ATC SCM40
3-Way Passive Floorstanding Loudspeaker
“Given a serious source and recording the new ATC SCM40 is superb – I know of no price rivals that give this level of accuracy, speed and insight…it’s capable of a level of transparency you normally only expect from loudspeakers at three or four times its price.” Hi-Fi Choice, October 2014

Engineered for Excellence
- New ATC designed and built 25mm Soft Dome HF unit with precision alloy wave guide
- ATC 164mm short coil bass driver
- Massive optimised motor assembly
- ATC Soft Dome mid-range driver
- Flat impedance curve allowing easy load for amplifiers
- 6 year warranty
DRIVER COMPONENTS
Finally, after years of painstaking development, we are proud to introduce a pair of HF drivers worthy of partnering ATC’s range of formidable bass/mid and mid-range drive units. The outstanding SH25-76 and range-topping SH25-76S are the product of over 40 years’ experience building the world’s finest acoustic transducers.

1 Waveguide
The precision machined alloy waveguide is profiled to produce accurate stereo imaging.
2 Mounting Ring
An ultra-stable and acoustically inert compression moulded composite material forms the ideal chassis.
3 Proprietary Diaphragm
FEA optimised dome profile combined with a low mass and highly damped material delivers a smooth extended frequency response with very low colouration.
4 Voice Coil Assembly
Kapton former with damping layer carries a copper clad aluminium ribbon voice coil resulting in a lightweight and stable assembly for a smooth, extended response.
5 Lower Suspension
This unique secondary suspension element ensures pistonic motion of the moving assembly, lowering distortion and negating the requirement for ferro-fluid.
6 Top Plate
The magnetically annealed/heat treated top plate ensures the best magnetic performance from the motor assembly.
7 Acoustically Absorptive Plug
Undesirable acoustic energy at the rear of the diaphragm is attenuated by a small felt component, linearising the frequency response.
8 Neodymium Ring
Powering the motor assembly, this large nickel coated high grade Neodymium ring magnet ensures an extended and colour free response.
9 Back Plate / Pole
Forming part of the magnet assembly the geometry is optimised for the highest performance and the component is electrophoretically coated black to ensure maximum heat dissipation.
Dual Suspension Tweeter
ATC’s approach to tweeter design is unique in the marketplace. By incorporating a secondary suspension component the moving assembly is naturally constrained to travel only in the axial direction. The result is a design that suppresses rocking modes and ensures lower distortion levels. The additional stability that this approach provides over more conventional tweeter construction negates the need for ferro-fluid (usually required for cooling, damping, etc). As a consequence, the magnetic gap can be made smaller allowing ATC tweeters to not only perform optimally, for longer, but also offer improved power handling over conventional designs.
While this unique tweeter topology offers superior performance, the resultant increased moving mass and overall complexity must be offset and overcome by the perfect alignment of all components. Consequently manufacturing and assembly demands exceptional care and accuracy — a level of capability that ATC excels at.
The additional stability over other designs negates the use of ferro-fluid, so ATC tweeters perform at their best for longer, and the magnetic gap can be made smaller, further improving power handling.


Fully Optimised Neodymium Motor Assemblies
Each tweeter motor assembly employs a magnetically annealed top plate and huge N48M Neodymium ring magnet, the geometry of which has been individually optimised using finite element analysis to ensure the best possible performance. Achieving an incredibly high flux density of over 2.0T in the magnetic gap, the magnet assembly of the SH25-76 is fully saturated and therefore free from the effects of flux modulation in the surrounding metalwork, lowering odd harmonic distortion to below -70dB across the operating band. The high levels of flux density in the gap combined with a short coil long gap configuration result in a linear and extended frequency response beyond 20kHz.
SPECIFICATIONS
- HF: ATC 25mm dual suspension Tweeter
- Mid: ATC 75mm Soft Dome
- LF: ATC 164mm SC
- Matched Response: ±0.5dB
- Frequency Response (-6dB): 48Hz – 22kHz
- Dispersion: ±80° Coherent Horizontal, ±10° Coherent Vertical
- Sensitivity: 85dB @ 1W @ 1 metre
- Max SPL: 112dB
- Nominal Impedance: 8 Ohm
- Crossover Frequencies: 380Hz & 3.5kHz
- Recommended Power Amplifier: 75 to 300 Watts
- Connectors: Binding Posts / 4mm Plugs, tri-wire
- Cabinet Dimensions (HxWxD): 980 x 370 x 305mm (inc. foot plinth; spikes add 25mm to height, grille adds 34mm to depth)
- Weight: 31kg
- Veneered Finish Options: Cherry, Black Ash
- Painted Finish Options: Satin Black, Satin White
- Warranty: 6 years






