Volume potentiometer issue (I guess)

[Arcade-Projects]

Hi,
Last time I did a serial config. to my speakers (pls see the image below) but the sound comes only when my volume pot is at max. I cannot fade the volume from low to loud since my volume pot. works like a switch. When volume is at min its off, and when volume is at max its on, but no way to make it loud gently like with a pot based on the pcb for exemple (if we take a watch, volume min is 7am and volume max is 5pm, so I've to put my volume pot to 4pm to have sound, before no sound at all, and from 4pm to 5pm no volume difference, so like I said, it's like a switch...)

When I had only one mono speaker, the same potentiometer worked fine, I could gently fade the volume from low to high like with any other pots, but now I have two speakers in serial and maybe its too much for that pot (whitch is 500ohm).
Btw, my speakers are 6ohm each
highland-audio.com/FR/Produits/Seis_1201.html

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