by the centre and surround speakers.
The same performance parameters of sound staging, dynamics and frequency response that make for good two-channel also benefit surround sound – so we’re not dealing with two entirely different animals. Home cinema just presents a few environmental challenges that must be overcome through clever engineering.
Picture the quintessential high-end two-channel system: a room dominated by two monolithic speakers sitting way out in the room. Surely that rules out home cinema already? Those big speakers will never work with a screen. They’ll block it for most of the seats – not to mention how odd it will be to have the speakers way out in front of the picture…
Here’s where we need to do a little myth-busting. Those giant monoliths are not the only – or perhaps even the best – way to experience two-channel. Research demonstrates that smaller L/R speakers plus subwoofers have sonic benefits for the entire frequency spectrum. In fact, many highly-respected speaker gurus wish to see an end to full-range speakers and only continue to support them by popular demand – not science or sound quality. If we’re talking about small L/R speakers plus subwoofers, our high-end two-channel system suddenly starts to look a lot more like a home cinema.
A small speaker out in the room may block less of the screen than a large speaker, but it’s still in the way. Any self-respecting audiophile knows we can’t shove the L/R speakers back inside 1-1.5m from the front wall without seriously degrading sound quality. So what do we do? We push them all the way back into the wall. More accurately, we bring the wall out around the speakers, creating a baffle wall effect.
This is a radical concept to the audiophile community, but it’s even more high-end and exclusive than giant monoliths. The finest two-channel environments in the world – with the most expensive gear, best acoustics, and most precise tuning – are fancy recording studios. Baffle loading is the de-facto standard for their super-high-end main monitors. We should do the same at home.
Now, baffling the speakers does not equal stuffing them in a cabinet or some other acoustically compromised location down near the floor or way up at the ceiling. Baffles must be carefully constructed to optimise speaker position and aiming for two-channel relative to the screen and seated ear height. It takes a bit of tweaking in AutoCAD, but it’s possible.
The next major issue is bass. Subwoofers aren’t just providing extra thump for soundtracks. They have to convey the subtlety, delicacy and beauty of classical and jazz. Think of them as part of the L/R speakers. No less care should be taken in their selection and placement. They can’t just be shoved in the corner where they make the biggest bang. Moving them around the room can make dramatic improvements in frequency response and timing. In fact, adopting one of the popular four-subwoofer configurations is even more important with high-end music than cinema, because the source material is less forgiving of errors.
What else? Obviously, the centre speaker needs to be like the L/R, and it must be placed in an acoustically similar position. This means baffle loading it, too, and positioning it behind an acoustically transparent screen.
The noise floor must be low to support the wide dynamic range of high-end music, so the noisy projector has to go in a hush box or projection room. The same goes for any other gear that makes noise. As with any high-quality audio room, the interior acoustical environment must be engineered and treated.
Finally, the system must be tuned to the room with careful analysis and EQ; however, these steps are all relatively straightforward once the big hurdles of L/R speaker size, positioning and bass reproduction are solved.
Anthony Grimani is president of PMI, Ltd., an award-winning home cinema engineering firm; MSR Acoustics, a manufacturer of fine acoustical tuning systems; and Grimani Systems, a maker of groundbreaking and forward-thinking audio systems. MSR is represented in Australia by Wavetrain (www.wavetrain.com.au).