Initial Listening
As mentioned earlier, I was curious about how well the AVAA C214 would perform in my space, which was already quite well-treated with passive methods. However, I believe most people will prefer to buy a pair of C214s before undertaking the extensive passive treatment of the room that I have described. Thus, the units will normally be used in a space with predominantly bare walls.
To accommodate this, I removed the two 110 x 160-cm Mass Spring Bass Absorbers from the back of the room, which are normally located behind the listening position to help tame the room’s largest room mode at 30Hz. Because this resonance is so low, it is very hard to fully eliminate, even with multiple large, tuned panels (I use six). These panels are tuned to my room’s problematic 30Hz, but still work quite well up to several octaves above. With these panels removed, a large, untreated acoustic area remains, 1,5 meters deep and more than 3 meters wide. A corridor with a bare ceiling, wall, and floor of this size is normally a recipe for trouble, and indeed, when standing in that area and talking, you can hear that it sounds hollow. The reflections color the sound, add blur, and greatly increase the decay of several low frequencies when playing music.
Adding such a small product as a single AVAA C214 in the middle of this bare space seems visually silly, but its effect is anything but small! In fact, the single C214 provides a very similar improvement in bass to the two passive panels. When playing the aforementioned pulsating test tones, the C214’s benefits are immediately obvious. Without the C214, the pulses at these frequencies blur together, sounding like wobbly continuous tones. With it switched on, the pulses suddenly resemble a square wave: much drier and staccato, and now distinctly switching on and off. There you have it: the AVAA C214 does precisely what they promise, reducing the loudest room mode at 30Hz and removing most of its decay while improving other boomy low-bass frequencies just as easily. Importantly, it works fully transparently, affecting only the room’s undesired reverb, blur, and boom, and doing nothing else whatsoever. This is something that porous absorbers can only aspire to. And even when they work at such low frequencies, then only very narrowband, while the C214 simply covers the entire bass range between 15Hz and 160Hz.
When playing music, you also hear right away that the sound is now much tighter and cleaner. The more even-handed bass and significantly shortened reverb lead to a much more articulate and precise bass. Bass lines are easier to follow, and the performance becomes rhythmically more interesting.
Adding a second C214 unit and spacing them almost two meters apart again did precisely what one would expect. The second unit enhanced what the first unit did and delivered even more precise, incisive bass. While it was definitely better, it was not twice as good. For this area, a single unit and two other passive panels would be a more reasonable solution.
Remarkably, the improvement in bass from a single C214 is equivalent to that of two large panels, which is even more amazing given the unit’s small size. However, the C214 has a different impact on the rest of the sound than the two large panels. This is only logical, as the C214 stops working at 160Hz, where the panels continue to provide damping. This is audible as a reduction in midrange clarity, some flutter echo, and a larger, albeit more diffuse soundstage. With the panels back in place, the sound becomes more intimate and direct, confirming that a large empty space also needs a bit of damping in addition to bass treatment alone. However, treating higher frequencies is far easier than treating low bass, and much more cost-effective as well.
Gain
The gain can be set on the unit itself using two buttons on the back, or via the Android or iPhone app. In most cases, the default 0dB gain setting will work very well. If there are obstacles near the unit, a lower setting may be needed. Alternatively, where possible, a higher setting can yield even more efficiency. I found that +3dB maximizes performance in my room. It should be noted that when set too high, the C214 can enter a feedback loop in which it starts amplifying its own signal, like a microphone too close to a speaker. This can also happen when standing in front of a unit with high gain or when covering the microphone area. However, unlike a traditional microphone feedback loop, the C214 auto-senses this condition and temporarily reduces gain until it stabilizes.
Above: The setup before testing for this review, with the speakers halfway into the room.
Below: The rearranged setup after testing for this review, with the speakers much closer to the rear wall.
About the room
The front wall of my listening area is already well treated with two Mass Spring Bass Absorbers in the left and right corners, and one more in the middle, covered with ArtNovion Douro W diffusers to avoid excessive damping, which is especially important because the Apogee Duetta Signature speakers are full-range dipoles. There are also three Vicoustic VicTotems: one in each corner to reduce upper bass resonance and manage reflections, and one more in the left corner to help treat the bass. With these measures, the front wall is almost entirely covered. The back of the room is asymmetrical and only problematic on the right-hand end. This corner is covered with two R.T.F.S. Big Blocks. Since the kitchen area and an adjacent open space are on the left, the far-left corner is essentially non-existent.
With these passive bass traps, I was able to place the speakers closer to the front wall than before (now 194 cm versus 3,5 meters), resulting in more powerful bass with no more nulls. Before the addition of the Mass Spring Bass Absorbers, such placement came at a steep price, with huge bass peaks, a boomy sound, and significant coloration. Although I now finally had a relatively even-handed frequency response down to 40 Hz, I still had to accept some room-induced bass blur and coloration, as well as some remaining peaks with too much decay at 30 Hz and 40 Hz.
Before this review, the only way to reduce the aforementioned resonances was to position the speakers much closer to the listening position, almost halfway into the room. This yields a very clean and transparent sound, but at the expense of rolled-off bass below 70Hz and the introduction of nulls, which cannot be effectively corrected with acoustic treatment or, for that matter, with DSP. This has to be addressed by adjusting the speaker placement and the listening position, which, in turn, results in excess coloration. And that is where my primary interest in the AVAA C214 comes in.
Serious Listening
Initially, I got sent one pair of AVAA C214s. After connecting them with long power cables, I tested the room using the Grimm test tones. As expected, the two front wall corners were the biggest offenders, and predominantly the left corner. When standing in the right back corner, I could hear multiple resonances, but at a lower volume than in the other corners. In any event, since the sofa was positioned further from the back wall, I no longer felt that this corner had much of an influence on the listening position anymore. Nevertheless, I placed a C214 in several positions in that corner and listened to all the test tones, not just in the listening position but everywhere in the room, but the C214 did not appear to have an effect in that corner.
Interestingly, the C214 was initially highly beneficial when placed in the recess in the glass wall on the right, where the room widens. Usually, bass traps do not increase bass output, but sometimes they do. Here, they counteracted a 50 Hz mode that reduced bass output at that frequency in the listening position, making it very noticeably stronger and clearer.
However, its benefit was specific to 50Hz, and I felt that the C214 had a broader effect when placed at the front wall, so I continued experimenting with that first.
Next: Listening Continued
