PA4401

Click-Pop Suppression Device

ANALOG PRODUCTS DIVISION

561 E. Elliot Road #175, Chandler, AZ 85225 Tel: (480) 539-2900. Fax: (602) 414-5141

www.protekanalog.com

95025. Rev.0. 05/2008

NOT FOR USE IN LIFE SUPPORT SYSTEMS

Pre

Amp

+

+

Pre

Amp

Power

Amp

Power

Amp

DETAILED DESCRIPTION

Figure2. Shows the normal setup of a Pre Amplifier system. Since the system is built on a single ended power supply the

outputs of the pre-amplifier need to be routed through a bypass capacitor to get rid of the DC bias.

Figure 2: Normal setup for a pre amplifier output

When the power supply to the system is turned ON there is a spike in the output of the system because of the charging of

various components in the system. This spike is called a “Click or Pop Noise”. When this click/pop noise passes through the

Power Amplifiers, the noise is amplified and listeners hear an audible ‘pop’ which causes discomfort. The reverse operation

happens when the system is powering down. These operations are shown below in figure3. The top waveform shows the power

supply Powering Up and Powering Down. The middle waveform shows the voltage appearing at the positive terminal of the

bypass capacitor. The bottom waveform shows the voltage at the output of the bypass capacitor. This is the Pop-Noise that is

amplified by the power amplifier.

Figure 3: Power Up and Power Down sequences and waveforms

t

t

0

0

>500mV

start-up “pop”

time

mSec

50mS

50mS

>500mV

shutdown “pop”

Power Supply Waveform

Bypass capacitor input plate

System output