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Reviewer: Srajan Ebaen
Financial Interests: click here
Source: Esoteric UX-1, Yamamoto YDA-01, Ancient Audio Lektor Prime, Raysonic Audio CD228 [on review]
Preamp/Integrated: Esoteric C-03 (transistor), ModWright DM 36.5 (valves)
Amplifier: Yamamoto A-09S, FirstWAtt F5, ModWright KWA-150, Octave MRE-130 monos, FirstWatt J2 [on review]
Speakers: ASI Tango R, Zu Essence
Headphones: Audio-Technica WHT-1000, Beyer Dynamic DT880, AKG K-1000, Sennheiser HD800
Headphone amplifier: Yamamoto HA-02, Woo Audio Model 5 with EAT 300Bs, KingRex HeadQuarters [on review]
Cables: Complete loom of ASI Liveline
Stands: ASI HeartSong [on review], Ikea Molger with butcher-block platforms
Powerline conditioning: 2 x Walker Audio Velocitor S
Sundry accessories: Furutech RD-2 CD demagnetizer; Nanotech Nespa Pro; extensive use of Acoustic System Resonators, noise filters and phase inverters, Advanced Acoustics Orbis Wall & Corner units
Room size: The sound platform is 3 x 4.5m with a 2-story slanted ceiling above; four steps below continue into an 8m long combined open kitchen, dining room and office, an area which widens to 5.2m with a 2.8m ceiling; the sound platform space is open to a 2nd story landing and, via spiral stair case, to a 3rd-floor studio; concrete floor, concrete and brick walls from a converted barn with no parallel walls nor perfect right angles; short-wall setup with speaker backs facing the 8-meter expanse and 2nd-story landing.
Review Component Retail:
€3,500/pr
within the EU, certain offsets to be expected due to different VAT rates
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What happens when one marries Italian design flair and fine wood working with Chinese driver know-how?
One answer will have to be Pearl Evo's Ballerina range of open baffle speakers. With drive units by HiVi Research Swans*—ribbon tweeter, 50mm fabric dome midrange, Alu/Mag alloy woofer—plus Italian manufacture and R&D, it fits our profile to the 'T'.
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* • The HiVi iso dynamic RT1C-A tweeter combines a Kapton membrane with aluminum traces over ca. 90% of its 50 x 13mm surface suspended between two rows of Neodymium bar magnets. An aluminum mounting flange with flared wave guide controls the frequency response and directivity of the tweeter. The clamped membrane area is connected to the front metal plate. Combined with a special heat conductive compound, this provides effective cooling of the aluminum conductors. The tweeter is magnetically shielded and only 18 mm deep including the mounting flange. Its sensitivity is 94dB, its recommended high-pass >4500Hz.
• The HiVi DMN-A runs a 50mm/2" hand-treated fabric dome with two big Neodymium rings in a vented design with a large non-resonant acoustic chamber inside an open plastic frame for effective cooling and a detachable back cap for critical flat-mount applications. The DMN-A is 91dB efficient and rated for power handling of 108dB peaks. Its resonant frequency is 800Hz, its recommended bandwidth >800Hz to <9000Hz.
• The HiVi M8A uses a gold-anodized Magnesium Aluminum alloy cone with Conex spider, Kapton voice coil former and underhung voice coil in a long-throw design mounted in a die-cast aluminum basket. Recommended crossover frequency for a 2-way speaker is 1-2kHz. Fs is 33Hz, sensitivity 88dB.
I first encountered the PearlEvo brand at the Milan Top Audio Show 2009 where the entire Ballerina range was on display. It stretches across four models. They are differentiated by the use of one dome (as shown) or two then in a d'Appolito array mated to either an 8-inch or 12-inch woofer. This nets two three- and two four-driver 3-ways with smaller and bigger woofers and scales up what is otherwise very similar performance to rooms of progressively larger size.
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Unlike the kind of cosmetically challenged open baffles whose guts of driver backs, magnets and wiring hang out to dry and in plain view, PearlEvo designer Silvano Cremonesi bestowed on his Ballerina 301 and its larger siblings a sufficiently thick, shapely minimum two-tone baffle to completely conceal the shallow tweeter. The dome only shows a cleanly encased bullet end. The woofer presents an enclosed canister ported out the front. This enhances bass performance from a small driver over typical open-baffle figure 8 cancellation at omni-radiated frequencies. All wiring runs invisible below the black baffle insert. For a box-less speaker concept, this is as clean as it gets.
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Related large planars and electrostats always suffer stability problem when their broad but very shallow plane meets some variation on an L bracket on the floor. PearlEvo neatly circumvents that with their heat-curved multi-laminate D frame. What's involved in its manufacture is chronicled succinctly in export manager Andrea Calabresi's photos to require little commentary.
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The first steps involve cutting, then bonding the 25 wooden sheets in cross-fiber orientation.
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Specific sections that undergo heat treatment are subjected to a molding process in which custom jigs press the steam-softened wood into the desired shape.
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After heat bending, the L blanks need to be shaped by router, then receive the cut-outs, recesses and channels required for the drivers and their wiring.
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After various hand finishing steps not shown—including the manufacture of the baffle inserts—the final product is rather more attractive and labor intensive than what most open baffles with dynamic drivers offer. Considering the work involved, the pricing begins on the low end with €3.500/pr for the 301-8" under review. The 401-8" sells for €4.200, the 301-12" for €4.700/pr and the top 401-12" for €5.700.
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First Italian dealerships show how various environments respond to the cosmetics of the Ballerina. The maker prefers reasonably close boundary proximity (as close as 16 inches to the rear wall) and recommends against toe-in.
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The crossover networks combine to 4th-order acoustic functions at 900 and 6000Hz. The working principle is hybrid open-baffle dipole. The iso dynamic tweeter bandwidth is direct-radiating only while the mid-dome is semi dipole as is the woofer, the latter due to the ABS housing which becomes sonically transparent below a certain frequency. "Taking an average measurement, the back emission is lowered by 25dB. While the remaining dipole effect is deliberately reduced, it remains audible to create a wider deeper ambience without all the in-room positioning challenges associated with full dipole emission. As one descends in frequency, the Ballerina's dispersion pattern becomes smoothly dipolar like that of many musical instruments and quite unlike for example hybrid MartinLogans whose electrostatic radiation is radically different from their dynamic woofers.
"The very low-tuned port is not a conventional reflex port. Due to the varying pressure inside the bass enclosure, its appendix and opening, it effectively lets the driver see a variable volume. Conceptually, this is more similar to an old two-stroke engine expansion exhaust than conventional reflex port. Compared to the latter which at the tuned frequency adds output like an extra driver, the Venturi port adds only a very minimal amount of gain. Rather, its combination of small diameter and short length coupled to the sub volume of the lossy bass enclosure creates a change of speed (lower) and pressure (higher). The structure is energy dissipating rather than absorbing. Energy follows the path of least resistance and our structure will let vibrations travel to the triangular base as the heaviest and grounded part."
The Ballerina 301-8" counters common precedents of bringing in the woofer as low as possible. Here the 8-incher rather than midrange is responsible for many instrumental fundamentals which could benefit power handling. The 2-inch dome has broad measured dispersion. For a smooth transition to the ribbon tweeter, the latter must be narrow and tall exactly as is while its lateral deflectors and phase correction bar are intended to further improve its off-axis response.
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Measured minimum impedance is 4.6 ohm at 4600Hz to suggest a benign amplifier load. Audio Review's Gian Piero Matarazzo was surprised to measure attainable max output levels of 115dB across most the band limited only in the lowest octaves by woofer size and excursion. He noted very low THD above 200Hz even at high levels and remarkably low bass THD up to 90dB.
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The brand name Pearl Evolution is owned by Più Uno Distribuzione and was launched in 2005 as adjunct to Mr. Cremonesi's 15-year career as a professional designer for many third parties, an activity he continues today. One invention which can be revealed—ongoing OEM work is contractually secret—was S.A.P's Relaxa magnetic levitation base. "As an independent speaker designer, Silvano Cremonesi has followed a clear research path into preserving the full dynamics given drivers are capable of; sharp well-defined imaging; and the elimination of box colorations. He introduced to the loudspeaker world certain innovations, many of which were popularized later by major companies. An important one was the RSS reflex suspension system which is still used at Pearl Evolution in the EVO line of mid/high-priced loudspeakers. RSS is a mounting system whereby midrange and woofer detach from the enclosure by neoprene ring while being fixed from their magnets with a stiff steel rod that is bolted to the rigid cabinet back. RSS allows for dynamic integrity and greatly reduced box coloration. The same basic principles are at work behind our Amie line though there they found a radically different expression and new mechanical solution." More soon...
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