The speaker cable model Type 4 was first introduced about 1983. It wasn’t the prettiest cable, but the performance advantage of its polypropylene insulation was dramatic and much appreciated. Several evolutionary steps later, the current version of Type 4 was introduced in 1995—a design whose foundation is so well balanced that it hasn’t changed since then—and still isn’t changing.

Types 9+DBS Low-Distortion & Low-Noise speaker cable is essentially Type 4 with better metal, added layers and techniques of Noise-Dissipation for more effective noise control and AQ's patented Dialectric-Bias System (DBS)

In addition, Type-9+DBS conductors are a little bigger than previous 4-series cables. The conductors are a little farther apart, reducing interaction between adjacent conductors by 35%.
 
HIGH PURITY CONDUCTORS - SOLID PERFECT-SURFACE COPPER+ (PSC+)
Solid Perfect-Surface Copper+ (PSC+) conductors prevent strand interaction, a major source of ear fatiguing transient intermodulation distortion. The astonishingly smooth and pure Perfect-Surface Copper+ eliminates harshness and greatly increases clarity compared to OFHC, OCC, 8N and other premium coppers. The superior purity of PSC+ further minimizes distortion caused by grain boundaries, which exist within any metal conductor. The astonishingly smooth and pure Perfect-Surface Copper further eliminates harshness and greatly increases clarity compared to OFHC, OCC, 8N and other premium coppers.
 
MULTI-LAYER CARBON-BASED NOISE DISSIPATION
Multi-Layer carbon-based Noise-Dissipation plus Direction-Controlled conductors and shielding significantly lower noise-floor and reduce amplifier Transient-Intermodulation Distortion (TIM).
 
SOLID CONDUCTORS
Eliminate harshness and confusion due to strand-interaction.
 
72v Dielectric-Bias System (DBS)
Insulation is also a dielectric that can act like a shunt-filter. Biasing minimizes dielectric-noise and linearizes the filter, significantly improving wide-bandwidth dissipation of induced RF noise.
 
STAR-QUAD GEOMETRY
Balanced Star-Quad Geometry reduces time-smearing while preserving dynamics, and clarity.