Thread: Noob Q: What does "Active" mean?

Originally Posted by Slimline

Just like the title: I read somewhere about someone wanting to go "active" and I have no clue what that means in relation to car audio. In the PC world, I assume it means Active PFC or fans vs. passive heatsinks, but as for car audio - no clue. Help, please? Google gives me too many results to filter (even with "car audio" as helpers)

This forum is a great place to learn this stuff, I came here at the beginning of this month not knowing anything and now I feel that I can see the big picture.

Anyway, the whole reason the terms active and passive even exist is because no 1 speaker can produce the entire range of audio. Obviously a subwoofer isnt going to produce high notes like a tweeter, and vice versa. So every speaker has a frequency range that it produces the best and with the least amount of distortion, and if you try to play a different frequency through it then you'll get crappy sounding music.

So that's why we need multiple speakers. We break the audible range of sound up into a few different parts. Normally it's three parts, one for the low frequencies (subwoofer), one for the middle frequencies (woofers/speakers that go in the door/mids/whatever you want to call them), and the tweeters. This way, each speaker has its own range of frequencies it can focus on to provide you with the most accurate sound!

But remember I said you get crappy sound if you use a speaker to play a frequency that it wasnt designed for? Well we need to send only the frequencies that we want each speaker to play to each speaker. That's what crossovers are for! There are two types of crossover -- active, and passive.

Passive crossovers are the most common and easiest to set up, because speaker component sets already come with them. Just wire them in between the amp and speaker, and go! Active setups are a little harder, though. Rather than filtering out the frequency range for each speaker after the amp, an active setup filters it out before via software (well in our case anyway, since we conveniently have a computer already in the car).

The reason this causes more complication is because you have to have as many channels in your amp as you have speakers, since you need a dedicated channel for each speaker. You also have to tune your crossover yourself, but that can be a good thing because you'll get to tweak it more to your liking. Active crossovers are also nice because they don't suck power like passive crossovers do.

can i dumb the term active a bit for him?

Active = crossover through RCA(including high level inputs on some units but blah)
Passive = Crossover through Speaker wire

simple...or not lol

Originally Posted by scott_fx

or another way:

active = crossover before the amp
passive = crossover after the amp

thats even more dumber

Thanks a lot netchris, that was the missing link. I knew it had something to do with crossovers but other than that I was clueless. Great explanation

Passive can be crossover before the amp too, it just normally isn't.