Genelec 8351A Acoustically Coaxial Smart Active Monitor -

Genelec 8351A Acoustically Coaxial Smart Active Monitor

From a purely technological viewpoint, the Genelec 8351A offers something rare in today’s loudspeaker market—truly innovative technology.
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From a purely technological viewpoint, the Genelec 8351A offers something rare in today’s loudspeaker market—truly innovative technology. Let’s begin with Genelec innovations that have become familiar: internal amplification (which Genelec pioneered); the molded aluminum chassis with rounded edges (what Genelec calls its Minimum Diffraction Enclosure— MDE) for more consistent directivity and controlled internal cabinet reflections; an effective HF waveguide (Genelec calls it the Directivity Control Waveguide—DCW) that is integrated into the MDE; the Iso-Pod foot that both provides vibration isolation and a method of adjusting vertical tilt; the long, curved internal reflex tube (rear ported) that affords extended LF output (both in level and LF frequency response); digital (up to 192 kHz sampling) and analog inputs; and the Smart Active Monitor system (SAM) that incorporates Genelec Loudspeaker Management system (GLM) for configuration, level, delay and EQ control (and the AutoCal room optimization algorithms) under software/network control.

On top of that distinct family of technologies, Genelec introduced a coaxial mid/high driver with its flagship portable monitor, the 8260A. Dubbed the Minimum Diffraction Coaxial Driver (MDC, and I’m almost done introducing acronyms), the mid driver is designed to be part of the HF waveguide, smoothly integrated with the MDE. This allowed a three-way cabinet that achieved size and output level goals. While the performance of the 8260A is stellar, Genelec next tackled the task of introducing the MDC to a compact three-way design, one the size of its 8250A two-way, which incorporates an eight-inch woofer. The MDC is too large for use with a traditional, round, eight-inch woofer in that size cabinet, so a new approach was needed.

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As outlined in the PSN “Sound Innovations” column in October of last year, the solution was a new woofer approach. Unique oval woofers, with flat plane surfaces over a honey-comb-like infrastructure, 8.5-inch by 4-inch, were developed. Two of these woofers are in the 8351A, one above and one below the MDC, behind a larger continuous front DCW, with gaps top and bottom between the DCW and the main chassis (giving the monitors a distinct appearance). This Acoustically Concealed Woofer (ACW—last new acronym, I promise) technology allows for directional LF and coaxial performance across all three frequency bands (for more detail, link to the 8351A “Sound Innovations” column and the PAR review of the 8260As at prosoundnetwork. com/may2015)

Enough background; how do the 8351As perform in practice? In a word, stunning. The 8351A shares an operating guide with the operationally similar 8240A, 8250A and 8260A. Horizontal and vertical directivity plots are included for each. While the horizontal directionality plots are familial, the 8351A bests the pack in the vertical plot, the horizontal performance being near identical to the vertical as one might expect from a coaxial system. The 8351As excel in imaging and off-axis performance. I wasn’t in a position to A/B them critically, but I believe the 8351A imaging is a notch ahead of even the 8260As.

The 8351As perform exceedingly well at low volumes. In a dialogue with Genelec’s Will Eggleston, he noted, “The directivity pattern of the LF in the 8351 is also equivalent to about a 18-inch driver, if the 8351As are oriented vertically. Simply more direct sound comes at you and less reflective energy. The 8351A is on par in directivity down to about 350 Hz with our 1038 [Genelec 15-inch, woofer loaded, three-way midfield].”

By taking the system three-way, the crossover frequencies can be optimized and each component can perform more efficiently within a narrower operating range. Higher SPLs are also possible. As each component operates more ideally across a narrower band of frequencies, there are no holes in the response or the detail; the dynamic frequency response is accurate across the audio band. The percussiveness in the upper low-end is as lifelike as I’ve ever heard, which I credit to the combination of the MDC and the new woofer technology.

The two woofers have a combined surface area near that of a 10-inch woofer cone. The 8351As match the LF specifications of the 8050As, but with all the advantages of a three-way, coaxial system.

I pushed the 8351As with my normal battery of test tracks. The only audible negative I could find was with a track with a sustained pipe organ note at about 29 Hz (well below the rated response), I could consistently produce some bass port chuffing with the volume up high.

All the technological innovations packed into the design yield a remarkable level of performance. As one might expect, leading-edge technology doesn’t come cheap ($4,795 each, list). Construction is labor intensive; the MDC and woofers are handmade at the Genelec factory in Finland. The unique value proposition includes outstanding imaging and detail, LF extension that will satisfy most without a sub, and high SPL performance from the reasonably portable cabinet size. The 8351As beg to be heard.


8351A Spec Summary

► acoustically coaxial three-way design
► controlled directivity, excellent neutrality on-axis and off-axis
► AutoCal in-room system calibration
► peak SPL ≥ 123 dB (per pair, SPL referenced at 1 m), maximum short term SPL ≥ 110 dB (one unit in half space, on axis, referenced to 1 m, averaged 100 Hz - 3 kHz)
► frequency response 32 Hz to 40 kHz (–6 dB), 38 Hz to 21 kHz (± 1.5 dB)
► two woofers 215 x 100 mm (8.5 x 4 in), MDC midrange 130 mm (5 in) and tweeter 19 mm (¾ in)
► crossover frequencies 490 Hz and 2.6 kHz

Genelec Loudspeaker Management

I’ve used the GLM/AutoCal software alignment and control system in the past, now up to version 2.0 (for Windows only; Mac OSX support is coming soon). The review monitors came with Genelec’s Loudspeaker Management System package—a microphone and network interface (USB to computer, Ethernet to the loudspeakers [daisy-chained], 1/8–inch connection for the test mic—$495). Once hooked up, the downloaded GLM software auto recognized the loudspeakers (the system can control up to 25 loudspeakers with up to 5 subs). A simple drag and drop on a graphic layout tells the software how the monitors are physically arranged. Clicking the mic icon starts AutoCal—a sweep burst from each monitor is measured by the test mic in the listening position and the internal DSP is tweaked for maximum performance (four LF and two HF notch filters, two each HF and LF shelving filters are available as needed, per cabinet). The whole process takes just a couple of minutes for a stereo pair, and is sonically effective as well as being educational about one’s listening room performance. The results can be stored locally in the speakers so that the computer is not needed, though I kept GLM open for its volume control tool when sourcing digitally.