Amp problem: 1 RCA plugged in sounding louder than both of them plugged in

[mexiken 10+ year member]

View attachment 26525113

That is a pic of my old Kenwood sub and where the gain was, that I haven't touched since it was removed. As you can see, its less than halfway up, and that hit PLENTY hard (for my car anyway).

Now, with the Sony, I get NOWHERE near that kind of sound at that same position on its gain, but I just noticed something !!!! Above the gain, the operation switch is on MONO !!!! Again, I haven't touched ANYTHING since the amp was switched. Does that mean it was only pulling the signal from the left RCA on my old amp !!!!???? That would make sense now....I have no such switch on my Sony, and by unplugging the right RCA, I'm basically duplicating SAME function as the switch I had on my Kenwood, and ONLY WHEN I do that, do the gains just about line up on both amps !!!!

Is my logic here correct ????

 

[keep_hope_alive Premium Member]

yea, that could be.

here's what I would do:

1. eliminate the LOC

2. re-terminate new speaker wires to the factory speakers (wherever your LOC gets a signal now) and route them to the Sony amp high level inputs.

3. verify sub wiring

 

[keep_hope_alive Premium Member]

The LOC is tapped off the right rear 6x9. It has the 2 females (one of which doesn't seem to work, even by itself, not when BOTH are plugged in on both ends) that I have the accompanying RCA cable plugged into that are plugged into the line in on the amp.

I assume its stereo ????

this is the magic piece of information. whoever did that, should not work on your car in the future.

no, not stereo. you have right channel only. left and right would be a stereo input. ideally, you'd bridge the amp to the two subs, but you would need a 4 ohm mono load. what are the impedance rating of your subs?

the LOC should have had inputs from both Left and Right rear 6x9's. When you re-wire the system to bypass the LOC, grab a signal from both left and right speakers. make sure to get polarity correct when going from speaker to amp.

your kenwood might not have had high level inputs, so the LOC was necessary. The Sony does, so remove the LOC. take care to trace LOC power wires back to source.

I have input Connection A but I DON'T have Speaker wiring 2. I have speaker wiring 1. I have a set of pos and neg for one woofer, and another set for the other, so 2 sets of wires coming out of opposite sides of the box both plugged into the 4 different speaker terminals on the amp.

make sure polarity is correct for the subs. you can quickly test this without removing the subs with a small AA battery. with the sub wires disconnected from the amp, touch them to the battery - positive to positive and negative to negative. the sub should move out in one direction. do this for the other sub wires. that will verify polarity.

the Mono switch on the Kenwood sort of bypassed the wiring problem with the LOC.

for diagrams, most people just draw them in Paint then host on a free photo site, like Photobucket.

 

[andr3w]

Ive seen this problem several times. You probably have one sub wired backwards to the amp, and when you plug in the left (or right) side RCA, the other speaker plays reverse of what the other does, basically cancelling each other out. Reverse the wires on one speaker then plug both the RCAs in and see.

Thank you so much! I was so confused why MY subs were not working. Switching the wires fixed the problem. I know I know, these posts are from 2011 but whatever.