can somebody explain this?

[temp123456]

I brought an used car speakers,with rated power 70w and peak power 300w,but even with tda1554 on max volume, the speaker is overexcursed on bass, voltmeter reading is 7,4VAC and spaeker resistance is 4ohm and that is 13,69W

So, why do speaker is being overexcursed when it's pushed only 13,69W?

 

[Ty_Bower]

You've got the speaker in the wrong box and/or the frequencies you are using are too low. For all we know, you might be testing it in free air. You need to design your enclosure so the speaker can handle the desired power at the intended frequencies.

 

[steviedon]

I brought an used car speakers,with rated power 70w and peak power 300w,but even with tda1554 on max volume, the speaker is overexcursed on bass, voltmeter reading is 7,4VAC and spaeker resistance is 4ohm and that is 13,69W

So, why do speaker is being overexcursed when it's pushed only 13,69W?

Used car speaker? You'll need to divulge some details before any assessments can be made. What model speakers specifically? Are they in an enclosure?

 

[Spatz]

There are electrical and mechanical limits on a driver. You just met the mechanical limits. Now guess if those 300 watts are real!