Ok I just installed a Jensen VM9312 headunit in my car yesterday. I bought the harness from bestbuy which includes the Mitah adapter and 2 harnesses. I could not determine which harness to us because they both used the same connectors but one only had 4 wires coming out. Needless to say I used the harness with the most wires the smaller harness did not have any speaker wires coming out.

Anyways the unit works fine but I cannot ge the sub to crank like the stock headunit. At first I had to see if the sub was even working and it is but it's only working to 25% of it'a capability at normal volume. I have to really turn up the sound to get decent bass but the sound is then too loud. I noticed on the Mitah adapter there is 2 sets of outputs, 1 pair for the front and one pair for the rear but there is no sub output so I cannot connect anything to the sub input on the aftermarket unit. Has anyone experienced problem like this before? Is there a solution?

 

i used a different harness...i bought it from sound design or something like that. It had the wire harness and then another black piece for the sub.... i also bought an eclipse deck ... maybe that is the difference, but i doubt it. My sub woke up and was loud as hell.

 

Mines the same thing it has a wiring harness and then a black piece that has two pairs of rca outputs that go to a round style connector. This piece hooks up the factory amp/sub to any aftermarket unit. My problem is that my sub does not reach the power it should have.

 

hmm...maybe its a setting in the deck ? no offense but jensen isnt exactly the greatest name for car audio you know ? i'd look thru the menu's and see if you can pinpoint something... or maybe the connection is loose ? good luck man....

 

I haven't seen this harness at all. But if you are using the rca's to drive the speakers and the sub, maybe the voltage output of the Jensen is wicked low. If its like 1.2 volts or something like that, then that would explain it. Friends don't let friends drive with Jensen.

 

its just out of the harness, its roughly the same thing the stock one uses...

you shouldnt have the jensen sub output hooked up... it should just be the front and rear. I've since jumped to an aftermarket amp and subs and i left everything connected and just used my sub pre out for my amp.

 

Yeah I figured I shouldn't have the sub preout on the Jensen hooked up. I'm going to check settings later on and see if that helps. The unit is extremely nice it's been recommended to me by many people. Something just doesn't seem right becuase I did turn up the bass to max and it still does not kick as much as my factory unit.

Correct me if i'm wrong but doesn't the SSL system run entirely off of the inifiniti amp including the speakers? I'm asking this because maybe I was supposed to use the smaller harness with fewer wires because I have an SSL, the one with more wires would be for a non-SSL.

 

i think so... the one i bought was specific for the SSL package. It came with the black piece and then a smaller harness with 4 or 6 wires... i dont remember. that is probably a good place to start.... and yes, everything runs off of the amp

 

yep, the front/rear/sub all run off the Infinity amp. Just make sure the RCAs are hooked up to the front/rear outputs of the Jensen. That should do it.

It shouldn't matter which adaptor you used. One of them probably has speaker wires, the other doesn't. But, shouldn't matter since the Infinity amp is powering all the speakers and it gets its signal from the RCAs.

 

Yeah there is no reason to switch out the harness now, I guess those speaker wires are just not being used. However how is the sub being powered if there is not preout for it on the Mitah adapter?

 

im sure it pulls the signal from the amp through a crossover

 

*Found the problem!!*

It was a setting afterall. I went into more detailed settings and just for the hell of it I turned subwoofer to "off" because it was set to "on". and instantly my bass kicked in and went nuts! It sounds exactly like it should right now. I don't know why that made a difference but it's good to know that was the only thing holding it back. Now I just have to take care of the low volume hiss and everything should be good!

 

its because the deck probably has a cross over in it and was cutting out the lower freqs to the midrange speakers for sound quality, now its basically set at full range. glad you found it.

 

The headunit was most likely sending all the lowpass signal to the Subwoofer output when it was enabled. The front and rear rca's were producing highpass signal only(probably 60 - 80 Hz and up), instead of full signal (5 Hz - 20 kHz). Glad you found the issue.

Edit: ^^^^^What he said above is correct.

 

Other than the cable from best buy, what is all the talk about the 12v oem adaptors? I'm unsure what this is...