The implications of subwoofer efficiency, as seen in the removal of boundary reinforcement by an algorithm, are far-reaching and imply a shift in home audio design, and possibly industry measurement standards and disclosure. Let's find out how to be on the right side of physics as this new tech emerges.
This is an interesting topic and development in the industry with far-reaching implications that, I personally feel, the inventors do not fully understand, especially from a resulting physics standpoint in speaker systems design vs resulting capability. Newton's third law is critical, same with the law of the conservation of energy contributed to by Joule, Helmhotz, Mayer and others. Essentially, what these two laws mean is that compression is inefficiency and a form of audible distortion that cannot be stopped, but it can be managed. Now here is the juicy bit; we can find out how to control it, and it's something that Harbottle-Funk has been doing for close to 20 years so it is certainly not new.
As you try to manage frequency reflections and reinforcement effects, you must acknowledge that the room has its own impulse response and resonant frequency. True, this element can be ignored to a certain degree, but not when your system and room reach the point of trying to manipulate the effects of these factors. You cannot manipulate the result of physics by ignoring the cause of its effects. This point is found in car audio where competition car systems will be tuned to the resonant of the actual car structure in order to hit insane SPL numbers at that resonant.
If you look at any mechanical properties of materials book or database, you will see that many of these properties are all given a range (See footnote 1). This means that the mechanical behavior of building materials must require that the building is designed with a safety margin... which they are. This is why room modes are not 100% predictable. Yes, you can get close, but there are effects that shift, especially as the bandwidth and amplitude change. Any static structure has a threshold of maximum frequency and SPL; this is why seismic engineering measures are included in building design. However, this also means that on a much smaller scale, that is enjoyable and non-harming to people and the building itself, there are going to be effects that need to be designed around, or their existence acknowledged at minimum.
So now that we know that the room has a "personality," the ability to control the way sound behaves in that room must include the ability to control frequencies with their amplitude. This is a point to efficiency within the driver and subwoofer ecosystem because this is what efficiency means: controlling the frequency within the amplitude that equals the applied power into the driver. Now the bass control system can determine that the subwoofer will actually hit its target.
Every. Single. Time. And this means that your audio experience will be as consistant as the actual audio production mix is consistant.
So when a subwoofer is efficient within its stroke and ecosystem of parts; the box, the amp, the DSP, there are fewer unpredictable behaviors coming from the subwoofer, and now the Trinnov can do its job to a much larger and all-inclusive degree. The punchline is this; when a group of smart people come together and say "let's take DBA-like results and make it into an algorithm that we can use to make a planar wave and then direct said planar wave across many seats, and also make sure there is infrasonic ability while killing room modes," what they are in effect asking for is for the room to shut up to an extent that a DBA design can't really match. This represents a massive leap forward in audio, which is awesome for LDLC. Using logic, if you cannot hear the room reacting because all the subwoofer sound reflections are gone, then what you will hear is the stroke of the subwoofer, and by extension, you will hear its compression character or, more specifically, the character of inefficiency of the subwoofer. Now, because the subwoofer will reproduce 50 to 100 or so frequencies at the same time and in different combinations and durations and amplitudes, the sound below the first room mode will be unpredictable at maximum stroke and maximum power output. However, before you even get to maximum stroke, we must consider that first, it is a modulating efficiency curve reacting to the physics of a room, and so it will look more like a phase issue that gets worse as the output increases. The system will fall short in performance at unpredictable points due to the efficiency of the subwoofer being nonlinear, and the phase behavior below the first mode will only be predictable within a range or margin of error.
So if you are going to do any kind of bass control system, a subwoofer that is designed for maximum efficiency and full bandwidth from 180 Hz down to 5 Hz will be the best thing you can do for that result. This is found in Cassini, by Harbottle Audio.
So why do I say that the inventors of these systems may not understand the impact of their work? Because what they are doing is not only creating a DBA bass system, but then targeting the listening positions with the actual and very real sound that the subwoofers make... good or bad or inconsistent. The listener will hear the actual mechanical and electro-magnetic efficiency sound of the subwoofer, however quiet or loud that may be. This process is 100% dependant on the ability to create stroke that is clean from a mechanical standpoint, ie, THD, as well as from an electro-magnetic standpoint, ie compression and efficiency. Will Waveforming make bass better or worse? The answer depends on if your subwoofer system is efficienct. What it can do is expose audio system capability as it realtes to efficiency, and this can change the audio industry to a level that I, as an engineer, can't even imagine. The primary issue with subwoofers has always been room they are in, remove that effect and all you are left with is what the subwoofer can do... as in, what it can honestly do. The delineation between sound quality and capability can end up resembling the Grand Canyon, and this can really shift the entire audio industry in a huge way. Do I like Waveforming? Yes, I love it, my clients love it, I love the massive big brains at Trinnov, and I am thankful that I am not the only one gunning for efficiency.
Consumer Advice.
How to spot an efficient subwoofer: Look for a maximum allowable compression limit in dB at Xmax or past Xmax.
We use LDLC as a list of engineering mandates as well as the 1% Guarantee and the Xmax Guarantee. All of these serve the engineering model as they are all directly related to efficiency.
If you cannot find a guaranteed stroke limit and a compression limit, chances are the subwoofer will compress early and cause inconsistent audible behavior based on the program playback it is running. Remember, program playback (content) is about a million times more complex than a sine sweep or a sine burst.
Harbottle Audio: Engineering with purpose, removing design variables, and making the speaker play cleaner and purer content while discarding inefficient nonsense.
Footnote 1. The PDF below is the data that we use to engineer our LDLC compliant enclosures.