Floor Loudspeaker Reviews

After a great deal of experimentation, I finally aligned the speakers so they fired close to straight ahead—with all the other ProAcs I've owned, I've aimed them directly at the listening position. The soundstage was very wide, but with too much toe-in, the stage became more narrow, the bass more uneven. Depth was excellent, mimicking whatever the source (analog or digital) contained. The deep, wide soundstage was located behind and around the speakers, with realistic layers in both directions. Placement upon the stage was precise, with no vagueness or wandering, while images within the stage were full and dimensional. Interestingly, the perception of the soundstage remained very good from locations other than the primary listening seat. All things considered, the 4s were superior to the 3s in soundstaging. Considering the speaker's size (which is necessary for deep bass extension), I'd assumed this would be one area where compromises would have to be made.

The 4s' soundstaging strengths were wonderfully illustrated by Chesky's marvelous reissue of Fritz Reiner and the Chicago Symphony Orchestra's performance of Rimsky-Korsakov's Scheherazade (RC4). The reproduced stage was realistically large for a full symphony orchestra, offering layers of width and depth for each section of the orchestra to occupy. Placement within the stage was precise and well-focused. I often found myself trying to find where the snare drum was located. With less populated soundstages, such as that found on PJ Harvey's Rid of Me (Island ILPS 514 606-1), the sensation of space between the performers was as tangible as the locations of the performers themselves. Once again, the sensation of depth was amply demonstrated by the placement of the drum kit.

While many small speakers have been criticized for creating small soundstages, many large speakers have been faulted for portraying larger-than-life soundstages. These kinds of shortcomings have often been misinterpreted—many of them are actually due to room and/or placement problems. Still, many speakers are incapable of conveying the differences in scale and dimensionality between solo performers and symphony orchestras. But the Response 4s always re-created the appropriate size and space of the performance—they effortlessly handled any full-sized musical event, including live heavy-metal recordings.

Historically, Stuart Tyler-designed speakers have impressed me with their extended, clear, and delicate treble performance. The ProAc 4 uses a special version of the tweeter found in the ProAc 3 and 3 Signature, with a lighter diaphragm and slightly different coating, and crossed over at a higher frequency. I expected a faster, more open presentation, so was surprised at the 4s' slightly closed-in sound—until I removed the grille covers. Once they were off, the top end opened up and displayed the characteristic ProAc treble splendor. The triangle on Scheherazade was clear and delicate, floating realistically within the stage, with quick percussive attacks and naturally diminishing decays. The cymbals on the SBM version of "Blue Rondo à la Turk" on Dave Brubeck's Time Out (Columbia CK 52860) were remarkably lifelike, especially on a digital source.

Although the 4s are big speakers (footnote 2), their overall sonic performance was remarkably seamless and coherent—and I was sitting as close to these speakers as I do much smaller two-ways. The coherency was particularly impressive on full-range, well-recorded piano, such as Dick Hyman's direct-to-CD rendition of Fats Waller tunes (Reference RR33 DCD).

The speakers' amplification needs also surprised me. Many big speakers make awesome demands of amplifiers—they often require tremendous amounts of power, unlimited current delivery, or multiple amps capable of both power and current delivery. But because the 4s have a high sensitivity (89dB/W/m), a nominal 8 ohm impedance, and jumpers (so they can be driven with a single amp with output as low as 50W), they didn't need unusual or unduly expensive amplification—a single, sonically excellent, low-powered amp could do the job. This will dramatically lower the cost of using this expensive speaker in a real-world audio system. Although an unlikely combination, I had very good success using the modestly priced and powered AMC CVT-3030 (footnote 3) with the 4s.

Conclusion
The ProAc 4's musicality was consistently satisfying—the speaker never sounded offensive. There wasn't anything obviously added to the music or done to the sound. From simple performances such as Dick Hyman's solo piano to such full orchestral warhorses as Scheherazade, the ProAc always sounded natural and musical. It never drew attention to itself with excessive deep bass, ruthlessly revealing detail, or blistering transient re-creation. The music was always the center of attention.

One of the enduring paradoxes of high-end audio is the lack of convergence on the sound of real music. I've always expected ultra-expensive products to sound more similar to one another as they (supposedly) approach the real thing. I'm always amazed that megabuck speakers such as the Apogee Grand, Wilson WAMM, Infinity IRS V, and Genesis One sound as dissimilar to one another as modestly priced speakers like the Vandersteen 2Ce, Spica Angelus, and Thiel CS1.2. Part of this paradox is the growing number of truly excellent speakers in the $10,000-$25,000 range, including the Wilson WATT/Puppy/WHOW, B&W Matrix 800, Avalon Ascent, Sonus Faber Extrema, Hales System One Signature, Apogee Studio Grand, Magnepan MG-20, Sound-Lab A-1, Thiel CS5, and now the stunning ProAc Response 4.

A second irony almost mimics genetics: Differently priced speakers from the same designer tend to sound more similar to one another than similarly priced speakers from different companies. Just as there are family resemblances among the various Vandersteens or Thiels or MartinLogans, the ProAc line has clearly sprung forth from Stuart Tyler's fertile mind. While the Response 4 is clearly a sonic relative of the Response 2 and 3, it has the added dimension of wonderfully deep bass performance.

Probably the 4's most important innovation is the bass's three-way electrical crossover and four-way mechanical crossover. The top woofer has a smaller chamber than the bottom one, which causes them to cover slightly different ranges. Both bass chambers load into a center chamber ported out the rear.

The ProAc Response 4 is a stunning, world-class performer in every regard. It is well deserving of a Class A recommendation and has become a cherished component of my reference system. I recommend that you do whatever it takes to hear this lovely loudspeaker. It deserves to be compared with any speaker at any price.

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Footnote 2: The five drivers are arranged in a pseudo-D'Appolito configuration; ie, the speaker arrays aren't strictly vertical as the higher-range drivers are progressively offset toward the inside of the mirror-imaged cabinets. The 4 also has a complex crossover and a rear-firing port in its physically imposing cabinet.—Jack English

Footnote 3: Reviewed in Stereophile, Vol.16 No.6, p.146.—Jack English