Bridging a 4 channel amp

[ladysmanfelpz 10+ year member]

K so im pretty new to car audio but im really trying to learn. I had my sup and amp done professionally, then I threw in a new sub myself as well as capacitor, did the big 3 with 0 ga this weekend, and my buddy and I did a 4 channel amp a while back. So thing is the car was already wired up for a 4 channel amp. I didn't quite know what was going on, but when wiring it, we only had 4 speaker wires. My friend said it was no big deal and that we could bridge it and it would actually be better (less ohms more power i guess). But as im understanding more about car audio, im really wondering wtf we did. So on my mtx400.4 the bridge is for front + to - and rear + to - (sorry can't remember sides at the moment. I'll have to take a look tomorrow.) Since it is for my speakers we wanted it to play left and right, so it looks like he tried to do a bridge between left and right. He wired it all on the rear speakers, and I do get left and right speaker play which is nice. Thing is looks like amps aren't gonna put any more power out by doing this. I still have the switch on 4 channel, and when I switch it to 2 it still plays but just at very little volume (guessing its the positive or negative for a set of speakers thats playing).

Question is, is can I fix this ***** and get it bridged and still play left and right? Will it require me taking out the head unit and/or switching rca's?

And sorry if there have been questions like this. I am a newb but ive been searching the audio reference stickies to learn up and all they talk about is sub box size and design and stupid ****. Nothing about 4 channels. Im gonna take a look at it tomorrow and see if I can figure it out and repost with what I learn.

Thanks everyone.

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[UnderFire 10+ year member]

Pictures of speaker wires at the amp and at the speakers themselves would help.

Sounds like you wired up 2 speakers to each channel bridged. If they are 4 ohm speakers that would be a problem, that amp isn't capable of running a 2 ohm load bridged.

Solution, run each speaker on it's own channel, with the amp not bridged.

 

[sam_b03 10+ year member]

The way I wired my 4 channel up was left speaker wired to the front channels +left and -right. Then right speaker to the rear channel +left and -right. I set my gains as equal to one another. When bridging an amp they usually can't handle low Ohm loads. This is why the specs always list Xwatts x 4 @ 4ohm; Xwatts @ 2Ohms (this number is usually double the 4ohm). Then Xwatts x 2 @ 4Ohms. (the bridged is usually around double the 2Ohm rating).

You are not upping the wattage by reducing the Ohm load. You are upping the wattage by powering 1 speaker off 2 channels from amp.

 

[ladysmanfelpz 10+ year member]

Pictures of speaker wires at the amp and at the speakers themselves would help.
Sounds like you wired up 2 speakers to each channel bridged. If they are 4 ohm speakers that would be a problem, that amp isn't capable of running a 2 ohm load bridged.

Solution, run each speaker on it's own channel, with the amp not bridged.

Ya I went into my local car audio shop and thats what the guy was telling me. My legacy's rears are right above the amp, so that will be easy to run those, and then I'll just have to run them to the fronts which wouldn't be too hard I guess. So that means all my speaker wire would be coming off my amp correct? Nothing from my deck? And also, im sure it depends on each specific amp, but one of my rca's is going bad. Can audio experts fix an rca fairly easily?

Oh and if I do run each speaker to its own channel, ill be pushing 50 watts at 4 ohms. Will that be significantly better sound than my deck? Is it worth just getting a new amp? Can't remember the speakers, but they are pioneer with a yellow fibrous looking cone and 225w max.

 

[UnderFire 10+ year member]

Basically amped with any power sounds way better than HU power. I went from HU power to an amp rated @ 20x4, same as the headunit, but the sound output nearly doubled and sounded much cleaner.

What do you mean by Bad RCA? Cables or inputs?

 

[ladysmanfelpz 10+ year member]

Input. One just feels loose and you can hear the difference from wiggling it and of course its one of the two that im using for my jerry rigged set up. Is that an easy fix an audio repair shop can do? If I take it to them, can they do any other upgrades to make it more worth the money, such as making it run cooler (it tends to get very hot, much hotter than my sub amp) or produce more power? It was a pawn shop amp but it does the job ha. And I get rms power and all that, but how could an amp rated at the same power give you better sound? Cleaner power and signal since it is dedicated?

 

[ladysmanfelpz 10+ year member]

And why is my mid-bass lacking? I dropped my sub lpf to 85 hz and it sounds way better now, but im having a hard time tuning my amp. Like I said I have the speakers wired in parallel (left side and right side) so that I'm using two rca's. I think I have the gain set correctly, but what do I do with my equalizer (right now it is barely above 0) and my crossover settings? I can't tell the hz, but I think I have it at about 100-120 hz but my speakers distort pretty badly especially if I try to go any lower. I have to turn my eq way down on some songs cuz of the distortion. Is this normal? Does my amp not have enough power to drive my 6.5s?