This is the speaker protection circuit, provides stereo speaker protection and prevents switch-on clicks and DC components on the output of the amplifier connected.

Speaker Protection Components List:

R1,R2 : 3K3
R3,R4,R5,R6,R7 : 8K2
R8,R9,R10,R11 : 330K
R12,R13 : 18K
R14,R15,R16,R17 : 47K
R18 : 47
R19,R20 : 680
R21,R22 : 100K
R23,R24,R25,R26 : 1K2

C1,C2,C3,C4,C5,C6 : 1uF
C7,C8,C9,C10 : 100uF
C11 : 220uF
C12,C13 : 470uF

D1,D2,D3,D4,D5,D6,D7,D8,D9,D10 : 1N4148
D11,D12,D13,D14 : 1N4007
ZD1 : 6V8

T1,T2,T3 : BC547B
T4 : BC517

LD1 : Red (ERROR INDICATOR)
LD2 : Yellow (WAIT INDICATOR)

RY1,RY2 : VR15M121C (12VDC – 15A – 1C)
Transfo (1,2VA – 2 x 6V / 2 x 0,1A)
IC1 : LM324

Circuit Notes:

• This circuit uses center tap transformer and the power supply circuit design already provided in the schematic diagram. It powered with 6V dual polarity power supply.
• This circuit available in kits, you may order the kit online. The manual assembly of the kit can be download at the end of this post.

This stereo loudspeaker protection will protect the loudspeakers against the switch-impulsions and the direct current component on the output of the connected amplifier.

Suitable for:

• Amplifiers with symmetrical power supply
• Amplifiers with asymmetrical power supply.

Specifications :

• Switch-delay: ? 6 seconds
• DC protection: +1V/-1V
• Max. input voltage: 200Vpp + DC
• Max. switching current: 10A
• LED indication for: WAIT (switch-on delay) and ERROR (DC on speaker output)
• Supply voltage: 220VAC

Download Speaker Protection Kit Manual Kit