Please explain how to match up stereo watts with speaker watts and what are the guidlines?

ok I have been looking around but I haven't found a thread that explains in simple terms how to go about matching the right sized stereo to the right wattage speakers and how far apart can you miss match them?

for my sound system I want just a simple stereo unit in the dash with no external amp involved yet looking at speakers they are like 500-650 watt speakers out there and many stereo units I have looked at only put out 60-100 watts max so I am "assuming" it cant run those speakers, but since I just don't know for sure, can someone explain the rules on matching speakers to stereo units?

thank you

 

Stereo 101. Music is dynamic and most of the relationships are not linear. A 50 watt amplifier does not put out 50 watts continuous. Most of the time an amp is running at 1,2 or 3 watts. To double the perceived vol. you need 10 times the power. So an amp, with the same speakers, running at 10 watts is running double the vol then when it is running at 1 watt.

Then you need to take in account speaker efficiency. You will see specs like 85 DB at 1 meter at 1 watt. Higher the number the better. 10 DB difference is twice the speaker efficiency.

So you can get more power in your amplifier or with more efficient speakers you need less amplifier power.

An amplifier with 10 watts of power would need 20 watts of power to increase the perceived vol from 84 dB to 87 dB....or to double the perceived vol (84 DB to 94 DB) you need to double the power to 100 watts. Confused yet?

Then speakers will have an additional rating of OHMS. Typical it is 2, 4, 8 or 16 Ohms. This changes things, however, I wont go into that here. I will leave that to someone else if the want to tackle it.

You asked for a simple rule where there really is not any. I will make one up for you. For a simple stereo that I would put in a 2004 Tacoma: get two, 2 way, 4 ohm, 6 inch speakers that are 90+ db efficient and an amp that puts out 20+ watts RMS, 40+ watts peak of power. Yes, we did not talk about RMS. Go to some place like http://www.crutchfield.com they will help you about speaker mounting. I think you will need adaptors... I have a gen2 Tacoma and don't know about a gen1. Also you need to ask about wire harnesses. I assume you want direct plug and play for both the head unit and the speakers. You should be able to put together a 2 speaker system, CD receiver with adapters for under $300 delivered. Hope this helps.

 

rnish (for me forever a.k.a. root mean squared) provides good advice.