Experimenting with the X1 and Evolution System

      The X1's extraordinary control flexibility, especially when combined with the flexibility of the W1 and M6 to reach beyond the usual range, means that the Evolution system can be tweaked to give superior bass and superior integration (between subwoofer and satellite) in virtually every situation, for virtually every combination of room acoustics, loudspeaker placement, program material, and listener taste. The good news is that you can experiment with the Evolution's many parameters (placement and orientation of the M6s and W1s, and the many X1 controls, all of which interact) until the cows come home, to dial in exactly the type of sound that you want in your room. The bad news is that you can experiment with the Evolution's many parameters until the cows come home.
      It does take time and patience, and a willingness to experiment, to exploit the Evolution system's flexibility to its fullest, in order to get the best out of this system. But at least the Evolution system affords you this flexibility, whereas most other systems offer you far fewer options, and thereby force you to accept the suboptimal sonic performance that comes with their simplified options.
      We'd suggest that you give yourself generous time (a period of at least weeks) to get the hang of the Evolution's various options (especially the X1's interacting controls), on a variety of program material, and makes notes to keep track of which controls do what, in your room as you hear it (the Evolution owner's manual offers some guidelines, but we find them somewhat misleading compared to what we hear happening, so you should regard the manual's guidelines only as a starting point, not as final gospel). Feel free to make a lot of changes during the first few days, but then, after you have settled on some preliminary choices for all the control settings, listen for several days to one setting, on a variety of program material, to get thoroughly familiar with the sonic pros and cons of the current settings (again, keep a diary).
      Throughout this extended period of experimentation, which might try your patience, take heart from the shining light at the end of the tunnel. Remember that you don't have to worry about getting all the settings absolutely right. Indeed, you can't get them wrong. That's because you are the final arbiter of what is the best bass and warmth sound for your taste, given your room, your choice in program material, and the rest of your playback system. Neither NHT nor I are there in your room with you, so you are the expert on what your own room is doing with the sound from the Evolution modules, and how best to work with the Evolution system's many parameters to optimize its performance within your particular room. And of course neither NHT nor I share your electronics, your program material, or your personal taste. Thus, whatever you decide is best for you and your room is by definition best for you. But do take the time to experiment. You'll learn a lot, and you will be richly rewarded by the Evolution system's flexible capability to adapt.

A1 Power Amplifier

      As a bonus, the Evolution system also makes available to you the A1 power amplifier. It is a monaural (single channel) unit, in a handy and attractive rack width package that is very slim in height. This slim height package is made possible by a high quality, very flat pancake toroidal power transformer, and by the A1's efficient class G operation that requires minimal heat sink and fin area for dissipating heat (this class G technology is available throughout the Rockford corporation's several brands of power amplifier).
      Rated at 200 watts into 8 ohms, and 250 watts into the nominal 6 ohms that characterizes both the W1 and M6 (and all the Evolution loudspeaker modules), the A1 is modestly priced at $400 each. The A1 is designed as a full range amplifier, capable of handling the entire audio spectrum.
      The modular nature of the Evolution system, and the fact that the Evolution systems are not driven by built-in power amplifiers, means that you are free to employ the power amplifiers of your choice with the Evolution loudspeakers. You could buy the A1s to drive the subwoofers, or the satellites, or both, or you can choose other power amplifiers and not use any A1s at all.
      In the world of power amplifier design (particularly solid state amplifiers) it is axiomatic that a power amplifier can be designed to be fast, pure, and delicate -- or it can be designed to put out tons of current with a large safe operating area to drive reactive loads. But it cannot be designed to do both optimally. The former set of desiderata is ideal for driving mid and upper frequencies fed to a satellite, while the latter set is ideal for driving subwoofers. A power amplifier designed specifically to excel at driving subwoofers should have huge current drive capability, very low source impedance, and a large safe operating area into reactive loads, but does not need to excel at handling mid and upper frequencies. Thus, you can and should consider buying different types and brands of power amplifier, one ideal for driving the W1 and another ideal for driving the M6. There isn't room here to give you a power amplifier survey of the two types. But it is appropriate to evaluate here the A1's prowess at these two very distinct tasks.
      In driving the W1 subwoofer, the A1 proved very capable. Its bass quality driving the W1 was a little on the full and loose side (which some of you may prefer). We evaluated some other power amplifiers driving the W1, and their bass quality was tighter and drier than the A1, with quicker bass impact and slightly better definition (others of you may prefer this). So by all means feel free to explore the full gamut of power amplifiers for driving the W1. Don't feel constrained to the A1 just because it is part of the Evolution system.
      What about the A1's sonic performance in handling the majority of the spectrum, for example as when driving a nearly full range satellite like the M6? At this task the A1's performance is mediocre, and you can do far better among competing power amplifiers. The A1's single sonic strong point here is that it does have a nicely liquid quality. However, it has many sonic weak points. Its upper frequencies sound softened and veiled, with a slight layer of grundgy distortion. Its overall tonal balance is not neutral, as follows. There is not enough bass and warmth, which might be a clue as to why the A1 is slightly bettered by some other power amplifiers even at the first task of driving the W1 subwoofer with merely bass. The upper frequencies are slightly recessed, in part because of the softening and veiling they experience in the A1. This leaves the midranges as being tonally overly prominent. And this midrange over-prominence is further exacerbated by an ugly sounding quack or honk, at the border between the midrange and upper midrange. It's possible that the class G transition in the A1 is not managed smoothly, and that some time constant associated with this transition is producing this quack or honk.
      For the task of driving the Evolution satellite monitors specifically, our chief concern about the A1 is its sonic veiling. We found that there's already some sonic veiling in the M6 itself, which we attribute to economical crossover parts. Because the M6 itself already imparts enough veiling to be on the brink of acceptability, it deserves to be driven by the clearest, most transparent power amplifier you can afford, so that the overall veiling is not taken over the brink into unacceptability. Unfortunately, the A1's considerable veiling adds to the M6's inherent veiling, producing a sum total of veiling that we find unacceptable. To do justice to the M6, you need a power amplifier that veils less than the A1 does.
      Incidentally, if you do use the A1, we recommend that you set the rear panel slide switch controlling power/standby mode to a setting other than audio trigger. In this audio trigger mode, the A1 sits in standby mode until it senses an audio signal, and then turns on. That might seem like a handy feature. But in practice there's a small fly in the ointment. There's a short time delay, after the start of the audio signal, while the A1 turns on. And during this time delay, you'll miss hearing the first note of the music or soundtrack. If you employ the A1 to drive the W1, and if the recording begins with a bass note, you'll never hear that first bass note. The fix to this tiny problem is simple: just set this slide switch to always on (or 12 volt trigger if your system is thusly configured).

Conclusion

      The Evolution system, like every audio product, has its strong points and weak points. We've gone to great lengths in this review to show you how to get around the weak points and make the most of the strong points. If you set up the Evolution system in accordance with our recommendations, it achieves very good sonic performance on virtually all counts, as judged by my very critical perfectionist high end standards. An important added plus is the flexibility engineered into the Evolution system, which allows you to adapt and optimize the Evolution's performance for a wide variety of rooms and situations. The Evolution's subwoofer phase control, which gives the Evolution superior integration to most other loudspeaker systems, is alone worth its weight in gold.
      Then, when you finally factor in the low price of the Evolution system, you have here an outstanding bargain, making the Evolution a strongly recommended loudspeaker system for anyone on a budget. It's especially recommended for those of you who like a mellow loudspeaker sound (you could easily make the M6 brightly aggressive instead, but that creates other problems, such as foreign spurious colorations and degraded spatial imaging).
      The W1 subwoofer also merits special recommendation as a very good general purpose subwoofer for use with other brands of satellites. Because the price of the W1 and X1 is so low, you can easily afford to put multiples of the W1 all around your room (even one at each satellite location), which will give you much better bass than the merely one or two more expensive competing subwoofers that you could get for the same total cost. Our hope here is that NHT could introduce a slightly modified X1 crossover that would have a gentle corner at 27 Hz and a user defeatable option for its subsonic filter, in order to allow you to hear the W1 at its true intrinsic best capability.
      It's rare to find such thoughtful, thorough engineering in a loudspeaker system, even among the ranks of perfectionist high end loudspeakers, and NHT deserves special praise for giving you all this sophisticated engineering at such a bargain price.

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