ATC C4 Sub MK2 Active Subwoofer

ATC has a rich history of developing loudspeaker systems from component level up and the C4 Sub Mk2 is no different. The subwoofer features a new sub-bass driver, developed by ATC’s R&D team and optimised for reproduction of the lowest four octaves of the audio band. To best achieve this, it is designed with a 30mm magnetic gap, 50% longer than any other offered by ATC. The long-gap and short-coil configuration takes a long-standing ATC design feature to its limit. Distortion is minimised, while simultaneously delivering the high linear excursion required to generate accurate and dynamic low-frequency output. Generating a high level of magnetic flux over such a long gap required extensive FEA computer modelling and the resultant 6"/150mm N48M Neodymium magnet is the most powerful ever assembled by ATC and a first for the company. As well as minimising distortion, the short-coil long-gap configuration ensures the voice coil remains surrounded by the motor structure - even at high drive levels - maximising cooling, reducing power compression, and improving reliability. Turbulent air noise within the driver is minimised via a large, flared vent running through the centre of the motor structure, which has the added benefit of increasing voice coil and motor cooling.

The C4 Sub Mk2 delivers an extended low-frequency response without employing electronic equalisation, quite unlike many subwoofers available today. Instead, the more elegant combination of exceptional transducer engineering and a marginally larger cabinet volume is used. The simplicity of this approach reduces phase shift and group delay, aiding the integration of the sub with the partnering monitor loudspeakers. Ultimately, it delivers a more balanced and coherent experience for the listener, extending the low-frequency response without masking details or changing the tonal character in the upper bass/lower mid-range.

Drawing on 34 years of experience in amplifier design and development, ATC's electronic engineering team have delivered an all-new amplifier for the new subwoofer. The 300W class AB design is hand-built by ATC at their UK facility and precisely optimised to the requirements of the drive unit, resulting in fast, dynamic bass with minimal colouration. Two balanced inputs provide connectivity suited to both stereo and AV/home cinema systems plus two balanced outputs provide connections to partnering loudspeakers or to 'daisy-chain' multiple subs. Low-pass filters are analogue, 4th order Linkwitz-Riley and filter frequency options ensure optimal integration with a wide range of studio monitors. An industry-standard 80Hz low-pass and an 'off' option (for use with external processing) are also provided. A polarity switch plus a continuously variable 180° phase adjustment allows further optimisation of the subwoofer crossover and a stepped attenuator with a 21 dB range provides precise level matching.

In-Use

The size and performance of the C4 Sub Mk2 make it the ideal partner for a wide range of ATC loudspeakers, from the SCM19 up to and including the SCM100. Multiple subs can be employed to elevate performance, to fill larger rooms and also when partnering with larger models of loudspeakers. Buffered linkable inputs and outputs make connection of multiple subs simple. Home cinema can be particularly demanding of subwoofers and this new design offers improvements in dynamic range and clarity at higher SPLs. Designed and engineered with a focus on resolution and integration, the C4 Sub Mk2 offers additional low-frequency extension and dynamic range but without compromising balance in the upper bass and lower mid-range. They provide an upgrade path to customers owning smaller loudspeakers and lacking space for larger stereo loudspeakers whilst also strengthening ATC’s options in AV & home cinema applications.

We endeavour to despatch same day for orders placed up to 1pm on available stock items (items with stock message "Usually dispatched within 24 hours"). Please remember to check with us first for a physical stock check if next day delivery is important to you. Any items with stock message "Usually dispatched within 72 hours" are items that we do not hold in stock but order in from the importer or manufacturer as soon as a customer order is received. Occasionally these may be delayed beyond 72 hours due to importer/manufacturer stock levels but we will inform you as soon as we can if this is the case.

UK Orders

We despatch the bulk of our UK mainland items on a 24 hour service – Free of Charge.  Non Mainland locations - Isle of Man, Isle of Wight, the Scilly Isles, the Scottish highlands and Islands, the Channel Islands and Northern Ireland may take a day or so longer and are not Free of Charge. Smaller items are delivered using Royal Mail 24 or special delivery. Larger items are delivered using a courier service such as DPD or UPS.

International Orders:

Due to the nature of our products and brand restrictions we are only able to send certain items internationally. Smaller items are delivered using Royal Mail Small Packets Airmail with International Tracked and/or Signed depending on value of item and availability of the service. Larger International shipments are sent by insured and tracked services using UPS. If there are any delays due to specific customs regulations, etc, you will be contacted by Hifisound or by the courier with a request for any further information required. Customs duties can apply for shipments to any countries outside of the UK depending on where the product you have bought is made. Customers are responsible for all taxes and duties incurred when the items enter their country.

Collect in Store or Home Install

At the request of the manufacturer some items cannot be supplied by mail order but you can click and buy them and then elect to collect them from our store or arrange a home install (if applicable). Applicable items clearly state that they are Collect in store or home install. Once ordered you will receive a message prompting you to contact us by phone or email to arrange for us to deliver and install or to reserve and collect from our store at your convenience, you will also be advised of the delivery time / stock availability as not all Home install / collect in store items are held in stock.