press the brake pedal and i get pop sound

I have finally installed my 2nd amp and 12in sub through a distribution block. At the same time I shortened all the power earth and rca cables as I had the excess laying under the back seat cushion... they were not coiled but I know doing this caused the ground loop. The alternator whine has finally gone and the audio is now crystal clear - Yippie!

But what I have noticed is I now get a click pop sound every time I put the foot brake on and again when I take my foot off the brake. So now I have a switch contact click going through my speakers! Doh!

So now how do I fix this?

VW golf 1996 TDI Mk3

You can't shorten RCA's that way man, you ruined their shielding ability and you will need to fully replace them with a good set that are the right length and twisted pair for noise rejection. I would make sure the ground is free of paint and is bare metal that shows good voltage. Run power down one side of vehicle and RCA down the other side. Check voltage for any drops down line from source.

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The wire I'm test'n isn't doin' what it's supposed to be doin'... I am so glad I printed that tech sheet, with the wrong info.
Do it right the first time... or I might have to fix it for ya

Yes you can shorten RCA cables... My Stinger RCA cables have Screw ends that undo so I can unsolder the sheilding and core to shorten the leads. There is no shorts between sheilding and core as I tested them with a multimeter.

My RCA's do run down the right hand side of the car and the 4 Gauge Power cable runs down the left.

Nothing wrong with my cabling of the amps.

Blinkers, lights and clutch (cruise control switch) do not give me a pop sound when turning off and on.

Unfortunately you failed to mention the type of RCA's you had leading me to believe you cut regular set down. The pop noise is not normal and so there is a issue somewhere or you would not have posted for advice. Hope you find out what it is.

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The wire I'm test'n isn't doin' what it's supposed to be doin'... I am so glad I printed that tech sheet, with the wrong info.
Do it right the first time... or I might have to fix it for ya

try grounding your amp somewhere you have very close to 0 or 1 ohm resistance to the actual chassis. Or run a 18g wire ( like another remote wire)from the radio ground to the amps ground. You can easily pick up noise if you dont have the same ground return path with the radio or if your sharing it with another component in the vehicle.

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RTFM

Yep I know it's not normal.

A similar problem exists with any switching contact - noise is produced when the contacts come close and a tiny electric arc is formed milliseconds before the contacts do touch. Very common with relays for driving lights and spotlights on cars.

I have Relayed Driving lights on my car - but I cannot recall if I also hear the pop when I activate High Beam... I will have to check on this. From memory it does not do it... as I have only noticed it when using the break pedal.

You're gonna have to troubleshoot those input wires.  Get a pair of new cables and run them wild over the seats to the amp.  Unplug the current wires and use the new ones to test.  You are hearing induced noise from the brake light system, likely a voltage spike.  Pull the brake light fuse if you want to ascertain that first.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

The popping noise on a relay is actually caused by the collapsing of the magnetic field of the coil. If it is a relay causing the noise, you can eliminate it by placing a diode across the coil of the relay. Cathode (the banded end) on the positive wire of the coil. Anode connected to the ground wire of the coil.