Let me start off by saying that I am in no way an expert at car audio this is all fly by the edge of my seat type of stuff for me.

I recently tried wiring my factory head unit to my MTX JH300 amp. When I turned on the head unit the sub started playing just fine but when I turn the volume down on the head unit the sub still keeps playing at the same volume. Even with the head unit turned down to zero the sub is still playing.
Has anyone encountered this type of situation and if so can you tell me what I need to do to fix this?

Thanks in advance for any kind of help.

 

Does your factory head unit have RCA pre-outs? Seems this amp does not have any speaker level inputs. If so, did you wire the speaker wires to the RCA inputs of this amp???

 

The factory head unit has right line out +/- and left line out +/- but not RCA pre out.
The speaker wire is hooked up to the RCA inputs of the amp!

 

make sure smart engage is on and recheck your wiring.

 

uhhh, why?

heres what I'd suggest you do. buy some real rca cables, short ones will work depending on the location of the amp and rear speakers, and get a line out converter, which will create an rca preout type thing from the signals being sent to your speakers. then you hook that up to your amp with the rca cable and then run the sub to the amp. the LOC basically splices into your factory speaker wires to get a signal and create an rca jack kinda thing. I've used these things before, and for A head units with no sub preouts or B saving time and using factory head units because the harness to wire up an aftermarket deck costs like 150+

 

Sounds like you have a high voltage input (speaker level) going directly to a low voltage input (amp's rca inputs), so even when the volume is very low on the deck, there's still sufficient voltage to drive the amp to high levels of output. Do as the guys above suggested and get a line out converter. Just out of curiosity, how did you hook up the speaker wires to the rca inputs, did you splice them onto rca connectors and then plugged those into the amp?

 

greggerge8.. I was wondering about the SMART ENGAGEHow does that effect the signal I am sending to the amp. I don't think I have smart engage turned on.. so I will definitely try that.

freash1.. I meant to say the line out from the head unit is hooked up to the RCA inputs of the amp. I actually am using a line out converter.

I am going to hopefully try and take a second crack at it this weekend and report my results.
I have a feeling it's that damn smart engage switch.

Thanks again guys for all the replies!