4-channel amp -> active crossover or rear channel?

maxxell · 12-18-2005, 12:13 AM

Hey,

I have been upgrading my system piecemeal since the beginning and I'm up to the point where I want to replace the stock speakers. The carputer is up and running, and I've put in a pair of 12" subs on their own amp.

Here's the question:
I have a JL 300/4 running all four channels for the in-car (stock) speakers right now. Should I get a pair of components and run an active crossover*, leaving me with no rear channel OR should I run a passive crossover**, keeping the stock rear speakers OR should I get components up front and coax in the rear?

I hear active crossovers are hot *****, but would it be worth losing the rear speakers?

* - active crossover, as I understand it, is passing the audio signal through the crossover before the amp, thus requiring 1 channel for the tweeter and 1 for the woofer for each of the right and left channel, for a total of 4 channels for just the front speakers.

** - passive crossover would be putting the crossover after the amp, allowing 2 channels to the fronts (R/L) and 2 to the rear (R/L).

maxxell · 12-18-2005, 12:22 AM

Actually, just had another thought.
I do have a POS pyramid 2-channel amp that I could use to fill out the rears, so I could go with an active crossover and still have something coming from the rears.
Thoughts?

3onDubs · 12-19-2005, 12:21 PM

Quote: Originally Posted by maxxell

Actually, just had another thought.
I do have a POS pyramid 2-channel amp that I could use to fill out the rears, so I could go with an active crossover and still have something coming from the rears.
Thoughts?

I'm actually in the same position as you. I have a sound processor that has an active crossover function on it and I also have passive crossovers that came with my front components. I want to use the active crossover because it will allow me to tune my tweets much better to get optimal sound, but I only have a 4 channel amp. I don't want to get rid of my rear coaxials because I tried turning them off and didn't like the sound without them. I thought about adding a weak 2 channel as well, but then I'd have three amps and my computer feeding off my battery...

...The best thing that I can think of is either getting some really nice components up front that can stand alone (you would lose the ability to have surround sound) or get a six-channel amp for the insides (i've seen the Soundstream 5.1 amp on ebay for around $522 I think which is a really good amp). You could use the sub pass through for your sub-amp and you'll be set.

Will Albers · 12-19-2005, 12:33 PM

Use the passive x-over with the seperates. Much easier than bi-amping. Keep them up front. Try to avoid placing the tweeter high and the woofers low. Try to keep them on the same plane. Get coax for the rear. Use the amp like you are using it now. If you have the ability to mono the rears, I'd recommend mono rearfill.

jizzajam · 12-19-2005, 12:41 PM

The problem with that is I feel like you're throwing away power biamping off of a symetrical 4 channel (or 6 channel) amp. I have a JL 500/5, which is well suited for bi-amping, 100x2 + 25x2 + 250x1. I was considering a JL 450/4 which is really nice for this sort of setup, 150x2+75x2. Thats a solid frontstage! The preamp on those JL slash amps is well suited for biamp, as you can set it to bandpass the woofer and use the lowpass freq as the hipass freq for the tweeters. makes it simple to adjust that xover point precisely. JL 450/4 + Alpine h700 > *

then go with some DIY speakers like dayton RS series woofers and tweeters from partsexpress.com (~$170 for some high quality ****) and it'll blow you away.

Screw the rears. spend the money getting more power and better speakers up front. IMO the only reason to have rear speakers is DTS, and getting proper speaker placement for correct imaging is a nightmare in cars, I've never seen (heard) it done correctly.
Heres an example: my car

3onDubs · 12-19-2005, 06:59 PM

I found the Soundstream 5.1 amp on ebay for $384, but the listing ends in an hour...it would be perfect for an active crossover...

http://cgi.ebay.com/SOUNDSTREAM-D-AR...QQcmdZViewItem

maxxell · 12-20-2005, 10:55 AM

Quote: Originally Posted by 3onDubs

but then I'd have three amps and my computer feeding off my battery...

Do you think that's too much? I can handle the power back there now without serious light-dimming. I'd probably get a cap and a grounding kit if I put in another amp, but that should be enough, wouldn't it?

Quote: Originally Posted by Will Albers

Use the passive x-over with the seperates. Much easier than bi-amping. Keep them up front.

What's bi-amping?