All ServoDrive loudspeakers incorporate a unique, patented operating principle involving the substitution of high-speed rotary servo-motor and belt-drive system for the traditional loudspeaker voice coil/magnet transducer system. The concept was created by renowned engineer, Thomas Danley. In the years since their introduction, ServoDrive subwoofers have heightened the awareness of the tremendous effect massive low frequencies have in both fixed installations and touring sound applications.

ServoDrive's BassTech 7s provide more sound pressure level capability than any other subwoofer on the market. Features include: exceptionally low harmonic distortion, true high-fidelity performance, virtually no output loss due to power compression, frequency response virtually flat to below 28Hz, extraordinarily efficient - low power requirement for full SPL output. The BassTech 7s display smooth frequency response (essentially flat from crossover frequency down to 28Hz). Revolutionary motor-driven belt design increases linear excursion and efficiency, handles large low-frequency peaks without damage or sonic compromise.

The BassTech 7s have been on tour with the Rolling Stones, Michael Jackson, U2, Garth Brooks, Phish, and Lyle Lovett. From Super Bowl half-time shows, to Disney World, Universal Studios, the Mirage Volcano, Buccaneer Bay at Treasure Island, Crystal Cathedral, and Blumenthal Theater - wherever crowds gather, these subwoofers are guaranteed to bring a new level of excitement!

Compare this



9 - High Quality Dual 18" Driver, Vented Box Subwoofers

4 - ServoDrive BassTech 7, Servomotor Driven, Horn Loaded Subwoofers

Required Power = 5400 Watts


Required Power = 1600 Watts

Frontal dimension = 108" x 108"


Frontal dimension = 45" x 96"

System weight = 2000 lbs.


System weight = 920 lbs.

Truck packing volume = 189 cu. ft.


Truck packing volume = 105 cu. ft.
(ideal truck packing dimensions)

Amplifier dollars = 4,320.00
(at 80 cents / watt)


Amplifier dollars = 1,280.00
(at 80 cents / watt)

Harmonic distortion = 2% to 20%
(typical at full rated power)


Harmonic distortion = 0.5% AVG. to 1.5% MAX.
(measured at full rated power)

Power compression = 4dB to 6dB
(typical at full rated power)


Power compression = LESS THAN 1.5dB
(typical at full rated power)

Sound level at ten meters = 122dB
(measured at full rated power before power compression)


Sound level at ten meters = 124.5dB
(measured at full rated power)

Amplifier Capacity

Continuous Power
(per modified AES procedure, 24 hrs.)
Musical Peak Power Capacity
(<15 seconds)

400 Watts RMS

800 Watts RMS

Power Compression

Full power after 15 minutes
2x full power after 15 seconds


Nominal Impedance

4 Ohms


Spectrum (28-125Hz)
(1/2 space, groundplane)

2 units - 107.5dB (1W, 1m)
4 units - 110.0dB (1W, 1m)

Sound Pressure Level

Full Rated Power (28-125Hz)
(1/2 space, groundplane)

2 units - 136dB
4 units - 142dB
(Peak SPL: +3dB)

Low Frequency Corner (-3dB)

2 units - 30Hz
4 units - 28Hz

Distortion, Full Rated Power

Second Harmonic, 28-125Hz
Third Harmonic, 28-125Hz

<1% typical
<1% typical


2-15" pistons

Maximum Excursion/Driver

>1" peak-to-peak linear excursion +3dB excursion headroom at 400 watts/30 Hz

Crossover Slope


>18dB per Octave @ <125Hz

Dimensions & Weight

45" x 45" x 22.5" - 230 lbs.

Finish and Features

Black "TNT" indoor-outdoor carpeting

Enclosure Construction

•14-ply Baltic Birch with extensive bracing
•27 Hz Hyperbolic Flare T=.55
•Horn Length 10.6 feet

Horn Throat Compression Ration

3.4 to 1


Neutrik "Speakon" or EP4


•Dolly Tray
•Custom Connectors
•Custom Handles
•Painted (Texlac)