Do I need a bridgeable amp for subwoofer?

jayjay4735 · **Posted:** Thu May 19, 2016 11:18 pm

I really don't know much about car audio and the terminology used to describe a lot of the equipment and their features. I'm not a real audiophile with an ear for picking up differences between the best stereos and the average ones, but when I bought the boat it was wired with an amp that powered a kicker subwoofer inside of the cabin that definitely gives the music a better sound than just the 2 speakers in the cabin and the 2 in the cockpit. Last year the sub started cutting in and out, and I replaced the RCA cables that went from the preamp outs of the radio to the amp, and it started working again. Around the end of last season, the amp stopped working totally, and I figured there was no sense in installing a new one before winterizing the boat so I would just wait til the boat went in the water this year.

I ordered a new amp, hooked it up, lights come on as powered, but no sound to the sub. When I look at the new amp vs the old one, they are both 4 channel 400 watt amps, but the old one was a bridgeable, and the new one I bought was not. As there is only one set of speaker cables going to the subwoofer, would they need to be bridged since it would be only one channel coming out otherwise? I don't mind buying the bridgeable amp if that will solve the problem, I just don't want to return the one I bought and buy a new one, if that isn't even the issue.

I don't think it is the sub, because I tested the wires to it with the multimeter on the ohm setting and was getting about 4 back, which from everything I've read seems to be ok.

Any help would be appreciated.

Jdpber · **Posted:** Fri May 20, 2016 12:01 am

If you are bridging the channels for a single out then you need a bridge able amp, test the speaker on one channel just to make sure speaker is still good

jayjay4735 · **Posted:** Fri May 20, 2016 12:08 am

I originally hooked it up with a non bridgeable amp, and connected the sub from the + and - outs from channel 1 (which I think is just the right output?). There was nothing coming out of the sub.

Jdpber · **Posted:** Fri May 20, 2016 9:11 am

one of 3 things. either the amp is bad, the speaker wire is bad, or the speaker is bad.

start at the amp with multi meter ont he amp outputs, then the speaker wire

jayjay4735 · **Posted:** Fri May 20, 2016 10:10 am

Ok, sorry if this is a stupid question, but when you say test the amp outputs, just put the multimeter leads to the + and - speaker terminals and look for 12v? And then do that again at the end of the speaker wire that attaches to the sub? I've never tested this type of stuff before, so really didn't know what to look for.

Jdpber · **Posted:** Fri May 20, 2016 12:08 pm

https://www.youtube.com/watch?v=lRGwPZEh7bE

jayjay4735 · **Posted:** Fri May 20, 2016 12:49 pm

I appreciate the help, but unfortunately that video didn't really help because it didn't show what to look for when you're not getting any sound.

Jdpber · **Posted:** Fri May 20, 2016 1:08 pm

go get your big hammer

deafwish · **Posted:** Fri May 20, 2016 4:11 pm

Almost every 4 channel amp should be bridgeable from the 2 rear channels.
What is the amp?
Post a photo of your wiring.
Why not buy a 2 channel amp if it's only powering one driver?
Are the power & ground wires in good condition/ not corroded?
Is the remote 'on' lead from the head unit operating correctly?

jayjay4735 · **Posted:** Fri May 20, 2016 4:40 pm

Thanks for the responses guys, and Jdpber I was VERY close to getting the hammer out lol, but was able to resolve the issue. So even though the power light was on, the multimeter was only reading 3 volts from the + to the ground when the amp was on. This must have been coming from the remote wire, because when I disconnected the power cable and ground, I got no reading at all on the meter. I checked the power cable before the fuse and still no reading. I was able to find the amp was wired directly to the battery, but the ground wire was not connected to the terminal. Connected that and all good to go.

The model is a Pyle Marine PLMRA400, and had I known a little more about this stuff before purchasing I probably would have just gone with a 2 channel amp, but the one I replaced was a 4 channel, so I just went with that.

Wylie_Tunes · **Joined:** Mon Oct 01, 2012 10:21 am **Posts:** 176

Jay,

Very quick look at that amp and it looks like it will ONLY run some full range coaxial speakers. I do not see that it has the ability to be set to Low-Pass in roder to run a woofer. Now, if you can list the specifics about the woofer and the number of coax speakers, you have, we can easily make a couple quality amp recommendations. I can assure you they will likely be in a higher price point then that pile, um i mean pyle, but they will be good solid values that will deliver.

jayjay4735 · **Posted:** Fri May 20, 2016 7:11 pm

Yeah I realize that that amp is not high quality at all, but it sounded pretty good to me ... but I'm the guy who can't really see any difference in different quality stereo components. Once I got the ground connected it powered up the sub and sounds good to me.

Wylie_Tunes · **Joined:** Mon Oct 01, 2012 10:21 am **Posts:** 176

Not about being "hi quality" but rather being about an amp designed for the job you are asking. That amp is not.

jayjay4735 · **Posted:** Fri May 20, 2016 7:49 pm

Ok, so since I really don't know anything about this stuff (don't have a clue what you mean by setting Low-pass), what is the negative of using this amp to power the sub since it sounds pretty good to me. Also, none of the speakers are run through the amp, they are connected directly to the radio.

Wylie_Tunes · **Joined:** Mon Oct 01, 2012 10:21 am **Posts:** 176

speakers are divided in to 3 stages based on the frequencies they are designed to reproduce. Those that produce bass notes, are sub woofers. Mid notes are for smaller mid-bass woofers and then tweeters, designed to reproduce the highs. A typical "speaker" is a pairing of a mid-bass woofer ans tweeter and it has the greatest range of frequency response, playing from the mids to the hi's. This leaves the woofer to supply the lows.

For a speaker to play in its ideal environment and at its most efficient, we need to only send it the frequency its best suited to play. This is where the amp comes in. A good amp will have filters that allow us to select the range of Hz (frequency in Hertz) we want to send to a given speaker based on its type.

That Pyle amp looks to be only "full-range". meaning, it only sends out ALL ranges of HZ on all chnls. This means your small speakers get low range that they dont like to play and the woofer gets the hi's that it cant play. This makes both the amp and speakers work way harder than they should. It also makes it impossible to actually tune a system.

www.iFourWinns.com

Do I need a bridgeable amp for subwoofer?

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