Oh the fun problems we can have...

[johnnyrichards]

So I installed a pair of Infinity Kappa Perfect 10.1 subs a few years ago in my vehicle. Although I have always loved how they sound (very low distortion driver), I was always less than impressed at their output. They would give me a nice, gentle bass - never missing a beat at all. However, they never gave me that "in the chest" slam that a lot of my past setups have given me.

Well, earlier this year I hit a deer with my car and it went to the body shop last week. I got it home today, and decided to do some work on the stereo... I was sitting in the backseat setting the gain for the front speakers. I unplugged one of the subwoofer RCA cables, and instantly the output increased. "Strange", I said to myself. "That should have dropped the output." So I plugged the CA back in and output suffered again.

Now I'm curious. I suspect either the RCA or the head unit is out-of-phase on one channel of the two channel subwoofer output. I really don't want to run another RCA cable back there - it is a PITA the way I ran them, involving removing carpet, trim, etc. Aaarghhh!!!!!!!!

Anyways, it now appears that I will soon have both quality and quantity of bass in my little car. I just hope it isn't the head unit giving me issues. I could sacrifice the rear outputs on the head unit and use them to output to the subwoofer amp (which also could be at fault). That will be my first troubleshooting step.

[scott_s]

Why don't you just swap the positive and negative wires on one of the subs? The result will be the same, unless I am misunderstanding the problem (which is completely possible).

[johnnyrichards]

Amp is bridged, and subs are wired in parallel.

[trevorg]

Check the operation for bridge mode... Some amps only require one rca, so maybe having both in is harming it...

[johnnyrichards]

Hooking the rear channels of my head unit to the amps input brought it back to life. So now I have to determine if it is the patch cable or the head unit at fault.

[AJ]

Like trevor said, bridged mode for most amps only involves one channel input (usually the left input) which is inverted and sent to the other channel.

[dthomas]

Amp is bridged, and subs are wired in parallel.

I think the original poster was on the right track. If you have one sub wired out of phase with the other sub they will cancel each other out. You need to check the polarity on the two subs. I bet you will find that one of them is wired out of phase.

Quick way to check this is wire up both subs as you had it before but reverse the wires from the amp on just one of the subs. If the volume comes up to where it should be then you will know that the subs were wired opposite in polarity.

[johnnyrichards]

If it haddn't come out of it using a different set of inputs, I would have checked the subs wiring for the three-hundreth time, but that ain't it. That would show up whether I was running one channel in or both, anyways.

The problem is farther up the line than the subs wiring. It came out of it using a different set of inputs.

It's a little more complicated than a newbie wiring mistake - which it could have been had I not eliminated that right off the bat. I've done stupider things in the past (ask me about the time I thought it was a good idea to run 4awg through the fender and into the vehicle from there, rather than through a firewall hole like a good boy. Smoky!).

I've never run into this, it's odd. If the RCA has a one end terminated out of phase, I could see this happening I suppose. Just... weird.

[dthomas]

If it haddn't come out of it using a different set of inputs, I would have checked the subs wiring for the three-hundreth time, but that ain't it. That would show up whether I was running one channel in or both, anyways.

The problem is farther up the line than the subs wiring. It came out of it using a different set of inputs.

It's a little more complicated than a newbie wiring mistake - which it could have been had I not eliminated that right off the bat. I've done stupider things in the past (ask me about the time I thought it was a good idea to run 4awg through the fender and into the vehicle from there, rather than through a firewall hole like a good boy. Smoky!).

I've never run into this, it's odd. If the RCA has a one end terminated out of phase, I could see this happening I suppose. Just... weird.

I really was not implying you were a newbie but I would not underestimate the fact that somewhere the polarity is reversed. It could be in the amp or in the interconnect cables. My son bought a guitar cable that was reversed. Of course it was mono and they only way we ever noticed was when we replaced the plug on the end that was failing. The ground wire on one end was attached to the center of the plug and on the other plug it was on the ground prong.

I assume you checked to make sure the drivers polarity is labeled correctly. I have seen Vifa tweeters reverse labeled.

[johnnyrichards]

I really was not implying you were a newbie but I would not underestimate the fact that somewhere the polarity is reversed. It could be in the amp or in the interconnect cables. My son bought a guitar cable that was reversed. Of course it was mono and they only way we ever noticed was when we replaced the plug on the end that was failing. The ground wire on one end was attached to the center of the plug and on the other plug it was on the ground prong.

I assume you checked to make sure the drivers polarity is labeled correctly. I have seen Vifa tweeters reverse labeled.

I always do a battery check after I get everything wired up - it sucks taking eight screws out to switch wires.

I am almost positive one of my RCA's is out of phase - probably much the same way your guitar cable was out of phase. Aaargh.

Well, on a positive note the bass is loud as hell now and I am currently more enamored of the Kappa Perfect series than ever before.

[dthomas]

I always do a battery check after I get everything wired up - it sucks taking eight screws out to switch wires.

I am almost positive one of my RCA's is out of phase - probably much the same way your guitar cable was out of phase. Aaargh.

Well, on a positive note the bass is loud as hell now and I am currently more enamored of the Kappa Perfect series than ever before.

I hope it is just an RCA patch cord... I would not underestimate that the jacks inside the amp are wired out of phase. Some how I doubt the QC in some Chinese factory is checking a lot stuff... probably lucky if you get a plays/won't play test.

At the end of the day it might be easier to just to reverse one channel externally and call it good.

[johnnyrichards]

I eliminated the amplifier by using a different set of outputs from my head unit.

And no, I don't doubt for a minute that the head unit may be to blame. I have had good luck with Kenwood over the years, but you never know.

The patch cable is a P3 I bought right here at good ol' PE.