Sub and stock speakers off 1 amp...but how?

[TexasTea]

I was given a Fosgate 250.2 auto amp that I wanted to install in the AR to power the stock speakers in the boat. Then I thought about installing a 10" something and using the amp to power all 5 speakers but I'm struggling on the "how" without popping the stock speakers. Any ideas or suggestions? I have the Infinity tower set-up but the cabin speakers are virtually null when underway, my main goal is to hear the cabin speakers but if I can get away with a tad more bass; I'm game.

 

[txav8r]

Is that a 2 channel, 250 watt amp? I am guessing it is going to be hard to power both the sub and the 4 channels of speakers combined. It also won't be adequate to power the house speakers enough to hear them underway very well. I had good speakers, JL MX650's and a 10" JL IB sub, and it was great to listen to the music when running WOT across the lake! But I had a JL M700 watt/5 channel amp powering my 6 6.5" speakers as well as the subwoofer. Maybe use that amp to power the sub and get another amp to power the speakers. I wouldn't put much hope in the stock speakers handling the load however, they are made of paper and have very little capability.

 

[David Analog]

I was given a Fosgate 250.2 auto amp that I wanted to install in the AR to power the stock speakers in the boat. Then I thought about installing a 10" something and using the amp to power all 5 speakers but I'm struggling on the "how" without popping the stock speakers. Any ideas or suggestions? I have the Infinity tower set-up but the cabin speakers are virtually null when underway, my main goal is to hear the cabin speakers but if I can get away with a tad more bass; I'm game.

You can do it using the 'multimode' method which is simultaneously running the amplifier stereo on the coaxials and bridged on the subwoofer.....however, you cannot parallel the speakers playing over the same bandwidth. You would need a lowpass inductor in series with the woofer, and a highpass capacitor in series with two coaxials run in series per channel, and the lowpass and highpass circuits would be wired in parallel.
It's completely doable but I don't recommend it. Wait and get another amplifier or use a single 3 or 4-channel amplifier.

 

[TexasTea]

Ok, so the sub is out then. I have the stock "house" speakers and the stock head unit. I know I need to replace the stock speakers but am waiting tondo that in the off season. Would the amp push those enough to at least tell there's sound coming out of them or should I just replace the stock speakers with Polks or equivalent? Trying to go on the cheap here but I don't want to work for nothing...

Thanks for your helps guys

 

[txav8r]

@TexasTea , David is retired from Earmark Marine A/V/Lighting. He is a true expert on the stuff. I didn't think you could do it with a 2 channel, but you could sure power the speakers, just don't know what your results will be. One thing is possible, it may facilitate you getting better speakers sooner! I removed one speaker once just to get behind it to get to a nut on a cleat, and just removing it caused the paper cone to tear loose of the surround. Luckily, I had my JL speakers in hand and could change them out. It just pushed up my stereo overhaul.

 

[jawsf16]

Get a four or five channel amp if you want to properly amp the stocks and a sub. Well worth it. Also Polk db651 are an awesome speaker for the price and they drop into stock location.

 

[Binymac]

Yes, get a name brand 5ch amplifier. I am currently running an Alpine PDX-F9 5ch powering four 6.5" Rockford PM262B and a single 10" Rockford P3 sub. Great sound quality !
( Alpine PDX-F4 4ch amp powers four RF 8" wake speakers )

 

[bigblank69]

Technically you could run the stock speakers off that amp, and get a mono amp for the sub... or get another 4 channel and use the 250.2 for the sub.