I am running Alpine PDX 4 channel Amp to the Alpine SPR 60c speakers. My system has been running good with no problems for a long time. All of a sudden, the speaker (only on the driver side) goes out along with the tweeter. So I removed the door panel and disconnected the wires then connected them back on and it started working. However about 2 weeks later, the same speaker went out again. I should mention the speaker just goes out suddenly. It doesn't phase in and out like if there's a short or something. So far I have tested the speaker with a multimeter and the speaker is good. What else can the problem be?