C4 Sub Mk2


The C4 Sub Mk2 is a high-performance 12″/300mm active subwoofer, designed to deliver the exceptional levels of performance demanded by audiophiles and film & music lovers and integral to partnering with ATCs range of loudspeakers. The subwoofer performance and features make it ideally suited to stereo, AV and home cinema applications.

  • High performance sealed box design using 12”/314mm ATC proprietary sub driver
  • Ideal partner to SCM19, SCM20, SCM40, SCM50, SCM100
  • Suitable for use in stereo, AV and home cinema applications
  • On-board 300W convention cooled discrete MOSFET class A/B amp
  • 2 x balanced XLR inputs
  • 2 x balanced XLR outputs (un-filtered/processed)
  • User adjustable gain, low pass frequency, polarity and phase settings
  • 6 Year warranty.


Acoustic Specifications
Drive Unit – 12″ SS75-314SC 8Ω
Low Frequency Cut-off: 22Hz (-6dB, half space, low pass filter set at 80Hz).
Low Pass Filters: 50Hz, 65Hz, 80Hz, 320Hz. (-6dB, 4th order Linkwitz Riley).
MaxSPL: 110dB continuous, 116dB peak (IEC Weighted Pink Noise, 1m, half space, low pass filter @ 80Hz).
Sensitivity: +4dBu ref. 88dBC (single channel driven, Gain +6dB, Level 0dB, pink noise, low pass filter @ 80Hz).

Electronic Specifications
Amplifier type: Grounded Source MOSFET based Class A-B, convection cooled
Output Power: 300W into 8Ω
THD+N: <0.003%/-90dB, at 100Hz, 300W into 8Ω over 90kHz bandwidth
Balanced Inputs: 2 x Rear Panel Mounted Female XLR, pin 2 hot
Input CMRR: 90dB at 200Hz
Input Impedance: 20kΩ (differential)
Balanced Outputs: 2 x Rear Panel Mounted Male XLR, pin 2 hot
Output Impedance: 100Ω (differential)
Frequency Response: <2Hz (-3dB) – 320Hz (-6dB, set by panel-controlled LP filter)
Low Pass Filters: 4th Order Linkwitz Riley
Gain Control: 0, +6dB, +10dB
Level Control: 0dB -11dB in 1dB steps. Total range 21dB with use of Gain switch
Phase Control: 0-180° ref. Input
Polarity Control: In-phase/Out-of-phase ref. Input
Limiter: ATC Active FET Momentary Gain Reduction.
Sensitivity: 1.55Vrms for full power (single channel driven, Gain 0dB, Level 0dB)
Mains Input: 220-230V or 115V – Factory set. Please observe panel markings and labels!
Power Consumption: Idle 8W/14VA. 1/8th Power 170W/230VA. Full Power 500W/600VA.
Additional: Mute via ¼”/ 6.35mm Jack socket, controlled via latching footswitch*.
*Footswitch supplied separately, latching type, ¼”/6.35mm jack connection.

Physical Specifications
Dimensions: (H x W x D): 568 x 465 x 519mm / 22 3/8 x 18 5/16 x 20 7/16 inches
Heatsink protrudes a further 40mm / 1 9/16 inches from rear and optional spikes add an additional 22mm/ 7/8 inches to height.

Net Weight: 42kg / 92.6lbs.



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