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August 2021

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Zu Audio Omen MK.II Floorstanding Loudspeaker Review
A classic loudspeaker from Zu Audio that remains new. 
Review By Ric Mancuso


Zu Omen MK.II Floorstanding Loudspeaker Review


  I asked this question of Sean Casey, owner and creator and founder of Zu Audio loudspeakers. "You know, how did you come with the name for the company?" He said, One evening having some conversation about birthing the company with his wife, the name Zu popped into her head! It sounded cool and they came up with a logo and from then on it was Zu Audio. Sean heard members of the industry say never to disclose the origin of the name, fearing it would evoke a perception of fictionalization, that would somehow undermine the brand's quality. What's in a name? Well, Prince did pretty well with his symbol and his brand.



About Sean Casey Of Zu Audio
Sean Casey's background in audio is an interesting one. He and Ray Kimber, both Utah audio heads knew of each other and crossed paths involving PA's and sound systems for clubs in the early days in Ogden. Ray of course started up Kimber Kable. Sean was doing DJ work and dance party gigs in clubs at the age of 16. Sean said his parents were not a fan of his musical tastes, but were supportive of his efforts. Sean claimed to be a recalcitrant Mormon! Along with that endeavor, Sean being a motorcycle enthusiast had teamed up with Ron Griewe, motorcycle legend, and inventor. This will blow your mind; much of the technology behind Zu Audio loudspeakers is based on a motorcycle muffler!


What Is Zu-Griewe Loudspeaker Technology?
This technology is used in the majority of Zu Audio's loudspeakers. Its concepts can be used in any loudspeaker where there are internal velocity changes. The technology concept was introduced in Zu's very first loudspeaker, the Druid. The Zu-Griewe technology is a multi-octave impedance modifying acoustic model that can be applied to any acoustic system with alternating velocities; electro-acoustic, electromechanical, internal combustion engines, and so on. The concept evolved from the relationship between Ron Griewe, motorcycle legend, and apprentice Sean Casey. Sean says he was a punk kid and that Ron had mentored him and gave him ideas that would be eventually be incorporated into the Zu Druid loudspeaker. The original concept is Ron Griewe's and had a nice bit of engineering insight as he sat inching through Los Angeles traffic one afternoon.

Zu's first speaker was the Druid in 2001. Sean had been intrigued with the Cerwin Vega folded horn designs along with Klipsch and RCA speakers. "Speakers you could get through the door," Sean says. You will always notice full, deep, and effortless bass tones emanating from Zu Audio speakers' designs.



Zu OMEN MK.II Loudspeaker
I always was impressed with the sound of Zu speakers when exhibiting at audio shows. Sean and his staff exude passion and know-how to have fun with show-goers. The fun makes the listening experience more enjoyable. Sean employs a Rupert Neve 5060 (high-end) mixing board in a DJ format driving his favorite amps of the day powering usually two models of Zu speakers. The Demo allows people to choose their favorite LPs to play from the bins of various genres of music that Sean collects. It's like attending a party. You even get a cool Zu t-shirt.

I had ordered a pair of Zu Audio Soul Supremes to audition a few years ago and was impressed with their sound. Unfortunately, We were in the process of moving back to Portland, OR, from Pacifica CA. I never really had the chance to fully evaluate the speakers. Ok, so I was inspired to get another pair of smaller Zu speakers to review in my Near-Field-Nirvana sound space in our smaller house. Sean told me that the Omen MK.II's would work well in a near-field application. I was skeptical based on previous listening experiences with Zu speakers in large exhibit venues. I originally wanted to review his bookshelf model. "Nope, Sean said, I'll send you the Omen Mk.II's, you can even put them two feet away from your listening position obtaining great sonic results!" I guess I couldn't say no.


Zu Audio speakers typically always receive many votes for best sound at audio shows. Must be a reason? Well, I had to wait a while before getting the speakers. As we all know the year 2020 had put serious constraint on the supply chain of materials, along with the company having to employ health safety practices for staff workers. The company like many other audio manufacturers is deluged with backorders. Home audio is thriving because of the lockdown. Folks are investing in home entertainment products, including expensive audiophile gear in lieu of going out to see concerts, dining, and movies because of the event during 2020.

The Zu Audio Omen MK.II floorstanding speakers arrived in sturdy cartons and were easy for me to unpack. I walked them out of the box, in which they were tightly wrapped in shrink material. I did not use the supplied spikes and elected to use the Black Ravioli pads instead. They are superior to most any spikes on the market. More on those in another article.

I set them up in my standard near-field mathematic formula. Three feet from the back wall with an ear focal distance of an equal lateral triangle of seven and one-half feet with a slight toe-in of five degrees. These speakers immediately defined a center image with vocals rock-solid in the middle. Sean says that the best way to set up Zu speakers is to achieve a perfect tonal balance with the music. He says if you get that part right, then everything else will fall into place. I remember the late Gordon Holt mentioned the same thing years ago regarding speaker set-up.



What Do They Sound Like?
Zu speakers have the reputation of being able to play loud and rock out. So, I took the opposite tack and played a few classical pieces with a variety of symphony, piano concerto, and vocal choir.

I played the CDs at soft to moderate volumes with very satisfying results. This speaker can whisper at you and blow a kiss to your ears. My ears heard all the spatial cues in the recording with correct perspectives of soundstage and tonality. What I noticed first off was the instruments sounded authentically real. Kind of reminiscent of an LS3/5A design. I own a pair of the Falcon's and was struck by how similar the midrange qualities were shared!

Playing a Rolling Stones cut off the Sticky Fingers LP album I used an Audio Technica entry-level turntable with their moving magnet AT 95 cartridge. This fed an ancient Hegeman HAPI 2 phono preamp. Stunning performance. More on that combo in a retrospective piece about vintage and beyond.

I goosed up the volume and had a Big Boy Rock performance speaker experience. Again, the tonality is spot on. Vocals properly painted across the stage with the biting guitar of Mick Taylor throbbing those famous licks. More than ample bass, but not overly plump. Most of us have been weened away from enjoying life-like bass over the years. Most high-end audio speaker designers focus on ultimate transparency and spatial sound reproduction as the holy grail, however, at the expense and sacrifice of low bass and correct tonality. All this in order to accommodate those sonic attributes, which makes most speakers sound too lean IMO.

Also, perhaps aging ears and loss of some HF contributes to designers voicing their speakers with a tilted frequency response. Do you wonder why Klipsch and JBL have been resurgent in the high-end speaker market again? I think it's because people are lusting for a more robust listening experience. Full-bodied, rich and full, and yet delicate at the same time. The Zu Audio Omen MK.II can do the boogie thing as well as stroke you with a velvet glove.


More From Sean Casey
Speaking with Sean about his choice in drivers and performance, he commented regarding the 10" driver; which all Zu Audio loudspeakers utilize in the product line, that produces, bass, midrange, and much of the high-frequency bandwidth. He said a lot of the MI industry uses 10" drivers, because of its ability to have a rightness of sound and realism of the fundamental tones. Musicians (Tone-Heads) generally prefer 10" versus 12" speakers. Sean also said, the 10" driver approximates the size of a human head! I guess logic would say, our heads are the reciprocal of a 10" driver?

Vocalists are projecting from the human head, so it stands to reason the Zu Audio Omen MK.II's would have a natural-sounding midrange with voice. It is the one thing that defines Zu speakers, the correctness of tone. I kept hearing instruments and voices in recordings that sounded real. The 10" human head not only projects sound, but listens to sound. It makes total sense to me. So, when someone calls you a Head Case, agree with them!



Associative Synergy
Most all speakers prefer and / or have demands for amplification that can match up well to bring out their best performance. Other system components are in play too! I've heard many different amplifiers paired up with Zu Audio speakers at shows over the years. They all were in grand partnership with the company's speakers. I asked Sean, what synergistic methods did he employ to find the right match-ups? He mentioned a bunch of solid-state and tube amplifiers that one could successfully use and get the Zu loudspeakers to sound great, including the original NAD 3020!

When I had the Soul Supremes I remembered I had used the NAD along with Jolida FX 10 EL84 vacuum tube amplifier with fabulous results! I used three different amplifier types in evaluating the Zu Omen MK.II. I first started with a Rogue Audio Pharaoh hybrid Class D tube design with close to 400 Watts per channel into 4 Ohms. The Omen's are a 12 Ohm load. I fell into the trap of playing the Omen's too loud at first. My ears were ringing. I got out my SPL meter and settled on about 85dB as a good place to start. The speakers are so efficient at 97dB range, you have to dial down the volume!

The damping factor is very high with the Rogue. I was ready to call it a day just to say, "Game set match." With this setup. Very tight and full bass, sound stage so wide, it stretched well beyond the room. The midrange was spot on, dead in the center vocals with excellent depth. Image height was believable. Only the Magnepan LRS would slightly best the Omen MK.II's in this regard. I played an Alison Krauss CD to test for vocal purity. She was present and with me in the room.

I then switched over to the classic Manley Labs Mahi vacuum tube monoblock amps. I tried various combinations of feedback, triode, and push-pull settings. I used the Rogue Audio Pharaoh as the preamp. It has a tube preamp output. Good match as it turns out. The sonic flavor of a pure tube amp had a magical quality with the Omen MK.II speakers. The slightly added warmth is just undeniable what tubes can deliver. All settings slightly changed the flavor. The bass was a little loose, as I would have suspected, but it was fun and not subtractive to the presentation.

The NAD Original 3020 was next up. Ok, let's get real here. A 1979 integrated amp with spring clip speaker wire connectors. This amp is stock, actually have two of them! I used 16 gauge lamp cord wire with the Zu Audio Omen MK.II's. Guess what? It's one of Sean Casey's favorite amps! The speakers brought on another magical experience. CD going through the AUX input. Funky set up. Musical pairing that defies one's sensibilities. Soundscape width and depth were wonderful. There was a rightness to the sound too. Plenty of drive and pace.



I believe if a speaker is designed right, it will check all the boxes to be entertaining with various types of music and gear. I see parallels with Zu Audio and Klipsch. Sean Casey and Paul Klipsch basically are / were cut from the same cloth. Designers are blessed with inspiration and genius!

The Zu Audio's Omen MK.II floorstanding speakers belongs within the ranking of highly praised classics. They remain in the line-up of speakers still in production at the company. How about a classic speaker that is only three years old and as refreshingly new as they come? The Zu Audio Omen MK.II  speakers are staying within my reference system and will be used to compare other loudspeakers.





Sub–bass (10Hz – 60Hz)

Mid–bass (80Hz – 200Hz)

Midrange (200Hz – 3,000Hz)

High Frequencies (3,000Hz On Up)



Inner Resolution

Soundscape Width Front

Soundscape Width Rear
Soundscape Depth

Soundscape Extension Into Room


Fit And Finish

Self Noise

Value For The Money




Type: High-sensitivity floorstanding loudspeaker
Frequency Response: 35Hz to 22kHz
Sensitivity: 97dB/W/m
Impedance: 12 Ohms
Dimensions: 36" x 12" x 12" (HxWxD)
Weight: 54 pounds 
Price: Starting at $2349




Company Information
Zu Audio
3350 South 1500 West
Ogden, Utah 84410

Voice: (801) 452-5578
E-mail: info@zuaudio.com
Website: ZuAudio.com

















































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