Audio experts? Help needed!

[badlieutenant]

So when I bought my LJ, the previous owner included a brand new subwoofer for the center console since the old one was blown.

I replaced it but I discovered that it only works when two of the four leads are plugged in. If all four wires are plugged into the sub I get nothing out of it. With just two plugged in, I get a little bass but really it's barely noticeable.

I don't know jack diddly squat about audio systems. It's an aftermarket sub but it fit just fine with some minor modifications.

The stereo is not factory, which I don't care for. He included the factory stereo as well, though.

 

[EJD]

Is the:
Negative (-) terminal of the Speaker connected to the L (-) Amplifier Terminal?
Positive (+) terminal of the Speaker connected to the R (+) Amplifier Terminal?
What size sub is this by the way? Its all about the bass!

 

[Blade]

So when I bought my LJ, the previous owner included a brand new subwoofer for the center console since the old one was blown.

I replaced it but I discovered that it only works when two of the four leads are plugged in. If all four wires are plugged into the sub I get nothing out of it. With just two plugged in, I get a little bass but really it's barely noticeable.

I don't know jack diddly squat about audio systems. It's an aftermarket sub but it fit just fine with some minor modifications.

The stereo is not factory, which I don't care for. He included the factory stereo as well, though.

Is your sub a 2 or 4 ohm unit?

 

[badlieutenant]

Is your sub a 2 or 4 ohm unit?

The only ohms I know about are when I'm practicing my zen Buddhist meditation.

 

[Kevin Johnston]

Got any pics or model # on the sub? Does it have a built-in or separate amp? If separate amp got any pics or model #? What wires are you talking about?

Sent from my Pixel using Tapatalk

 

[JMT]

Need more information.

1) If the PO replaced the head unit we need to know the specs on that unit. Try to take the numbers off the front and post them here, we can check into it. Things we want to know are whether it has an internal amplifier with 50+watts to push a sub? Otherwise you're not going to get much out of a new sub. Does it have pre-amp outs?

2) Is there an external amp mounted somewhere in the Jeep?

3) Your situation is a little strange to me because usually a sub only has two wires going to the speaker. Not sure where they are coming from? If they were trying to run the sub off of the L and R rear speaker wires that won't work.

If you get this info here we can come up with the cheapest, easiest solution to salvage the sub.

 

[Jerry Bransford]

I just finished a double (triple?) single-malt scotch so I hope this comes out right... The four speaker connections connect to two separate 2 ohm voice coils in the speaker. Two speaker lugs connect to one 2 ohm voice coil, the other two speaker lugs connect to the other 2 ohm voice coil.

The subwoofer amplifier was designed to put out 75 watts when connected to a 1 ohm speaker.

Because the amplifier was designed to work into a 1 ohm impedance speaker, it puts out less power if connected to a 2 ohm speaker and even less if connected to a 4 ohm speaker.

If you connect those two 2 ohm voice coils together so they're in parallel (like how jump start batteries are connected), they then present a 1 ohm impedance to the subwoofer amplifier... what it needs to put out its full 75 watts.

The reason you get that "barely noticeable bass" is because the amplifier is putting out less power because it is seeing 2 ohms from a single voice coil... twice the resistance it needs to generate its full 75 watts. It needs those two 2 ohm speaker voice coils connected in parallel (which gives half the resistance) so the speaker presents the proper 1 ohm resistance (impedance) to allow the amplifier to be able to generate its full 75 watts.

I dunno if that made sense but I hope it did.

One caution when connecting the two subwoofer voice coils in parallel... make sure you connect the + to + and - to - so the two voices are "in step" with each other, a term I know you understand. That's how they'll generate the most power and bass.

Hopefully that made sense. I do believe I'll let my wife pour me another single-malt scotch now.

 

[JMT]

I just finished a double (triple?) single-malt scotch so I hope this comes out right... The four speaker connections connect to two separate 2 ohm voice coils. Two speaker lugs connect to one 2 ohm voice coil, the other two speaker lugs connect to the other 2 ohm voice coil.

The subwoofer amplifier was designed to put out 75 watts when connected to a 1 ohm speaker.

It puts out much less power if connected to a 2 ohm speaker and even less if connected to a 4 ohm speaker.

If you connect those two 2 ohm voice coils together so they're in parallel (like how batteries are jump started), they then present a 1 ohm impedance to the subwoofer amplifier... what it needs to put out its full 75 watts.

The reason you get that "barely noticeable bass" is because the amplifier is putting out less power because it is seeing 2 ohms... twice the resistance it needs to generate its full 75 watts. It needs those two 2 ohm speaker voice coils connected in parallel (half the resistance) so the speaker presents the proper 1 ohm resistance (impedance) to allow the amplifier to be able to generate its full 75 watts.

I dunno if that made sense but I hope it did.

One caution when connecting the two subwoofer voice coils in parallel... make sure you connect the + to + and - to - so the two voices are "in step" with each other, a term I know you understand. That's how they'll generate the most power and bass.

Hopefully that made sense. I do believe I'll let my wife pour me another single-malt scotch now.

Impressive Jerry. Maybe I should let my wife pour me up some single-malt scotches while I do important work! It does make sense. Will see if it makes sense to OP. These things can be confusing. The important thing is to connect the four wires correctly! AS long as there is 75 watts coming in from somewhere it should go boom...

 

[badlieutenant]

I just finished a double (triple?) single-malt scotch so I hope this comes out right... The four speaker connections connect to two separate 2 ohm voice coils in the speaker. Two speaker lugs connect to one 2 ohm voice coil, the other two speaker lugs connect to the other 2 ohm voice coil.

The subwoofer amplifier was designed to put out 75 watts when connected to a 1 ohm speaker.

Because the amplifier was designed to work into a 1 ohm impedance speaker, it puts out less power if connected to a 2 ohm speaker and even less if connected to a 4 ohm speaker.

If you connect those two 2 ohm voice coils together so they're in parallel (like how jump start batteries are connected), they then present a 1 ohm impedance to the subwoofer amplifier... what it needs to put out its full 75 watts.

The reason you get that "barely noticeable bass" is because the amplifier is putting out less power because it is seeing 2 ohms from a single voice coil... twice the resistance it needs to generate its full 75 watts. It needs those two 2 ohm speaker voice coils connected in parallel (which gives half the resistance) so the speaker presents the proper 1 ohm resistance (impedance) to allow the amplifier to be able to generate its full 75 watts.

I dunno if that made sense but I hope it did.

One caution when connecting the two subwoofer voice coils in parallel... make sure you connect the + to + and - to - so the two voices are "in step" with each other, a term I know you understand. That's how they'll generate the most power and bass.

Hopefully that made sense. I do believe I'll let my wife pour me another single-malt scotch now.

I'm sure it makes total sense to someone that understands what you're talking about.

 

[Jerry Bransford]

Post a good clear color photo of the back of your subwoofer with its four speaker lugs if you can.