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Positive Feedback ISSUE 23


zu cable

Tone loudspeakers

as reviewed by Gary Beard






Audio Note AX-2 Signature bookshelf speakers (in for review), and an REL Strata III Subwoofer

Fi-Xi passively integrated 2A3 amplifier, George Wright WPP100C Phono Stage

Music Hall MMF-9 Turntable with Project Carbon arm and Maestro MC Cartridge, George Wright Step-up Transformer, and a Marantz CC65SE 5 disk CD player. Squeezebox and Squeezebox2 (in for review) music servers, and a Birdland Odeon-AG Dac

Kimber 4TC speaker cables, Kimber Silver Streak and Hero IC's, Final Labs IC's, and Shunyata Sidewinder and homebrew Belden/Hubbell/Marinco power cords.

Richard Gray Power Station 400 power conditioner, Final Labs Daruma 3II isolation, Vibrapods, Lovan Classic equipment rack, DIY points, ceramic cable supports, and various homebrew isolation tweaks.


As a fresh convert to the magic sound of low-powered single-ended triode amplifiers, it has become necessary for me to explore the world of higher-sensitivity speakers. Good value is an important element of my audio mantra, and it should come as good news for SET fans that there are, in fact, quite a number of speakers in the value-oriented, high-efficiency niche market. One of the newer members of the club is the Zu Tone loudspeaker. Zu has made quite a splash in the marketplace with their Druid and Definition floor-standing speakers, and the addition of the $1800, bookshelf-sized Tones gives these Ogden, Utah audio upstarts a complete line of competitively priced speakers.

The Tone is a dynamic, full range, crossover-less design in a sealed enclosure. It utilizes Zu's proprietary 10.3-inch full-range driver and tweeter, with a high-pass filter at 12kHz to achieve a bandwidth of 50-60Hz (it varies depending upon the room) to 25kHz. At 12 ohms nominal impedance (dropping to a minimum of 8.5 at 20Hz), the Tone is a highly efficient 101dB@1 watt/1 meter, which should allow them to mate very well with low-powered amplifiers. The enclosure is 9.5 inches deep, 11 inches wide, and 16 inches tall, and weighs 30 pounds. The black DuPont Chroma System finish has a beautiful, minimalist look and a durable feel. Protruding from the lower portion of the front is a polished aluminum casing containing the Zu-designed tweeter. The full-range driver sits behind the black fabric grille cloth. This grille is not removable, and was designed to add additional stiffness to the speaker enclosure. The back of the speaker has a metal plate with Cardas binding posts. To finish the look, the stylish Zu Tone logo is embossed into the back of the enclosure. The speaker is only slightly larger than the drivers which call it home, but when you pick it up, you can feel its brick-like solidity. The Tones look a bit Clark Kent-ish to me—well dressed and unassuming, yet solid as a rock and ready to roll.

The Tones require a great deal of break-in, and need to be played loud and long before you can even begin to appreciate their sound. Trying to get their 10-inch paper cones to move with 3.5 watts when they are brand spankin' new is like trying to get a mouse to move a mountain. It just ain't gonna happen without help. Zu's Sean Casey, who was kind enough to set me up with the review pair of the Tones, told me to blast away with 100 watts of pure solid-state power for 160 hours or more. I did that, and more, until the cones and baskets broke away from their stiffly fortified bonds of electro-mechanical newness.

Even in their infancy, the Tones sounded very good driven by my Yamaha DSP-A1, whose duty is normally limited to the crashes and booms of The Lord of the Rings trilogy and related home theater applications, and while the Tones' efficiency rating should make them perfect candidates for flea power, I really enjoyed the way that the powerful Yamaha amp brought them to life. The bass was deeply articulated, and the treble sparkled. Transients were lightning-quick and dynamics startling at times, but until the breaking in of the cones had truly begun, the Tones sounded completely shut in with the Fi. Having had a similar experience with other speakers, I knew not to pass judgment, but since these were the first loudspeakers I had in my house that, on paper at least, would mate really well with a 2A3 amp, I simply couldn't help trying them out with mine. It was no use, of course. My initial excitement soon gave way to frustration as I left the house each day with the Tones crankin' on solid-state high, only to come home to find a somewhat improved yet still unfinished sound.

Somewhere around the 100-hour mark, the Fi began to drive the Zus with authority, though they still sounded thick and muddy. Finally, FINALLY, after around 200 hours they opened up enough that I could begin my audio experience in earnest. "Tone" is an apt name for these speakers, as they have a warm and inviting tonal balance. Though they were musical dynamos with the solid-state amp, they were much mellower with the Fi, yet they retained their dynamic snap. After they had been almost completely broken in, they were certainly capable of being driven by the Fi amp, even without an active preamp. Compared to other speakers that I have had in my house, the Tones can get very loud without distortion, yet I heard very little noise or hum from the direct-heated 2A3 tubes of the Fi.

The Tones' small size allowed for easy placement, and I experimented with many locations, including the corners of my living room. Sean Casey recommended stands up to 28 inches high depending upon the height of the listening seat. At first I believed they needed to be a bit higher, and tried makeshift stands that were approximately 30 inches tall. This raised the tweeters to a point where the treble was caressing my aural cavities rather than blasting the dust bunnies under the upholstery. As an experiment, I moved the Tones to a 20-inch-tall stand and found, to my surprise, that I liked them even better with the full-range driver at the height of my head in the seated position. Stand height affects these speakers as much as any I have tried, and after much experimentation I decided I liked them best when my ears were between the full-range driver and the tweeter. The Tones have solid imaging and a large soundfield. Lowering them just a little added a measure of depth and coherence. There are more options for stand height than I've experienced in the past, which gives the listener further opportunities to tune the sound.

As I said earlier, the Tones have a tonal balance that is on the warm side. They sound relaxed and musical—to me, very positive attributes—and aside from the importance of stand height, they are not finicky about placement. I found that I could plop them down almost anywhere and they would sound very good after I spent a few minutes adjusting their position. The Tones are not about hyper-detail. In fact, even after their long break-in, they still sounded veiled at times, particularly on recordings that were already mired in mud. This was the downside of the darker approach, but it could also be a benefit with recordings that were bright, hot, or grainy. It  was a godsend with the poorly recorded, ear-slashing rock records of the late 70s and early 80s. Just as bright speakers can work magic with muddy recordings, the Zu Tones worked wonders with poor recordings on the opposite side of the spectrum.

The Tones are dynamic and fast. They start and stop on a musical dime. While pinpoint detail is not one of their strengths, their imaging and soundstaging are very good. When set up properly, they disappear, leaving nothing but the performers. The stage is mainly between the speakers, and is very deep, yet it projects forward enough to create an intimate presence. What the Tones lack in openness and airiness, they make up for with a dense, palpable, meat-on-the-bones midrange that produces an alluring and sometimes ethereal quality. With their dynamics and rich tonal balance, the Tones are really good at reproducing bold, full-bodied music. I really enjoyed listening to the Living Stereo hybrid SACD of Scheherazade and one of my holiday traditions, Tchaikovsky's Nutcracker Suite.

I played all kinds of music through the Tones. I found them to be adept at all, but particularly small combo jazz and, oddly enough, 70s-era rock like Boston and Led Zeppelin. Their way with leading edge transients was very good, and the decay of notes was especially well done, which added an almost euphonic quality that relaxed the senses. The tweeters provided a smoothly extended treble, and were able to render the shimmer of cymbals very well. I did notice some beaming, especially when listening near field, but it was not nearly as obvious when I listened from eight to ten feet away. Like the 10-inch driver, the tweeter is never fatiguing, and I never had an ear-burning experience during my time with the Tones.

While the lightning-fast full-range drivers did not beam or get peaky on top to the extent that some full-range drivers can, they also lacked the clarity that I have heard in other full-range drivers. They roll off very quickly at the bottom, giving the bass a nice expressiveness without undue boom. And while there was a clear loss of output just above the upper-bass octaves, kick drum and bass guitar had a punchy naturalness that was quite appealing. The bass was really good with the Yamaha, as its additional grunt gave the bottom end more depth and impact. The Fi had difficulty creating bass depth and articulation, so I decided to insert my REL Strata III subwoofer into the mix. I love my sub. It has never failed to integrate wonderfully with a little work. This time, however, it took a mildly torturous day-and-a-half of trial and error to set the crossover and volume levels properly. Once that was accomplished, the REL again proved to be a capable partner for speedy speakers with limited low bass.

Sean Casey had warned me that the Tones required a lot of listening to appreciate their special qualities. I now understand what he meant. The Tones are not "me too" speakers, as the boys at Zu apparently do not subscribe to this audio party line. Rather, they seem to enjoy shaking the bushes of divergence. The Tones differ from every other speaker I have heard. They communicate with a specific voice, one that will seem perfect for listeners who enjoy velvety, rich, melodious sound rather than incisive, gripping, "master tape" sound. To avoid misunderstanding, I am NOT saying that the Tones don't rock, or that they are syrupy-sweet. They do and they aren't, but they did sound different enough from all the other speakers I have heard that they required some adjustment of my thought processes. My best audio-bud (who happens to have a pair of Zu Druids) reminded me of my first audio love, the Merlin TSM-MMs. He suggested that the unique qualities of the Tones were diametrically opposed to those of the Merlins, and that my brain might not have been prepared for so different a sound. That made sense to me. Perhaps I subconsciously compare every pair of speakers I hear to the Merlins, and strive to recreate their sound. I never thought of the Merlins as hyper-detailed or forward, but if memory serves, their sonic mission is poles apart from that of the Zu Tones. Of course, neither approach is wrong or bad, merely different.

I will admit that the Tones never completely won me over. Perhaps they never reached the magic break-in point, but at 250-hours-plus, they should have. Perhaps I never set them up correctly, but I made many efforts to do so. While the Tones sounded very, very good, with flashes of unmistakable brilliance, in the end I felt that they were not the perfect mates for my Fi-Xi. The one thing that really bothered me about them was the fact that they were missing a smidgen of clarity. After spending a great deal of time trying to optimize their performance, I have to call it like I heard it. On the positive side, they do not exhibit the hyper-detailed or stridently forward treble that plagues many audiophile speakers. I won't fault them for that, as I enjoy speakers that don't assault the ears. In fact, I think that the Tones' most endearing quality is their chocolately-rich, warmly balanced sound. Drums, basses, cellos, oboes, low brass, and the like, all sounded fabulous. As fast and dynamic as these speakers are, they never lose composure with complex music, and I was really taken with their ability to create images that had a reach-out-and-touch-it concreteness.

While the Zu Tones may not be the right speakers for my current system, I really enjoyed listening to them. They are music makers, and on top of everything else, they have that mysterious quality that makes it fun to listen to them. They are worthy of your consideration, particularly when you add their solid build and relatively reasonable price to the equation. Whether you gravitate toward their sound or not, they are fine examples of the art and science of audio, and my brief time with them certainly gives me reason to seek out the other speakers in the Zu line. Zu's 60-day money-back guarantee makes trying the Tones relatively risk-free. I say relatively risk-free, as you may have to come up with an excuse for that $1800 debit in your checkbook! Gary Beard

Tone loudspeakers
Retail: $1795/pair

Zu Cable
web address:

Manufacturer's Comments

Thanks for the review PFO! And a big thanks to Gary, we know what a huge commitment the review process is and do not think you guys get anywhere close to enough credit or appreciation.

The Tone—partly due to its limitations from 50Hz and down, and as it is a sealed enclosure—has a nominal full bandwidth efficiency of about 96 dB SPL at 1 Watt input at 3.3 feet. But again, this is the nominal, full bandwidth efficiency. If used with a highly agile subwoofer to round out the bottom two octaves—16Hz through about 50Hz—the system will measure at 100 dB or so SPL 1W, 1m nominal.

It may be of interest to those considering Tone in a low power triode based system to now what several users have recently noticed relative to efficiency of transduction. That is a dramatic improvement of efficiency during a Zu-styled very high power burn-in, playing big music—Harry James, Buddy Rich, Iron Madden, Zappa, Spine Shank... really pounding on them for 50 hours or more—they were able to realize the efficiency, plus the intimacy and transparency they were hoping for. Most reported the perceived gain to be in the neighborhood of 6 dB. Currently we are offering a free seven day high power burn-in for customers who request it, those with close neighbors or family members who don’t appreciate the glory of Zappa at concert levels should really take us up on this.

Gary also asked about the designation of "supertweeter". We do apply this term to the tweeter as it only contributes to the top octave or so of  the modern musical scale—highest harmonics on muted trumpet for example—and is also capable of ultrasonic reproduction with a high degree of fidelity. The modern musical scale is ten octaves starting at roughly 16Hz with middle A (A4) being 440Hz. Above 16kHz there is very little harmonic content, less than 1% of the collective power output in nearly all musical forms. Nevertheless, there does seem to be some advantage of a loudspeaker system being able to posses the capacity for greater than 16kHz, possibly even ultrasonic (typical active and healthy 20 to 35 year old being able to hear 13Hz - 17kHz) provided "timing" of the super high frequency are in the ballpark of the rest of content, and that the other much more critical areas of playback, such as voice and tone, are not compromised along the way. The effective bandwidth of the the ZuT1 supertweeter is 12kHz through 22kHz -1 dB, 12kHz - 25kHz -6 dB.

Thanks again Gary.