The Nova Field Coil Driver

The Nova field coil is a driver without equal.

In this fourth major iteration, the voice coils have been cryogenically processed, a three day effort in which the wire is cooled in liquid nitrogen for a full 48 hours at -300°F. This compresses the metal, purifies it, and its natural crystalline structure is restored. The wire becomes more conductive, with less distortion introduced into the signals passing through it. Spanning a decade of development, it is among the most significant improvements we've ever made.

The internal geometry of the motor has been redesigned. Its steel contains less than half the carbon content of its V3 predecessor, which allows for a higher saturation point. The pole piece is made from permendur in the magnetic gap. Permendur is a cobalt iron magnetic alloy, offering the highest saturation flux density of any commercially available metal. This significantly improves the strength and quality of our driver's magnetic field. While costly and difficult both to source and machine, permendur has improved the peak performance of our field coil magnet to 1.9 Tesla, or 19,000 Gauss. That strength and permeability confer immense control and accuracy of motion to the driver cones.

A new phase plug is milled from solid copper. The primary purpose of any phase plug is to guide sound and prevent cancellation, however in our application it is likewise used for thermal dissipation, and as a faraday ring. While typically found inside the magnetic gap of drivers, we have found the faraday ring to be effective above the gap as well, preserving gap width and flux density. In use, it lowers the measured inductance of the Nova, which improves treble performance and lowers distortion.

Design Philosophy and Materials

The goal of the music lover is to connect with the work of artists.

However, at each stage music passes through on its way from the artist to the listener, the intrusion of outside influences often makes that expression less true to the original work, and the listener's connection to it more remote.

Our goal is to preserve that connection for music lovers, and in doing so leave behind as little of ourselves as possible. That guiding principle can be found in every element of each product we make.

Field Coils

In our V4 Nova driver, powerful 1.9 Tesla electromagnetic motor is the central driving force behind our loudspeakers. It provides a constant, highly uniform gap density. It has a magnetic permeability, or stiffness, that is hundreds if not thousands of times higher than a permanent magnet. That stiffness translates into accuracy - much higher accuracy and lower distortion than permanent magnets are capable of.

It is adjustable. Simply increasing or decreasing the current from our variable power supply to the field coil modifies the measurements and behavior of a loudspeaker, providing the listener with freedom to tune the listening experience to his or her taste.

The performance of the magnet is further enhanced by the design of our power supply. It is uniquely capable of removing overlying AC signals and shunting electromagnetic back-force, which in other power supplies draws parasitically upon the electromagnetic field, causing unwanted distortion.

Voice Coil and Cones

To fully capture the music signal operating in that strong, precise magnetic field, the voice coil and cones must be sufficiently rigid and yet vanishingly lightweight.

For rigidity, our moving assembly consists of all curvilinear cones. They exhibit excellent radial strength, and maximize frequency response. The shape optimizes transfer of sound into the cones from the voice coil. The depth of the cones decreases cone distortion, particularly at low frequencies. Each cone and voice coil is handmade, from specially treated washi paper. Years of development invested in cone material and treatment have resulted in an excellent combination of transducer speed and damping. Rigorous refinement of cones size and curvature have minimized distortion and beaming, and enhanced off-axis performance.

In spite of its large 10" diameter, the entire driver moving mass, including suspension, weighs just 12.25 grams.

Suspension

To transmit that potential energy with fidelity, the lightweight mass must be left completely free to accurate, linear motion. Our patented spider design is years in the making, and perfectly suited to the task. It holds the voice coil in an exacting degree of tension with a flexible, acoustically transparent lattice and a carbon fiber composite collar. It places trust entirely upon the field coil and the signal of the music, offering no unnecessary resistances whatsoever.

Paired with paper thin, reverse roll lambskin surrounds the driver is very linear, and yet achieves a remarkable free-air resonant frequency of just 17Hz.

Cabinetry

To complete this system, as little as possible must be interstitial between the signal of your music and the field coil. This is where Songer Audio delivers absolutely everything, again by contributing almost nothing.

The S1 Design

Speaker cabinets by their nature introduce diffraction. The S1 minimally compensates for this natural diffraction, and nothing else. It is internally lined, damped and well braced. To preserve perfect phase and timing, no additional drivers are included in its design. The signal isn't needlessly degraded, as no crossover circuitry is necessary. The S1 simply holds the driver at ear level, where it plays free of coloration, and is port tuned for deep, accurate bass response.

The S2 Design

Like the S1, the S2 is a statement of simple elegance, in both form and function. It suspends the Type D field coil driver almost wholly in free space, attached at a single point to a layer-constrained, high mass, hardwood and glass-filled nylon mount for excellent imaging and clarity. The Acoustic Elegance LO15 dipole woofer is "port constrained" on the front side for a lower resonant frequency and higher efficiency. The baffle is then folded into a discrete, open chamber in the back, which greatly reduces sound wave cancellations common to woofers in dipole applications. It draws outstanding performance from the woofer, with full and yet unmistakably dipole bass response.