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Reviewer: David Kan
Digital Source: Marantz SA8260, Deltec PDM Two DAC, Restek Radiant, Assemblage D2D-1/DAC-3.1 Platinum, Philips DVP-9000S
Preamp: Symphonic Line RG3 MkIII, NuForce P9, Audio Zone PRE-T1, Dared MC-7P, Dared SL-2000A, Trends PA-10 [in for review]
Power Amp/integrated Amp: Audio Zone AMP-ST, NuForce Ref 9 V2, NuForce Ref 9 V2 SE, Sim Audio Celeste W4070SE, Thorens-Restek MMA-5, Symphonic Line RG$ MKIII, Winsome Labs Mouse, Dared VP-20, Elekit TU-879S, JohnBlue TL-66 [in for review], Virtue Audio Two [in for review]
Speakers: Mark & Daniel Maximus-Monitor, Omni-Harmonizer, Ruby, Topaz, Sapphire; Klipsch Synergy F2, JohnBlue JB3/JB4 [in for review]
Cables: Clearaudio Silver Line interconnect, Deltec Black Slink interconnect, Luscombe LBR-35 interconnect, OCOS speaker cables by Dynaudio, Aural Symphonic Digital Standard digital cable
Power Cords: Aural Symphonic Missing Link, Ensemble Powerflux
Power Line Conditioning: Tice Power Block IIIC, Belkin PureAV PF60, Monster Power HTS-3500 Mk II (modified by NuForce), Monster Power HTS-1000 Mk II
Room Size: 15' x 13.5' x 7'/8' diagonal setup / 11' x 18' x 7'/8' opens to 18' x 19' x 7'/8', long wall setup, carpeted concrete slab floor, suspended ceiling and all walls finished with drywall (basement with small window on one side, which is concrete foundation wall with insulation) / 15' x 15' x 8' / 12' x 24' x 9' opens to 12' x 17' x 9' L-shape, short wall setup / 13' x 28' 8" x 9' with openings on one side to hallway and staircase, short wall setup, suspended hardwood floor, suspended ceiling and all walls finished with drywall, external wall finished with insulation inside and concrete on the outside.
Review component retail: $2,650/pair, matching stand $700/pair

If you think 1mil (0.025mm) Kapton is thin enough... well, cough, Daniel Lee of Mark & Daniel didn't. He thought he'd opt for even thinner. Half mil (0.0125mm) to be precise. If ±10mm linear Xmax excursion seems impressive enough for a 5.5" woofer, be prepared for even bigger: ±12.5mm (1"). It's these kinds of envelope-pushing efforts that gave birth to a new series of Mark & Daniel speakers, the premium Plus models. Those include the Maximus-Mini+, Maximus-Diamond+ and Maximus-Monitor+. They all are two-way bookshelf speakers incorporating the new super-thin Kapton Dreams-a AMT tweeter and new Super X-max QMA mid/woofer.

For those not familiar with Mark & Daniel the company, let me quickly take you through the technical jargon by recapping their core design philosophy. They believe that most traditional two-way loudspeakers are a bit complacent when adopting available technologies for compromised full frequency coverage. If I may substitute the balance between the tweeter and woofer of a two-way speaker with the front and rear weight distribution of a super sports car, the golden ratio would be a 50/50 balance. Alas, most two-way speakers are 70/30 top-heavy at best. The reason is two-fold. First, most conventional tweeter's narrow bandwidth limits their operation from 2.5kHz (or 2kHz) to 20kHz. This means 3, hardly 4 octaves. Second and as a result of the first, the woofer has to take on the unwieldy remaining burden of 6 to 7 octaves. This is asking for trouble. Her name is FMD - frequency modulation or Doppler distortion. That is a transitional form of behavior that occurs when the driver diaphragm simultaneously carries far-spaced frequencies while the frequency with the stronger sound pressure level causes fluctuations in the other. To limit FMD, the displacement and operating bandwidth of the mid/woofer must be optimized, which in the end limits useful bass output.

Among other things, this explains why most two-way monitors are bass shy and not capable of restaging the density and élan of a life performance. It's also why the crossover frequency of most 2-way speakers has been hovering around the 2.5kHz mark. Mark & Daniel redesigned all their tweeters and mid/woofers to approach a more ideal top-to-bottom distribution ratio of 50/50 - as though to give the speaker the responsive handling and agility of a super sports car. To redistribute the 'axle weights', the crossover point of today's review subject was lowered to 700Hz (it is 800Hz for the standard Maximus-Monitor) so that tweeter and woofer each become responsible for roughly 5 octaves.

The 50/50 rule
A common-sense approach that ends in an uncommon solution you say? Well, yes and no. While for two-way speakers, an 800Hz crossover point or lower remains rare, it's been done before. The two Apogees that are still serving me well today -- Centaur Minor and Stage -- run 800Hz and 600/700Hz crossover points respectively. To get away with that, their tweeters had to be able to cover a wide bandwidth. Undoubtedly the Apogee aluminum/Kapton ribbon is famous for that (and its transparent airiness of course). The M&D wide-bandwidth tweeter is somewhat different. It is based on Dr. Oskar Heil's AMT or Air Motion Transformer and has been romantically coined Dreams: Directly Responding Emitter by Air Motion Structure.

Unlike a cone or dome, AMTs produce sound waves by squeezing air with pleated diaphragms that fold like accordion bellows mounted vertically with coils and magnets on both ends. Larger diaphragms and improved displacement efficiency translate into an air mass movement 5 times larger and a propagation velocity 5 times higher than that produced by diaphragmatic push/pull actions of cone or dome tweeters. Using the Mark & Daniel Maximus-Monitor as an example again, its DM-1 tweeter sports a diaphragm area more than 60 times that of a 1" dome while its attendant mass is less than 20%, with a wide bandwidth of 800Hz to 22kHz. Other derivative AMTs have been developed by high-end speaker manufacturers like Adam and Elac, to name just a few. It is fair to note however that (A) the crossover points of these German AMT-based two-ways never drop below 2kHz, and (B) that even though the aforementioned Apogee crossover points descended to 800Hz or 600/700Hz, they could not match the same bass potency of the M&D speakers. While the crossover frequency is pivotal in this philosophy, you still need balanced power on both ends of the pivot to approach the 50/50 front and rear axle balance of a super sports car with all-wheel drive. While the larger and more expensive Apogees certainly did achieve that effortlessly, my smaller cheaper versions fall short in the lowest octaves.

The killer bass of M&D speakers derives from their patented SX woofers, which are basically long-throw underhung woofers. By reworking voice-coil length and magnetic gap height with the mathematical minds of physicists and the passionate hearts of musicians, Mark & Daniel have achieved new excellence in small bass drivers capable of delivering distortion-free maximum linear excursion of ±10mm to ±15mm with at least 7dB higher outputs than conventional drivers of equivalent size.

Obviously Mark & Daniel have more than one set of Dreams and SX drivers to apply different combinations to various models with different crossover frequencies. Their floorstanding flagship Apollo has a crossover point at 500Hz (possibly the lowest for a two-way design) and employs two SX10-1.2 10" woofers with an awesome ±15mm of linear excursion. Its DM-3 wideband 'tweeter' incorporates a huge curved pleated diaphragm 160 times larger than a conventional 1" dome tweeter (probably the largest of its kind). It covers 500Hz to 20kHz at full dynamic output and minimal FMD distortion. Aided by the DM-2 up-firing omnipolar ambient tweeter, high-frequency extension soars to 35kHz. The Apollo II limits itself to a single SX10-1.2 woofer and nudges the crossover point upward to 600Hz.

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In the miniature speaker portfolio, the DM-4 Dreams tweeter and SX 5.5 woofer were first introduced in 2006 with the Maximus-Ruby. The following year saw two new versions of the SX 5.5 woofer in the Sapphire and Topaz models. These three mini monitors share a 900Hz crossover point and a nominal impedance of 3 (or 4) to 6 ohms. The new Diamond+ is the top model of the 'precious stone' lineup and like the other two models in the new Plus range, incorporates the next-generation ultra-thin Kapton AMT and QMA woofers.