8 replies to this topic

[Dion2]

I've searched hard but can't find a solution
I am using a smartphone as head unit. The 3.5mm output has 2 RCA plugs. The 2 RCA inputs are split to 2 el cheapo amps. One for front 2 x 5", one for back 2 x 6x9" The amp power is direct off the battery. The amp grounds are direct to the battery. When one amp is plugged in all good and quiet. As soon as I attach the second amp RCA input to the splitter (home made) I get buzzing through all the speakers. I have substituted the RCA cables so its not a cable issue. The gain setting does not have an influence. The amps both work and play fine, except for the buzz. Should I ground the RCA plugs on the input side since the phone is not grounded anywhere? Do I need to modify the split from the 2 inputs to the 4 outputs with some diodes or something. Any suggestions for a mechanically inclined dude?

 

[cal844]

Take the amps out the circuit or try suppressors first?

[Ruckus]

What happens if you use the 'buzzy' amp on its own?

Before knowing that... it sounds like an intrernal problem with the second amp.

[Ruckus]

Any update?

[vx220]

Shouldn't the amps be grounded to the body?

[Ruckus]

The Neg - terminal should go to a close ground point or the Neg terminal on the battery yes.

 

Its not normally needed to ground the amps case.

[Dion2]

I tried the following so far:

Removed the remote connection from the ignition acc input and jumped the power and remote so amps are always on - First one then both - No change

Swopped the in and outputs around on the splitter box - No Change

Wrapped the wires incide the splitter box with foil - No Change

Used seperate RCA cable on outside of car - No Change

Used different input device (MP3 player) - No Change

Status - 1 amp RCA plugged in - All good (either amp) as soon as second RCA lead plugged in buzz is back on both amps

Next steps - unpower one amp while leaving RCA cables in

Try to measure output voltages on the amp RCA inputs to see if they drop with one versus 2 amps

Then - put suppressor on 12V input lines to each amp

[Ruckus]

Your second amp has a ground loop. Must likely broken some how.

What amp is it? If it's worth it you can send it to the Amp Doctor (Gordon Taylor) he will fix it and can tweak it's output ;)

[Dion2]

I could buy a new one with 4 outputs for the cost of postage

Will continue F'ing about a little longer....