Tell me more about Zu's 10" full-range driver.

Zu is responsible for the net parameters of the driver, designed to sound good to us—and hopefully others—with heavy bias on dynamic expression, dynamic resolution, tone and texture, baritone weighted and designed to work with Zu-griewe acoustic loudspeaker loading technology.

Zu’s 10” Driver Chronology


Original Development on this 10” platform by Olson at RCA in the 1930s


Zu103/ND/G1–16 16 ohm, 5336 grams (2011–). Model engraved on center cone.

Zu260FRD/ND-12 12 ohm, 4650 gram, (2013–), model engraved on center cone. Warm tone, less shove, undercut magnet.

Zu103CX/ND/G1–8 8 ohm 10” full-range co-ax, axially mounted super tweeter rolls in at 12kHz. 


Zu260FRD/G1 12 ohm, 5010 grams (2001–2003). Original design. Used in original Druid and Definition loudspeakers.

Zu260FRD/G2 12 ohm, 4660 grams (2003–2006). Second generation with changes to the motor and surround to improve bass.

Zu260FRD/G3 12 ohm, 4660 grams (2007). Changes made to the cone, assembly technique, and batching / matching process.

Zu260FRD/G4/Essence 12 ohm, 4807 grams (2008–2012). Essence specific, stiffening/weighting ribs on cone.

Zu103FRD/G1 16 ohm, 5193 grams (2007–2009). Used on Presence. Max shove / low Qes motor assembly.

Zu260FRD/Experience 16 ohm, 5350 grams (2011). Model engraved on center cone.

Zu260FRD/G4/HO 16 ohm, 5338 grams (2009–2013). Model engraved on center cone.

Zu machines and assembles the final motor work, finishes the driver frames, performs the final cone prep, binds and treats the cone, soak tests and proves the completed driver with a minimum of 600 hours of burn-in, final QC, testing, and tolerance matching. Our driver is made primarily by us and Eminence, with a few parts coming from other suppliers. It has many things finished by Eminence: the voice coil/former assembly, the charging of the magnet and the riveting of the yoke/magnet/frame. As stated, the driver is based largely on the 1930s technologies and research of Harry Olson. One of the greats that had his hands all over this format: the cone geometries, jib factors and suspension, voice coil size.... From what we can find the original cones were made by the Hawley paper company, and this full-range platform originated from RCA in Harry circa 1934. To say this is Eminence's or Zu's is delusional. Zu has certainly added it's feature to the platform, modern materials, improvements to bandwidth, power handling, power transfer.... All versions of the Zu 10” platform are unique, with differing applications and Thiele/Small electromechanical parameters. It’s funny that in 70–80 years audio hasn’t been able to really improve the basic design of a this rock solid 10” full range platform (we are however entering the age of nano engineering...).

Zu full-range drivers utilize diamagnetic materials in its motor to influence and shape the inductive dynamics under power of the interaction of static field and field of the coil. Considerations and design features relative to frequency, the eddy currents formed (the shape of the B fields of the coil relative to frequency and waveform) are also designed into our driver. These features are fully operative and designed to continue to be effective even under extreme SPL demands.

The center cylinder (phase plug) in a Zu 10” driver

A machined phase plug assembly, which is not in motion, directly connect to the frame/motor assembly, with both visible and hidden features allowing for the following benefits: 

  • Extending high frequency limits of the driver assembly through a combination of whizzer cone and center pole detail profile and acoustic impedance matching.
  • MLS diffuser function of pole piece profile and rings aids in the widening of the high frequency (polar plot or beam pattern).
  • Aids in control of dynamic behavior through diamagnetic shunting (shorting) of spurious B fields.
  • Zu’s implementation of shunting is regulated, providing virtually no dynamic damping at low level play and increasing logarithmically to maximum in high SPL play.
  • Dramatic improvement in cooling as the assembly is press fit and uses thermally conductive adhesive. (Only significantly in play when you are pushing huge power, but there nonetheless.)

NOTE: layup is post centering/aligning/shimming of the motor/voice coil assembly, a process that then requires the hand removal of the center dust cap.


Posted on August 18, 2013 and filed under Loudspeaker, Technical, Show All.