high pitched sound

[DBfan187 5,000+ posts]

My friend (who was there) said that the reason that both amps are jacked up is because "I grounded the subs through the casing which sent negative power to the car through the ground. This went through the ground of the other amp and jacked it up too" Why wouldn't the whole care have a problem then?

LOL
Your ground is connected the (-)negitive terminal. In a DC circuit electricty flows from negitive to positive.

 

[Flipx99 5,000+ posts]

So my friend is correct.

 

[Flipx99 5,000+ posts]

ground the RCA's. That fixed the problem with my HU.

ground loop isloators will do the trick?

 

[Flipx99 5,000+ posts]

What would explain why when I tap the ground wire to a grounding surface (bare metal) it makes the subs thump. Is the connection because of ground or because of RCAs. I say RCA, my friend says ground.

 

[Flipx99 5,000+ posts]

ttt