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ATC SCM20ASL + C4 Mk2 Sub - Limited Edition Active Loudspeakers with Subwoofer

Sale price£17,995.00
1 in stock

Pickup also available at Doug Brady HiFi

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ATC SCM20ASL + C4 Mk2 Sub - Limited Edition Active Loudspeakers with Subwoofer

ATC SCM20ASL + C4 Mk2 Sub - Limited Edition Active Loudspeakers with Subwoofer

High Gloss Blue lacquer

Doug Brady HiFi

Pickup also available, usually ready in 1 hour

Kingsway Studios
Kingsway North
Warrington WA1 3NU
United Kingdom


The ATC SCM20ASL Limited Edition 2-way active stand-mount with the limited edition C4 MK2 subwoofer continues ATC’s philosophy of combining the best in-house loudspeaker drive units with matched on-board active amplification for optimal fidelity.

These new models integrates a 2-way active system, previously only available in a floor standing model, into a smaller stand-mount cabinet. The SCM20ASL Limited Edition features ATC’s proprietary 150mm/6” ‘Super Linear’ Mid/Bass driver paired with a 25mm/1” ‘S-Spec’ dual-suspension tweeter. Partnering the SCM20ASL loudspeakers is a sonically matched limited edition C4 Sub Mk2 Subwoofer.

Limited to just 150 pairs, the 2-way active stand-mount and the limited edition C4 MK2 subwoofer design is finished in a stunning high gloss lacquer in the ATC company dark blue.

Complementing the cabinet, the front baffle is hand-upholstered in royal blue full-grain Napa leather by German leather specialists Eissmann. The exterior alloy components feature a silver anodised finish in striking contrast to the blue lacquer and leather of the cabinet and baffle. 

Loudspeakers Key Features

  • Compact sealed cabinet finished in high-gloss blue with leather upholstered baffle
  • On-board ATC active 250W ‘Amp Pack’ module
  • 2nd order Linkwitz-Riley active crossovers
  • 2 x class A/B MOSFET amplifiers, 200W bass/mid & 50W high frequency
  • User adjustable input sensitivity & bass shelf controls
  • Hand-built in England
  • 6 year warranty

Subwoofer Key Features

  • Compact 12″ Subwoofer sonically matched to the SCM20ASL limited edition active speaker system.
  • Handmade ATC 12″/314mm  driver with massive motor assembly and ribbon voice coil
  • ATC 200W class A/B amplifier
    High Level and Line Level Inputs
  • Comprehensive user controls to ensure best possible integration with partnering loudspeakers
  • Hand-built in England
  • 6 year warranty


The bass driver operates in a 20-litre sealed cabinet and power is provided by on-board class A/B MOSFET power amplifiers, capable of delivering 200W and 50W continuous power to the bass and HF drivers respectively. The loudspeaker crossovers are active, analogue 2nd order Linkwitz-Riley and an all-pass filter is included to optimise the phase response through the crossover region, resulting in far improved tonal balance and imaging.

Input to the loudspeaker is via balanced XLR, located on the rear panel and there are user controls for input sensitivity and low frequency shelf cut/boost.  The input sensitivity control allows the user to tailor the input gain to suit their source/pre-amplifier combination, resulting in more consistent performance.  The low frequency shelf control gives the user the option to subtly adjust the bass response to suit their room and/or their personal taste.  The speaker is supplied with a removable grille, wrapped in dark blue acoustically transparent cloth.

Only 150 pairs of the SCM20ASL LE and 20 partnering C4 Sub Mk2 subs will be manufactured

UK stock allocation is limited to just 10 pairs. (we have secured just three pairs)

Bring professional sound to your home with the C4 Sub Mk2

Call to reserve 01925 828 009 

Speaker Acoustic Specifications

Bass/mid driver: 1 x 150mm/6”, SB75-150SL 8Ω
High Frequency Driver: 1 x 25mm/1”, SH25-76S 6Ω
Low Frequency Cut-off: 55Hz (-6dB, anechoic)
High Frequency Cut-off: 25kHz (-6dB)
Crossover Point: 2.2kHz
MaxSPL: 108dB continuous, 114dB peak (per pair, IEC Weighted Pink Noise, 1m, anechoic)
Sensitivity: +4dBu rev 95dBC (Bass Boost 0dB, Input Sensitivity 1V, Pink noise)


Speaker Electronic Specifications

Balanced Input: 1 x Rear Panel Mounted Female XLR, pin 2 hot
Input Impedance: 20kΩ (differential)
Input CMRR: >60dB (10kHz)
Input Sensitivity: 2.2dBu/1Vrms for full power
Input Sensitivity Control:

6dB switchable, -6dB variable. Total adjustment 2.2dBu/1Vrms to14.2dBu/4Vrms

Bass Shelf: -2dB to +3dB, switchable in 1dB steps
Crossover Filters: 2nd Order Linkwitz Riley
Amplifier type: Grounded Source MOSFET, class A/B, convection cooled
Output Power: Bass 200W (8Ω), H.F. 50W (8Ω)
THD+N: <0.0017%/-95dB (1kHz, 1dB below rated power, 90kHz BW)
Frequency Response: <2Hz to >200kHz (-3dB)
Limiter: ATC Active FET Momentary Gain Reduction
Electronic Amp Protection: Amplifier d.c. offset and over-temperature (both indicated by rear panel LED)
Mains Input: 220-230V or 115V, factory set. Please observe rear panel markings and labels!
Power Consumption: Idle 26W/41VA, 1/8th Power 116W/161VA, Full Power 312W/398VA
Heat Output: Idle 89BTU/hr, 1/8th Power 311BTU/hr, Full Power 382BTU/hr


Speaker Physical Specifications

Net Weight: 27kgs/59.5lbs
Dimensions (H x W x D): 450mm x 250mm x 425mm
Gross Weight: 31.3kg / 68.9lbs
Carton Dimensions: (LxWxH): 56 x 38 x 60cm / 22 x 15 x 23 ½ inches (each)


Subwoofer Acoustic Specifications

Drive Unit: Bass: 1 x 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).


Subwoofer Electronic Specifications

Amplifier type:  Grounded Source MOSFET based Class A-B, convection cooled.
Output Power: 300W in to 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.



Subwoofer Physical Specifications

Net Weight: 42kg
Dimensions: 568x464x500mm


ATC SCM20ASL + C4 Mk2 Sub - Limited Edition Active Loudspeakers with Subwoofer
ATC SCM20ASL + C4 Mk2 Sub - Limited Edition Active Loudspeakers with Subwoofer Sale price£17,995.00