As promised in our last Cineluxe Basics post, which covered the things you should consider when picking source components for your luxury home-entertainment system, this time we’ll be turning our attention to one of the most important—but also one of the most overlooked—components required to make such systems work. It’s such an esoteric piece of gear that you may not fully understand what it does.
But hopefully by the end of this discussion you’ll not only have a lot more respect for the lowly preamplifier; you’ll also be better able to make a more informed decision about which one is right for your system.
Everyone understands that source components like disc players, satellite boxes, movie servers, and video streamers deliver the movies and TV shows you watch on a regular basis, either from a silver platter, the airwaves, or a hard drive somewhere.
It’s positively axiomatic that your TV or projector is responsible for delivering those images to your eyes, and your speakers transmit sound through the air to your ears.
The preamp, though? It’s the box that sits in the middle, functioning as a sort of air-traffic control for your entertainment system. It sends the video from your sources to your display. It decodes the digital audio stream from your source components and sends it to your amps and speakers in analog form.
And you may be thinking to yourself, “That sounds an awful lot like an AV receiver!” It’s true. Preamp/amplifiers serve the same function in a luxury home-entertainment system as do AV receivers. It’s simply that a receiver combines all of the preamplification and amplification in one box, whereas going the preamp/amplifier route gives you a lot more flexibility in terms of perfectly matching your amplification needs to your speakers and your room.
As a result, it’s not inaccurate to say that a preamp/amp combo will generally give you better performance than a receiver, especially in a larger room. A more accurate explanation would also be a much more complicated one, but if you’re itching for a geeky discussion about the topic, I wrote one a few years back for Home Theater Review.
At any rate, these days all of the above is only part of the equation when it comes to selecting the right preamp. Another important function that has arisen in the past few years is digital room correction. Broadly speaking, “digital room correction” is a catch-all term that covers a number of different technologies, but all of them ostensibly serve the same purpose: To use a combination of equalization and other filtering to reverse the deleterious acoustic effects your room itself has on the sound leaving your speakers.
These effects come in two forms: Those caused by the shape of your room and those caused by the surfaces in your room. The former affects the clarity and evenness of bass in the room, as the low-frequency sounds coming from
your subwoofers and other speakers bounce off the walls and ceilings and either cancel each other out or reinforce one another.
Bass frequencies below 250 Hz or so (the highest note you can play on a double bass) have a really long wavelength, between five and 60 feet, so it takes a really big, flat surface to reflect them. So, it doesn’t really matter if your room is decorated with wood paneling or acoustic fabric; your subwoofer is going to sound overwhelming in one part of the room and wimpy in another. All good room-correction systems will listen to a microphone placed in and around the seats in
your entertainment space and tweak the sounds coming from your subs and speakers so the bass has impact and authority without sounding boomy or sloppy.
A great example of a room-correction system that positively excels in this respect is Anthem Room Correction, which you’ll find, appropriately enough, on preamps made by Anthem, like the AVM 60 (shown at the top of the page). If you have a dedicated home cinema space with acoustically treated walls, Anthem Room Correction is likely all you need to whip your bass into shape and make your subwoofers sounds like a million bucks.
If, on the other hand, you have a multi-use home-entertainment space in a living room or family room, your installer may recommend a more sophisticated—and indeed more expensive—preamplifier with a more advanced room-correction solution. That’s because it takes a lot more processing power and a lot more calculations to digitally correct problems that arise from hard or uneven surfaces in the room—like mirrors, windows, cabinets, hardwood floors, etc.—or even standard decorations like vases, coffee tables, or even columns along the wall. Since these surfaces are smaller than, say, the entire back wall of your room, they affect smaller wavelengths of sound—hence, higher frequencies.
You can attempt to correct for such problems with almost any room-correction system, but the cheaper ones—like you’ll find on most mass-market AV receivers—don’t do a very good job of it, leaving you with a sound system that’s lifeless, dull, and uninspiring.
Better, more sophisticated room-correction solutions, though, can go a long way toward erasing the harsh audible effects of such surfaces from the sound that reaches your ears, without making it sound like you’ve thrown a blanket over your head. Examples of such systems include RoomPerfect, which you can find on Lyngdorf’s MP-50 and MP-60 preamplifiers, as
well as Trinnov’s Speaker/Room Optimizer, found on the company’s Altitude line of preamps. Your installer may also recommend preamps that rely on Dirac Live room correction, an excellent mid-priced solution.
As for amplifiers? Your best bet here is simply to listen to the advice of your installer. You will, of course, need one channel of amplification for every speaker in your system (except perhaps for the subwoofers, which often contain their own amplification),
so if you’re installing a 7.2.6-channel system (that’s seven ear-level speakers, two subwoofers, and six overhead speakers), you’ll need at least 13 channels of amplification. That may come in the form of two seven-channel amps, seven stereo amps, or even 13 standalone “monoblock” amplifiers, with each configuration having its own relative pluses and minuses. But again, chances are good your installer is intimately familiar with the speakers going into your system, and knows what amplification will work best.
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.