Audiocircle.com consumer review of the Timepiece Mini

The Timepiece Mini boasts a crossover frequency to the woofer below 800 Hz. That is over two octaves lower than many other systems on the market! Such a low crossover frequency implemented utilizing a driver with a one inch diaphragm is almost unheard of.

Q: Why is the crossover point so low?

A: Because the acceleration potential or "rise time" of such a small diaphragm covering the entire upper half of the vocal region lowers transient distortion to the theoretical vanishing point. Diaphragm break-up modes, and the long wavelengths they are composed of, cannot propagate within the body of such a small diaphragm area. The result is the acoustic equivalent of a "perfect piston," transferring its energy of motion into the air with the entire vibrating surface moving back and forth in unison.

Now you can finally hear crucial midrange frequencies that are the embodiment of the human voice and other instrument tones -- without all of the distortion and "coloration" that woofer cones (including exotic carbon graphite, kevlar, etc. types) produce trying to operate well outside their "piston" region.

Q: How does that 1" driver go so low?

A: The Waveguide - Waveguides are similar to horns in that they change the air load that the driver "sees". The difference lies in the extremes.Our waveguides are characterized by the fact that they utilize relatively low compression ratios (a good thing). At higher frequencies the air load is virtually the same as a standard "baffle" mounted driver. This eliminates the associated distortion that is common at high frequencies with traditional horns.

Acoustic loading is only increased only at the lower frequency end of the driver's operating range. This provides added efficiency where it is needed most. At the low frequency range where its mechanical limits dominate and ultimately degrade its performance.

The effect of our waveguide on Dynamic Linearity (transient response) is nothing short of incredible. Reproduction of percussive instruments is truly life-like -- almost unnerving. Critical midrange frequencies of the human voice are reproduced with virtually no distortion, imparting a captivating immediacy seldom experienced in recorded music. The masking effects of Time Domain errors are minimized -- thus permitting the natural localization of instruments and performers in 3-dimensional space. Upon scientific analysis it will be found that our waveguide technology is truly an optimized design that leaves very little room for improvement.

The Waveguide also reduces diffraction effects
Another advantage of the waveguide is edge diffraction is virtually non existent. All frequencies that eminate "see" a more constant air load "impedance." This greatly improves the transient response of the speaker since there is no delayed energy reaching discontinuous enclosure surfaces and then "bouncing" back into the environment.

Seeing that edge diffraction is virtually eliminated, all of the tones that emanate from the waveguide appear to originate from the same point in space. This results in a coherent wavefront with respect to frequency. Such coherency preserves the time dependent information encoded in the recording.

Piston Power
All SP Technology Millennial Reference Series™ Loudspeakers employ aluminum cone woofers for true "piston-like" performance. Aluminum cones operate as near "perfect pistons" up to their "mass cut-off frequency" (an 8 inch aluminum driver is good up to around 1,000 Hz ). The aluminum drivers we incorporate just do not "break-up" and flex at the center as plastic, paper, etc. cones do.

The extended bandwidth provided by waveguide technology permits us to take advantage of the "perfect piston" behavior of a metal cone by crossing over at such a low frequency.

Hybrid Bass
SP Technology Precision Monitoring Products incorporate a proprietary, dual cavity, hybrid bass loading technique to provide unparalleled low frequency performance from a moderately sized enclosure. Back wave energy from the woofer is channeled through a short transmission-line type absorber that increases the loss of unwanted energy above box resonance.

A "hybrid bass" design was called for and has been successfully developed. The compact size and bass extension to 30Hz. (-3dB) of a ported design has been achieved with freedom from that "boxy" sound often associated with them. Low frequency transient response is fast and tight -- comparable with the best transmission-line designs. Boomy, bloated bass with that characteristic "overhang" is a thing of the past. Yet, bass "authority" and power must be heard to be believed.

Constrained Layer Enclosure Construction
Our Precision Monitoring products are constructed at all critical points with two layers of 3/4inch, Medium Density Fiberboard constraining an inner layer of "lossy" membrane. We also use large corner blocks at all panel joints (more info here).

Precision Crossover Alignment
All SP Technology products are designed with precision crossover alignments that include the "acoustic" response of the individual drivers in the final transfer function. Each and every design is painstakingly researched, repeatedly tested and modified to obtain the ideal summed driver responses. As much, if not more, time is invested in this single aspect of design as there is in any other area.

It is a costly and very time consuming fact that we go to extremes in order to guarantee that every aspect of performance under the control of the crossover is optimized. Impedance compensation at critical points is always implemented. Often this has secondary benefits in