Static From Speakers after RCA Y-Splitter put in.

[RedFred]

So for awhile I had a Hifonics Brutus 3k and 316.4. My HU only has 1 set of pre-outs for RCA.

I ran the RCA into the subwoofer amp, then it had an RCA passthrough out into the 4 channel. (Only used channels 1/2 of the 4 channel).

This worked and sounded great.

Then I upgraded to a SoundQubed 2200 and Q4-90. Neither amp has passthrough outs for RCA. So I put in some Y-Splitters, and now all my speakers have loud and annoying static coming from them.

Eventually I can turn up the volume loud enough that it can't be heard, but anytime the volume is low and I'm trying to have a conversation with someone, the static is there, and is very loud. It also changes pitch when I rev the car.

There is no static when the alternator is off, but the radio is on.

Any idea what the issue could be or how I can solve it?

Tested:

1) Disconnect one amp (either one) and it all works great, no static.

2) Several different pairs of RCA's, and Y-splitters (didn't change anything).

Some people are saying I have a ground loop, or that I need to ground my HU. I'd like to get some more opinions before I go tearing everything apart.

Thanks.

[boometro]

check your ground location and the gain setting.

[bluethunder]

I am willing to bet your gain setting is very high due to low rca input voltage having only 1 pre out. This could cause the issue. My suggestion would be to upgrade your head unit to something with more preouts. if you hot a unit with 3 sets you would regain fade and balance as well as have subwoofer control.

[reedal]

What head unit do you have?

[RedFred]

What head unit do you have?

JVC KD-A605

I am willing to bet your gain setting is very high due to low rca input voltage having only 1 pre out. This could cause the issue. My suggestion would be to upgrade your head unit to something with more preouts. if you hot a unit with 3 sets you would regain fade and balance as well as have subwoofer control.

Gain was set with an SMD DD-1 on both amplifiers. (track 5 for woofer, track 4 for 4chan)

Gain on the 2200 is maxed, while the q4-90 is roughly 70%.

However, the gain on my last set of amplifiers was the same, or higher, and had no issue.

[3vil]

Check the ground to your HU and the amps.

[ShadeTreeMechanic]

Gain is too high. You need a line driver so you can turn the gains down to lower the noise floor.

[reedal]

Firstly, that RCA preout is not a full range out, so using it for your four channel to power mids and highs is not recommended. JVC lists it as a rear/sub output. Though it does say 5v out, that's probably after boosting sub out and EQ to max levels, so you're splitting an already low output into less.

My recommendation is invest in a new HU that has two pair of 4-5v preouts, with a front pair and a rear/sub pair, or three pair of RCA outs, high, mid, low.

Not a line driver, and not a better ground.

[RedFred]

Check the ground to your HU and the amps.

Grounds are all solid as far as I can tell. DMM reading show a full 12.8V at each location with the car off, and 14.8V with the car on.

Firstly, that RCA preout is not a full range out, so using it for your four channel to power mids and highs is not recommended. JVC lists it as a rear/sub output. Though it does say 5v out, that's probably after boosting sub out and EQ to max levels, so you're splitting an already low output into less.

My recommendation is invest in a new HU that has two pair of 4-5v preouts, with a front pair and a rear/sub pair, or three pair of RCA outs, high, mid, low.

Not a line driver, and not a better ground.

in the manual for the HU, it says that I can use it and set the L/O mode to "rear" for actual speakers.

But it seems like a lot of people feel the gain is set too high, so I think I will be looking for a new HU soon.

[reedal]

I didn't catch that part in the manual. My apologies.

I do agree with the gain set to high. and honestly, I'm surprised you're unable to hear the amps make a whining sound without any music playing. I know all five of my SoundQubed/AudioQue amps I have make noise when you get about halfway up with the gain, even though the DD-1 said to keep going. That noise was my queue to back it down, regardless of the DD-1 indications.