Head unit power!
- by Eddie Runner (NU5K)
Car Stereo head unit power is VERY deceiving! Head units all
have HUGE power ratings on the
Boxes or right on the front of the units! The highest head unit power I have ever actually
tested was 13 watts (at a half way decent THD)
So even if the head unit says 35Watts
or 40 watts per channel on it dont EVER expect for it to REALLY BE more than 15!
Just cant happen!
REAL amplifiers use LARGE power supplies in them
with transformers to STEP UP the voltage So that large amounts of power can be made! Head units just dont have room
in them For transformers or large power supplies!!!! So NEVER expect more than 15watts per
Speaker out of head units! Some of the more reputable head units might LIE on the boxes but
If you read the small print in the spec
sheets in the owners manual they might admit to the 15watt figure!
This picture shows a typical car amplifier. The amplifier can generate much more
power per channel than the car head unit. Why can't a head unit generate this
kind of power??? In the picture above you will see a large power transformer
(coil of wire) in he middle of the amplifier (labeled 4)... This transformer
converts the 12 volts from the car battery into a much higher voltage (in this
case +36 volts and -36volts)? Since the car head unit doesn't have a
transformer to boost the voltage (not enough room in it) the head unit can only
limp along trying to make a lot of power with the measly 12 volts from your car.
Most high power head units use a bridged output (also called floating ground or
push pull), head units use an IC chip that makes both speaker wires to each
speaker work together with one pushing while the other pulls (so to speak) just
like a real amplifier does when you bridge it. But unlike a real amplifier, most
car head units cannot be un bridged. But even still, having no transformer in
the head unit limits it severely and your output will be around 12 to 13 watts
pr speaker. Don't fall for the high power LIES.