Page 1 of 1

car audio amp selection...

Posted: Mon Jul 30, 2001 2:40 pm
by b-man1
i have sony xplod components in the front (45W nominal, ~150W max) and polks in the rear (not sure on the power rating, but can't be more than 150W). the headunit is an xplod 50Wx4 cd w/ built-in low/high filters and sub control.

i have an xplod 10" sub w/ 150W nominal, 400W max (need to get a box for it), but here's the question:

can i get one amp to power the whole system, or do i need a separate amp for the components + rear and one for the sub?

additional info: ok, i spoke w/ a guy at best buy and he said a 4-channel amp would be ok for the front components and the sub...but to power everything the amp would be mucho $$$$ (for a 6-8 channel) and probably not worth it.

should i just let the headunit power the speakers since the amp will take all the work off of them anyways?


i know nothing about this, so any explanations will help greatly. :)

Posted: Mon Jul 30, 2001 9:12 pm
by bitSLAP
I think Reg is the one to ask here, but I'll put in my 4 cents (cdn) :)

What I think you should do is leave the filters on your head unit off and just run the mains directly. Put capicitors on the fronts to trim the bass to 100 hz. Put capacitors on the backs with the floor at about 60 hz. Then buy a 2 ch or monoblock for the sub.

The other option is to buy a 4 ch amp and power the back speakers with it as well. There isn't much point to boosting the fronts.

Posted: Mon Jul 30, 2001 9:59 pm
by Viperoni
bit, the front soundstage is the most important in the whole car.

if you get an amp, I'd suggest getting one for the sub alone, then another for the speakers, if you want to amplify them.

The fronts should be running no less than 60hz, where as the rears should be at least 150hz.
That way the bass sounds like it's coming from the front, where it's supposed to.

Posted: Thu Aug 02, 2001 5:44 am
by mplogic
I guess opinions are like @ssholes. We all have them and they are all hairy... or something like that.

Your system is actually one of the best designs. If I understand your description correctly you have 2 pairs of components (front and back) and a single 10" sub. No deck has enough true power to adequately run components (or at least good ones). Don't bother with trying to block out bass. The separation is the whole point of components and most reproduce bass very accurately. Let the crossovers do their job and send the right frequencies to each speaker in the component sets.

Several companies are making 5 channel amps now where the 5th channel has a sub crossover built in. You can probably pick up a decent one in the $300-500 range. Your deck would need 2 pairs of preamp outputs to allow you front to rear fader control. The sub input can come from any single preamp output and most amps will probably do this internally. Viperoni is right, the staging is the most important part of the install.

Low bass is all mono and omnidirectional so the sub can be placed pretty much anywhere with the same effect. For low end, one 10 should be plenty boomy and still tight unless you want that low rumble that rattles everything loose on those dumb@ss lowriders you see scraping around while the idiot driver literally can't even hear half of the music he's listening to. -gratuitous rant

Mid-bass is the punchy part you feel and you probably want that coming from your front component sets (like Viperoni said) although I wouldn't block it from your rears either. This is what you "feel" when listening to fast jazz or metal and some choice funk. :)

The tweeters require the most thought in placement as they are totally directional. I like putting them near the mids, maybe angled in door panels. If they are up high you just get an earful of tweet. You want to hear the highs, but wherever they are, your attention will be drawn toward them (like a small insect buzzing near your head).

Not sure, but I'd guess that sub control on your deck is made to work with a feature on xplod model amps. Go to a good quality car audio shop to research what you want and then buy it elsewhere. Soundwerks is about the best if you have them there. Try to talk to an installer and not a salesperson if possible.

If you can't find a good 5 channel amp you could go with a 4 channel for the components and a mono sub amp just for the 10.

When buying an amp look for a high amperage fuse, heavy duty terminals, big cooling area, and a quality build. Don't just go by the numbers on the paper. Manufacturers can make the numbers do whatever they want. I get a kick out of seeing Jensen amps rated at 400W with a 12A fuse. Lets see, 12 Amps X 12 Volts = 144 Max watts that the amp is capable of pulling (although it would probably fry if it did).

Posted: Thu Aug 02, 2001 9:16 am
by b-man1
wow, thank you for the great replies! :)

i'll let you know what i get and try to get a few pics of the finished product. :) :)