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  GR Research Drivers
12" servo-enabled subwoofer driver

We now sell three GR Research subwoofer drivers which have been designed to work with our Direct Servo technology. These drivers have a custom sensing coil which allows them to be used with custom designed Direct Servo amplifiers.

While these three drivers are identical in appearance, details of the motor are different to cater to different applications.

GR SW-12-04
Designed for a sealed box with 1.5 cu ft volume

GR SW-12-08FR (OB)
Designed for a open baffle and infinite baffle applications. 8ohm nominal impedance. Recommended for running a pair with HX300-12OB configuration

GR SW-12-16FR (reference only)
Designed for a open baffle and infinite baffle applications. 16ohm nominal impedance.

Single and double driver options

SW-12-04 is designed for a sealed box with 1.5 cu ft of volume per driver.

Open baffle and infinite baffle options

GR SW-12-08FR and SW12-16FR are designed to run two drivers on one amp with OB configuration. With 2 or 3 drivers, high output can be achieved even with an open baffle. To achieve higher output in an infinite baffle or dipole configuration, SW-12-16FR has been designed so that up to 3 drivers can be connected to a single amplifier with high efficiency Hypex module whereas SW12-08FR has been designed only 2 drivers can be connected to a single amplifier. SW12-08FR gives slightly more output per driver than that of SW12-16FR.

Conventionally, nonservo drivers with low Qts value suffer low output at around Fs frequencies (ie, stall effect). Drivers such as SW-12-08FR/SW-12-16FR with high Qts values on the other hand achieve the desired flat max output response curve. However high Qts in nonservo application means the cone control is also weaker. Servo control on these OB drivers allows the effective Qts value drop to 0.15, achieving a much higher degree of cone control even than that of a conventional nonservo driver. As a result, these drivers achieve both high output and high cone control at the same time.

Driver comparison

The GR drivers use a lower mass paper cone, which has a slightly better transient response. The result is slightly better dynamics. At higher output, due to less cone stiffness, the sound may become softer due to the pressure placed on the cone.

The GR drivers also have a more extended response, allowing a higher crossover point if desired.

The performance can be described as "different" rather than superior or inferior.

Thiele/Small Parameters
Model GR SW-12-04 GR SW-12-08FR GR SW-12-16FR (reference only)
Enclosure size 1.5 cu ft sealed Infinite baffle / open baffle Infinite baffle / open baffle
fs 25 Hz 27.4 Hz 28.3 Hz
BL 13.7 11.2 14.7
Mms 138 g 112 g 108 g
VAS 100 L 100 L 100 L
Qms 4.308 3.201 2.80
Qts 0.321 0.747 0.875
Sd 490 cm2 490 cm2 490 cm2
Re 3 ohms 6.2 ohms 14 ohms
Xmax 16 mm 16 mm 16 mm

These drivers are available for purchase separately to use in a non servo configuration with the intent to upgrade to a servo sub with the purchase of our servo amplifiers in the future. This will suit those who already have an amplifier and crossover. If you are starting from scratch and don't already have an amplifier and crossover, then we recommend that you purchase one of our Direct Servo kits.

  Description: GR drivers Price  
  GR SW-12-04 - 4 0hm - 12" driver $259 buy it now
  GR SW-12-08FR - 8 0hm - 12" driver (IB/dipole) $259 buy it now