I positioned the components of the Pro Room Pack 10 according to a diagram Calder supplied (shown on this review’s first page). Two CornerSorbers were deployed in each corner behind the loudspeakers, each with a Fabric-Wrapped Panel above it. This wall was also treated with a pair of Medium Curve Diffusors about six feet apart centered behind the speakers. Each sidewall was treated with three Curve Diffusors, one horizontally mounted on the wall next to the speaker, one at the sidewall reflection point, and one on the wall directly to the side of the listening seat. Behind the listening seat, four Fabric-Wrapped Panels were deployed in the corners, and two Curve Diffusors positioned horizontally directly behind the seat.
I had plenty of time to evaluate the Acoustic Geometry package. I started by listening in my untreated room, then added the Pro Room Pack 10 all at once. I lived with the treated room for several months, and then removed all the components of the Pro Pack 10 and listened again to the untreated room. I then incrementally added each component of the Acoustic Geometry package back into the room, but in pairs (two CornerSorbers, two Curve Diffusors, etc.) to maintain room symmetry. I listened to the effect of each product individually and then finally to the whole system, once all the treatments were back in place. A few months later I removed all the Acoustic Geometry products and listened again to the untreated room. This experience gave me a very good sense of exactly what each of the products contributed to the sound, as well as the efficacy of the entire package.
My main loudspeakers through these listening tests were Piega C711s augmented with a JL Audio Fathom f113v2 subwoofer and CR-1 crossover. This combination is capable of prodigious bass output, making it a good source for evaluating the treatment’s effect on the bass.
First considering each component’s effect, I brought one pair of CornerSorbers into the untreated room (one per corner) and listened, and then both pairs of CornerSorbers. Frankly, I was shocked by how effective the CornerSorbers were in cleaning up the entire bottom end. The CornerSorbers removed the boom and bloat in the bass, replacing a slow, muddy, and ponderous bottom end with one that had tautness, muscularity, pitch definition, and dynamic articulation. Transient detail that had been smeared was now vividly rendered, with sharper attack on the start of notes as well as faster decay. That quality engendered a greater sense of musicians playing together and driving the rhythm—a feeling of greater tightness and cohesion among the instrumentalists, a sense of agility, more propulsive and expressive rhythms, and a vividly upbeat quality. The untreated room sounded thick and slow by comparison. The music now had a solid foundation rather than a murky and ill-defined one. I could hear texture more clearly on acoustic bass, steeper attack and decay on kickdrum, and the wonderful way a great drummer and bass player work together to create the music’s dynamic underpinning. Adding the CornerSorbers was like lifting a wet heavy blanket off the sound.
By removing the smearing and bloat in the midbass, the CornerSorbers also allowed me to hear the lowest bass more clearly. It was an interesting phenomenon—I heard a lighter and leaner sound overall, but with simultaneously deeper extension. The midbass colorations had been masking the low bass. The album Jaco by bassist Brian Bromberg features some superb recordings of the virtuoso’s playing. His solo on the track “Portrait of Tracy” was a different experience with and without the CornerSorbers; each note was clearly articulated, defined, and with greater depth and power. His instrument’s timbre was also better resolved and more richly textured.
This wasn’t a subtle change. Often, adding a bass absorber in the corner behind the loudspeaker (always a good thing, by the way) results in an improvement, but one that doesn’t quite go far enough. That is, the absorber nudges the sound in the right direction, but not to the degree one wants. The CornerSorbers don’t suffer from that limitation, taking iron-fisted control over the low end rather than tinkering at the margins.
I noted all these qualities when I first heard the Pro Room Pack 10 as a complete package compared with the untreated room. But only when listening to individual components of the package did I fully realize what each was doing. All the wonderful improvements to the bass that I’ve just described increased in magnitude when I added four Curve Diffusors. Remember, the Curve Diffusors are also equipped with diaphragmatic bass absorption, although they are less effective at very low frequencies compared to the CornerSorbers. Each pair of Curve Diffusors that I added further tightened up the bass, made timbres more realistic, increased transient fidelity, and better resolved pitch. Rhiannon Giddens’ rendition of “That Lonesome Road” from her album Factory Girl features a huge-sounding “washtub” acoustic bass that comes in after her introduction with guitar and tambourine. With the CornerSorbers and Curve Diffusors the washtub bass was much more realistic in every way.
More importantly, however, the Curve Diffusors greatly opened up the soundstage, taking the sound out of the speakers and presenting a larger, more three-dimensional space populated by more clearly defined individual instruments. The Curve Diffusors also snapped the sound into focus, not just by making instruments more spatially distinct, but by generally clarifying their respective timbres. This made it easier to identify the tonal color of individual instruments rather than hearing them sounding smeared and homogenized. Going back to the Rhiannon Giddens’ track that starts with just her singing, accompanied by a guitar and tambourine, the tambourine without the Curve Diffusors sounded like a high-frequency noise, close to the front of the soundstage, dry with little air around it, and no resolution of the inner detail that conveys the mechanism by which the instrument makes sound. With the Curve Diffusors, suddenly the tambourine was surrounded by palpable air and bloom, conveying the impression of the sound expanding around it with each strike. The tambourine moved farther back in the soundstage, with the acoustic space around it better defined. I also heard much more resolution of fine detail that made the instrument’s timbre more realistic. The undifferentiated high-frequency transient noise was replaced by a richly textured rendering.
Similarly, I listened to background vocals with and without the Curve Diffusors. Without them, the vocals tended to sound fused together and attached to the speaker baffle. With the Curve Diffusors, they were detached from the speaker and seemed to wrap around the sides of the soundstage. Moreover, I could more clearly hear the contributions of the individual singers, with each one’s unique timbre intact. An audio component’s ability to resolve individual instruments from within the whole is an important quality in musical realism. I listen for this in DACs, amplifiers, loudspeakers, and every other component in the chain. But the degree to which the Acoustic Geometry products improved this aspect of the sound was far greater in magnitude than differences among electronics.