1amp system with a 2 ch amp?

[TomR123]

Alright, system on a budget time. As always any help is appreciated. Heres the situation. As of now I'm using a 2ch 420w amp to power a 10" sub. My components and weak ass stock rear speakers are running off my alpine 50x4 Head unit amp. What I would like to do is to use the amp to power the whole car, or at least the components, and the sub. I run into a problem when I try to figure out how to cross over the whole system. The HU has built in crossover functions HP and LP, and so does the amp. Either way I slice it i cant find a way to keep the low frequencies out of the components. Im not too concerned about the sub running on full frequencies but I dont want the components to be taking the same abuse. Any thoughts?

[BarracksSi]

What I did before, after asking the same question & spending $25 at a stereo shop:

Rear speakers off the head;
Front speakers off a 2x50W amp;
Sub bridged over the same amp;

I kept the bass out of the rear & front speakers with bass blocker capacitors, which were simply rigged inline between the speaker wire & connecting terminal at each speaker, then secured to the magnets to keep them in place.

I also placed a high-frequency-blocking coil at the sub, inline between the enclosure's terminal cup & the sub, and secured to the interior of the box.

No true external crossovers, no head unit frequency distribution tricks, no "tri-way adapters", and it still sounded pretty darned good. I don't know what the true power distribution was between the fronts & sub, but it got loud enough, and sounded pretty balanced.

I wish I still had the actual electrical specifications for the caps & coil, but the frequency cutoffs were listed as 200 Hz for the caps, and 100 Hz for the coil. The wide frequency gap wasn't much of a problem, because the slope of each was about 6 dB/octave. The caps could've probably worked well with a 150 Hz cutoff, too.

I couldn't vary the sub volume, phase, or frequency via any external controls, but like I said, it sounded good, and wasn't a BOOM-centric setup like too many systems tend to be. I'm still considering a similar setup for my EP.

[TomR123]

Ok, thank you much for the response, an informative one at that. New problem has come up. How do I get the signal to the front speakers? I tried splicing the signal wire into the front speaker wires and it made it so a protection circuit went off on the head unit and no sound came out of any speaker. This made me confused, what am I doing wrong?

[BarracksSi]

If you haven't already, you'll have to disconnect the fronts entirely from the head. In specific terms, there are a couple ways to connect them -

You could get rid of the stock wires and run new, dedicated speaker wire from the amp, through the door gap, and to the speakers. This way, you can go with larger gauge, higher-quality speaker wire.

You could also connect the speaker wire from the amp to the speaker leads in the aftermarket harness (a lot simpler than it sounds). Imagine, on the harness's instruction sheet, ignoring the head unit front speaker outputs, and replace them with the amp's speaker outputs. That way, you'll use the existing Honda speaker wiring, and you won't have to run new wires to the doors.

Either way, when you're done, the head's front speaker leads will be dangling unused. Clip the very end tips so that there's no bare wire, and tape them off to be safe.

[TomR123]

Thats what I did and nothing was coming from the amp. I got confused and gave up. stock now.

[BarracksSi]

How do (or did) you have the head unit wired?

You would have had the front preamp outputs going to the amplifier, and the rear speaker outputs going to the rear speakers. Nothing else, apart from power, ground, and turn-on lead, should have been connected to anything.

Then, the amplifier would have received its power, ground, and turnon leads, plus music from the preamp cables. Output would be through six wires total -- left +/-, right +/-, and sub +/- (bridged, of course).

If that's exactly what you did, and you still had problems, I don't know what to tell ya, at least not without doing it myself.