I just have very very basic knowledge about electrics/electronics and car audio. I am thinking of changing stock speakers of a 27 years old car. There are four speakers, 2 on front door panel, 2 on rear, inside window.

All of them shows 20W Nom, 40W Max, 4 Ohm.

My Pioneer DEH-1450UB stereo's box says it has 50W x 4 Mostfet output. It was working fine with stock speakers.

My new speakers are;

  • Alpine SXE-1025S 4" (10cm) Coaxial - 25W RMS, 180W Max, 4 Ohm (for front door)

  • Alpine SXE-1725S 6-1/2" (16.5cm DIN) Coaxial - 40W RMS, 220W Max, 4 Ohm (for rear)

The problem is, the wires connected to my rear speakers are AVSS 0.35mm (I think equals to 22 AWG) wires and their amperage limit seems below 3.3A.

Would it lead to any problem if I will connect those speakers to that wire? Should I change the wires or shouldn't worry about fire hazard or anything?

I am not looking for high volume or detailed audio, I just need something mediocre.

1 Answer 1


The stereo can put out a maximum of 50 watts per speaker and it has been working fine -- no overheating, no melting, no fire. Attaching higher power speakers won't make the stereo produce more power. Therefore it is safe to keep the existing stock wires.

Note that if you play the stereo at full power -- 200 watts total inside a car -- you will suffer a hearing loss in a short time. Since you would never do that intentionally, the stereo is never really putting out 200 watts. It's probably not much more than 5-10 watts for normal listening.

  • But my rear speakers are 40W RMS, does that mean it constantly draws 40W from stereo and approximately 3.3 A continuosly? In that case can it lead to overheating? Because my ex speakers were 20W RMS Mar 24 at 21:34
  • @shehatesme No. Speaker power ratings are the maximum power the speaker can accept without damage. Speakers don't "draw" anything; they dissipate the power that is sent to it by the amp. If the amp only sends 5 or 10 watts to the speaker, it will dissipate just 5 or 10 watts. Speakers don't work like light bulbs which "draw" power from a constant voltage supply. The voltage and current that an amp sends to a speaker are variable and depend on the volume control. A 40W speaker can accept more power than a 20W, but if the amp is set to the same volume, the 40W uses the same power as the 20W.
    – MTA
    Mar 25 at 4:01
  • thank you for great explanation. So can we say RMS (or nominal) value is what speaker able to handle constantly for a long time and actually it works with 5-10-20W or whatever volume needs? And peak values are what can it handle for much shorter times? I was thinking wrong as RMS value means that speaker constantly "draws" 40W (with lowest volume) and peak/max value is what it can handle when volume increased. Mar 25 at 7:37
  • @shehatesme Correct, you have a good understanding now of how it works.
    – MTA
    Mar 25 at 12:22

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