installing Creative PC speakers in my car

[ferez]

hi guys
i want to install cretive 2.1 speakers in my car (dont ask why)...
i saw a few models of them (creative have alot of models of 2.1) and it seems that most of them gets 12v from their transformer...
my question is - can i connect them to my car just like that? assuming that a car's battery gives 13.8v while engine running.

the power consumption of the speakers is 28w so a 7812 reg. cannot be used (gives only 1A - not enough).

 

[audioguru]

A 7812 voltage regulator needs an input of at least 14.5V to regulate properly so it won't work in a car.

You probably looked at the cheap Creative Inspire T3000 dinky little satellite speakers with a little wee 5.25 inch "subwoofer".
The RMS power is rated at a horrible-sounding 10% distortion when only one speaker is driven and is less if both or all three are driven.
If the amps are capable of low distortion then the satellites will produce a whopping 3.7W each at clipping.
The sub will produce 10.5W at clipping.
There is very little total power. Nobody knows how little is the total power when all 3 speakers are playing.

Ordinary "200W" car radios have 4 channels with 14W each at clipping into 4 ohm speakers. The front speakers in the doors are usually the size of the Creative's little woofer. The rears are much bigger and more efficient 6"x9" times two and have much more bass than the little Creative speakers.

The Creative speakers are designed for indoors. The wooden enclosure for the sub will dissolve in the humidity inside a car when it rains or when it is foggy. The speaker cones are probably paper and they will also dissolve.

I suggest using a real 4 channels car radio amplifier with 4 real car speakers.

 

[ferez]

first of all tnx for the reply
secondly, ive heard those speakers in a car in real time with a lot of engine and road noise and they sounded great...so in all aspects they suits me.

so im going back to my original question - will the speaker system be damaged if a voltage of 13.8v will be supplied? (originally rated 12v on the transformer).

tnx and good day

 

[audioguru]

The transformer is probably not regulated so it might be 12V when it is playing loud and 15V at rest. The car voltage will be close enough.

The transformer probably limits the power if the speakers are turned up too loud. A car battery is extremely powerful so turning up the speakers might blow up the amplifiers or the speakers.

Connect a resistor in series with the positive DC power wire. 0.47 ohms/3W will drop the voltage 1V when the current is 2.1A. The 13.8V will drop to 12.8V and the total power in the speakers will be 27W.
Then the resistor heats with 2.1W, the speakers play with 15W and the amplifiers heat with 12W.

Are you going to bring them indoors each night?

 

[ferez]

nope , have another speakers for the computer.
im gonna fabric them to the new dashboard im building out of fiberglass...

should i put a fuse? where and what should be his value?

tnx

 

[audioguru]

A fuse is very important because it prevents a fire if the car is in an accident.
29W/13.8V= 2.1A. Use a 3A or 5A fuse in the fuse box.

My old ordinary car radio had four channels at 14W and used a 10A fuse.
My new car radio is very powerful. I think its fuse is 40A.

 

[ferez]

tnx mate....and another question
does the 3w resistor need a heatsink?

 

[audioguru]

A 3W resistor is big enough to radiate heat and to be cooled by the air around it.
I have used 25W resistors that come in a small aluminum housing with fins and they can be bolted to a heatsink.

 

[Hero999]

I would use a fuse instead of the resistor.

I'd use a 2A slow blow fuse so it doesn't blow if the bass gets too loud, yes I know it says 28W but it won't draw it continiously so it doesn't matter.

A polyfust would be ideal as you never need to replace it.