Essence Mk.I-B Upgrade Kit

Essence Mk.I-B Upgrade Kit


$200 refund with the safe return of the old full-range drivers and high-pass network.

The Essence upgrade kit [Essence Rev. 1-B]. Users that want to keep the timbre of the original Essence but would like improved dynamics, intensity, full-spectrum resolution and get a bit more presence—this kit is for you.

Designed to best match up with amplifiers that have an output impedance that is greater than 0.1 ohm (a spec’ed damping factor of less than 80), so tube amps, the great sounding ‘60s and ’70s solid-state receivers and amplifiers and some modern solid-state amps.

(Kit price is for a match set of parts—both left and right speakers.)

Get your tools here.


Add To Cart


This kit works with all Essence loudspeakers (Essence never had a revision in it’s four years of production) and can be done with minimal effort, with no soldering and no fitment issues. All kits are purchased direct from Zu Audio Ogden, Utah—U.S.A.

Essence was the only loudspeaker from Zu to feature a ribbon tweeter. It was designed to give the listener great stereophony and bass/treble response at low level listing. It was a very successful speaker for us but diverged a bit from our tenets of max efficiency, max tone and live presence. This upgrade kit gets you much closer to our view of sound while keeping that great low-level listing Essence is known for.

On the technical, the upgrade kit reduces the impedance differential between the low Z ribbon and the new 16 ohm full-range driver. The kit also reduces the destructive interference between the ribbon tweeter and the full-range driver.

Note: identification for this upgrade is the machined model number in the full-range driver.

Difficulty: easy.
Time: one hour.

Here’s What The Kit Contains

1x Matched pair high-output nanotech (Zu103ND/G1-16) drivers w/ 600 hours burn-in.
1x New high-pass network (ClarityCap MR based).
16x #9 Torx T-25 stainless FRD mounting screws.
1x Additional gasket tap.

Required Tools

  • Clean workspace; a blanket over coffee table is perfect.

  • #1 square drive, for removal of your old drivers (not included).

  • 3mm hex (Allen) driver for tweeter high-pass work (not included).

  • T-20 screwdriver, some late production used a T-20 fastener (not included).

  • T-25 screwdriver, used to install the new T-25 FRD fastening screws (not included).


Make sure you are button, snaps, belt buckle and wristwatch free.
Switch off your electronics and disconnect your speaker cables.
With a clean work space and a clean blanket on the floor, lay Essence down with drivers facing up.

Removal Of Your Full-Range Driver

  1. Careful not to poke a hole in the cone or surround, remove the full-range driver fasteners.

  2. Remove the full-range machined trim ring and set it aside.

  3. Grab hold of the machined center cylinder of the driver and lift it up. Or turn the cabinet to the side so the driver will slide out from the baffle.

  4. With it just clear of the cabinet cradle the driver from the backside with your other hand.

  5. Remove leads from the full-range driver by gently rocking the connector longitudinally and pulling.

  6. After all four disconnects are disconnected from the full-range driver set it off to the side.

Removal Of The High-Pass Network From The Tweeter

  1. Look into the cabinet and notice the tweeter (removal of the tweeter is not necessary). With a 3mm Allen wrench/driver remove the only visible small binding post screw.

  2. The freed solid-core wire lead should now be insulated with a bit of tape, then bent it back out of the way. This is the inductor (coil) and it will no longer be used.

  3. Remove capacitor assembly by gently rocking the connector longitudinally and pulling from the tweeter.


  1. Apply the new gasket tape on top of the old gasket tap.

  2. Connect the new capacitor assembly to the tweeter; “+” end (short lead) to tweeter.

  3. Connect the new ZU103ND/G1-16: 2x red leads to (+), 2x black or white leads to (–).

  4. Position the new FRD, line up the holes, put the trim ring in place, set with new screws.

Torque The Full-Range Driver Screws

First pass around, gently torque the screws.
Second pass around, torque firmly; using standard screwdriver and one hand).
Third pass around, torque as tightly as you can; using standard screwdriver and one hand (80 inch pounds [9 N-m]).

Repack Old Drivers And Networks.

Repack the old drivers exactly like you received the new nanotech units. Use the hard gasket between the two drivers. Use the same fasteners. Torque the screw with a 3/16” hex screwdriver or a T-25 screwdriver. Now send them back for refund.

D.I.Y. Warranty

Limited two year warranty on parts only. No warranty for your workmanship. Zu will cover shipping on parts and D.I.Y. service is expected.

Factory Warranty

Limited two year warranty on parts and workmanship, cabinet areas that are not modified are not covered. Zu will cover shipping on parts and D.I.Y. service is expected.

Limited five year warranty if extended warranty and factory service are purchased/performed. Covers all parts and labor including the whole of the cabinet. If warranty is needed complete loudspeaker shipping may not be covered. Zu will cover shipping on parts and D.I.Y. service is expected.