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You have the LPF set and not the HPF, right?

my amp doesnt have hpf, its a mono amp.. JBL 600.1 sir.

before all this this happend my input level is around 4, the lpf freq is about a quarter up. and bass boost is off.. but now after the problem accured to even achieve now the loudness as before, i have to turn the input level up a little more and the bass boost on just a tad more.. and to note, no matter what you put the settings at, it still plays vocals unless the input level is all the way down..and then ofcourse no bass or anything plays..

Hmm, very sucky. So you're sending the amp back then? Any crossovers on your HU that you could possibly use?

If we can take a step back for a minute:

Good effort on the troubleshooting - sounds like the Xover stage (if not the whole preamp section) took a dump on you on the HU.

However - before we go thinking up a bunch of different ways to work around this HU issue, I'd suggest taking a minute to try to figure out WHY this happened to begin with! Because I've seen this happen myself, in person, and it's ALWAYS meant "there's something that needs to be fixed!"

Typically, it's caused by a bad ground on the amplifier (or something else in the RCA signal path), and what that causes is the amplifier to "seek" a ground, to complete the voltage circuit, through whatever means it can...

Any time I've ever seen this happen, it was due to this, and it took out the HU, or some part of it.
Early in this thread, there was some mention of this, and wanted to make sure we had a real positive conclusion here.

So, I'd check that ground - what are you grounded to?
Make sure that:

1) it is grounded solidly to CHASSIS METAL - not something bolted to something, not "I slipped a ring terminal around a nut", no compromises - actual car structural chassis metal.

2) make sure it is tightly secured. I've seen too many cases of "it was the only screw I had!", something loose, something stripped, a wood screw with a tapered seat, etc. Use the right screw, or better yet - a nut and bolt with washers - and make sure they are tight.

3) You aren't grounding to a painted surface. Paint is an insulator. Scrape / sand / wire wheel it off, then secure your ground, then paint or dilectric grease over it.

Your grounds aren't anything to trifle with - now you know why!
(sadly, it's not just "noise" issues )

damn you beat me to it.
curse you!

guys... great news.. i traded my friend cd players, he had the Pioneer 6700(i had the Premier 670, basically the same), now everything works fine.. my CDT's sound good, subs works/sounds great..etc.. before i had to put my speaker amp on mono to get them to sound right, now i have it on stereo and they sound great..everything is back to normal!!! im so happy.. the reason we traded is because, well ive been his best friend for over 17 years and well we wouldnt f#ck each other over, so.. plus he doesnt like subs or nothin so he didnt care..

nice deal buddy!!!!!!!!!!!!!!

welp alot of you know that i got this problem fixed by switching hu's.. well guess what? its back.. this time the sub is all staticy and crap.. this $hit is really pissing me the F#ck off.. tomorrow im going to re-do the entire wiring and see what happens.. :help:

Kinda sounds like what Geo was mentioning above. The HU took a dump because of another problem. Re-wiring sounds like a good start to try to fix it though. Just have to hope that it didn't screw the HU up again. Sorry to hear about the torubles. Good Luck.

Did you manually ground your HU or are you using the supplied ground?