Headunit pre amp problem.

[bass junkie]

I have rca going from alpine HU to mmats mono amp. Each rca output on hu and input on amp work.

Problem is, with both rca connected it will play at the same loudness with just 1 rca connected.

If you lost me , rca should put out 2v to amp, then im getting 1v from 1 rca out and 1v from both rca outputs.

[Perry Babin]

The input may not add the signals, it may simply mix them. If both RCAs produce audio no matter which RCA jack on the amp is used, I don't think there is a problem.

[bass junkie]

I tested different model mmats amp and it doubled output with the second rca input connected. Ill try to test it with a different audio source.

[bass junkie]

The head unit has rca rear/front. I tried connecting sub amp to the front rca output, had major difference 2-3 times louder. Could it be rear rca output is damaged or something?

[Perry Babin]

It may have an open shield (but that should have produced noise when the engine was running). Did you check the shield ground for continuity to the case of the head unit?

[bass junkie]

Yes, i did check that, it was ok.

[ppia600]

The mono amp will have the same output with both rcas or 1, the input signal doesn't double. On the full range multi channel amps its different. Also be sure the rca output from the deck that you're using isn't high passed.