Yet another perfectionist feature in the Odeon is a simple ground lift switch. This can optimize the grounding configuration for various installations. In most installations, you the consumer utilize the grounding lug on the power cord, for all of the various components in your system chain. This is great for electrical safety, but unfortunately it means that your various components are grounded to each other via two distinct paths, via the power cords and also via the signal interconnect cables. This doubling of the ground connection creates ground loops. Ground loops are an undesirable no-no, for several reasons. Ground loops allow circulating ground currents, which create spurious hum and noise. Furthermore, these circulating currents, traveling through the non-zero impedances of the various ground paths, degrade what should be a single reference baseline for ground throughout each audio component and indeed throughout your system. In all audio components, the signal is literally defined by its (usually voltage) level measured with reference to ground as a reference baseline. If that ground reference level is different among different components, or among different parts of any single audio component, then the whole reference baseline is corrupted, and the audio signal is perforce similarly corrupted. Thus, ground loops effectively corrupt and degrade your audio signal. Sonically, the stereo imaging suffers, and the music can become more veiled and less pristine and pure.
The Odeon's ground lift switch separates the chassis ground from the signal ground, which allows you to separate the ground path via the power cord from the ground path via the signal interconnect, thereby eliminating ground loops through the Odeon (there might still be ground loops within other audio links in your chain, unless they too have this perfectionist feature of a ground lift switch). This has the sonic benefit of reducing hum and noise, and also improving the sound of the music. How do you set this switch on the back panel of the Odeon? As a general rule, if you don't lift the ground lug on the power cord (via a three into two prong cheater plug), then you should lift the chassis ground using the Odeon's switch. You can also make your choice by ear. Flick the switch both ways (with no music playing), and select the option which gives you lower background hum and noise. If both choices are equally quiet, then play music, and listen carefully to see which choice gives you cleaner sound and better stereo imaging.
A quick note on channel configuration. The Odeon's amplifying channels are contained in removable modules, so there is considerable flexibility in configuring this amplifier to your application. There are six bays for six modules, and you don't have to fill up all the bays. Furthermore, each bay can contain a mono 200-watt module, or a stereo 100-watt-per-channel module. Thus, you can configure the Odeon to have anywhere from one channel, to the conventional home theatre five channels, to seven channels for a 7.1 home theatre setup (assuming a self powered subwoofer), or up to 12 channels maximum. Note however that the 100-watt-per-channel stereo module has lower current capability as well as lower power capability, so it is recommended only for auxiliary channels that will carry only ambience information and not much direct sound energy (e.g. rear or overhead ambience channels for a seven channel system). The Odeon's USA price is $10,995 equipped with your choice of six modules (the 100-watt stereo and 200-watt mono modules cost the same). The modules are priced at a very reasonable $600 each, so if you want only five channels, deduct $600 from the $10,995 figure.
The Odeon's Share Of The Plinius Sound
All these perfectionist features make the Odeon something very special, and better than most home theatre amplifiers from other manufacturers, which are heavily compromised relative to their two-channel premium stereo siblings. The most amazing feat of the Odeon is that, in some ways, far from being a home theatre compromise, it actually outperforms the premium stereo amplifiers in Plinius' lineup. That's because each channel of the Odeon contains circuitry essentially identical to a channel of the SA-102, which as noted sounds slightly better than the older SA-250 circuitry. But the SA-102 only puts out 100-watts per channel, which might be somewhat limiting for some home theatre demands. Thus, in the Odeon, this better sounding SA-102 circuitry has been boosted to 200-watts per channel, as much power as in the SA-250. In effect, the Odeon gives you the best of both worlds, the better sounding circuitry of the newer SA-102, plus the double muscle of the SA-250's 200-watts per channel.
So now let's ask the big question. Just how good does the Odeon sound? How much of the Plinius sound, already famously established by Plinius' premium stereo products, does this home theatre amplifier deliver? Well, it depends. You see, you have some choices about how you want to use the Odeon. And your choices will determine just how good the Odeon sounds. At its best, the Odeon is a glorious paradigm of the Plinius sound, supreme in its musical naturalness and thrilling in the way it involves you. At its worst, the Odeon sounds disappointingly like many other solid state amplifiers, with some artificial glare that sounds obnoxious in its own right, and that also blocks, clogs, and obscures musically natural details.
How should you use the Odeon, in order to hear it at its best? And what should you not do, in order to avoid hearing it at its worst? A product with the perfectionist aspirations and potential of the Odeon deserves more than the causal plug in and play listening report that you see in most reviews. We wanted to probe deeply, to learn about all aspects of this amplifier's performance, and ferret out the very best it could do. So we spent a lot of time and effort, researching and analyzing and isolating the variables that made this amplifier sound better or worse. We finally managed to coax magnificent musical performance out of this creature. And now we can advise you what to do, in order to enjoy this creature at its magnificent best. Here is a distillation of what we learned in our research. Here are your keys to hearing the magic from this amplifier.
First, feed the Odeon a balanced signal. This is an unusual suggestion, given that the majority of players and processors for home theatre are still restricted to only single ended unbalanced (RCA) outputs. It means that, in order to get the sonic best from the Odeon, you should go to the trouble and expense of seeking out and buying at least a processor and perhaps also a player that provides a balanced output signal (usually via XLR connectors).
The Odeon's 200-watt modules offer both balanced (XLR) and unbalanced (RCA) input jacks, with a switch to select between them (the Odeon's optional 100-watt stereo modules offer only unbalanced RCA inputs, since they are intended only for low intensity ambience channel use in 6.1 and 7.1 setups). We found that the balanced input sounds far better. In fact, the Odeon's performance is totally transformed into a whole new sonic world.
We could easily hear this sonic improvement on our high resolution lab testing system, and we presume (in view of the Odeon's high-end cost) that you too will be partnering the Odeon with the high quality associated audio equipment it deserves, so you too should be able to hear and appreciate this large sonic improvement from going balanced. In our case, we conducted as pure and direct a test comparison as possible, going straight from our lab reference player at this time, the superb sounding Audio Aero from France, directly into the Odeon, in either balanced or unbalanced mode.
Now, in unbalanced mode, the Odeon already sounds great through its two primo channel modules (the high bias ones; see below). The sound is musically very natural, an excellent representative of the Plinius sound. And the ample muscle of the Odeon is already obvious in unbalanced mode, effortlessly driving and controlling speakers on very loud transients. Already it is clear that the Plinius engineers made the right decision in giving you the best of both worlds, combining in this perfectionist home theatre amplifier the better sonics of their more advanced (100-watt-per-channel) SA-102 circuitry with the much greater power (and higher current capability) similar to their 200-watt-per-channel SA-250 premium stereo amplifiers.
But the Odeon's sonics in balanced mode are better yet. Far better. A whole new world of sound opens up when you use the Odeon in balanced mode. Now, we evaluate many audio components in balanced vs. unbalanced mode. And there is almost always some sonic advantage to balanced mode. Typically, the sound becomes more relaxed, delicate, open and airy, even at low volume levels. This much sonic benefit we attribute to the electrical advantages of a balanced interconnection: lower noise, better rejection of external interference, and higher signal level (which further improves the signal-to-noise ratio). But our jaw hit the floor when we heard the Odeon's sonic improvements going to balanced mode. They went far beyond the sonic advantages of a balanced interconnection that we were accustomed to hearing.
In a word, the Odeon in balanced mode becomes much more expansive. This expansiveness is especially notable in the imaging and in the amplifier's dynamics. In terms of dynamics, the change is startling. The Odeon in unbalanced mode already boasts excellent muscle and control, when the signal demands it. But in balanced mode the music (and other sounds) literally leap to life, and suddenly jump (or rock, as your vernacular prefers). Interestingly, this jumping dynamic life is audible in balanced mode even when the signal is not playing loudly. All the music, all the time, has a vivid, energetic openness without ceiling, and the amplifier sounds even more effortless in handling all these expanded dynamics. This effortlessness, combined with the expansive dynamics, gives music a sense of open freedom, to jump out in the open without limit. Going back to unbalanced mode imposes a subtle sense of constraint on the music, so that it sounds concise rather than expansive, almost as if it was playing with an imposed ceiling. In this respect, the Odeon in unbalanced mode still fares better than most other solid state amplifiers, which can make the music sound even more constrained and closed in, as though it were playing in a low ceilinged closet. But in balanced mode, the Odeon gives music (and other sounds) an open freedom that you have to hear to believe.
The expansive improvement in imaging is even more amazing and multi-faceted. In unbalanced mode, the Odeon's imaging is good, but not as good as the best competing amplifiers. This can be heard even in two channel stereo. Stage width is very good, and does extend beyond the speakers, but there are still hot spots where sound is localized near the speakers. Moreover, stage depth and hall ambience are only fair, so the sonic portrayals of the stage and hall spaces sound shallow and flat. It's like looking at a flat photograph, of the music on stage or of the recording venue, hung on your room wall--accurate, but still flat or two dimensional. This is not the best situation for surround sound, and for the whole point of home theatre, which is to transport you out of your room and into the alternative venue of the recording or film. Changing the Odeon to balanced mode puts you in a whole different world. The imaging becomes far more expansive and gives you everything you could want for stereo, surround music, and home theatre. Suddenly the imaging depth and ambience expand dramatically, expanding the spatial image three dimensionally, far beyond that flat portrayal of a mere picture on the wall, and filling that expanded space with rich ambience information captured by the recording. The sonic transparency also improves, in part because you can now clearly hear independent sonic events happening in different locations, at different spatial depths and framed by different ambiences. Even the width dimension of the imaging portrayal improves, as there is no longer a hot spot localized near the loudspeakers. The loudspeaker locations disappear, and you are transported out of the confines of your small room, into the expansive alternative venue of the recording. The balanced mode changes the Odeon's imaging portrayal from a flat photograph to the real thing. That's a huge improvement, and vital to the success of your audio system. Finally, in balanced mode, the Odeon achieves that ideal which you need for suspension of disbelief, for all stereo, surround music, and film soundtrack listening.
You'll realize an even further benefit from using the Odeon's balanced mode if your CD or DVD player employs dual differential DACs (this feature is available from Theta Digital units). This DAC configuration improves resolution, lowers noise, and lowers distortion, at an even earlier stage, during the initial decoding of digital to analog. If your player has this feature, it provides a balanced signal at this point, so it naturally makes sense to keep the signal balanced for the rest of your chain, including your surround processor and the Odeon.
The second key to realizing the full sonic potential of the Odeon concerns bias level. You see, we perfectionists might long for a home theatre power amplifier to be a true no compromise product, that gives us in a single convenient multichannel package all the virtues of those premium monoblock and stereo power amplifiers we love. And the engineers at high-end companies like Plinius might sincerely want to give us such a perfectionist no compromise product. But, alas, the laws of physics forbid it. It can't be done. You, and I, and the engineers at high-end companies, must all bow to the laws of physics. And so we must maturely accept the dictates of physics, and try for the best, most intelligent compromise possible, which still gives us the best possible sounding home theatre power amplifier, in a package with reasonably manageable size, weight, and cost.
The chief problem is heat. As you know, all power amplifiers produce heat, due to the fact that they are less than 100 percent efficient, so that some of the power they consume from the powerline goes into heat rather into your loudspeaker. Now, solid state devices have the unfortunate foible of being sensitive to temperature, such that their amplifying characteristic changes with temperature. This means that they sound different at different temperatures, better at some and worse at others. So for best sound we want to keep the solid state devices at or near their best sounding temperature. It also means that, for best sound, we want to keep the temperature stable, even when the ever changing music signal gets louder or quieter, and even as the music signal simply goes from its frequent zero crossings (zero amplitude) up to its maximum amplitude of the moment (whatever that amplitude might be, whether loud or quiet). That's because, if any amplifier's amplifying characteristic changes with signal level, we automatically get distortion (indeed, the very definition of nonlinear distortion is a change of amplifying characteristic with signal level).
The heat produced by a power amplifier will of course tend to raise the temperature of the entire amplifier chassis, including all the solid state devices therein. A certain small to moderate amount of heat (produced by an amplifier) is actually good for solid state devices, helping to raise their temperature into a range (above ambient room temperature) where they perform better and sound better (that's why many solid state products don't sound their best until they have warmed up). But a large amount of heat will lead to temperatures so high that other parts inside an amplifier can bake into premature failure. And these very high temperatures can even lead some solid state devices to self destruct, as they go into a thermal runaway whereby their changed performance at these high temperatures produces higher gain, which generates even more heat and even higher temperatures, which in turn produces even higher gain, creating a self destructive vicious circle. Clearly, then, there must be a means for stabilizing the temperature of a solid state power amplifier, and at a moderately elevated but not excessive value, by keeping some amount of heat produced by the amplifier on board the chassis, so as to optimally elevate the temperature above the ambient room temperature--but then dissipating the excess heat (that would tend to raise the temperature too high) into the surrounding air of the room.
Enter heat fins, that ubiquitous appendage of solid state power amplifiers. The heat fins radiate or dissipate the unwanted excess heat into the surrounding air of the room, allowing the amplifier and its solid state devices to heat up somewhat, to an optimum elevated operating temperature, but not too much. The amplifier's design engineer can calculate the required area of heat fins, and their required external exposure to the surrounding air, in order to obtain optimum and safe temperature results for the power amplifier. Obviously, the more power a given type of amplifier circuit puts out, the more excess heat it will generate, and the more heat fin area is required, all with sufficient exposure to the surrounding air. Adding heat fin area of course makes the chassis much larger in physical size, since all that heat fin area has to have access to external room air. And heat fins are also heavy and expensive. Thus, heat fins contribute significantly to the size, weight, and cost of a power amplifier. That's one of the chief reasons why a power amplifier of a given circuit type having, say, twice the power capability of its junior sibling, is much larger in size, much heavier in weight, and much more costly.
Consider now a monoblock power amplifier rated at 200 watts, with heat fins on three sides. If you want to make a stereo amplifier using the same circuit, with the same power output per channel and the same high sonic performance, you'd need to make the chassis much bigger in size, so that (simply speaking) you could mount twice the heat fin area on it, all of this area still having good radiating access to the external room air. And of course this stereo amplifier, with twice the amount of heavy heat fins and a much larger chassis to support them, would also be much heavier and more costly. Then, if you want to make a truly no compromise six channel home theatre amplifier, using the same circuit and delivering the same power per channel with the same no compromise performance, you'd need to make the chassis unmanageably humongous, in order to support (again simply speaking) six times the heat fin area, while still providing all this area with good radiating access to the surrounding air. And this home theatre amplifier would weigh roughly six times as much, or three times as much as the stereo amplifier. This means that a truly no compromise six channel version of Plinius' $9995 200-watt-per-channel stereo SA-250, which weighs 156 pounds, would weigh roughly 450 pounds. The unmanageable weight and humongous size of such a package would obviously defeat the whole point of home theatre power amplifiers, which is to give you multichannel sound in a single conveniently manageable package. Not to mention the unmanageable cost of such a package (about $30,000 for a package equivalent to three SA-250 amplifiers).
All home theatre amplifiers must therefore face some sort of design compromise, relative to their premium monoblock or stereo siblings, just to reduce the amount of heat generated by the
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