CoDrive™ Technology

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CoDrive subwoofer with NeoSym™ motor. The business end......a view of the throat.

Shown above is the production CoDrive subwoofer which incorporates both our compound air movement technology (US patent #6,466,676 "Compound Driver for Acoustical Applications", 2002) and our dual coil NeoSym™ linear loudspeaker motor (US Patent# 6,778,677 "Repairable Electromagnetic Linear Motor For Loudspeakers And The Like", 2004).

Compound drivers are unique because there are two cones in tandem which are connected by a "drive link". The drive link creates a central port ("throat") in the front cone while mechanically coupling the two cones so they move in phase. Air displaced by the rear cone must pass through the throat, but since the area of the rear cone is greater than the area of the throat, air velocity in the throat is multiplied. This "Compression Loading" provides both rapid air movement and desirable damping so the sub has good transient response for "quickness" at higher crossover frequencies, while also helping to lower the mechanical "Q" of the speaker to improve low frequency extension in a small sealed box.

Because Compound Drivers have higher air loads than conventional subwoofers of similar cone area, in our prototypes we discovered that even 4" voice coil conventional subwoofer motors were operating too close to their power capacity to have adequate headroom for reliable performance. So Ron Coffin (CoDrive founder) invented NeoSym™ motor technology, which couples two NdFeB speaker motors together in a unique way that increases power handling, cancels distortion, and provides other benefits.

The audible result is a subwoofer that has thundering low frequency response, while at the same time having the "speed" needed for use at higher x-over frequencies. All the typical audio marketing hype cannot prepare you for your first demo of a CoDrive low frequency system. These technologies must be experienced before you can fully understand their importance.

Click on the link for details.

The CoDrive Neo Symmetrical subwoofer motor (US Patent# 6,778,677)

NeoSym™ motors provide the thrust to power our compound drivers. The design utilizes two identical neodymium magnet structures that are mounted face to face in finned aluminum heat sinks. Dual voice coils are bonded to opposite sides of an armature that is precisely centered by a single large spider attached at the armature mid-point. The armature has a central hub where a tubular drive rod attaches and connects the motor to the output cones.

There are many benefits to the design.

• It's an efficient way to utilize high energy NdFeB magnets, which have superior performance compared to the ferrite magnets most speaker companies use.
• Neo pot structures do not generate a large stray magnetic field, so they are safe to use near sensitive video equipment.
• The motor has precisely the same thrust on either side of the center position (a symmetrical BL curve) because as the voice coils move, one coil is always moving into it's magnet structure as the other is moving out, effectively canceling position relative unsymmetrical forces, regardless which direction the motor is moving. This is important because an unsymmetrical BL curve produces distortion.
• Our dual 2.5" coil version has a linear winding equivalent to a 5" diameter voice coil, which can generate a lot of force and permits a lot of power handing.
• Since each coil has it's own magnet structure in a generously finned aluminum heat sink, the motor can dissipate heat rapidly for high reliability.
• Voice coil alignment is enhanced because the centering spider is precisely in the middle between the two voice coils. This creates a more stable structure over the life of the driver which improves reliability while at the same time allowing tight air gaps for improved magnetic efficiency.

Field replaceable voice coils........ another CoDrive innovation!

Because of the NeoSym™ motor's modular construction and our precise manufacturing technology, the voice coil assembly (armature) can be easily replaced. This means the driver can be quickly repaired it's "cooked" at an automotive dB drag race competition. Also, it can be hot-rodded with aftermarket coils, and hobbyists or pro speaker builders can easily change voice coil windings to optimize their drivers for specific applications. The below illustration is one concept of a heavy duty conventional woofer that utilizes NeoSym™ technology.

If you would like to incorporate patented NeoSym™ technology in your next woofer design, call us now for details.

For more about NeoSym™ click the link

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