amp / subs mismatch?

[whizzer]

I recently bought two new 15" Rockford Fosgate subs (rfz3815), a speaker box and a 1000 watt Kenwood 2 channel amp (KAC-7203) to run some base in the trunk of my honda accord.

after i received the stuff, i realized that each sub is rated for 8 ohms and the amp is rated for 4 ohms per channel. the documentation for the amp says to connect speakers that are rated "4 ohms or higher" so I'm wondering whether it will work okay to hook these speakers up one per channel?

the amp channels can also be bridged, so I've also considered using bridging and running the subs in parallel to bring the impedance down to 4 ohms for the speakers. Will that work better for me?

I've asked a couple local installers and gotten mixed opinions. One of them said he would just buy upgraded subs that were rated for 4 ohms. I'd hate to do that since mine are new...

Also, I replaced the factory door and rear window speakers with some Infinity's. The front door speakers are 6 1/4 inch 2 ways (6002i) and the rear window speakers are 6x9 3 ways (9603i). All four are rated for 4 ohms, the fronts are rated 60 watts RMS 180 watts max, the rear are 100 watts RMS 300 watts max. Right now they're just connected to my JVC KD-DV5100 head unit which i think puts out 50 watts MAX per channel.

Should I consider running an amp on for these speakers too? I was thinking I should look for a 4 channel 1000 watt amp for these. Is there anything else I should look for in an amp for these speakers? Can a 4 channel amp be configured to send more power to the rear speakers than the front speakers? Or is this just a matter of adjusting the fader on the head unit?

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[helotaxi 5,000+ posts]

The guy that told you to get 4 ohm speakers was a moron, don't go back to him for more advice. Those subs are a decent match for that amp. Your were correct in thinking that you should wire them in parallel and bridge the amp. That will get the most power from the amp.

For the rest of your speakers, they will sound better with a real amp on them. Ignore anything amp realted that says "max watts." That is a totally useless and usually incredibly inflated bogus number. The only number you should concern yourself with is RMS watts. For your infinty speakers an amp that does a real 50 watts should be more than enough. If you want to stay with Kenwood the 8403 would do what you need and matches the sub amp. If you don't care about brand, there are a ton of amps out there that will suit your needs and are pretty inexpensive.

 

[johnson 10+ year member]

Why do people ask questions about compatibility after they buy their stuff? If the local installers couldnt figure out what you figured out then I'd find new installers.

Wire the subwoofers to give you a 4 ohm load like shown in the picture. Read the manual on the amp and find out how to bridge the channels which should give you 500w. Measure with a multimeter (cheap $2-3 one will work fine) to make sure everything is right.

 

[whizzer]

Why do people ask questions about compatibility after they buy their stuff? If the local installers couldnt figure out what you figured out then I'd find new installers.

I am new to car audio wiring and terms, but I like to learn and do things myself so I thought this would be a fun project for me. I thought I knew what I needed to know when I bought the components. After I received them and started reading the specs and installation instructions I had more questions, so I started asking. Thanks for your help, it has been very valuable. I'll try to ask more questions before I buy more equipment next time.