About Zobel circuit

I know that the Zobel circuit is to maintain a certain impedance of the load of the speaker at high frequencies. When I test the circuit, the way to measure the impedance is (after measuring the output AC voltage, divide it by the output AC current), but After I came out on the side, whether there is a Zobel circuit or not, the AC current will decrease as the frequency increases. In this way, the impedance will continue to rise, so I don't understand why the Zobel circuit has no function.
Below is my circuit diagram and measure,R9 and L1 are the resistance values of the speakers measured by me.
 

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A Zobel network is not useful in your circuit because it is a complementary emitter follower which generally does not need feedback compensation. However, the LM3886 is a quasi-complimentary chip which does require a Zobel network. While you may see a Zobel network applied to EF circuits, it is required for CFP aka Sziklai pair amplifiers (including quasi-complimentary) that potentially are unstable due to their local feedback. The 10 Ohm+100nF Zobel network is a pole at 160KHz, below which it has no effect. Perhaps more important than the Zobel network is a series R+L build-out that prevents the load impedance from shunting the amplifier global feedback. To understand a Zobel network, you need to understand feedback stability criteria, including phase margin and gain bandwidth product.
 
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