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Tannoy Revolution XT 8F Loudspeaker

Tannoy Revolution XT 8F Loudspeaker

It’s no secret that Tannoy is one of the oldest and most prestigious audio brands in the world. Having been in the public arena for decades, Tannoy has become synonymous with public address in the UK, the phrase “over the Tannoy” being commonly used to describe a PA announcement. The company’s Scottish factory is located near Glasgow where it’s been based for the past 35 years. Tannoy is also a major player in the U.S., predominantly for its commercial beam-steering, touring, and stadium speakers. Its impact on the high-end scene is primarily due to its Dual Concentric driver that approximates a point-source radiator. The majority of Tannoy loudspeakers, including all of the high-end residential, Prestige traditional, and most pro-audio/touring models, are made in Scotland. However, in order to attain affordable price points, entry-level residential loudspeakers (Mercury, Revolution, and Precision lines) are manufactured in China. These days, the paradigm of “designed in the West and manufactured in the East” applies to any product with mass-market aspirations, including the Hewlett-Packard laptop computer I’m using to write this review.

The Revolution XT line represents a significant overhaul of the Revolution series. The trapezoidal cabinet shape has been retained, but the internals feature sweeping changes. The top-of-the-line 8F, as well as the smaller 6F, are both floorstanders with integrated spiked bases (aka plinths). The numerical designation refers to the driver diameter, and in both cases the design can be best characterized as a two-and-a-half-way. In the 8F, the coaxial woofer is allowed to work into the bass while being augmented below 250Hz by an 8-inch woofer, with the crossover network being a second-order low-pass. The coaxial tweeter and woofer are crossed over at 1.8kHz using asymmetrical networks: first-order high-pass for the tweeter and second-order low-pass for the woofer.

The woofers are loaded by two chambers connected via an internal port. The lower chamber is smaller in volume, and vents to the exterior through a downward-firing port at the bottom of the cabinet. This type of dual-chamber bass-reflex alignment was described as early as 1961 by George Augspurger in an article in Electronics World, but has seen little commercial application since then. In contrast with a conventional bass reflex, which is tuned to a single frequency, the dual-chamber design is tuned to two frequencies typically an octave apart. As a consequence, compared to a conventional bass reflex, the double bass reflex is able to control woofer excursion over a wider range, well into the deeper low end. This was evident in the impedance magnitude plot that showed well-damped woofer resonance peaks. The impedance minimum in the upper bass clocks in at about 3 ohms while the maximum is about 40 ohms in the upper midrange.

The star attraction is of course the new coaxial driver, said to be a fresh interpretation of Tannoy’s point-source drive-unit philosophy—and a major milestone in more than 65 years of the company’s audio research and development. If you think that there’s a bit of hubris embedded in such a pronouncement, think again. My own listening tests and measurements have convinced me that it is indeed a major success. There was a time when speaker designers saturated a front baffle with multiple drivers giving little consideration to the resultant acoustical interference effects. And before Siegfried Linkwitz in the mid-1970s, crossover design was purely an electrical engineering exercise with no accounting for path length differences between individual acoustic centers. Published frequency-response specifications for these multiway speakers seemed to be based on a single mike position where the drivers integrated reasonably well. Move the mike a few inches, and the integration would collapse, resulting in severe response dips.

I’ve been a longtime fan of coaxials; functionally they perform as wide-range drivers and can be thought of as improved versions of 1930s twin-cone, full-range transducers such as the Lowther range. The first coaxial design, the Duplex 601, was unveiled in the early 1940s by Altec Lansing. An improved version, the Altec 604, was introduced circa 1945 and quickly became the standard studio monitor in the U.S. Then Tannoy’s Dual Concentric design arrived a couple of years later and was to become the leading studio monitor in the UK and throughout Europe. Both designs used high-frequency waveguides, but the unique aspect of the Tannoy was that the woofer cone provided the final horn flare for the tweeter.

The ideal of a point-source coaxial driver where the acoustic centers of the tweeter and woofer are nearly spatially coincident has been difficult to execute in practice without some serious side effects. The tweeter typically sits on the woofer magnet’s pole piece. Cavity resonances and the horn loading provided by the waveguide and woofer cone can color the response in the transition region between the two drivers—a “cupped hands” coloration being a common descriptor of previous Tannoy coaxials. In the new driver, a single magnet, dubbed the Omnimagnet by the marketing folks, powers both the tweeter and the woofer, improving time alignment and phase coherence. The tweeter diaphragm is one inch in diameter and is formed of polyetherimide, also known as PEI, a high-performance thermoplastic whose characteristics include high strength and rigidity at elevated temperatures. This is no ordinary dome; it is actually donut-shaped, a torus if you insist on a more precise geometrical description, and is coupled to a rocket-nosed (ogive-shaped) phase plug. The phase plug is enclosed by a waveguide that is brought further forward into the woofer cone. The waveguide is designed with an aggressive flare rate that results in a shallower profile to improve high-frequency dispersion through the mouth of the bass driver.

 

The end result of all of this engineering innovation is a superb midrange. I certainly could not detect any obvious midband coloration. In fact, the vocal range was reproduced with exceptional timbral fidelity. My own personal reference, David Manley’s Lesley album, never sounded any closer to the original mastertape. This is high praise indeed, as very few speakers manage to get this right, regardless of price. They either reproduce Lesley’s voice as harmonically too thin or too thick. In contrast to much of the competition, the Tannoy 8F hits the harmonic Goldilocks zone, sounding just right. The range from 300Hz to about 10kHz left little to be desired in terms of textural purity, microdynamic integrity, and tonal accuracy.

A coincident driver’s primary reason for being is coherence—the music’s fundamentals and their harmonics originate from essentially the same spatial location. Thus it should come as no surprise when I tell you that the 8F generated a colossal soundstage populated by tightly focused image outlines. The listening sweet spot was enormous, being far more expansive than that produced by a typical two-way design, extending to at least 15 degrees off-axis. The tonal balance and image focus remained stable even with substantial head movements about the listening seat; no need to hold your head in a vise with the Tannoy. In particular, image stability was a joy to behold. This attribute isn’t something that is often mentioned in print, but it reduces the amount of mental energy required to accept the soundstage illusion as believable. The 8F made it effortless for me to virtually embed myself in a recording’s acoustic space.

What was surprising was the Tannoy’s Formula 1-caliber transient speed. I didn’t expect that at this price point, ditto for its soundstage transparency. For example, driven by the Perla Audio Signature 50 integrated amplifier, the combo gave the soundstage quite a sonic flossing, clearing away crud that would otherwise have obscured image outlines. Partnered by the First Watt SIT-1 single-ended monoblocks, the mids sang sweetly with the purity of expression that these reference amplifiers are capable of. Musical lines soared effortlessly with dynamic conviction and minimal electronic intrusion. Time and time again, the 8F was able to decisively reveal amplifier differences, a testament to its resolving powers. For the record, it gave its best imaging performance when partnered with tube amps that also happened to flesh out the most convincing spatial impression.

You shouldn’t expect perfection at this price point. The fly in the ointment was its performance at the frequency extremes. I’m not much bothered by the slight emphasis in the lower treble, with the real issue being in the midbass. At least in my room, there was just too much of it. In-room measurements showed a peak of about 7dB relative to the upper bass and lower midrange over the octave from about 50Hz to 100Hz. Of course, room modes become prominent below 300Hz, so I took care to average the bass response at several room positions. It appeared likely that while the coupled dual-cavity, bass-reflex alignment was exercising tight control over the woofers, the port output was excessive. To test that theory, I wedged a one-inch-thick section of acoustical foam into the space between the base and the down-firing port. The result was a 4dB attenuation of the peak and a much more satisfactory overall bass balance. When I related my findings to Tannoy, I was told that Tannoy has concluded that for some rooms, a foam bung should be used in the port, and will be including this on future production. That is a welcome development indeed, as it would give the end user the ability to tune the port output to his or her own listening environment.

The Tannoy Revolution XT 8F was Robert Harley’s top discovery at the 2015 Consumer Electronics Show. His first impression was as follows: “After listening to it and looking at the real wood enclosure, I guessed the price at $7000 to $10,000. The Revolution XT’s price was then revealed to be just $2600 per pair.” After living with the 8F happily for several months, I was ready to declare it a sensational entry-level loudspeaker. But I see that I need to slightly amend that statement—the only thing entry-level about it is the price. The real wood veneers and level of finish don’t suggest an entry-level product, and sonically it performs to a much higher standard. I’m in total agreement with Robert’s assessment: The Tannoy packs a virtuoso midrange that is competitive with speakers approaching $10k retail. I’m in no rush to displace the XT 8F from my listening room. And that’s high praise from someone who is in possession of much more expensive speakers. So do yourself a favor and give the Tannoy a listen—you’ll be glad you did.

SPECS & PRICING

Driver complement: 1″/8″ coaxial tweeter/woofer, 8″ woofer
Frequency range:  34Hz–32kHz (-6dB)
Sensitivity: 91dB (2.83V/1m)
Power handling: 25–200 watts
Nominal impedance: 8 ohms
Dimensions: 12.6″ x 42.5″ x 13.6″
Weight: 43.9 lbs. (19.9 kg)
Price: $2600

TANNOY LTD.
Rosehall Industrial Estate
ML5 4TF Coatbridge, UK

TC GROUP AMERICAS INC. (U.S. Distributor)
335 Gage Avenue, Suite 1
N2M 5E1 Kitchener, ON
Canada
(519) 745-1158
tannoy.com

ASSOCIATED EQUIPMENT
Lamm Audio M1.2 Reference and VTL Manley reference series 100/200 monoblock amplifiers, First Watt F7 and Futterman H3 stereo amplifiers; Perla Audio Signature 50 integrated amplifier; Monarchy Audio NM24 DAC with April Music’s Stello U3 USB Link, Sony XA-5400 SACD player with ModWright Truth modification; Kuzma Reference turntable; Kuzma Stogi Reference 313 VTA tonearm; Clearaudio Da Vinci V2 MC phono cartridge; Conrad-Johnson PV-5 preamp; FMS Nexus-2, Wire World, and Kimber KCAG interconnects; Acoustic Zen Hologram and Kimber KCAG speaker cable; Sound Application power line conditioners

Dick Olsher

By Dick Olsher

Although educated as a nuclear engineer at the University of Florida, I spent most of my career, 30 years to be exact, employed as a radiation physicist at the Los Alamos National Laboratory, from which I retired in 2008.

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