jbl amp help RCA problems

**koteman** · 05-31-2009, 08:56 PM

so the other day my line ou converter went out so i put a new one in and then i went to retune the amp since it was a diferent lineout converter. but the subs were barely hitting but if i unplug one of the input rcas on the amp it get loud like its sposed to be and it doesnt matter which one right or left. i even tried useing a y conector and making th 2 rcas 1 but it was just quite too what do u think is wrong.

**jake789** · 06-01-2009, 12:15 AM

probably your subs are wired out of phase.

**koteman** · 06-01-2009, 12:54 AM

i didnt touch the subs they were workign fine 2 days ago. but what would out of phase mean

**thewizard** · 06-01-2009, 03:52 PM

It's likely because your subs are seeing a mono signal with only one RCA plugged in, and attempting to play in stereo out of phase with both. Try reversing the polarity on one of the subs and both RCA's plugged and you will see what we mean.

**koteman** · 06-01-2009, 04:42 PM

ok ill go try it will be quick since they r reverse mounted

**koteman** · 06-01-2009, 05:27 PM

so i had the idea after what u said that maybe my amp internally switched over to mono so i pluged both rcas in with the car off and then took the main fuse out of the power wire started the car just so it would use up the cap power thats was left over then turned it off and put the fuse back in and its working fine with both rcas again. it did it once before and i took eveything out of my trunk and put it back in and it worked then im guessing that the amp has a volitile memory that controls the mono or stero input so once u fully unplug it it resests its self and will have to chose between streo or mono again when it is powered on the next time. idk just my though on what it was

**thewizard** · 06-01-2009, 09:15 PM

If the phase is reversed on one of the subs then they will cancel each other out, which is why they were not as loud. What model of amp are you using? If it is a two channel amp are you using it in bridged mode? How many ohms are your subs and are they single or dual voice coil?

**Danbert** · 06-03-2009, 12:59 AM

It could be that either the new converter is funky or the input wiring to the line converter got out of phase. Remember this is the only thing he reports changing in the system. For example, one side of the input could have the pos and neg reversed. Either unplugging one RCA or changing the polarity on one of the subs will be a fix, but not the right fix.