Sub amp compromising head unit speakers

[Jordan Guess]

Installed a memphis 500 watt rms monoblock amp in my buddies toyota corolla. I wired everything standardly how it should, clean and proper; but when attempting to turn up gain or playing subs at a high volume, the rear 6x9 speakers that are connected to the head unit distort majorly as if the amp is giving them as massive amount of bass. I double checked all the wiring, even re-routed a ground; and still no luck. does anyone have any ideas on why the 6x9's are picking up a bad signal? maybe a bad HU?

[OrionStang]

Do they do it if you unhook the sub amp?

What head unit?

[Jordan Guess]

no they dont, it only happens when the amp is hooked up. the head unit is a pioneer DEH-20UB

[dereileak]

do you have a high pass set for the mids so they dont get anything low, id set it around 60-80hz, they are probably getting tons of lows, or it cause your having a voltage drop and when that happens the headunit outputs less power to the speakers, so its clipping every time the sub is playing loud when you you have everything hooked up.

Try this: unplug the positive subwoofer wire so the subs wont play, then play it like you were does it still distort the 6x9's, this will leave the amp in the equation, but it wont be pulling really anything for amps, also check your voltage when the sub is playing loud, see how low its going?