ES-38     Speaker Protector for Stereo Power Amp.   ( 2022 )
( AC/DC  12 ~ 24V)

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This add-on device for your power amp has two functions:

(1) Eliminating power-on "POP"
When your power amp is turned on, this protector circuit disconnects the speaker temporarily for 2~ 3 sec.(blue LED on) so that the "pop" sound produced by the speakers at the instant of power-on will not be heard

(2) It protects your valuable speakers by disconnecting them from the power amp. in case the amp is faulty.  The circuit uses two transistors (Q5 & Q6) to check the DC voltage at the outputs of the R- & L-channel.  Normally the DC voltage should be zero 
If the DC voltage of the output(s) changes from 0 volt to positive or negative by a few volts, the circuit
will turn off the relay & thereby disconnecting the speakers from the amplifier for as long as the fault cond-
ition persists.

Step (1) : Connect the the protector to a power transformer (12V... 24V, @200mA). (Do Not connect anything
to the inputs & speaker terminals at this moment)
Step (2) : Turn ON the power & the LED will light up immediately. After a delay of about 2 sec. the LED goes out
& the relay switches ON.
Step (3) : Now test the response of the protector by connecting a 3V battery to the L-channel input (battery negative
to earth) . You can use two AA 1.5V batteries in series. You will notice that the LED comes ON again & the
relay de-energized.
Disconnect the battery, the LED turns OFF in about 1 sec.
Step (4) : Repeat Step(3) by reversing battery polarity & the protector should give the same response as in
step (3).
Step (5) : repeat step (3) & (4) for R-channel.