---

Tech Talk

Sparked by a desire to achieve "live performance" through loudspeakers and unable to find any capable of reproducing the live experiences with which he was familiar, Daryl Powell set out on a project to develop a speaker unlike any that existed or exists today.

Daryl is a former lead vocalist of a popular traveling rock band as well as a refined computer design engineer & programmer. Having developed and written programs for some of the largest corporations in the country, his knowledge of computers provided the perfect laboratory for solving many of the typical problems facing speaker design engineers. After painstakingly researching data from every conceivable source on loudspeakers and acoustics, over a 7 year period, Powell created a data base and developed the SDC^TM Computer Modeling Software.

He used this new Computer Modeling System to create the theoretical optimal loudspeaker. While the results were astounding, the total impact of the loudspeakers performance in the lowest octave was somewhat lacking due to some inherent problems with speakers. Daryl then focused on the age-old problem of internal cancellation and difficulties in the bass spectrum which created another problem of muddy mid-range response as well as many others. The final result was so revolutionary (as opposed to most evolutionary designs) the United States Government Patent Office issued a patent for Daryl's Acousta-Reed Bass Technology. In a nutshell, this technology incorporates an enclosure design that corrects the internal standing waves common to all enclosure designs and eliminates the trade-offs normally experienced between the upper bass and lower bass transients. This was the beginning of the Digital Phase Loudspeaker story. And what a story it is!  

Besides gaining critical press attention at the first two CES shows in which they were displayed and selected for Award as a CES Show Stopper Product, Digital Phase unveiled a small bookshelf speaker utilizing not only the very unique neodymium magnet based titanium tweeter but also a woofer with an actual cone diameter of less than 2.625". This small speaker is the epitome of the Acousta-Reed technology. The frequency response on this speaker is 35 - 20kHz + 2 dB! . . . lower than most if not all passive popular subwoofers on the market at twice the price. Let's look a little deeper into some of the design and technology.

"Straighter is Better". . . Actual AP-1 Response Graph.

The Acousta-Reed Technology is an operating system based around some "platters",  operating together with other parameters and new information learned in the course of his research.  They cancel the back waves of the woofer that are 180 degrees out of phase with the front wave of the woofer. By eliminating or reducing the standing waves inside the speaker enclosure, it is now possible to use smaller diameter woofers that more effectively reproduces and tracks the lower octaves of bass. Transients are cleaner, audible distortions are greatly reduced, and with the Acousta-Reeds the lowest octave is reproduced providing the full bass spectrum and a much fuller foundation!  In addition to the incredibly low, accurate bass reproduction, further evidence of the technological breakthrough is the ability of the system to remain linear even at almost inaudible levels. By that, we mean, the response curve is the same whether at 1 watt, 1/2 watt, 10 watts or even 1/32nd of a watt.

Substantial time and research went into the development of our tweeter, and by its' design,  it is a unique function of the system. This is a titanium 1" dome tweeter that incorporates a unique voice coil as an extension of the dome. While the typical tweeter dome is glued to the voice coil former, Digital Phase has eliminated the need for this and the associated inherent problems. The dome goes through some very special procedures to ensure symmetry and uniformity among all systems. The underside of the dome is later coated with a special damping solution to eliminate resonant frequencies common to metal domes. The dome is then pressed to form the final voice coil former, thus eliminating the need for a glued voice coil. In a typical dome tweeter the glue its self can out weigh the dome assembly and sonic degradation occurs. With the sonic purity of our design, the mass of the system is decreased improving the transient response and tonal reproduction. Then the assembly is placed in a doped silk surround which is far less prohibitive than the typical stamped dome tweeter surrounds. This is powered by a powerful neodymium magnet motor which is the strongest magnet structure available (approximately 10 times the strength of conventional magnets) and is self shielding. To extend the power handling and improve cooling as well as increasing the damping, ferro-fluid is injected into the magnet gap. The ferro-fluid also serves to assist the surround in damping and reducing resonances to help provide overall tonal purity. With the ferro-fluid and the stronger magnetic BL properties of the neodymium motor, the tweeter has significantly better control and allows the voice coil to cool better, producing dramatically less distortion with a greater dynamic range. While titanium domes can become harsh due to material resonance at about 24kHz, the real problems (distortion) become obvious at the lower octaves. This is where our design really shines and comes into play damping the driver to allow smooth mellow sound with excellent high frequency extension with superb transient response. Our tweeter also uses a very special phase plug and dispersion screen. This screen mounted over the dome serves three purposes. The first is to act as a place to affix the phase plug assembly. The second is to protect the dome from damage and the third is to keep frequencies from concentrating and thus producing a beaming effect. We have one of the widest dispersion radii even at the highest frequencies.

16Khz Polar Plot

The next element of the system is the woofer. The 6.5" woofers of the AP series uses an aluminum cone with the same damping coatings. This process gives the device better damping and rigidity than the typical paper, paper coated or just about any other material type cones. We selected this material because it is lighter than other materials and much more rigid. 

Improved efficiency and lower distortion is gained through the use of a thicker top plate. Typically, the top plate of a conventional woofer in the 6" diameter size is 4 or 5 mm, but the top plate on a Digital Phase woofer is 9 mm. Additionally, the magnet gap is set at tighter tolerance than most conventional drivers of this size. Most voice coils are made from paper, plastic, or Kapton. We use an aluminum voice coil which is lighter in weight, stronger in structure and a much better heat sink than paper, cardboard or Kapton. The Kapton voice coil is said to be just as strong as aluminum but can not withstand as much heat. We have found that it is not as good a heat sink and does not dissipate heat away from the voice coil wire as well as aluminum causing dynamic compression. The aluminum former we use provides the greatest heat reduction to the voice coil wire itself. This in turn keeps the voice coil DCR lower and more uniform. If the DCR of the voice coil is more constant, then the crossover and the frequency response as well as the tonal purity of the system are preserved and will not fluctuate as much at normal power levels. If the DCR fluctuates then you are no longer listening to "the designed speaker system."  To add to the cooling efficiency of our voice coil we have added 5 large voice coil former holes. These holes are between the pole piece (inside voice coil) and the top plate (outside voice coil) and exchange the air more effectively than a vented pole piece. The air exchange passes directly through the voice coil, not just exchanging the air inside the center of the voice coil. The conventional vented pole piece passes air through the pole piece to the inside of the voice coil area and not directly through the voice coil itself. This conventional pole piece venting causes changing pressures in the voice coil area acting like a bass reflex cabinet itself, creating unwanted pressures (distortion). The other conventional way is to use a porous dust cap to cover the voice coil which allows for air exchange between the inner voice coil with the air in front of the cone. This creates air moving one direction and the speaker cone moving the other which can cause another form of distortion. With our venting system you get the absolute maximum cooling with no induced distortion. Now, our selections of surround material. While foam surround is an adequate surround material, it has a large inherent air leakage factor. Butyl is more dense, better damped (dead) than foam and less likely to introduce its own sound. Our woofer cones are anchored to the basket via a butyl surround.

The Digital Phase family of loudspeakers consists of only premium quality capacitors and coils and are held to the tightest of tolerances. The capacitors are premium metallized polypropylene while the inductor coils are made of oxygen-free copper. The cabinet itself is lined with 2" of premium grade acoustical foam, resulting in superior cancellation of back waves of 200Hz and up. All wiring in the cabinet is 14 gauge/360 strand electrolytic grade oxygen-free(99.9999) copper. This high grade, high definition wire ensures the purest signal integrity and a superior damping factor over standard smaller gauge wiring. The input terminals are 5-way 24K gold plated binding posts.