Sub hums randomly and often when I brake

[kensho]

Hi guys,

I'm getting a hum from my sub (JBL BassPro Hub) randomly. The stereo doesn't have to be on and it will still hum randomly for a bit then stop and then randomly hum again. It often happens when I brake the car.

My car is a Hyundai Tuscon 2016.

Any ideas what could be causing this?

Click to read more...

 

[1aespinoza 10+ year member]

Any ideas what could be causing this?

How is the remote wire connected? How is it getting signal, from speaker wires or RCA?

 

[kensho]

I didn't wire it up and the guy isn't available till next week who did. Will let you know as soon as I do but I'm pretty sure it's with RCA's

 

[1aespinoza 10+ year member]

I didn't wire it up and the guy isn't available till next week who did. Will let you know as soon as I do but I'm pretty sure it's with RCA's

Gotcha. Is the radio OEM or aftermarket?

 

[kensho]

Gotcha. Is the radio OEM or aftermarket?

It's OEM

 

[1aespinoza 10+ year member]

It's OEM

With the radio OEM and amp has RCAs going into it, I think they used an active Line Output Converter. Some have "signal sense" that activates the amp. Maybe the signal wires are picking up a signal therefore activating the amp. Try unplugging the RCAs and see if issue stops. If yes, then rerouting the signal splicing may fix the issue. If no, then the built in amp is the issue.

 

[kensho]

Thanks for that reply. I spoke with the guy and I told him what you said. He told me that because they've wired to the ignition the signal sense shouldn't be activated. He said the next thing they will try is to wire it to the OEM radio and if this doesn't fix it it must be the sub. Any thoughts on this?

 

[1aespinoza 10+ year member]

. Any thoughts on this?

He is right. Using a direct switched supply should keep from undesired activation. Check the enclosure for an activation switch.

 

[Buck 5,000+ posts]

Sounds like a loose connection on the signal wire somewhere that’s going to your sub amp. Half broken RCA cables can do this, or loose screw or something. The motion of you stopping or shifting momentum is causing changes in wire contact, if that’s what is happening. How often it happens will be displayed by the sub, and the hum comes from a resonance vibration where the wires or loose connection are flapping together.

I had a house sub start playing in the middle of the night, when it got colder, due to an RCA head to wire solder coming loose.

The amp has to be powered for this to happen.

 

[Buck 5,000+ posts]

You could just unplug your RCA cables from the amp and leave the sub on, and see if that fixes it.

 

[1aespinoza 10+ year member]

The amp has to be powered for this to happen.

He did mention the amp turns on randomly with no key. Has me thinking the signal sense has a play in this issue.

 

[Buck 5,000+ posts]

He did mention the amp turns on randomly with no key. Has me thinking the signal sense has a play in this issue.

I see. The amp could have a problem. The RCA’s turn this amp on?

 

[1aespinoza 10+ year member]

I see. The amp could have a problem. The RCA’s turn this amp on?

I am not sure. It is a newer amplified enclosure so I assume it does. He also has a brand unknown active LOC and most of those new ones come with signal sense as well.
Scratch the latter, the remote wire is wired to the fuse box I believe. So I am now unsure on passive or active LOC.

 

[Buck 5,000+ posts]

I am not sure. It is a newer amplified enclosure so I assume it does. He also has a brand unknown active LOC and most of those new ones come with signal sense as well.
Scratch the latter, the remote wire is wired to the fuse box I believe. So I am now unsure on passive or active LOC.

You can do testing on all of that. It’s a lot to explain.

 

[Buck 5,000+ posts]

It really sounds like a messed up wire or loose connection on the signal from the radio to the sub amp, to me. That’s the only thing that I’ve seen make a sub him like that is broken wires or loose connections somewhere. You may check your amp ground too and make sure that’s not loose.