Some ATC active loudspeakers may make a small noise when turned on/off, this is due to the DC coupled amplifier momentarily passing a low-level DC voltage to the output as the voltage rails power up and down. This noise is nothing to be concerned about and causes no damage to the loudspeaker.  

Music is a dynamic signal by nature and to reproduce those dynamics effortlessly and accurately at realistic levels, an amplifier with adequate headroom is required. The specification for a passive loudspeaker should include its Sensitivity, which is a measure of Sound Pressure Level at 1m for 1W of amplifier power dissipated at its terminals. A loudspeaker with a sensitivity of 85dB/w/m will require 2 x the amplifier power to achieve the same SPL compared to a loudspeaker with a sensitivity of 88dB/w/m. It must be stressed that the notion of a loudspeaker “being difficult to drive” refers to the nature of the electrical load presented by the loudspeaker, not the sensitivity. A loudspeaker with a lower sensitivity can be an easy load to drive. 

Take a 50W power amplifier delivering 20Vrms into 8ohms, this will sufficiently drive ATC loudspeakers to a high sound pressure level, however the amplifier will be operating in a region of very low dynamic headroom, probably approaching overload, and the sound quality will likely be affected. An amplifier being continuously driven to limit can also be a cause of damage to a loudspeaker. 

Now take a 150W power amplifier delivering the same 20Vrms into 8 ohms. The amplifier is comfortably operating at 1/3 of its rated output power and will have an additional 5dB of dynamic headroom. 

The majority of ATC Power Amplifiers and Active Amplifier modules have an input impedance of around 10kOhm/leg (10kOhm unbalanced/20kOhms balanced) and an input sensitivity of 1Vrms (in some instances adjustable to 2Vrms). Therefore, the most suitable partnering pre-amplifiers will have an output impedance well below 1k Ohm, preferably as low as 100 Ohm. ATC preamps/line drivers have an output impedance of just 10 ohms to ensure the effects of longer cables/inter-connects are minimised.

For loudspeaker cables we recommend using oxygen free multi-stranded copper cables. For lengths under 5 metres we recommend using 2.5mm2, and for longer cables up to 10m we recommend using 4mm2.

For line level cables we suggest good quality oxygen free multi-strand copper cable. Ideally bare silver-plated copper with less than 100pF/metre capacitance from core to screen.

ATC recommend that you always use balanced connectors where possible in your system, for this reason we only have balanced XLR connecters on all our amplifiers and active loudspeakers. Balanced lines are able to reject any common mode interference and noise introduced from preamplifier to power amplifier, where unbalanced cables will be unable to do so.

It is perfectly normal for there to be a small difference in operating temperatures between amp-packs, this is due to inherent differences in the individual MOSFETs themselves and how our amplifiers are set up for minimal distortion.

All ATC power amplifiers have an input sensitivity of 2Vrms (in some instances 1Vrms, adjustable to 2Vrms).

ATC electronics are designed to operate at a decade below and a decade above the audible hearing spectrum. We do this to ensure that there is minimum phase shift across the audio band and to maximise transient response by having a high slew rate. For this reason, our power amplifiers operate well up to 200KHz and our line level amplifiers operate well above 500kHz.

If you are using your ATC electronics regularly then leave them powered on. However, if they are not going to be used for a longer period of time – for example inactive for 6 hours or more – then it is best to power them off or place them in standby. This will help to extend the life of the components and also reduce energy consumption.

If you are using your ATC active loudspeakers regularly then leave them powered on. However, if they are not going to be used for a longer period of time – for example inactive for 6 hours or more – then it is best to power them off. This will help to extend the life of the components and also reduce energy consumption.