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C2/C4/C6/C7 Active

Sub-woofer Installation

4.4 Operation

The sub-woofer amplifier control and connection panel provides a range of

adjustment facilities to assist its integration with the satellite speakers.These facilities

are explained below and illustrated in Diagrams 4,5 and 6.

Level:Sets the overall sensitivity of the sub-woofer.Initially the level control should

be set towards the centre of its range and only adjusted once the Low Pass and

Contour controls have been set.

Low Pass:Varies the upper crossover frequency as

indicated on the control panel and Diagram 5.This

is the fundamental parameter that defines the

integration of the sub-woofer with the satellites.

The Low Pass control should be set at or slightly

above the specified low frequency cut-off of the

satellite speakers.

Contour: With the Contour control set to the

Flat+ position the sub-woofer pass-band frequency

response is fundamentally flat and in phase with the

satellite speakers.With the Contour control to the

Flat– position the frequency response remains flat

but the phase is reversed. Depending on the

relative position of the sub-woofer and satellite

speakers within the listening environment, phase

reversal can result in more consistent integration.

The Flat position is recommended for music programme material.The response

curves for each Low Pass filter position with Flat+ selected is shown in Diagram 5.

With the Contour control in the Lift+ position the frequency response is lifted in

the 40 - 60Hz region. This boosted setting is designed to provide a more

demonstrative sub-woofer performance appropriate for audio/visual programme

material.The response curves for each Low Pass filter position with Lift+ selected

is shown in Diagram 6. The Lift– position retains the frequency response but

reverses the phase.

Badge Indicator (C6 Only):The badge located on the lower front of the C6 cabinet

incorporates an amplifier status indicator. GREEN indication shows that the

amplifier is operating normally. RED indication shows that the amplifier is

operating at the full available output.Any more than brief RED indication means

that the amplifier is being over-driven and that its protection circuits are operating.

Protection will limit and distort the acoustic output of the sub-woofer so the

operating volume should be reduced.

Due to the nature of the electronics in ATC active loudspeakers it is quite normal

for a sound to be heard from the speaker when the power is applied or

disconnected.The noise heard will not damage the speaker and is quite normal.

Although ATC uses the highest-grade components, a different noise may be heard

from each speaker due to slight tolarance variations in the amplifier components.

4.5 Listening

The ear and brain tend to interpret distorted sound as loudness and thus

underestimate the actual level of undistorted sound. ATC sub-woofers, like all ATC

products,demonstrate very much lower levels of distortion than conventional systems

Diagram 4 - connection and control panel

Diagram 5 - low pass options, contour flat

Diagram 6 - low pass options, contour lift

2kHz

90Hz

80Hz

70Hz

60Hz

50Hz

15dB

10dB

5dB

0dB

-5dB

-10dB

-15dB