thereby, like a repeating echo, stretching this same frequency over time, so that the later response of the room sounds like the mantra "ooooooooooooommm", appended after the genuine, quick initial musical transient. The composite result of this would sound like "Pop! Ooooooooooooommm". Now, if you address the true room problem, by moving your loudspeakers and using Tube Traps, you will be directly attacking the "ooooooooooooommm" suffix, and get yourself back to hearing just the genuine, accurate musical transient "Pop!".
      But what happens if you employ electronic room equalization instead? The only place that the electronic equalizer can do anything at all is to alter the electronic signal, the genuine initial musical transient "Pop!", since it cannot directly change the acoustics of the room, as you did do by moving loudspeakers and installing Tube Traps. The electronic room equalization system takes a time averaged measurement, indiscriminately summing both the initial musical transient "Pop!" and the later room response "ooooooooooooommm", and indiscriminately measuring the total sum of both accurate energy (the "Pop!") and spurious garbage (the "ooooooooooooommm"). The system sees that there is too much "oooo" energy over time (corresponding to the frequency of room resonance). Since it can't directly reduce the unwanted "oooo" energy in just the room resonance response alone, it reduces "oooo" energy in the only place it can, in the "Pop!".
      Thus, electronic room equalization changes the genuine musical transient into something that sounds different and wrong, sucking a lot of the rich, weighty sounding "o" (say 40 Hz) energy out of the genuine "Pop!" transient, and changing it into something that sounds very different, probably thinner and leaner, like "Pip!". Meanwhile, it has not improved the intrinsic room resonance misbehavior, the room's lingering booming response to whatever 40 Hz energy there still is. Thus, the final product you hear from electronic room equalization system is "Pip! ooooooooooooommm". In contrast, moving the loudspeakers and installing Tube Traps directly attacked the "ooooooooooooommm" and kept the genuine musical transient "Pop!" sounding accurate, like "Pop!". I submit that the ear/brains of most humans can tell the difference between achieving "Pop!" in their room or getting "Pip! ooooooooooooommm" instead.
      In effect, electronic room equalization robs Peter to compensate for the excesses of Paul. It alters the spectral content and balance of the genuine initial musical transient, in a mistaken and misguided attempt to compensate for the excesses in spectral content and balance of the later room response. It thinks and reports that everything is OK, since it robbed enough energy from the genuine initial musical transient to compensate over the long run for the excess energy from the room, so that the sum of spectral energy averaged over the long run looks OK.
      But our ear/brains hear in the short run, not the long run, so we can hear that something is wrong (indeed several things are wrong). We can hear that the altered spectral content of the initial genuine musical transient makes it no longer sound genuine or accurate, and we can hear that most of the energy we're hearing at (say) 40 hz now consists of lingering, booming garbage rather than genuine musical energy as part of the genuine original initial musical transient.
      To compound the felony, electronic room equalization has further pernicious effects. It not only alters the spectral content of the genuine musical (or sound effect) transient in the frequency domain, but it also mangles the waveform in the time domain. It distorts the waveform of the genuine musical (or sound effect) transient to a different shape. Thus, the temporal waveform of the genuine original sound is altered or distorted, in a way that we might be able to hear. Our ear/brain is a very sensitive temporal analyzer, evaluating the attack and decay of transients (inherited from the cavemen's skills in analyzing snapping twigs), and we can often tell that a waveform mangled in the time domain sounds different and wrong, not like the accurate, genuine sound of the musical transient as it was recorded.
      To continue our vocal example here, the time domain mangling by electronic room equalization might change the quality of transient attacks and/or decays, changing their sound to more or less hard than the accurate genuine transient sounded. We saw above how spectrally sucking the rich lower frequency weight out of the initial musical transient changed the genuine "Pop!" into "Pip!". A time domain mangling which softened the attack and decay could soften the "Pip!" into a "bib" or even a "mim". Thus, the final result from electronic room equalization, including both its spectral and temporal alteration of the genuine initial musical transient, and its inability to cure the room hangover, might well take the original "Pop!" sound and turn it into "mim- ooooooooooooommm". Such inaccurate alteration of the genuine original musical transient sound is pretty sad.
      Further pernicious effects of this time domain mangling derive from the fact that the first arrival sound, coming directly from the loudspeaker to the listener, is distorted by the electronic room equalization. The ear/brain relies on this first arrival waveform for comprehending and interpreting a lot of information about the sound, including all aspects of transient analysis, and all aspects of the various cues it needs to hear and decode spatial imaging. Indeed, the only aspect of perceived sound, that is not virtually wholly dependent upon this first arrival direct waveform, is overall tonal balance, which does also take into account the later reverberant sound that is received indirectly from the loudspeaker via the room's acoustics. Thus, it is a huge mistake for electronic room equalization to mangle this first arrival direct sound, and thereby mangle all the information that our ear/brains derive from this first arrival sound, just for the sake of getting flatter overall tonal balance from the room's reverberant sound (and flatter only over the long run, which itself is irrelevant to how we hear).
      All of the genuine initial musical transient comes from the loudspeaker (and from its driving electronics, including the electronic room equalization), whereas all of the spurious lingering resonance boom after the genuine initial musical transient comes from the later room echoes. And the only thing that the loudspeaker does put out (assuming for the moment an accurate loudspeaker) is that genuine initial musical transient. It does not directly contribute any of the later lingering boom from the room's resonant response. Also, all of the first arrival sound comes from the loudspeaker, and none of it from the later room response.
      Put these three facts together and you see that the direct first arrival sound consists entirely of (and represents only) the genuine initial musical transient, and comes only from the loudspeaker (not the room), and passes through the electronic room equalization on its way to the loudspeaker. Thus, electronic room equalization mangles all of the direct first arrival sound, as well as mangling all of the genuine initial musical transient, and in both the time and frequency domains. Therefore, electronic room equalization mangles all the important sonic information that our ear/brain derives from direct first arrival sound, as well as mangling the entire sound of that genuine initial musical transient.
      The true problem is the room's later misbehaving resonant response, after you have already heard the accurate genuine initial musical transient in its entirety and after you have already heard the direct first arrival sound in its entirety. But electronic room equalization can't directly attack that true later problem, so it attacks and alters the genuine signal at the only point in the chain it can, earlier in the chain, before you have even heard the genuine initial musical transient and before you have even heard the direct first arrival sound. The only way that electronic room equalization can do anything, to affect the true later room problem, is to mangle the genuine initial musical transient and mangle the direct first arrival sound, thereby distorting these vital sonic keystones, and making the sound inaccurate.

-- Buttkicker Control

      We've seen that the X1's boundary EQ control is actually ineffectual at addressing any of the three distinct boundary phenomena discussed above. What then, if anything, is this control good for? It is very good indeed at one thing. The owner's manual should drop its instructions to set this control in accordance with your loudspeaker placement relative to room boundaries. And the label above this knob should not include the word "boundary" at all. Instead, the label above this knob should simply say "Buttkicker". And this owner's manual instructions should simply tell you to adjust this control as you please, for your taste (and for the program material), depending on how much you want your system to kick butt.
      Why does this control work so well as a buttkicker control? Recall our opening discussion on this control. We noted that its 40 Hz frequency, for boosting or cutting, was very effective for three reasons. The ear is more sensitive to bass here than at lower bass frequencies; and a woofer driver can pump out more audible energy here than at lower bass frequencies without suffering excessive excursion; and most program material has more energy around 40 Hz than at lower bass frequencies. Hence, if you are in the mood to have your system kick more butt on some occasions, or with certain film soundtracks, but have it kick less butt on say relaxing cocktail music or chamber jazz, you can simply use this control to quickly and easily tailor your system sound to suit your mood and the program material.
      This boost or cut control, centered at this optimal frequency of 40 Hz, can and should be used as a purely subjective tool, to kick as much or as little butt as you want to, whenever you please. Note that there are no instructional guidelines for the proper setting of this control. You can't do it wrong. Whatever you want is right, and you can change what you want from day to day, from one type of music to another kind of film soundtrack. Because its sonic effect at 40 Hz is so audible, and so easily accommodated by a decent subwoofer, and so richly fed by energy at 40 Hz from most program material, your changes to this control are instantly gratifying. It's a wonderful tool for getting the most enjoyment out of your Evolution system, and enjoyment is really what it's all about. So just relax and enjoy playing with this so-called boundary EQ control. Crank it up to whatever degree pleases you best when you want to kick more butt, and turn it down to whatever setting you please when you want to kick less butt.
      Our only advice is that you set this control to zero flat (straight up) during the several week period when you are fine tuning all the other parameters of your Evolution system (including loudspeaker placement and orientation, and all the other X1 controls), so that you hear the sonic effect of all these other parameters against a neutral baseline at 40 Hz. We'd suggest that you do play with this control when you first set up the Evolution system, just so you become familiar with its sonic effect. Then set it to flat and leave it there while you do your several weeks worth of experimentation to fine tune all the other Evolution system parameters. Toward the end of your fine tuning period, you might try dialing in a little boost or cut at 40 Hz with this control, just to see if this gets you closer to the neutral baseline that you want for the sound of your Evolution system. If you do find that you prefer a setting other than flat (zero) for this control, to give you the sonically neutral baseline you want for your Evolution system, then make a written note of what this other setting is, so you can always return to this sonically neutral baseline in the future. After that, you're free to cut loose and have fun with this buttkicker control.

Phase Control

      This front panel control is subtle in its sonic effect, yet spectacular in its effectiveness. It is nothing less than the lynchpin which brings the Evolution system together as an integrated, seamless presenter of sound.
      Most other loudspeaker setups incorporating physically separate subwoofers have a big problem with sonic integration. Over in left field you hear the satellite playing the mid and upper frequencies, while over in right field you hear the subwoofer thudding and pumping away, as a separate entity. The two are creating and contributing distinct, separate, and different kinds of sonic events. Sometimes it sounds as if there is no common game plan between them, and they might as well be playing different pieces of music. Certainly there is little sense that they are coordinating their outputs into a single, integrated sonic presentation.
      One key reason, for this common failure to integrate, is timing error. The human ear/brain is quite sensitive at discerning when two sonic sources are temporally misaligned and out of synch with each other. And we are more sensitive to hearing the effects from two sources being out of synch when they are both radiating energy at the same frequency, which a subwoofer and satellite are both doing throughout their mutual crossover region, where their frequency responses overlap. Furthermore, when two sources radiating the same frequency region are out of synch, interference patterns between their radiated energy cause peaks and dips in the response curve, and our hearing is very sensitive to hearing the tonal colorations wrought by these peaks and dips.
      Just how sensitive is human hearing to such misalignment, down at the 80 to 100 Hz frequency where subwoofers and satellites typically cross over to each other and are therefore jointly radiating? We conducted a research experiment to specifically find this out, and we discovered that the quality of bass, and the sense of sonic integration between subwoofer and satellite, was audibly degraded when the subwoofer and satellite were misaligned by merely 1/2 inch away from their sonically optimum alignment. Since sonically optimum integration, between subwoofer and satellite, requires alignment within 1/2 inch, yet subwoofers are usually several feet away from satellites, it's no wonder that most loudspeaker setups fail by a wide margin to achieve sonic integration between subwoofer and satellite.
      It would obviously be a painstaking task for you to physically align your subwoofer with your satellite, within this 1/2 inch tolerance. The sonic effect of proper integration is subtle, so you'd have to listen for a subtle effect, get up to move the subwoofer 1/2 inch, and then try to remember the subtle effect while you go back to your listening seat to hear whether this subtle effect gets better or worse with each small movement of the subwoofer.
      And there are other reasons why physical alignment is impractical and even undesirable. Ideally, you want to place your subwoofers where they minimally excite your room's resonance modes, but you want to place your satellites where they can give you the best spatial imaging portrayal, and these two kinds of locations do not coincide. Furthermore, correct physical alignment of a subwoofer with a satellite would place the subwoofer in front of the satellite (closer to you), where the subwoofer might well act as an undesirable degrader of the satellite's sound coming at you, artificially coloring and diffracting the satellite's sound, and degrading spatial imaging by acting as a secondary reflecting source.
      If it is impractical and even undesirable to physically align the subwoofer with the satellite, what can you do in order to achieve good sonic integration between them? You could align them electrically instead of physically.
      And that's exactly what the magic phase control of the X1 accomplishes. By electrically rotating the phase of the signal it feeds to the subwoofer, this X1 control effectively moves your subwoofer closer to you or farther from you. Because the X1's phase control is a continuously variable rotating knob, you can achieve perfect temporal alignment with your satellite, giving you optimum sonic integration between subwoofer and satellite. And, because this control is continuously variable, it's very quick and easy for you to lock on to this perfect alignment, because you have instant feedback between your hand rotating the knob and your ear hearing the sonic change.
      When you set this magic phase control on the X1 just right, the whole Evolution system sonically integrates and jells, in a way that eludes most other loudspeaker systems that have separate subwoofers. The bass literally becomes part of the music (and all sounds), rather than being a separate sonic event. The upper bass and warmth regions, shared by the two sources (subwoofer and satellite), assume a solidity and coherence that they lack when the phase control is out of alignment (and also lack in most other loudspeaker systems, where the bass phase and timing is very much out of alignment). Incidentally, NHT has also included this bass phase control in their previous electronic crossovers and subwoofer control units.

-- Easy Sonic Optimization

      It's very quick and easy for you to optimally set this phase control, if you merely employ suitable program material. The best we've found so far is sustained legato bowing of massed string double basses, such as you'll find in many 19th century works for symphonic orchestra. This sound has ample energy throughout the crossover region, thereby being suitably critical of exact alignment between the two contributing sources, the subwoofer and satellite. And, because it is a continuous, steady sound, you can very quickly dial in the optimum setting for the X1 phase control, since you always hear the same sound as a constant test signal, while rotating the knob back and forth.
      Most importantly, this kind of sound makes it aurally more obvious when you are at the optimum alignment point. Why? If you had to listen for subtle sonic effects like solidity, coherence, or integration, it would be more difficult to find the optimum control setting. But with this sound of a bowed double bass ensemble, all you have to listen for is maximum loudness in the upper bass and warmth regions. And of course it's much easier to listen for the point of maximum loudness than it is to be listening for a subtle sonic effect that you're not even familiar with yet.
      This bowed double bass sound furnishes this wonderfully easy cue, of maximum loudness, because it contains so much energy right in the crossover region, which means that, when the subwoofer and satellite are in perfect temporal alignment, they sum to produce the maximum loudness in this crossover region. Conversely, when the subwoofer and satellite are slightly off perfect alignment, there is destructive interference between these two sources outputting the same signal in the crossover spectral region where they overlap, so this destructive interference partially

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