alpine mrp f240 speaker level input

I am wiring an alpine mrp-f240 amplifier it is a 4/3/2 channel. I'm going with the 3 channel mode- 2speakers front on ch.1 right speaker ch.2 left speaker. Then I am going ch.3&4 bridged.my problem is I'm using stock radio with no rca outs so I went with a line output converter which worked well except that the ch.4 rca on the amp is no good when connected I have to wiggle into a certain spot to work(I bought the amp used)so no warrenty. I purchased the speaker level input from cructhfield to solve year problem. This is how I wired it-right speaker wire from radio to ch.2(right side)left speaker wire from radio to channels 1(left side)and channels 3&4 for the sub.the problem is the sub sounds like it is only as loud as one channel not like its bridged.I know this because I know how loud it is when its hooked up to both ch.3&4 from when I used the loc and wiggled the rca on ch.4 to the spot it worked it Was more than twice the power it sounded good.the front 2 speakers sound great just like they did with the loc. My question is- how do you wire the speaker level input to bridge ch.3&4?the owners Manual showed how to bridge using rca inputs by using Y splitter from left split into ch.3&4.the manual doesn't show anything about speaker level input. Did I wire it wrong?here are the specs on the amp- 40X4X4ohm 50X4X2ohm 100X2X4ohm.   [50X2X4ohm-100X1X4ohm] I checked all the connections and polarity

Connect the White wire and the Green wire to your left speaker positive, connect the WHITE/ black and GREEN/ black to the left speaker negative.

Connect the Grey and purple to your right speaker positive, and connect the grey/black and PURPLE / black to your right speaker negative.

Then bridge the sub to 3/4.

Is that how you have it wired?

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

No that's not how I have it hooked up. I have ch.1,3&4 hooked up to the left and ch.2 hooked up to the right speaker.the reason I didn't hook it up the way you described is because I would have the right and left side going into the bridged signal,I didn't know that would work.ill try the way you detailed because it makes sense I just didn't know it was ok to have 2 different signals into a bridge. Thank you. Ill let you know how it works out

Yeah, the way you had it hooked up would result in lower output, let me know how it turned out.

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

I hooked it up the way you(alpine guy)outlined and that produced an even lower output and some distortion. Is there another way I can try?

Humm, that should work, thats odd. You did re-adjust the gain correct?
Where are you getting the speaker signals from? At the back of the head unit, or right from the speaker wires going into the doors?
What kind of vehicle is it, and does it have a factory amplifier for the factory speakers?

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

Yes I adjusted the gain.I'm getting the signal from the wires that were run to the speakers. 97 ford taurus is the car. It is a strange setup the actual hu is in the trunk. The tuner is up front its one piece(radio controls display casette player and climate controls) there is no seprate amp.

humm, theres not much else I can think of, sounds like you have it right. You might want to try to take the amp apart and fix the RCA jack if your handy, sounds like that would solve all your issues.

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.