Head unit current draw?

[cmk05]

A question to the stereo/electronics gurus out there...

I'm putting together a little boombox with a 20w rms x 4 headunit powering a pair of 6x9s for home use.

I was wondering what the power requirement for this sorta setup would be.

I have an old 12vdc power supply rated at 5 amps and 50 watts that can't supply enough power to the head unit to play at moderate volumes. Then I realised it's running a 1amp fuse that wouldn't blow! Does this mean this power supply's putting out less than a single amp?

Also, can someone explain the difference between a regulated and otherwise ac to dc power supply?

Any advise would be appreciated...

[PhatBox]

I use a 10AMP (with 4A fuse) regulated power supply at work. I use it to power all sorts of headunits at the same time. Most headunits draw about an amp when running speakers. The ones that draw higher current are ones with Video screens (2-3A).

I just used a multimeter to measure the current of a Kenwood radio rated at 47Wx4 (probably around 20W RMS), and the draw was about 1.1 A. Current spiked to about 1.4A when the CD was loading, but playback at full volume was at 1.1A.

If you are using a changer or something else connected, more current will be used. If just tuner, less current (nothing moving).

Voltage regulators are used to regulate the output voltage regardless of the load connected or the input voltage. Therefore a 13.8VDC regulated supply will output a constant 13.8V. We use one in our product but it is a dc/dc voltage regulator which forces the output voltage levels to be correct even if the input voltage is variable or dips below the expected value.

[cmk05]

Thanks - I guess I'll pick up a new 12vdc 5amp regulated power supply from ebay - that should be adequate for my needs.