DIfference between Sub-OUtput and Pre-Amp output?

Question

I am looking at buying a new headunit for my car and they all come with pre-amp outputs. BUt there are also some that have a sub out aswell. What is the difference between the pre-amp outputs and the sub output?

Also some of the Pioneer have Direct Sub Drive. IS this the same as a sub out?

Thanks

Answer 1

A sub output is just a pre-amp output that's made for a subwoofer.  It's not affected by the front/rear fade control or the balance control.  It's usually a mono output, and often has a crossover circuit so that it only plays bass.  Decks with sub outputs usually have built-in sub volume controls so that you can adjust the volume of your subwoofer, as well as a sub on/off setting.  Some decks have a "non-fader" output, which is similar to a sub output, but it's stereo instead of mono, and doesn't have a crossover.

Some decks allow you to designate the rear pre-out as a subwoofer pre-out instead, using the programming menu.  This is common on newer decks with only one pre-out.

Pioneer's Direct Sub Drive is a feature that lets you connect the deck's rear speaker outputs to a subwoofer instead of regular speakers.  It's much lower power than a typical sub amp, and you can't use it to drive a sub and rear speakers at the same time.

Answer 2

A sub output usually has a few characteristics that a regular preamp out won't have.

1) it isn't affected by the fader control

2) It usually has it's own volume or gain control

3) It can usually be filtered by an internal crossover.