ATC speakers, ATC is a British manufacturer of loudspeaker drive units and speakers. Notably, the company has been in production for nearly fifty years. They produce a wide range of domestic loudspeakers in the SCM range. Moreover, even the budget SCM7 has a stunning performance. Additionally, their drive units outperform most of their rivals. Finally, a professional approach to design, materials science and production methods, ensures that ATC are always at the forefront of speaker design.
ATC and their design philosophy.
A research team, led by Billy Woodman, has been at the forefront of the companies innovations. A significant problem with speaker design is Magnetic Hysteresis. This can be though of as a kind of resistance to the magnetic field. This resistance causes the audio signal to loose linearity and causes distortion. ATC developed the Super Linear Driver which reduces third harmonic distortion by 10-15dB between 100Hz and 3kHz. This is in the vocal range, and provides unequalled performance, when reproducing voice and piano
The SCM range technical details
Then SCM series from ATC uses the legendary ATC drivers. These are manufactured in house and have many innovative features. The voice coils are edgewise wound ribbon. The wire is OFHC (oxygen-free high conductivity) and operates in a precision machined magnetic gap. The magnet assembly also has innovative features. Such as an air vent hole. This reduces airflow noise at low frequencies. The whole assembly is well damped. Thus eliminating unwanted resonances.
Soft dome midrange driver and constrained layer damping
The SCM40 floor-standing monitor features a unique soft dome midrange unit. This type of unit is still the best performing midrange speaker available. Another innovation is constrained layer damping. This provides a step change in music reproduction. The benefits include lower midrange harmonic distortion. Moreover, there is also an extended frequency range.
The SH25-76 tweeter
Some speakers in the entry series use the The SH25-76 tweeter. This is a new design that has a unique dual suspension system. The suspension suppresses diaphragm rocking even at high volume levels. The voice coil is designed to have exceptionally low distortion.
A summary of the SCM range from ATC.
The SCM range runs from the budget bookshelf, SCM 7, at around £1000 to the SCM300ASLT Active Speakers ,which retail for £47,000.
Next,we will look at a cross section, across the range, to get a feel for what is available.
The diminutive SCM7
At only 3ocm high these speakers pack a mighty punch. Notably, They use all of the design elements from the larger speakers in the range. The tweeter is a 25mm unit with a soft dome and precision alloy wave guide. Additionally, the 125mm ATC mid/bass unit has an integral soft dome. Moreover, they have a large optimised motor assembly.
Finally, they are best driven by a more powerful amplifier in the 75W to 300 W range. Four high quality finishes are available. White, black ash, black satin and cherry.
ATC SCM20PSL Speakers
The SCM 20 PSL are the top of the range bookshelf speakers from ATC. They have a 75mm soft dome tweeter as well as a 150mm bass driver. This is a hybrid design that uses ARC’s Super linear magnet assembly. The large motor units allow these speakers to handle 300 Watts.
The SL system reduces time domain distortion. This is a complicated subject but involves magnetic saturation as well as distortion caused by harmonics of the fundamental frequency. The driver’s dome and cone are made of acoustically “dead” polyester wave material, doped with ATC’s own formulation. This corrects any non linearity. The result is bass with great articulation and authority. Moreover, the midrange has more clarity and dynamic range.
ATC SCM40 Speakers
The SCM40 is an award winning passive floor stander. It is a three way design available in three beautiful finishes. Black ash, cherry or satin white. These flagship speakers have a performance ‘three or four times the price’ according to Hi-Fi Choice magazine. They provide more bass than the bookshelf range, as you would expect from a floor stander.
The key features include a 25mm Neodymium tweeter, a 75mm ATC Soft Dome midrange unit and a 164mm bass unit.
ATC SCM19A Active Speakers
The SCM19A are the entry level active speakers in the range. they have won many awards including the HiFi choice editor’s choice award. Each unit features two amplifiers, with a 150W amplifier for the bass and a 32w amplifier for the high frequencies. Both amplifiers are class A/B with MOSFET outputs.
The curved cabinets feature a multilayered laminate finish. Moreover, this is a rigid and well damped enclosure that provides a resonance free base for the high-end drivers. The tweeter is the renowned SH25-76 and the woofer is a super linear, 150mm unit.
Electronics
The amplifier modules have been upgraded to reduce noise and distortion. For example, noise has been reduced by 10dB at 10kHz. The modules also run at a lower temperature to improve reliability. The amplifiers have good protection with both DC offset protection and overload protection. Moreover their is an active crossover. Active crossovers are preferred as their response is not affected by variable voice coil impedance.
Finally we take a look at the flagship ATS speaker, the ATC SCM300ASLT
ATC SCM300ASLT Active Speakers
The flagship active speaker is the SCM300ASLT. This speaker has an extended bass response and uses the same soft dome technology as the rest of the SCM range. Notably, this speaker uses the rack mounted P4 amplifier. This is actually four amplifiers in one. There are two bass amplifiers of 275 watts in total as well as 200 watts for the mid-range, and 100 Watts for the tweeter. The drivers have large motor assemblies giving great precision and impact.
ATC also make a range of audiophile components such as the ATC CA2 MkII Pre Amplifier. this is a perfect companion to the Active speakers in the range.
This unit uses discreet components in the signal path. Moreover, the power supply uses a separate power transformer for each channel. A remote control is provided and there is a digital input control on the front panel. Connectivity is good with five line level inputs. There is also a phono pre-amp for a magnetic cartridge equipped turntable. Finally, unusually nowadays, there is a tape loop.
See the entire ATC range on Audio Affair