Reviews of Attainable Hi-Fi & Home-Theater Equipment


Reviews of Attainable Hi-Fi & Home-Theater Equipment

In response to my recent love letter to integrated amplifiers, I received some interesting feedback that came in the form of a question: isn’t there some contradiction in the fact that I use integrated amps almost exclusively in my dedicated two-channel system while relying on separates in my main home-theater system? Why not use an A/V receiver in my media room instead of an A/V preamp and multichannel amp if I’m so enamored with one-box solutions?

Separates or Receiver?

There are a lot of assumptions built into that question, and a lot of conventional wisdom to boot. But to keep this from being a tome of monumental proportions, let’s leave aside the issues of stereo integrated amps and focus on the question of A/V separates vs. A/V receivers. What are the advantages and disadvantages of each? Which one should you buy?

As will become clearer the more I ramble here, that’s not a simple question to answer. The conventional wisdom I mentioned above holds that all A/V receiver owners are simply A/V separates enthusiasts in training—that the lowly AVR is merely a stepping stone or a way station on the way to one’s eventual purchase of a standalone processor and amps. That’s a really reductive view of things, though. In fact, many people are probably perfectly well-served by a receiver. The trick is to figure out whether or not you’re one of those people.

But before we dig too deeply into this topic, let’s define some terms, just in case any fledgling audio enthusiasts stumble upon this discussion.

What do we mean by “A/V receiver”? And what are A/V separates?

For this discussion, we’ll consider an A/V receiver any component that includes A/V switching, processing, preamplification, volume control, and multichannel amplification all built into one chassis. You wouldn’t think this would be a controversial topic, but the definition above actually leaves out one of the essential functions of a receiver: the radio tuner. Most AVRs still include them, but some high-end solutions don’t, and some such manufactures eschew the word “receiver” entirely, either to account for their products’ lack of terrestrial reception or to distance their products from the stigma associated with AVRs.

For whatever reason, Rotel, for example, refers to its one-box solutions as “Surround Amplified Processors,” but we’re going to lump them in here with the Denons and Yamahas and Anthem MRXes of the world. For our purposes, they’re receivers.

Rotel

An A/V separates system, by contrast, generally exists in the form of at least two black boxes. One integrates preamplification, processing, volume control, A/V source switching, etc., in a product called the preamp/processor or pre/pro, or sometimes simply preamp. Amplification then comes in the form of separate multichannel amps or, in extreme setups, individual monoblock amps for each speaker. A preamp/processor could also be useful for driving active speakers, but that’s not really within the scope of this discussion.

A/V receivers: pros and cons

The biggest advantages of having your processing and amplification in a one-box solution are obvious: fewer cables (since you don’t have to run interconnects between your preamp and amplifier for every channel of audio), simpler setup, and less ouch-factor in terms of price. A great AVR might cost you only $1500 to $2000. A good A/V preamp alone will likely run closer to $3500 to $5000, and that’s before you factor in the cost of amps. There’s also the issue of economy of space. Most AVRs take up only as much space as your average A/V preamp sans amplifiers.

Speaking of amplification, most AVRs provide more than enough power for many people’s needs, especially those with small- to medium-size rooms. But that’s as dependent on your speakers and your desire for loud sound pressure levels as it is on the size of the room.

Let’s walk through a few hypotheticals to give you a sense of what I mean. Crown has a fantastic calculator that lets you estimate exactly how much power you need given all of the relevant variables. Plug in the distance between you and your speakers, the desired listening level and desired amp headroom, and—most importantly—the sensitivity of your speakers, and it will spit out how much power you’re actually going to need.

So if you sit six or seven feet away from your speakers and want to make sure you can listen to film soundtracks at THX reference levels, plug in a distance of 2m, a desired listening level of 105dB (the peak per-channel loudness for which film soundtracks are mixed), amp headroom of 3dB (just to be safe), and a sensitivity of 87dB, the rated spec of SVS’s popular Prime Tower. The required amplifier power you get from that equation is . . .

Um . . . 504Wpc.

Denon

And you’re thinking, “Ah HA! Gotcha! No A/V receiver can deliver that kind of power!” Yes, but very few standalone amps can, either. That’s also far beyond the power-handling capabilities of the Prime. So let’s adjust those figures for more real-world settings, because the truth of the matter is that most people don’t listen to films at home at THX reference levels. The most my wife will let me get away with is around -8dB (8dB below THX reference level). And that’s still pants-flappingly loud. On the rare occasions when my dad comes over to watch movies with me, I have to turn it down to around -10dB or -12dB. But let’s stick with -8dB, just for the sake of this argument.

That lowers the peaks to 97dB. Using the same speakers, in the same seating position, with the same headroom, that gives us a required amplifier power of 80Wpc, well within the capabilities of most mid-tier-to-higher-end AVRs.

Now let’s swap those excellent SVS Prime Towers for something like Focal’s also-excellent mid-tier Aria 948 speakers, whose sensitivity is rated at 92.5dB. Change nothing else about the system, and that speaker can hit 97dB peaks with only 22W of power. If you wanted to get closer to THX reference levels, you could hit 100dB peaks with only 45Wpc.

Crown

And keep in mind, we’re talking about peak output here, not average. Your amps will only be called upon to deliver that kind of output during explosions, gunfire, car crashes, Hulk smashing, etc. With the volume knob of your AVR set to -5dB (the level at which your peaks would be 100dB), the average sound reaching your ears is more like 80dB. With the Focal speakers, that would require less than a watt of power to achieve. With the less-efficient SVS speakers, you’d need more like 3Wpc—or 5Wpc if you want to be really safe.

And look, I’m not advocating the use of flea-watt amplifiers in home-theater applications. Those dynamic sounds that demand quick bursts of high power from your sound system are what make the viewing and listening experience engaging. I’m merely saying that, on average, we don’t use nearly as much power as we think we do. So for many people, with most speakers, in most rooms, an AVR may be more than adequate in terms of power needs.

But—and this is a big but—when has our hobby ever been about mere adequacy? What’s more, the biggest downside of most AVRs is that they deliver the power they claim to deliver under only the most forgiving test conditions, so it can sometimes be difficult to determine whether you’re really getting even the limited power you truly need.

I’ve reviewed receivers that claimed on the side of the box to deliver 165Wpc. Read the fine print, though, and that output was measured with a limited-bandwidth signal into a 6-ohm load, with only one channel driven, at 1kHz. Rate the same receiver’s output using the industry-standard 8-ohm load with two channels driven, using a full-bandwidth signal, and its output would realistically be more like 80Wpc. That’s still plenty for most people’s needs, but it’s far from what that receiver promised. So you do need to read the fine print to make sure an AVR meets your power requirements.

Many AVRs also struggle to power speakers with a nominal 4-ohm impedance. Some will trick you into thinking they do, by including an impedance switch on the back panel or a setting in the menus that functions the same. The reality, though, is that in almost every instance, what these switches or settings do is limit the voltage of the amps to ensure the speaker doesn’t draw more current than the receiver can deliver.

So if you have speakers with nominal 4-ohm impedance—a few popular examples that come to mind are PSB’s Imagine T tower, ELAC’s Uni-Fi UF5, and MartinLogan’s Motion 20i—chances are good that an A/V receiver may not deliver the amplification you really need, or you’ll find yourself dealing with the dreaded “Protection Mode,” where your AVR shuts itself down to avoid overheating, more frequently than you’d like.

Arcam

There are exceptions, of course. The excellent Arcam AVR30—with its seven channels of beefy class-G amplification—should be able to drive just about any speaker like a rented mule. But it’s the exception rather than the rule. And it ain’t cheap.

A/V separates: cons and pros

Yeah, no, that’s not a typo. I’m digging into the downsides of separates first to hang a lantern on the reasons why many people avoid them. As mentioned above, building a good surround-sound or object-based A/V system using a preamp/processor and standalone amps can get spendy really quickly.

There’s also the issue of space. Generally speaking, a setup with separate pre/pro and amplifiers requires at least twice as much space as your average A/V receiver—far more if you want to get jiggy with a full-fledged Atmos/DTS:X sound system with multiple overhead speakers.

Perhaps the biggest drag is that A/V preamps simply aren’t updated as frequently as are A/V receivers. Marantz, for example, just introduced its first new A/V preamp in three years. And I don’t care to count how many new AVRs the company has cranked out in that same time period. This means that pickings are a little slimmer if you want or need the absolute latest in terms of HDMI connectivity or other features. Not that most people need all the new features of the HDMI 2.1 spec just yet. But if you’re a next-gen gamer and you absolutely do need those features—well, there aren’t a lot of surround preamps yet that are so capable (even if you ignore all of the bugs plaguing the newest HDMI chipsets).

Marantz

Speaking of features, pre/pros aren’t always as packed with goodies as are AVRs. There’s a good reason for that: they’re typically designed for and marketed at consumers who prioritize pure performance over doodads. But if you want bonus features, like streaming music support, etc., just know that they’re not as common on separates-based systems, especially when you start looking at less-mainstream brands.

On the other hand, having your amplifiers separate from your preamplification and processing means that you have much more freedom to find the right amp for your speakers. This could be a pure function of room size—for example, if we pick up our hypothetical scenario from above, let’s take that Aria 948 speaker system, assume you’re perfectly satisfied with 100dB peak SPLs, and up the room size such that you’re sitting 3m away from your speakers instead of 2m. Suddenly, instead of needing a paltry 45Wpc to power those dynamic peaks, you need more like 101Wpc.

Crown

Let’s say, on the other hand, you have those SVS Prime Towers, and you still think 100dB peak/80dB average is too loud. You’re more of a 97dB peak kind of listener. You really kinda need 180Wpc of power to make sure you don’t miss out on any of the Hulk smashing or, worse yet, send your amp into clipping, which is the easiest way to blow a driver.

There’s also the issue of speaker impedance. In the discussion above about A/V receiver amplification, I simplified things by talking only about nominal impedance. The fact of the matter is that the impedance of any speaker is a roller coaster of rising and falling numbers dependent on frequency and power.

You want to know the real reason I employ separates in my main media room rather than an A/V receiver, despite the fact that my beloved GoldenEar Technology Triton One.R towers have built-in amps for the woofers and are pretty darned sensitive at 92dB/W/m? The truth is that the One.R doesn’t need a heck of a lot of external amplification. But its impedance is a bit tricksy. GoldenEar Technology doesn’t list the nominal impedance of its speakers, reporting them instead as “compatible with 8 ohms.” And that’s true. They are compatible with 8 ohms. But the actual impedance curve of the towers drops below 4 ohms between ~200Hz and ~600Hz. And needless to say, there’s a lot of very dynamic sound in most movie soundtracks within that frequency range.

So in order to ensure that I’m providing the speakers with ample linear power even in the most extreme use cases, without triggering fault protection, I prefer to use beefier standalone amps. And the exact same reasoning would apply to the Focal Aria 948 I referenced above, whose minimum impedance is in the neighborhood of 2.5 ohms.

Anthem

This raises an interesting question, though. Why not use an A/V receiver with preamp outputs to drive my outboard amps? It would, in most cases, be a lot cheaper. That may be a bit beyond the scope of this discussion, but it really comes down to the complicated issue of voltage. Most A/V receiver manufacturers don’t specify the output voltage of their preamp outputs (if there even are multichannel preamp outputs), and if output voltage is insufficient, it won’t matter how your amplifiers are rated—your clean power is going to be limited.

Are many Denon, Marantz, and higher-end Yamaha A/V receivers perfectly capable of providing an outboard multichannel amp with sufficient voltage? Absolutely. But none can match the output voltage of the balanced outputs of my Marantz AV8805 or my Emotiva RMC-1. In general, I want to know that the maximum output voltage I’m feeding my amps meets or exceeds the voltage required for them to deliver their full rated power (in my case, 1.5Vrms for the Anthem A5).

Will a lot of good A/V receivers rise to that occasion? Sure. Is that a given? Nope.

Brass tacks, man! Should I get an A/V receiver or separate preamp and amplifier(s)?

As I hope is clear from the wall of text above, that’s not a question I can answer for you without knowing every variable of your sound system, listening room, and listening preferences. But in general, it’s a safe bet to use that Crown calculator and enter the rated impedance and sensitivity of your speakers (or, better yet, the measured impedance and sensitivity, which you can find in the speaker measurements section on the SoundStage! Network website), the distance from your listening position to your speakers, and your desired listening levels. This process will give you a good sense of your actual amplification needs. If the number the calculator spits out is well within the capabilities of a good AVR, congratulations—you’ve saved yourself some cash and a lot of space.

If you’re approaching or exceeding the output capabilities of a good AVR, though, or if your speakers have low nominal impedance (or some really low impedance dips), it’s time to consider stepping up to A/V separates. Alternately, if you’re planning on setting up a massive Atmos/DTS:X system with tons of speakers, you might find that it’s easier to figure out how much power you need, since good multichannel amps are more often rated with all channels driven, not merely one or two.

And hey, if you want to buy a separates system because you just do, that’s valid, too. Do you, boo.

. . . Dennis Burger
dennisb@soundstage.com