The DD multi-spider suspensions start with layers of fine weave cloth impregnated with thermal activated resin. These fine cloth sheets are then placed together with the weave grain at opposite angles, equalizing the inherent tension and increasing the strength. The layers are formed by heat and pressure until cured in molds with very high peaks and valleys. The two layers of fine cloth are far stronger than a single layer of heavier cloth, the higher surface area of the fine weave cloth gives more contact area for the resin. The high peaks and valleys, or corrugations, dramatically increase the strength over wide, shallow, progressive type rolls.
Two layers of laminated cloth are also more resistant to bending than a single layer. The layers are forced to bend along different section of their respective weaves, making the combined structure stronger and more resistant to fatigue.
DD then take these laminated layers and combine them for a given compliance target; most DD speakers will have 4 - 6 layers of cloth in the suspension.
These multiple layers of cloth formed in deep corrugations keep their inherent strength once the resin breaks down. The DD suspension retains restoring force to the cone after years and years of use. It does cost more to build mult-layered suspensions, but the benefits are many and long lasting.
DD developed the most electrically efficient connections, the Direct Connect, one of the latest DD innovations now being copied the world over. First off, multiple tinsel leads are twisted and soldered to copper power wire at the edge of the speaker frame. This twisted and soldered connection reduces any signal lost to an absolute minimum.
DD's 10 gauge power cable is made from Oxygen-Free copper. Copper provides perfect contact in contrast to speaker terminals or push-down spring connections which are made from low grade metal. Many of these "pretty" (but poorly made) terminals have 0.1-0.2 Ohms of resistance in just the terminal housing. If you don't believe us, unscrew one and watch it stick to the speaker magnet.
Another flaw of common speaker terminals is the inability to match up with large gauge speaker wire…And if one is able to find a terminal large enough to accept large gauge wire, it is still made from cheap metal thus the signal loss problem. DD's 10 gauge power wire Direct Connects can be twisted (the best mechanical connection possible) with any gauge wire, AND also be connected with ANY number of wires. Series and parallel connections can be done in any combination and WITHOUT signal loss.
DD suggests the use of wire nuts for direct wire to wire terminations. Twisted wire connections are the only code approved termination in building codes due to the no loss transfer ability and permanently held connection. These same wire nut terminals are the perfect connection for mobile audio connections.
Direct Connect allows virtually any gauge and number of speaker wires to be connected without signal loss.
The surround uses our EROM( Extended Range Of Motion) profile, copied en masse to become an industry wide standard. The EROM design gives long, controlled excursion while keeping the cone diameter as large as possible. This profile also saves mass over the sculpted rubber surrounds and inner tube style surrounds, less mass is louder and faster.
The EROM profile, nearly parallel walls with a half-round top, is more self-supporting than the wide half-roll type surrounds. This enables the surround to become part of the suspension compliance, helping to control the high forces of the accelerating moving mass and enabling the coil to better track incoming signal.
The DD EROM profile innovation allows for more cone area, lower mass and increased stiffness. It's no wonder than the DD EROM has become the most copied surround in the world.
This motor system also utilizes the DD exclusive FREE FLOW COOLING SYSTEM; separate cooling vents machined into the voice coil, top plate and pole piece which focus cooling air into the magnetic gap. This high-tech, precision machined cooling system actually lowers the working temperature of the voice coil, thereby lowering the stress on the entire audio system. The more the speaker moves, the more air is pumped onto the coil wire.
The dustcap and spiders of a speaker create changes in air pressure as the cone system moves up and down in accordance with the input signal, and the amount of movement is proportional to the amount of input signal.
The dustcap is used to push cooling air down through the pole piece. The pole piece has cross ventilation passages machined from the center vent to the outside of the pole piece, with rows vent holes at the top and bottom of the pole. Cooling air is pumped directly onto the aluminum former as well as drawing heated air out of the magnet cavity.
The spiders are used as forced air pumps o channel air through vents machined into the top plate inner diameter. These vents move cooling air directly to the voice coil wire. Additional vents are machined from the top plate inner dimension to the outside of the top plate and work in conjunction with vents tooled into the speaker baskets.
The voice coils are also part of the Free Flow Cooling System with rows of cooling vents located above the coil windings, below the coil windings and at the top of the former in the dustcap cavity. Cooling air is pumped through these rows of holes to move heat away from the wire; as close as possible to the source of heat.
Another DD innovation was eliminating lead wire noise, breakage and suspension offset distortions with the introduction of our Laminated Lead Wire System. DD pioneered this development as increased speaker excursion exceeded the limits that stretched tinsel jumping across the frame to cone gap could accommodate. The longer lead lengths cause excessive slapping against the cone as well as setting up oscillation modes that fatigued the wire.
The Laminated Lead Wire System placed the tinsel leads between layers of the spiders, eliminating hanging wires to clang around between the spider and cone. The spiders and lead wires become an integral unit with the corrugations of the spiders engineered for the excursion demand of the speaker.
Traditional hanging lead wires place weight and tension on one side of the cone, causing harmonic distortion. The DD system places the wires across the entire spider thereby balancing the weight and tension on each side of the speaker.
The DD system also allows for efficient handling of high current demand applications. Some DD woofers use 8 lead wires for every voice coil conductor, allowing even the most high power amplifiers to transfer power with minimal signal loss.
The cone is our multi-fiber synthetic blend, the type of construction used in the highest power handling concert drivers, not punched out from bleach bottle plastic. These special cones are designed for the highest strength with the lowest weight, again, lighter is louder and faster.
DD start with ultra-light weight synthetic fibers which are cut to varying lengths. These fibers are combined and mixed with high binding strength natural fibers and aerospace grade resins. High tensile binding increases the bond strength at the points where the fibers become interlocked.
The fibers are shot at the cone molds in angles which re-enforce the cone body perpendicular to the direction of the voice coil forces. This increases the resistance to bending modes at high power levels.
These high-tech fibers have incredible strength and are further enhanced by using techniques to increase the cone cross section area without adding additional mass. The resin used creates a hard outer skin on the cone surfaces, creating a sandwich construction format. One skin cannot bend without the other skin doing the same, the further these skins are moved apart, the higher the resistance to mutual bending becomes. The ratio of increased strength is exponential, twice the thickness results in 4 times more rigidity. The newest DD synthetic blend cones are state of the art in cone technology and an integral reason why their speakers can supply high SPL and low distortion.