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As paying customers, we award Zu an A+ for color matching. Due to the somewhat iridescent nature of the paint chosen, it's hard to capture on memory card the ambient lighting that correctly elicits the true tint which corresponds to the original Photoshop color sample. However, the following photos should clearly convey how close of a match it turned out to be. Suffice it to say, the resident color maniacs are 110% satisfied and thrilled to death. Down with boring black, up with Teal (or whatever your favorite color may be). Complete custom colors are now also available for the Druid [$300/1,000 paint/lacquer] and Tone [$200 paint, no lacquer]. Custom colors require a non-refundable deposit for the color/lacquer surcharge.

The Definition Pro eschews the plate amp of the regular version but replaces the rear-firing woofer units with a different Eminence model that features four times the raw SPL potential at 20Hz. Where the Mk1.5 has been optimized/averaged for a typical listening room, the Pro takes into account the end user's ability to dial in a deliberate boost in the sub-40Hz band which, depending on room size and listening levels, could make some significant demands on the woofers (and amp/s driving them).


As with the active Definitions, these drivers are again run exclusively below their free-air resonance. The Definition Pro now sports two input terminals, the left for the frontal array, the right one for the bass bank. Use of a dedicated bass amp with the Rane PEQ55 becomes mandatory. These woofers lack a low-pass filter and otherwise run wide open well to 1kHz and beyond.


As a professional unit, the Rane uses XLR i/o ports. If your preamp lacks balanced outputs or your chosen bass amp/s XLR inputs, Zu will sell you an RCA-to-XLR or XLR-to-RCA interconnect. Their recommended Gede is $199 for a 1-meter pair, with a $59 surcharge for each additional meter. Zu does not recommend their top-line Varial at $499/m for this application and deems it unnecessary. Rane units purchased through Zu at full retail will include an LED and damping mod. The former is a pin-hole film that reduces the Christmas light indicators to nearly invisible micro dots; the latter a chassis resonance tweak.
I really appreciate the LED mod since without it, your dimly lit reference rig would default into a pro-audio disco light show. Customers wishing to install the EQ within arm's reach to tweak proceedings based on track, CD or mood should purchase long runs of professional interconnects -- $100/12'/pr, perhaps run underneath the carpet -- to loop from the preamp's second output and back. The steel-cased Rane piece measures 3.5" H x 19" W x 5.25" D and weighs 7.3 lb.
A mandatory requirement for focused results with the PEQ55 is either a test tone generator -- above a pre WWII Hewlett-Packard all-tube unit with variable capacitor (the triple bread slicer in the top section actuated by the big frontal knob) which Sean Casey brought -- or a test CD. Simply log which frequencies boom (elevated amplitude) or recede (attenuation) as you slowly sweep up and down with your generator or "climb the stairs" of a test tone sequence in your listening seat. These hot spot/dip frequencies will then assist you in setting up the compensation values on the Rane.

From the available bass amps on hand, two Pateks bridged to 100 watts each did by far the best job and that's how I set up the system.

Connections were simple: RCA out from the Music First Passive Magnetic into the Yamamoto to drive the front array; XLR out from the Music First into the Rane, XLR out into the XLR-to-RCA bridging adaptors of the Pateks. I also acquired one RCA-to-XLR Gede pair to alternately run my ModWright SWL 9.0SE preamp which lacks balanced outputs.

From the PEQ55's architectural specifications, we learn the following: This equalizer is an analog-controlled DSP machine consisting of two discrete channels with 5 frequency bands each. This EQ can be configured for dual mono 5-band operation (independent settings for left and right channel); mono 10-band (requiring two PEQ55s for stereo); or linked stereo. As in-room measurements showed, I only had one identical main node between 43 and 47Hz on each channel, hence I set up the EQ stereo-linked, with the A bank contoured for low-level listening, the B (lower) bank for high-level sessions. As the Fletcher/Munson curves remind us -- and the old-style tone controls based on them -- when playback levels diminish, subjective bass output drops more steeply than your main attenuation rate since our hearing is less sensitive at low frequencies. Hence my A curve duplicates the B curve but applies higher gain to the boost center frequencies. Alternating between either response curve is as simple as flicking both channels to A or B. You could also use the stereo-link feature to compare two curves as you dial in your reference compensation. Use A for what you think you like, then B slightly tweaked to see whether you like that better or not. Flip back and forth as you make subtle adjustments on B, then transfer the working changes to A. For this dialing-in process, lengthy temporary interconnects that let you sit in the listening seat while you twirl knobs and move sliders are the ticket. Once you're dialed, install the unit in your rig and revert back to the short quality interconnects of your choice.

Gain for each equalizer band is adjustable from -24dB to +12dB. All frequency bands overlap and, via the frequency multipliers, adjust from 12.5Hz to 20kHz via x0.1, x1 and x10. For our purposes, all frequency multiplier toggles are naturally set to x0.1 since the only adjustment range that interests us is 12.5Hz to 50Hz. The BW bandwidth or Q control adjusts from 1/12th to a full two octaves to set the window over which your applied cut/boost (selected with the gain control and centered with the frequency knob) will be effective. Each band can be individuality disabled/bypassed. Each bank (A and B) includes a low/high shelving response filter (bands 1 and 5 respectively). Bands 5 (high shelf) become our low-pass filters while the low-shelf functions will likely not be engaged unless you need a rumble filter for vinyl. In 10-band mono mode, only one low/high shelf function each is active of course.

3-band accelerated slope tone controls cover +6dB to off and cross over at 300Hz and 4kHz respectively. 12dB/octave low/high cut filters sport adjustable corner frequencies between 15 - 240Hz and 5 - 20kHz. Input and output level controls with +/-12dB range are linked to peak dBU meters (minimized to the above-mentioned pin holes with the Zu mod). 24-bit converters, dynamic range of 106dB and a very low propagation delay of 1.29ms round out the relevant specs.
Sean Casey spent many long hours with me putting the Definition Pro through extensive measurements with his Clio software program. We covered gated FFT sinusoidal frequency domain tests, bursts, clicks etc. to generate water fall plots, step and impulse responses and all the other impressive-looking Stereophile-type graphs. I'm here to tell you that such measurements have zero relevance for a listener wanting to know what a speaker actually sounds like. Zero. Such measurements assist a designer during the R&D process and are mandatory for quality control (to compare production units against the reference sample). But they mean nothing to you, the end user. Moving a microphone by one inch can incur frequency response deviations by as much as 10dB. We spent hours comparing curves. And that's just the beginning. You can generate graphs and then smooth/average them to look like 50 different speakers, simply by changing smaller or larger measurement parameters as a function of protocol. Your ears tell you one thing, the bloody curves look like a completely different speaker or room. Remember, the only thing that matters to you is what it sounds like in your customary listening zone. Anechoic measurements tell you nothing about in-room bass response. They are thus equally useless and mere window dressing to pretend at scientific appearance when actual listening tests are purely subjective. None of us listen in anechoic rooms either. In-room response is what matters. But not only does that not translate from room to room, it doesn't even translate cleanly when you alter microphone height, distance, angle and placement. How about test equipment calibration, altitude, humidity, ambient temperature?


The most useful measurement as far as actually correlating between what we heard and what the graphs showed was the impulse response. The Definition had text-book performance. With a 2.83V input for 102dB+ output at 1 meter (this is a 6-ohm load), it settled to zero in clearly less than 0.5ms. No wonder these speakers sound so clean and fast. They start and stop on a dime. We also disconnected the rear-firing woofers and ran steady-state tones into the frontal array. There was audible output to 25Hz which doubled at 17Hz. Incidentally and depending on your bass amp/s, if you run prolonged infrasonic steady-state signals, watch amplifier operation temps. You could drive the amp/s into audible distortion at specific <30Hz frequencies as you apply boost. Music of course is transient in nature and will thus never force this kind of punishment on the bass amp/s while listening to tunes rather than geeky test tones.

Here's an in-room burst response of the low-level listening curve (bank A), essentially flat from 1 to 20kHz, then deliberately rising in the bass to offset our LF sensitivity loss at background listening levels (Sean wasn't sure what caused the 1K and 20K spikes - and if neither he nor I could hear the spike in the presence band, we're either both deaf to need Deafinitions or this was an artifact of the test protocol). My hearing extends cleanly to 17KHz, an easy test to make with a sine wave generator. 20kHz at high amplitude generated inner-ear pressures and a peculiar sensation inside the brain which traveled forward and backward as Sean lowered or raised the frequency above 17K. But ear hearing rather than skull vibrations cut off like a brickwall filter at 17kHz for both of us. My customary listening levels are 85-90dB measured at the seat, with peaks at 100dB, something my 2wpc Yamamoto delivers 24/7 still well below unity gain.

Because Les will pen the formal Definition Pro review, I shall restrict my listening commentary to simply this: There's no going back to the "active" Definitions once you've heard the "passives". By linearizing the in-room low-bass response in the listening seat, cobwebs and gunk vanish to not only improve pitch definition and spectral content to let you identify what instrument/s are mixing it up down low -- exactly -- but also to raise ambient night vision and outside the speaker imaging to new levels.


The greatest strength of the Definitions, to my ears, is their transient and dynamic fidelity which rely on timing accuracy and headroom. Literally weeding out (notch-filtering) boom and suck-out modes as a function of room geometries does far more than just reward with cleaner faster bass. How much of that is psychoacoustics -- how we perceive the entire audible spectrum when a single fringe band is improved (only the bass as here or just the treble as with add-on super tweeters) -- and how much of that is actual/measurable doesn't matter.


After all, whether a snake is poisonous or not makes no difference to the adrenaline fear charge coursing through your blood stream as you nearly step on it. Whether midrange openess and apparent treble extension are really better or just sound like it is of no consequence to the listener. If it sounds better, it is better, period. And so it is here - clearly and demonstrably better. Hurray.
Some pundits promote analog-only bass management which often merely provides cut functionality to notch-filter standing wave boom. The Definition Pro uses digital bass management to add cut and boost. Trust me - once you hear properly applied boost to linearize the response, you'll question the wisdom of condemning it.


Who should consider the Definition Pro rather than Definition Mk1.5? Anyone in possession of a test CD with half-tone intervals between 16 and 100Hz. The Rane is rather self-explanatory to use and the bypass feature on each band makes it easy to A/B its particular effect. Do not, however, attempt calibrating the PEQ55 with any hopes of real satisfaction by initially relying on music only. You need steady-state test tones and you must know what frequency you're listening to so you can map out your plan of attack. Naturally, you also need a bass amp. Sean conveyed that in their experience, many of the so-called digital amps are not completely happy being asked to reproduce 16Hz at any significant amplitude. Despite being cheap, they might thus not be the best tool for this particular job.

The Zu Definition Pro is a brilliant triumph of real-world smarts and practicality. Four feet tall, with a 1sqf footprint, it doesn't dominate your space. The anything-goes color options add designer appeal. They have you end up owning something that's uniquely and truly yours. What other $10,000/pr speaker can offer this kind of transient/dynamic fidelity? What other speaker can deliver true in-room extension to 16Hz to capture hall sounds and reveal all the synth trickery that's so prevalent on ambient and trance music? I don't know of anything that can compete fair and square. The Definition Pro offers no mere and raw performance potential, i.e. just a promise. It includes the mandatory flexibility to adapt to your personal room and listening tastes to then become actual and predictable performance, not just promise and potential.


If Thor was a modern-day music fiend rather than forgotten ancient god, the Definition Pro would be his hammer. I'm stoked. So is Ivette who, truth be told, wasn't fond of the black/silver look. Not only does she now adore the new happy color, she commented adoringly -- and unprompted -- on the matte driver trim rings, no longer complaining about the nude transducers. And any deeply satisfied audiophile with a happy wife knows just how lucky of a son of a gun he really is. I just joined that club. It's some awesome platinum-plated Country Club membership, lemme telly ya. Its particular rewards and bennies should be dead-obvious by now. Over and out then while the pen moves over to Les for the nitty-gritty performance reportage once he's ready.
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