AOM Logo August 1997

The ProAc Response One SC Loudspeaker
A Little Slice of Heaven

Andrew Chasin

Although some may malign mini-monitors for sounding anemic and small, few can deny that they have several innate advantages. A mini-monitor's smaller, more inherently rigid cabinet will resist the not-so-good vibrations that often lead to cabinet-induced colorations. A smaller cabinet also presents less of an obstacle to a developing sound wave, resulting in less diffraction of the wave, and more precise imaging. While the relatively small bass drivers used in mini-monitors usually means that truly full-range reproduction is not possible, it also means that a mini-monitor will be fairly easy to place and will work well when placed close to room boundaries.

While small loudspeakers have several theoretical advantages over their more brawny brethren, the fact remains that their smallish drivers are often unable to move the kind of air required for a truly visceral experience, and many fail to satisfy on large scale orchestral or high-decibel rock music. Many mini-monitors also exhibit a tonal balance on the bright side of neutrality due to their relative lack of bottom-end energy. And let's not forget the requirement for stands on which to place a mini-monitor, which can add significantly to the total cost of the loudspeaker system.

It is a truly great loudspeaker designer who can fully realize the potential strengths of a small loudspeaker while balancing these strengths with the speaker's inevitable sonic shortcomings. Vincent Bruzzeze of Totem Acoustics was successful at doing just that with his Model 1, a loudspeaker which has always struck me as one of the best buys in audio. Ditto for ProAc's Stewart Tyler, whose Tablette 50 and Tablette 50 Signature loudspeakers possess a set of strengths which far outweigh their few weaknesses. It was my admiration for the latter designer's ability to squeeze maximum performance from minimum cabinet dimensions that had me jumping at the chance to audition the latest revision of ProAc's diminutive Response One S loudspeaker, the Response One SC.

ProAC Response One SC

The Response One SC's compact enclosure was a welcome change from those of the heavy floorstanders I've reviewed lately - I could actually move them around the listening room without requiring a visit to the chiropractor! The One SC's heavily-damped Medite enclosure, unchanged from the One S, measures 12" x 7" x 9" (H x W x D) and employs surfaces of varying thickness in order to minimize cabinet resonances.

The rear of each enclosure sports a quartet of high-quality rhodium-plated Michell binding posts, allowing for easy bi-wiring - single wiring can be achieved through use of four supplied metal jumpers. Rounding out the One SC's backside is a port through which the bass/midrange driver is vented.

The One SC's tweeter is the same ¾-inch ferrofluid-cooled domed unit used in the One S, but is now mated to a radically new bass/midrange driver. This five inch, reflex-loaded, bass/midrange driver, with its distinctive solid copper phase plug and magnet assembly, is extremely light and rigid and is said to raise the loudspeaker's bass and midrange performance to a new level. The visually transparent polypropylene cone is mated to a high-temperature voice coil and is mounted on a die-cast chassis. Correct integration of the new bass/midrange driver with the tweeter has necessitated two component changes in the crossover, although ProAc is a bit tight-lipped on the details of the changes made in this area.

For those keeping score at home, the Response One SC has a sensitivity of 86dB/Watt/metre, a nominal 8 Ohm impedance, and a rated frequency response of 38Hz-25kHz. Although ProAc supplies the One SC with their familiar Crimplene grille covers, I suspect that after gazing upon a speaker that looks this good in the buff, few will elect to use them.

Not one to leave their customers out in the cold when product changes come down the pike, ProAc has made it possible for owners of the One S to upgrade their loudspeakers to full One SC status. For a fairly reasonable US$600, any authorized ProAc dealer will replace the bass/midrange drivers and the required crossover components in your pair of One Ss, leaving you with what is effectively a new loudspeaker.

The One SCs did not seem particularly fussy about setup. They sounded quite good when placed in the location previously occupied by the ProAc Studio 150s, but some sonic payback was realized by fine tuning things a bit further. Using the Visual Ears loudspeaker placement program, with a little help from a test CD and an SPL meter, and, finally, fine-tuning by ear, I wound up with the One SCs approximately 30 inches from the side walls and 44 inches from the rear wall, with my listening seat about 130 inches from the front plane of the loudspeakers. The One SCs were toed in towards my listening seat such that I could just see their inside edges, and a pair of Echo Busters panels was positioned so as to damp the point of first reflection at the side walls. When placed atop a pair of Atlantis Reference speaker stands, the One SC's tweeter was just above ear level. In this configuration, I obtained a relatively flat response (about as flat as it gets in my room), with a useable output that was below 35Hz.

Although broken-in by ProAc's Canadian distributor before they arrived, the One SC's were injected with large doses of John Coltrane, Miles Davis, and Bill Evans before any serious listening was done.

Associated Components

All auditioning of the ProAc Response One SCs was done with a digital front end consisting of a Theta Data Basic II transport connected to either a Theta DS Pro Progeny or Assemblage DAC-2 D/A converter via an XLO Type 4 digital cable. Amplification duties were handled by the now-discontinued Aragon 2004 Mk. II which was connected to either a Conrad Johnson Premier II or Sonic Frontiers Line 1 preamplifier (full review to appear soon) via a run of MIT MusicChord or WireWorld Oasis II interconnects. Speaker cables were either Transparent Audio MusicWave Plus or WireWorld Orbit. The One SCs were coupled to a pair of Atlantis Reference speaker stands using Blu Tack. The ProAc Studio 150s saw some duty for comparison purposes. All electronic components sat atop Target equipment racks and were energized from my listening room's dedicated 15A circuits. My dedicated listening space was fully treated using Echo Busters room treatments, including Echo Busters panels, Double Busters panels and Bass Busters bass traps.

It is very rare, in my experience, for an audio component to elicit the outpouring of emotion and the level of musical involvement that I experienced with the ProAc Response One SCs. How can I sum up, in a few hundred words, the three months of extreme musical pleasure that these very special loudspeakers have brought to my life? Let me begin by discussing the One SC's superb midrange performance.

The One SC's midrange was a revelation, with a complete lack of the nasal, congested quality often heard with other box loudspeakers. A total lack of enclosure-induced colorations, coupled with a superb bass/midrange driver, has resulted in a level of midrange reproduction which, I dare say, rivals that of an electrostatic panel. The One SC's standard-setting midrange treated me to an absolutely glorious rendering of the RIAS-KAMMERCHOR singing Brahms' Motets Op. 74 (Harmonia Mundi HMC 901591). Even at realistic playback levels, sopranos soared effortlessly above the choir, with nary a hint of glare, grit, grain or other such undesirable effects. And it didn't stop there. From Cassandra Wilson to Carol Wellsman, and everywhere in between, the One SCs faithfully and beautifully rendered each vocalist in a way that even the most jaded of audiophiles couldn't help but appreciate.

The One SC's transition from bass/midrange driver to tweeter was seamless and continuous, the requisite crossover changes having formed a near-perfect partnership between the two drivers. A wonderful example of the One SCs' coherence is the way in which they reproduced the tonal splendor and harmonic richness over the full range of Elizabeth Wallfisch's violin on The Orchestra of the Age of Enlightenment's traversal of the Bach Violin Concertos (Virgin Classics VC 7593192). I've listened to these musical masterpieces countless times before, but these little British wonders were so adept at presenting every ounce of their immense beauty, that I often felt as though I was hearing them for the first time.

Not to be outdone by the new bass/midrange driver, the One SC's tweeter proved to be exceptionally fast, refined and detailed. The upper reaches of violin sounded wonderfully smooth and natural, without ever becoming grating, edgy or fatiguing. Struck cymbals shimmered naturally and were surrounded with tons of air, rivets on ride cymbals danced and sizzled in a disarmingly-lifelike manner, and brass blasts sounded natural in their bite and power, without ever crossing the line into glaring or offensive territory.

One recording which I returned to numerous times during my auditioning of the One SCs was Rimsky-Korsakoff's Scheherezade with Charles Mackerras conducting the London Symphony Orchestra (Telarc CD-80208). The London Symphony's superb brass section was exceedingly well reproduced by the One SCs, with all of its power, glory, and instrumental color left intact. The One SCs were unmatched in their ability to faithfully render the micro- and macro-dynamics present in Rimsky-Korsakoff's scoring for cymbals, tambourine and snare drum, not to mention the wonderfully natural way in which they reproduced all of the harmonics and overtones of the triangle in the fourth movement. To my ears, the One SC's tweeter redefined the term "reference quality."

While the One SCs didn't always reproduce music's low frequencies with the weight and authority of larger loudspeakers (even Stewart Tyler hasn't yet managed to repeal the laws of physics), what they gave up in low-end heft, they more than made up for in control and articulation. Take Splanky from Christian McBride's Gettin' To It (Verve 314 523 989-2). This track consists of three acoustic basses playing in unison, and is a real test of a loudspeaker's low-end resolution and articulation. The One SCs passed this test with aplomb, allowing me to easily follow the individual acoustic bass lines from start to finish for the first time. On several occasions, the One SCs managed to startle me with their ability to plumb a substantial portion of music's nether regions. The One SC's diminutive bass/midrange driver presented the lower reaches of Ray Brown's bass on Oscar Peterson's We Get Requests (Verve 810 047-2), with surprising weight and authority, fooling me into believing that I was listening to a much larger loudspeaker. Those who normally think of mini-monitors as "screaming little boxes" will be pleasantly surprised by the One SC's low-end performance.

Fed by the appropriate source material, the One SC's were uncanny in their ability to render a realistic soundstage inhabited by living, breathing musicians. These small, magical boxes conjured up eerily realistic images of the members of Miles Davis' seminal quintet on Kind Of Blue (Sony CK 52861), each musician occupying his own three-dimensional region of space within my listening room. This same sense of "virtual reality" was apparent while listening to the Brahms Motets, during which the voices of the choir floated so convincingly in front me, that for a few fleeting moments, my ear/brain was fooled into believing that I was present at the original event.

Although British loudspeakers have long been characterized as sounding too laid back and lacking in "jump" factor, nothing could be further from the truth where the One SCs were concerned. The One SCs could boogie with the best of them, sounding electric and rhythmically involving given the right source material. Chick Corea's all-acoustic trio absolutely lit up the listening room on T.B.C (Terminal Baggage Claim) from the excellent Chick Corea's Akoustic Band (GRP 838 396-2). Dave Weckl's drum work exploded like a thunder-clap, and Chick Corea's chordal eruptions pounded forth convincingly into the listening room. It was hard to believe that all of the power and the glory of a cookin' jazz trio were being recreated by a pair of speakers that I could hold under one arm! While the One SCs could play at very loud levels without sounding strained or hard - louder than your neighbors or your hearing organs are likely to put up with - a speaker this small does have its volume limitations and, in a very large room, they may lack the ability to play at concert hall levels. Having said that, I will point out that the One SCs had little problem traversing Telarc's awesome recording of Rachmaninoff's Symphonic Dances (CD-80331) when played back in my 12'x16' listening room at levels approaching 100dB.

Having previously reviewed the $US2300 ProAc Studio 150s, I felt that a comparison of this excellent floorstander with the similarly priced One SC was in order. Starting at the bottom end of the spectrum, the One SC's single five-inch bass/midrange driver could not match the air-moving prowess of the Studio 150's dual five-inch drivers. The low bass notes on Enya's Shepherd Moons, for example, were much more potent when heard via the Studio 150s. Comparisons through the midrange and top-end yielded very different results however. When I reviewed the Studio 150s in January, I spoke of their "smooth, transparent midrange" and that statement still holds true on extended listening. However, in comparison with the One SC, the Studio 150's midrange did sound a bit colored and slightly congested. In addition to its new bass/midrange driver, I strongly suspect that it is the lack of cabinet-induced colorations that has given the One SC its outstanding mid-band purity and accuracy, that which a larger dynamic loudspeaker like the Studio 150 will inevitably have a hard time matching. And what of the comparison at music's high frequencies? Again, the One SC bettered the Studio 150, whose top-end couldn't quite match the level of smoothness, naturalness, and liquidity exhibited by the One SC's magnificent tweeter.

Both the ProAc Studio 150 and One SC are excellent loudspeakers, although they each excel in different areas of musical reproduction. The Studio 150s trade-off the last ounce of refinement through the midrange and top-end for a more weighty, full-bodied presentation that will likely appeal to lovers of full-scale orchestral works and high-intensity blues and rock music. The Response One SCs, on the other hand, trade-off the last ounce of impact and weight, for an overall refinement and a level of detail that will certainly appeal to those interested in exploring all of the subtlety and beauty of their recorded music collection.

The ProAc Response One SCs join that small, elite group of high-end audio components that offer far more in the performance department than their asking price would indicate. Quite frankly, the One SC is one of the finest loudspeakers I've ever heard, and is an absolute steal at $2100. Even factoring in the cost of a relatively good pair of speaker stands, the Response One SCs are still a bargain given the quality of sound they offer.

While I've tried to convey all of the things that the ProAc Response One SCs do well, they really only excel in one area - making music. If that's not enough reason to run out to your nearest ProAc dealer and audition a pair, then methinks you're in this hobby for the wrong reasons.

Anthony Kershaw Comments
My introduction to the newest ProAc came during the 1997 Montreal Audio Show. The Response One SCs were displayed handsomely by Canadian distributor Jim Griffin and certainly made an impact with their fabulous cabinetry, a bright copper phase plug and spouting a huge soundstage. Jim mentioned that they were just out of the box (one of several ProAc needs is for a substantial break-in period), thus, I assumed the sound could only get better. The Montreal show was large and I had only a short time in La Belle Ville, so I never did get the chance to hear them after a good kickin’! Luckily, Audiophilia Online Magazine editor Andrew Chasin received a pair from Griffin Audio for review.

When asked to add a few alternate thoughts to an existing review, I rarely get the chance to read the original. Impatiently, I wait for the publication date! However, with this particular product, the review secrets were happily given away under the most musical and social of circumstances during a recent visit to Audiophilia central.

The Response One SCs were setup to ProAc’s specifications in Mr. Chasin’s superbly treated listening room. They had been completely broken in. I was familiar with the wonderful sound of the original Response One, so I hurriedly put the Telarc version of Rachmaninov’s Symphonic Dances (CD 80331) into Andrew’s Theta transport to hear any perceived improvement. Powered by Aragon, and prepped through Sonic Frontiers’ fabulous new Line-1 linestage came a richly detailed, involving performance. The editor and myself, after a couple of energized seconds, glanced over at one another and smiled in unison - this was a very special speaker. The emotional involvement and visceral response continued to evolve over many hours of listening. Under these audio circumstances, the sound was one of the most natural and refined that has graced my ears and I felt honoured to be in their musical company. Stewart Tyler had certainly improved on his original design.

I waited several days before setting the speakers up in my listening room. The sound of the Response One SCs was still vividly retained in my aural memory. It was that powerful. After connection to my modest setup, the sound, sadly, was not as I remembered. All the excellent traits were there, but to a far lesser degree. Unfortunately, (or fortunately - depending on your equipment) the Response One SCs represent the genesis of your electronics with clinical accuracy. My front end was fine, but the Arcam Alpha 9 integrated amplifier I was using, while excellent, did not do the synergistic two-step, or even ask the speakers to dance! The following suggestions should help to alleviate the ProAcs of any wallflower status:

  • a careful choice in amplification is a must.
  • audition these speakers at home with your equipment.
  • quality stands that place the tweeter at ear level must be used.
  • setup in a well-treated room - not too large.

The Response One SCs do not do the bass "thing" - but you already knew that! We are in mini-monitor country. They do have low frequency impact when the music warrants, but ... there will be no slam-dancing tonight! However, these speakers represent the finest example of musicality and workmanship and will involve you like few others. The ProAcs are voiced to perfection and are true statements of today’s art. With designer Stuart Tyler’s wonderful track record, who knows what is possible.

ProAc Response One SC Loudspeaker
Manufactured by ProAc
Highpoint House, Riding Road, Buckingham Road Industrial Estate, Brackley, Northamptonshire, NN13 7BE, England
phone: 01280 700147 fax: 01280 700148

U.S. Distributor: Modern Audio Consultants
112 Swanhill Court, Baltimore, MD 21208.
phone: (410) 486-5975, fax: (410) 403-8675

Canadian Distributor: Griffin Audio
P.O. Box 733, Montreal, Quebec, H4A 3S2
phone: (514) 945-8245, fax: (514) 932-0037

Price: US$2100.00
Source of review sample: Manufacturer loan
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