Union 6
For economy-minded music freaks with ambitious listening objectives.
“Union Six sound anything but entry-level and can, truly, be your last speaker purchase.… I wish more companies would build entry level products like Zu does. The Union 6 has my highest recommendation, and is easily the best passive speaker I have heard under $3000.” - Sam Rosen, Positive Feedback Review
Order-to-ship schedule [updated 4/23]
Satin Black - 4 week
Black Starlight - 4 weeks
White Starlight - 5 weeks
Cosmic Carbon - 5 weeks
Mercury - 5 weeks
Rustic Hickory - 6 weeks
Black Hickory - 6 weeks
Ruby Red Hickory - 6 weeks
Electric Blue Hickory - 6 weeks
Blue-Teal Hickory - 6 weeks
American Walnut - 6 weeks
Other finishes - 7 weeks+
Included: simple and effective press-fit protective driver cover, cleaning cloth, and oval-ended stainless steel set-screw footers (installed), plus 4x per speaker 1–1/2” [38mm] adjustable carpet spikes. Installed stud-style footers make effective adjustable footers for most flooring. Packaging is designed for easy unpacking/repacking and tough enough to survive rough freight handling and reuse.
Price is for a matched pair. Singles are simply half price—if you need a single please email us and we’ll send you quote with payment link. In addition to the cabinet finish you can also select black or silver aluminum tweeter lens and driver trim ring, selected at the end of the checkout process (no up-charge).
Union Six is a medium format floor-standing loudspeaker. While it has some of the fun nature of DW 6, Union Six really elevates resolution of dynamics and tone, and is able to leverage associated gear well above its pay-grade. Union Six raises good amps and sources to new musical heights. There is also an upgraded version, Union Six Supreme. Both are astonishingly vivid, transparent and toneful such that either can tap the potential of the best associated gear in any system, without needing the same to thrive.
Union Six and Union Six Supreme speakers are based on the Soul Six’s full-range driver, and all use center-mounted supertweeters. All are rated for 99 dB/W/m efficiency and have amp-friendly, 8 ohms impedance. Union Six speakers feature our new more sophisticated ZuGriewe and scatter plate internals that eliminate the fussy floor gap and instead allow the main driver to "see" the room via a rear exit. You can place Union 6 as close as 2" from the wall behind it.
Union Six is a full spectrum, highly resolving and robust floor-standing loudspeaker. Zu’s full-range, ten-inch driver incorporates a coaxially mounted supertweeter which extends the high frequency response to 22k Hz before rolloff. Locating all of the moving elements around a single axis makes for an exceedingly cohesive and unified wavefront. When combined in a precision-matched stereo pair Union Six creates startling musical realism with a highly dynamic, stereophonic sound field, including excellent projection of spatial depth. Union Six, being a highly-efficient, broad-bandwidth loudspeaker, responds to your music with agility, precise timing and tone in ways that let you hear deeply into a recording without ruthlessly exposing every harshness upstream in the system or recording, nor contributing its own.
Union reviews
“Union Six sound anything but entry-level and can, truly, be your last speaker purchase.… I wish more companies would build entry level products like Zu does. The Union 6 has my highest recommendation, and is easily the best passive speaker I have heard under $3000.” - Sam Rosen, Positive Feedback Review
Easier to understand, setup and use
Tapping R&D work done for Definition Six and Soul Six, Union Six also introduces new technology within the cabinet’s acoustic functionality, greatly improving the bass through midrange performance over what we have been able to implement at the more affordable end of our designs in the past. The Henthorne Disrupted Flow Filter consists of a wide-band "scatter plate" that combines with air mass load tuning and the ZuGriewe function to optimize the acoustic impedance adaptation of the driver to the room. Designed initially for Definition Six, its first market appearance is in Union Six. Floor gap tuning is banished as we are able to put the exit interface out the back of the loudspeaker. Cabinet resonance distortions are held to very low levels through efficient energy transfer (1st rule: try not to induce harmonic resonance in the first place). The "decoherence" function of the scatter plate and a wide bandwidth / low Q distribution of plate modes within the cabinet design further minimize spurious resonances. Implementation of the scatter plate complex dovetails with our 10” [26.2 cm] coaxial driver as if it was specifically engineered around it, because it was.
Union 6 specifications
Bandwidth: 30 - 22k Hz [in-room average]
Sensitivity: 99 dB-SPL @ 2.8V, 39” [1.0m] from FRD face to mic [2π - 4π transition @ 200 Hz]
Impedance: 8 ohm nominal full spectrum Z-weighted
Wavefront: virtual point source
Near Field Transition: 10” [25cm] (driver face to your nose on axis)
Max SPL Program: 120 dB-Z (slow)
Max Input Power: 150 W (300 W w/ high-pass at 50 Hz, 12 dB/octave)
Left/Right Pair Matching: 0.5% on drivers and 0.1% on all other components
Amplifier power output guidance
2 - 15 watts for low to moderate sound pressure levels
15 - 50 watts for moderate to very loud SPLs
50 - 150 watts for very loud to ear damagingly loud SPLs
Build specifications
Internal Cable: Zu Mission Mk.II harness with silver plated connections
FRD: ZuCX-ND-8 (10.3” coaxial paper/CNT cone, under-hung 2” [50.8 mm] coil on paper/Kapton former
Tweeter: Eminence UAPT50-3
High-Pass Network: single element mono pole filter (ClarityCap MR 1.0 µF)
Crossover: none, and no filter components on FRD
Cabinet: North American made composite wood, skinned with real wood veneer or epoxy
Bottom Insert Threads: 3/8–16 (9/16 hex nut—14 mm wrench can be used but is tight)
1–1/2” [38mm] adjustable carpet spikes
Factory burn-in
200 hours for standard
400 hours for Union Six Supreme
Factory burn-in runs 24/7 cycling every 12 hours—moderate levels by day and soak levels by night. Program is full-bandwidth hard hitting music. Final QC is always post burn-in process.
Dimensions
12 x 12 x 36 inches [30.5 x 30.5 x 91.5 cm]
12 x 12 inches [30.5 x 30.5 cm] footprint
FRD protrudes 5/8” [16mm] from the face of the cabinet
Binding posts protrude 1-1/8” [29mm] from the back of cabinet
Union Six Weight: 60 pounds [27 kg]
Packaged Weight: 70 pounds [32 kg]
Package Size: 17 x 18 x 41 inches [43 x 46 x 104 cm]
Input connections
ZuB3 via speakON NL8 (parallel with binding posts)
Posts accepting 1/4” [6.3 mm] and oversized spades, bare wire ≤ #4 AWG [5.1 mm], banana plugs
Other detail
Union 6 entered production May 2022
Union 6 supersedes Union Mk.I - in product 2012 - 2014
Warranty
Like everything we make, Union Six is built to last a lifetime—cabinet materials, adhesives, driver assemblies... every component is a quality part engineered and built to create a loudspeaker system that will continually satisfy and amaze decade after decade, backing up that claim is our liberal five year limited warranty to materials and workmanship. Warranty does not cover misuse, abuse, components upstream from the loudspeaker system, modifications or non-factory overseen service. Full details here.
Q & A
Dirty Weekend Six or Union Six — which is right for me?
Union Six is a very high resolution loudspeaker that assumes you’re willing to rethink/changeup amplification and other aspects of your system. Union Six may require a bit of work to really get singing, and when it comes together… damn, pretty close to world-class and without spending a fortune. The higher efficiency of Union gives more shove and expression regardless of the amp; but all the efficiency also lets you explore low power single-ended triode amplification and esoteric transistor amps without much if any compromise to your desired playback volume.
DW 6 on the other hand is designed so you can hang most any good-enough receiver or amp on it and get great sound. DW 6 has that deeply satisfying, able to cast huge shades of dense tone, put a smile on your face sound baked in. Yes, the baked in tone does give up a bit of transient detail resolution. DW 6 is inherently a full, rich and warm toned loudspeaker, though less vivid and resolving than Union Six.
What about the DW 6 upgrades? DW 6 Superfly does improve resolution without hindering tone. If you want more res and your budget doesn’t mind the push, go DW 6 Superfly. If your budget still has some padding, and you want the warm tone of DW 6 just with max detail, push to the Supreme package.
If you are already stretching to get in the standard DW 6, know that user swappable upgrade packages will be released this summer. Union Six will not have user swappable upgrades as there are cabinet differences between the standard and Supreme versions (there is no Superfly version of Union).