Everytime the stereo turns on (start car, change cds), i get wierd noise from the subs. i think theyre sucking in, making a kind of bloop noise. what could be causing this? it didnt use to do this, it just started a few days ago

 

What’s the make and model of the HU and amp? Could be a ground problem.

 

heres what my system consists of
Pioneer DEH-6400 HU
Kenwood KCA-746 Amp for the components
Infinity Reference 4x6s
Inifinty Kappa 6x9s
Alpine 3555 Amp for the subs
2 10" Audiobahns in a sealed box

i will check the ground, but i dont think its the problem, unless a connector is loose or something, theres no interference otherwise besides the wierd noise

 

It is definately a turn-on thump...why it is just starting now is curious.

Are you running a relay for your remote turn on circuit? Maybe your remote turn on output of the headunit is giving up the ghost.
Usually you can get away with running 2 amps without using a relay, but your headunit is really only outputting like 200mA off that circuit.
I would try getting a spdt relay,
Wire 86 to a POS
Wire 85 to Grnd
Wire 87 to remote out from HU
Wire 30 to remote in on amps

This will cost you $5.00 and assure you will never wear out your remote circuit on the HU and likely will resolve your thump as both amps will power up at the same time.
Hope this helps,
Tuck

 

will the people at the parts store know what im talking about if i wonder in and ask for an spdt relay, or is it a sound store related thing? is POS power source?

 

The DEH-P6400, note the "P". Relay wouldn't help this. Get you hands on a DMM. You need to measure the resistance from the RCA ground to the chassis ground on the HU it self. I think that you've got an open/high resistance ground on the RCAs. This was the first HU to start having BIG problems with this.

 

Why would you think it just started to happen?
It he hasn't unhooked anything I wonder what changed on his grounding.
You haven't installed any new components have you?
The reason I was thinking it may be turn-on circuit related was becuase if your equipment requires a certain voltage to turn on, and your HU may be wearing out on the turn on circuit from being overworked for some time, is only sending 1/2 the necessary voltage and that would be causing the thump.
He is right though, because turn-on thump is caused by the amplifier already being "on" when audio signal is introduced to it from the head unit.
I was thinking backwards.
You should always use a turn-on relay setup when running 2 or more amps though!

If you find that your ground source is good, you could always install a turn-on delay module- PAC makes one and crutchfield sells them. It is a band-aid though.
Tuck

 

That's not what happens though, not with a Pioneer anyway. Just because it worked when you put something in doesn't mean you did the job right.

 

What happens with the pioneer unit?
I guess I don't understand what is being debated and what was done wrong as nothing has been done.

 

Just because the ground was 'Ok for now' when it was done doesn't mean it's a good ground. Rust and/or oxidation could have developed. Vibration could have shook things loose. It may have been bad, but the last base CD had the amp pulling more current. More current means more voltage drop, more voltage drop, the greater the difference in the ground points. Ground must be ground, zero needs to be zero.........