I recently installed a alpine 9815,and 4 Infinity Kappa 572's. They don't seem to produce enough bass. What would you suggest for a amp and sub, and should I use the HU to power the Infinities.

 

kel67, You can use the HU to power your Infinitys, but I personally wouldn't recommend it as a permanent set-up. Especially if you use a sub, you will have a problem with balancing your system because the bass will tend to overwhelm the rest of the sound. And your Infinitys will perform much better with a quality amp. There are several different ways to go. A lot depends on your tastes, listening habits, and available space. You can go with a 5 channel amp. They are essentially 2 amps in one chassis and the sub section tends to be 200 watts or so max. So you need to carefully choose your sub(s) to match. Another option is a 4 channel with the rear channels bridged for the sub(s), and the front 2 channels running your Infinitys. Or, if you have plenty of room available, the best way to go SQ wise, is separate amps for front and back. Like I said, it depends on your situation as far as budget, taste, listening habits, etc.

 

Would it be bad to run the speakers off a 4-channel amp, and then the sub off it's own?

 

Johngs, Of course it wouldn't be bad. That's a very common set-up. For my taste, if I were starting from scratch, I would NOT use 4 speakers. I would use the money spent on rear speakers to buy better front speakers. Just because Ford and others have installed speakers the way they have for many years doesn't mean it's the optimum way to do it. But if someone enjoys the sound of rear speakers, then they should definitely use them. That's the great thing, everyone should set their audio system up the way they want, not the way someone else does.

 

I personally don't plan on upgrading my rear speakers until the rest of my system is complete, but this guy has 4 speakers so it was just a thought

 

For what its worth, rear speakers are generally installed for what they call "rear fill". Basically they're just there to round out the soundstage and fill in the gaps.

Rear speakers are far less important than fronts for a few reasons, the most important (and obvious) of which is that the fronts are closer to your ears.

When designing systems, I always aim to get the best quality from the front speakers, and something just under that level in terms of quality for the rears. You don't have to buy top notch stuff, but that doesn't mean you should buy AutoZone junk either. A good rule of thumb might be to use the "top of the line" model from X manufacturer for the main stage, and then maybe the next step down family of drivers for the rears.

Another note, regarding power handling, I'd guess the range of rear speaker power should be about 70-80% of what the front is drinking up.

I'm sure this forum has a good supply of audiophiles that can be more specific.. These are only the guidelines I've used in my experience.