what do preamps do

[ChrisC 10+ year member]

What do preamps do in a headunit?

If a HU only has 2 preamps outputs for the front and rear, can i still add a sub?

so if i have a HU that has 3 preamp outputs, does that mean the HU will power the front,rear,and sub. Meaning i wont have to buy an amp for the sub?

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[negativezeroz 5,000+ posts]

Preamp sends the signal...Im not a technical person. Frost will answer this. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

You will need an amp for your sub. You can use a LOC if you only have front and rear preamps.....

 

[JimJ 5,000+ posts]

Provides the signal needed to drive external amplifiers.

Some decks (like my Alpine 7894) combined the rear and sub pre-outs.

The pre-outs themselves can't power speakers; they simply provide a signal for the external amps that actually drive the speakers.

 

[iceteebone 5,000+ posts]

they are rca outputs on the deck. they send music signals to the amps. the decks with 3 rca's, have a dedicated sub output that lets you specificly adjust the sub. you can run a sub on front and rear outputs, you just don't have a sub control on your deck and if you hook your subs to say the rear, when you fade to the rear you fade to the subs and vice versa.

 

[newdavid 10+ year member]

i have one question abt preamps voltage my p8mp has 6.5 volts preouts and 770 has 4.0 volts preout

whats the difference i know the higer the volt the better but can someone explain it to me how that works...

thnaks