50th Birthday Special
ATC SCM20ASL Limited Edition
The back story to the SCM20ASL LE
ATC’s first loudspeaker system, the 3-way S50, was released in the late 70s and by the late 80s had evolved into the SCM50 (which is still in production today). Both models were mid-size 3-way systems which were too large for many, making it clear that a smaller 2-way system was needed if ATC were to engage with a far greater number of potential customers, both in the professional and consumer Hi-Fi markets.
As a result,in1987 Billy Woodman began the development of a new 150mm/6” mid-bass driver that would become the heart of a new loudspeaker and ATC’s first 2-way design, the SCM20. Whilst the finished system may have been simpler than the existing 3-way designs, mid-bass drivers for 2-way loudspeakers present a challenge due to the bandwidth they need to cover and the conflicting requirements of bass and mid- range reproduction, so there was significant development work to complete.
The earlier development of the ATC 3”soft dome midrange and specifically the large voice coil it employed, highlighted the importance of power handling & dynamic range so this new mid-bass driver started with a 75mm/3” voice coil, operating in ATC’s favoured short-coil-long-gap (underhung) configuration, but with a much longer.
In the late 90s and early 2000s, the recording industry was beginning to use higher resolution digital formats, with 96kHz & 192kHz PCM recordings becoming more common. Sony had developed DSD, a single bit digital audio format using a 2.8224 MHz sample frequency and also Super Audio CD (SACD) the physical media that DSD recordings would be delivered on. All these changes resulted in recordings with an extended high frequency bandwidth, and it was no coincidence that in 2002, ATC updated and improved the SCM20 again, with a move to a new 25mm/1” tweeter from Seas which, provided slightly lower coloration and extended the high frequency response.
Improvements to the SCM20 high frequency response were made again in 2014, with the arrival of ATC’s in-house designed and built SH25-76S dual-suspension tweeter, developed by Billy Woodman and ATC’s new engineer, Richard Newman. This 1”/25mm soft dome part had been in development for many years and improved the performance of the SCM20 and larger top-end models via lower distortion and an extended high frequency response. Significantly, it also marked the move to building the majority of high frequency drivers in-house, after many years of out-sourcing.
Introducing the
ATC SCM20ASL LE
The SCM20ASL Limited Edition is a 2-way active loudspeaker released to mark the beginning of ATC’s 50th Anniversary year. This exclusive new model, limited to just150 pairs, packs ATC’s finest transducer engineering and active loudspeaker technology into a compact sealed cabinet, finished to exceptional standards in a stunning high-gloss blue lacquer. Complementing the cabinet, the front baffle is hand-upholstered in dark blue full-grain Napa leather by leather specialists, Eissmann Individual.
To support the SCM20ASL LE, a limited run of ATC’s new C4 Sub Mk2 have been produced with matching gloss blue cabinet finish, leather upholstered baffle and silver anodised amp hardware. As a system, the speaker-subwoofer combination offers the low frequency response of a large 3-way speaker, but in a more flexible and room friendly package.
From modest beginnings ATC has grown to become one of the very few manufacturers successful across both domestic and professional audio. By selecting ATC you join a group of music lovers, professional audio engineers, studios and musicians across the world that understand and value the engineering that goes into an ATC product – and the sound that comes out.
Whilst excellent results are possible from passive systems, a multi-way loudspeaker system will only realise its true potential if implemented as an active design, due to the advantages displayed top right.
The SCM20ASL Limited Edition realises these advantages via its on-board ATC Amp-Pack, a 2-way amplifier module featuring balanced input, precision 2-way active crossovers and a pair of class A/B power amplifiers. The location of the amplifier module, in the rear panel of the loudspeaker cabinet, results in a very short connection to the loudspeaker drivers and outstanding low frequency speed and control.
Connection to the amplifier is made via XLR and balanced input circuitry is used for high noise rejection. To ensure the best match to the partnering source/pre-amplifier, the amplifier Input Sensitivity can be adjusted via a combination of switch and precision potentiometer. In addition, a low frequency shelf cut/boost allows the user to tailor the bass response to the room and/or taste.
A classic Linkwitz-Riley 2nd order active crossover is employed to integrate the audio to the two drive units. The crossover has the added benefit of an all-pass filter stage which allows the Phase response to be optimised through the crossover region, resulting in superior tonal balance and imaging vs the equivalent passive model.
The two power amps deliver 200W and 50W to the bass/mid and high frequency drivers, respectively. The Output stages are a class A/B MOSFET design, and each amplifier is carefully optimised for its application. As with all of ATC’s loudspeaker driver components, the amplifier is designed and manufactured at ATC’s factory in the UK.elcome customers to your store.
The magnetic characteristic of the steel used in the magnet assembly of a loudspeaker is inherently non-linear due to magnetic hysteresis. The magnetic field generated around the voice coil modulates the permanent magnetic field of the motor and the magnetic hysteresis of the steel results in a delayed return to the permanently magnetised state. This results in a distortion of the input signal in the loudspeaker causing audible colouration.
To counteract this problem, the bass driver fitted to the SCM20ASL Limited Edition employs ATC’s Super Linear Magnetic System.
Whilst excellent results are possible from passive systems, a multi-way loudspeaker system will only realise its true potential if implemented as an active design, due to the advantages displayed top right.
The SCM20ASL Limited Edition realises these advantages via its on-board ATC Amp-Pack, a 2-way amplifier module featuring balanced input, precision 2-way active crossovers and a pair of class A/B power amplifiers. The location of the amplifier module, in the rear panel of the loudspeaker cabinet, results in a very short connection to the loudspeaker drivers and outstanding low frequency speed and control.
Connection to the amplifier is made via XLR and balanced input circuitry is used for high noise rejection. To ensure the best match to the partnering source/pre-amplifier, the amplifier Input Sensitivity can be adjusted via a combination of switch and precision potentiometer. In addition, a low frequency shelf cut/boost allows the user to tailor the bass response to the room and/or taste.
A classic Linkwitz-Riley 2nd order active crossover is employed to integrate the audio to the two drive units. The crossover has the added benefit of an all-pass filter stage which allows the Phase response to be optimised through the crossover region, resulting in superior tonal balance and imaging vs the equivalent passive model.
The two power amps deliver 200W and 50W to the bass/mid and high frequency drivers, respectively. The Output stages are a class A/B MOSFET design, and each amplifier is carefully optimised for its application. As with all of ATC’s loudspeaker driver components, the amplifier is designed and manufactured at ATC’s factory in the UK.elcome customers to your store.
The magnetic characteristic of the steel used in the magnet assembly of a loudspeaker is inherently non-linear due to magnetic hysteresis. The magnetic field generated around the voice coil modulates the permanent magnetic field of the motor and the magnetic hysteresis of the steel results in a delayed return to the permanently magnetised state. This results in a distortion of the input signal in the loudspeaker causing audible colouration.
To counteract this problem, the bass driver fitted to the SCM20ASL Limited Edition employs ATC’s Super Linear Magnetic System.
ATC SCM20ASL Limited Edition
The SCM20ASL Limited Edition is a 2-way active loudspeaker released to mark the beginning of ATC’s 50th Anniversary year. This exclusive new model, limited to just 150 pairs, packs ATC’s finest transducer engineering and active loudspeaker technology into a compact sealed cabinet, finished to exceptional standards in a stunning high-gloss blue lacquer. Complementing the cabinet, the front baffle is hand-upholstered in dark blue full-grain Napa leather.
Price is for a pair of ATC SCM20ASL Limited Edition.
Specification
SCM20ASL Limited Edition
The SCM20ASL Limited Edition continues ATC’s philosophy of combining the best in-house loudspeaker drive units with matched on-board active amplification for optimal fidelity. The new model 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. 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.
1 x 150mm/6”, SB75-150SL 8Ω
1 x 25mm/1”, SH25-76S 6Ω
55Hz (-6dB, anechoic)
25kHz (-6dB)
2.2kHz
108dB continuous, 114dB peak (per pair, IEC Weighted Pink Noise, 1m, anechoic).
+4dBu rev 95dBC (Bass Boost 0dB, Input Sensitivity 1V, Pink noise).
Features
- Compact sealed cabinet finished in high-gloss blue with leather upholstered baffle
- ATC on-board 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 cut/lift controls
- Matching subwoofer – C4 Sub Mk2 LE – available for extend bass response
- Hand-built in England
- 6 year warranty
1 x Rear Panel Mounted Female XLR, pin 2 hot
20kΩ (dif ferential)
>60dB at (10kHz)
2.2dBu/1Vrms for full power
-6dB switchable, -6dB variable. Total adjustment 2.2dBu/1Vrms to 14.2dBu/4Vrms
-2dB to +3dB, switchable in 1dB steps
2nd Order Linkwitz Riley
Grounded Source MOSFET, class A /B, convection cooled
Bass 200W (8Ω), H.F. 50W (8Ω)
<0.0017%/-95dB (1kHz, 1dB below rated power, 90kHz BW)
<2Hz to >200kHz (-3dB)
ATC Active FET Momentary Gain Reduction
Amplifier d.c. of fset and over-temperature (both indicated by rear panel LED)
220-230V or 115V, factory set. Please observe panel markings and labels!
Idle 26W/41VA. 1/8 Power 116W/116VA. Full Power 312W/398VA
Idle 89BTU/hr, 1/8 Power 311BTU/hr, Full Power 382BTU/hr
27kgs/59.5lbs
450x250x425mm 17 11/16” x 9 13/16” x 14 3/16”
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