quarters of its fully spherical radiation pattern. Thus, the subwoofer's bass will now be four times stronger within that one quarter sphere, in which both you and your entire room happen to be situated.
      Finally, suppose that that you back the subwoofer up against the junction of two walls, also known as a corner. The subwoofer's free radiation will now be confined to just one eighth of a sphere, by the floor and the two walls meeting at the corner. The remaining seven eighths of the subwoofer's output will be reflected by the floor and two walls, and will thereby add to the subwoofer's free radiation into the one eighth sphere. Thus, you will hear the subwoofer playing bass eight times louder than you would in open space. And since your entire room is situated within this one eighth sphere, as the subwoofer looks out at the room from its corner, your entire room will experience bass eight times louder from the subwoofer.
      Now, we can assume that you'd always be keeping a subwoofer on the floor. If you position the subwoofer on the floor but away from all walls, you and your room will experience one given level of bass energy from this subwoofer (which incidentally happens to be twice the bass energy you'd experience in the unrealistic setting of open space). But, if you position the subwoofer against a single wall instead of the middle of the floor, you'll get twice as much bass energy. And, if you position the subwoofer in a corner, you'll get four times as much bass energy. In short, you can vary the amount of bass energy by a four to one ratio, depending on where you position it relative to your room walls (keeping it always on the floor). And you could therefore use subwoofer placement as a means for fine tuning the amount of bass energy you get.
      However, there are other important reasons for choosing particular subwoofer locations within your room, relative to your room boundaries. It is wise to place the subwoofers pretty close to at least the main satellites (or even all satellites), in order to obtain better sonic integration between subwoofer and satellite, and satellites need to be placed for best spatial imaging and other considerations. It might also be wise to place the subwoofers at positions where they do not trigger bad resonant modes that your room might have, and locations at wall boundaries (especially corners) are worst for this desideratum. It's sonically detrimental to excite room modes because they degrade bass quality, adding a lingering overhang that destroys bass definition and generally muddies the overall sound. Thus, you should place your subwoofers to optimize these important factors. And that means we must look to other means to control the quantity of bass energy.
      Fortunately, the X1 provides a handy such means, for adjusting the amount of bass energy you get from your subwoofer, and for thereby compensating for the bass energy boost you get if you place the subwoofer near room wall boundaries. But this means is not the X1's boundary EQ control. Instead, this means is simply the X1's subwoofer master gain control (and of course every subwoofer control center has such a gain control).
      You see, this boundary reinforcement phenomenon, which multiplies the subwoofer's bass output, affects the entire spectral range of the subwoofer's output. Thus, in order to compensate for this multiplying boost, all you need do is turn down the subwoofer volume control that likewise affects the entire spectral range of the subwoofer's output. It would be most inappropriate to turn down the volume of only a portion of the subwoofer's spectral range. And that's all the X1's boundary EQ control can do: turn down (or boost up) the portion of the subwoofer's spectral range at 40 Hz.
      As you can see, the essential reason that the X1's boundary EQ control fails to adequately address this first boundary phenomenon is that this phenomenon affects the whole subwoofer output, over its whole spectral range, and therefore requires compensating adjustment of the subwoofer's whole spectral range, whereas the X1's boundary EQ control is narrowly restricted to chiefly affecting only the 40 Hz portion.
      The X1's boundary EQ control likewise fails to adequately address the second distinct boundary phenomenon. This second phenomenon does occur at a specific frequency, in contrast to the first phenomenon that affected the entire subwoofer range. However, the specific frequency, at which this second phenomenon occurs, varies with room placement of the subwoofer relative to the room boundaries. So a compensating adjustment would have to have the ability to be applied at a variable specific frequency, but the X1 boundary EQ control only operates at a fixed specific frequency (40 Hz). Thus, the essential reason that the X1's boundary EQ control fails to adequately address this second boundary phenomenon is that this phenomenon can occur at various frequencies, and therefore requires that the compensating adjustment be targetable to these various specific frequencies, whereas the X1's boundary EQ control chiefly affects only a fixed, invariable frequency.

-- Boundary Interference

      This second boundary phenomenon comes into play when you position your subwoofer at any distance from a room boundary (i.e. wall), instead of right at a wall boundary (thus, it comes into play for every placement save corner placement). Whenever a subwoofer (or any loudspeaker) is located any distance from a room boundary, the reflection, coming back at the subwoofer from that boundary, interferes with fresh new sound coming out of the subwoofer. This interference produces an additive hump in the frequency response, at the specific frequency whose half wavelength corresponds to the distance to that boundary. And it also produces a subtractive valley in the frequency response, at the specific frequency one octave lower, whose quarter wavelength corresponds to the distance to that boundary.
      Obviously, as you change the position of the subwoofer relative to the room wall boundaries, you change this distance to nearby boundaries, and so you also thereby change the specific frequency at which the frequency response hump (and valley) occur. Thus, in order to deal with and compensate for either the frequency response hump or valley, a filter like the X1's boundary EQ control would have to be adjustable in frequency. The bandpass filter behind the X1's boundary EQ control does have the correct general shape to deal with this second boundary phenomenon, and equalize it, but it lacks the crucial ability to be variable in frequency, in order to match the actual frequency of the frequency response hump or valley that was caused by your particular positioning of the subwoofer relative to the room boundaries. And of course there should be two such filters, one to equalize (compensate for and flatten) the hump and another to equalize the valley one octave down. There are parametric equalizers which do have this ability, to vary the frequency at which they compensate for a hump or valley, but they cost more than the entire X1. The X1's bandpass filter could be modified to include this variable frequency capability, and a pair of such filters could handle this second boundary phenomenon, but adding this feature would naturally add to the X1's price.
      What about the tactic of simply positioning the subwoofer at the correct distance from your room boundaries, specifically to take advantage of the fact that the frequency of the X1's boundary EQ filter is preset at a fixed 40 Hz? In other words, why not simply move the subwoofer until it is far enough away from your room walls so that the hump or valley from this second boundary phenomenon occurs at 40 Hz, at which point the X1's boundary EQ control could come to the rescue?
      Unfortunately, this won't work in practice. First, you should give priority to the other, more important factors for optimally locating your subwoofers (integration with the satellites and minimization of room modes). Second, this second boundary phenomenon normally occurs at frequencies much higher than 40 Hz, so it is way beyond the reach of the fixed X1 filter preset at 40 Hz. In fact, in order to move the valley from this second boundary phenomenon down to 40 Hz, so the X1's boundary control could address it, you'd have to move your subwoofer until it was 7 feet away from the nearest wall. And, in order to move the hump from this second boundary phenomenon down to 40 Hz, so the X1's boundary control could address it, you'd have to move your subwoofer until it was 14 feet away from the nearest wall. Thus, even if you were willing to have only one subwoofer and place it dead center in your room (which is inadvisable for triggering room modes), this tactic would only work if you had a giant listening room that was 28 feet across (in its smaller dimension).

-- Room Resonance Modes

      The third boundary phenomenon pertains to your particular room's resonant modes, which are established by the distances between your several room boundaries. These distances are fixed (unless your walls are movable on tracks, as in that Poe horror story), which means that the frequencies and nature of your room modes are fixed. In the case of this third boundary phenomenon, then, the locations where you choose to position the subwoofers, relative to the room boundaries, does not affect the frequencies of this third boundary phenomenon (in contrast to the second boundary phenomenon above). Moving the subwoofers to different room locations merely serves to trigger these fixed frequency room modes to greater or lesser degrees.
      Incidentally, the corner location for a subwoofer, which does give the strongest amplitude bass, is the worst for triggering the most room resonance modes to the worst degree. And it is very undesirable to trigger these room resonance modes significantly, because their lingering temporal overhang horribly degrades bass quality, and also muddies your system's transparency over the entire spectrum (since the overhang obscures genuine music or sound occurring immediately after each bass transient that triggers the room's resonance overhang).
      Can the X1's boundary EQ control help you deal with this third boundary phenomenon? Not very well. If your one (or more) of your room dimensions just happens to be 14 feet, such that your room has one of its resonance modes right at 40 Hz, then and only then might the X1's boundary EQ control be of slight help in reducing the magnitude of the sonic problems of this one mode (but it would still not help at all with your room's other resonance modes at other frequencies, modes which occur between the other sets of boundaries along the other dimensions of your room). And even if your room does happen to have this 14 foot dimension between boundaries that yields a resonance mode right at 40 Hz, the X1's boundary EQ control still doesn't address this problem correctly. That's because the X1's boundary EQ control can only reduce the magnitude of the lingering overhang, but it cannot reduce the temporal duration of this malicious lingering overhang. Thus, the lingering overhang would still be degrading bass quality and muddying your system for as long a period of time as before, and the only benefit achieved by the X1 would be that the amplitude of this lingering degradation would not be as obnoxiously obvious.
      The true cure for this acoustic problem is to avoid triggering this lingering overhang, from the room's resonance mode, in the first place. And this is achieved by moving the subwoofer to a different location in the room, not by leaving the subwoofer in situ and reducing its input via the X1. If you leave the subwoofer in a place where it excites your room's 40 Hz resonance mode, and merely use the X1's boundary EQ control to lower the input to the subwoofer until it "sounds flat", then all you've accomplished is to make the majority of the sound you hear at 40 Hz consist of poor quality garbage, a lingering boom that still lasts long after it should stop. You have not improved the slow, long lasting time signature of the misbehavior at all. So you would not have achieved quick, high quality bass transient response at all, around 40 Hz.
      If you want to make the majority of sound at 40 Hz consist of quick, high quality, and accurate bass, instead of booming lingering garbage, you have to move the subwoofer to a different location in your room. In other words, the X1's boundary EQ control is of no help at all in solving the real problem, in turning garbagy boom energy into high quality and accurate bass. And, after you do move the subwoofer to a location in your room where it does not trigger the room's 40 Hz mode, and get your quick, high quality bass at 40 Hz, then you'll probably be moving the X1's ineffectual boundary EQ control back up to flat anyway.
      The X1's boundary EQ control is actually deceptively misleading in handling this third boundary phenomenon, because it might fool you into thinking that it has solved the problem by excessive room resonance mode energy at 40 Hz, but in fact all it can do is to fool you into accepting lesser quantity of the lingering booming garbage (which still lingers just as long) as a poor substitute for quicker, more accurate bass transient response.
      Incidentally, that's also why electronic room equalization products, including the latest ones that are all the rage in some quarters, are also ineffectual at solving the problems caused by this third boundary phenomenon of a room's resonance modes. If the loudspeaker is in a room location where it triggers those room modes, then the slow, long lasting time signature of the garbagy boom will remain, regardless of whether you lessen the amplitude of the triggering frequency. All the room equalization box can do is to lower the overall energy at 40 Hz, as averaged over time, but it cannot change the composition of that energy to make more of it into quick, accurate bass and to make less of it be that slow, lingering garbagy boom. If 90% of the energy you hear at 40 Hz is in the form of a long, lingering room boom instead of quick, accurate bass, then the room equalization box can only reduce the amplitude of this boom, but it cannot improve upon the sorry fact that 90% of what you hear at 40 Hz is slow, lingering boomy garbage, regardless of what volume level the equalization box reduces the level of overall energy at 40 Hz down to.
      Indeed, it's a complete misnomer to even call these electronic boxes "room equalizers". They don't change the room's behavior or the room's reaction to the triggering loudspeaker location. Only changing the location of the loudspeaker can get it out of the triggering location that triggers the room's resonance modes and the consequent lingering misbehavior of the room. And only genuine bass absorbers (like ASC Tube Traps) can address the misbehavior of the room itself.
      Electronic room equalization makes the same fundamental, fatal mistakes that conventional frequency response curves do: they can only measure an average over time, so they cannot tell if something is very wrong for part of the time (but seemingly offset by a complementary error later in time); and they cannot tell the difference between energy from accurate reproduction and garbage energy from spurious response, so they conflate the two and can only tell you if the sum of the two seems OK. But the human ear/brain is excellent at time slicing and temporal analysis, so we can easily tell if something is wrong for part of the time, and then something else is wrong later in time, and for us these two errors do not at all average out to offset each other over time, as the frequency response measurement and the electronic room equalizer was fooled into reporting. And the human ear/brain can easily tell the difference between accurate reproduction and spurious garbage energy, and we enjoy one but detest the other, so it is emphatically unacceptable for a frequency response curve or room equalizer to only look at the total sum of accurate energy plus garbage energy and report everything is OK, when what matters most to us is the composition of that total sum (what proportion of it is accurate and what proportion is garbage).
      If a room resonance imparts a lingering boom at 40 Hz, when triggered by a musical transient containing some 40 Hz energy, then electronic room equalization is helpless to attack or cure the true problem, the room. The only thing that electronic room equalization can do is to diminish the amount of 40 Hz energy in the initial genuine musical (or sound effect) transient. But that's the wrong thing to attack, and the wrong thing to change, and the wrong thing to diminish.
      The human ear/brain can easily tell the difference between the genuine initial quick musical transient and the subsequent long lingering boom from the room. Electronic room equalization mistakenly lumps them together, performs a time averaged measurement of their sum over time, and says, hmm, since there's too much energy at 40 Hz over this long span of time, I have to reduce that, and since the only point at which I can do anything is when the initial quick musical transient occurs (that's when the electronic signal passes through all electronics in the system, even though the actual problem to be fixed is the acoustical room resonance that occurs and lingers much later), I have to suck energy at 40 Hz out of that initial genuine musical transient, and since that 40 Hz room resonance lingers so long while the initial musical transient is here for such a short time, I have to suck a whole lot of energy at 40 Hz out of that genuine initial musical transient, so that the average sum total of 40 Hz energy over time, including that long lingering boom later on from the room, comes out looking OK.
      But of course that doesn't sound OK to us human listeners. For we can hear that the genuine initial musical transient now sounds very different, having been sucked dry of 40 Hz energy. And we can hear that the long lingering room boom is still there.
      And even though that 40 Hz room boom is now quieter in level (since the triggering energy has been reduced), a discriminating listener can tell that the sound is now actually worse. Why? Because the 40 Hz energy he is now hearing consists primarily of garbage (the lingering room boom), with proportionally less of the accurate 40 Hz energy in the genuine initial musical transient than there was before. Thus, the composition of the 40 Hz energy has perceptually worsened, becoming primarily garbage lingering boom and very little genuine initial energy. Furthermore, the sound of the genuine initial musical transient has also worsened and become less real, since it has been robbed of the 40 Hz energy in its composition (and, with our ear/brain's time slicing capability, we can separate out and analyze the sound of that initial musical transient, and we can tell that something is no longer genuine about it).
      A vocal example, which you can participate in, might help illustrate the charade that is being foisted upon you. Imagine that the explosive word "Pop!" represents the original, genuine, quick musical transient, and pretend that the quick "o" sound in the middle of "Pop!" represents 40 Hz energy (or any other frequency at which a room might resonate). Now, suppose that the room resonance responds to this quick "o" sound with a spurious, lingering boom at this same frequency,

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