Sub thumps when amp turns on

[THATpurpleKUSH 5,000+ posts]

This is happening to a friend of mine who lives 150 miles away. 2 days ago I was visiting and we unhooked his DD 2515sc from his Diamond TX1000.1 and swapped in a Sundown E10v3 that I just built a box for. When we turned his car on, the sub made a thump sound when the amp turned on. There is still a thump after we put the DD back in. We didn't touch any other wires or play with any settings on the amp. He's been running the DD sub for over a year with no issues until we recently unhooked it and played around with the Sundown. Headunit is a Kenwood X500. Wiring is Knukonceptz Kolossus OFC 0ga with Knu Krystal RCA cable. I told him to check the grounds and he said they are good. The thump happens regardless of what input source (cd, usb, radio.) He said it doesn't thump when he disconnects the RCA cables. How do we make the thump go away?

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[audiobaun 5,000+ posts]

The issue I had running several amplifiers, even two at one time I had an issue with the remote wire that is generally like 16-18ga..I found that a 30 amp relay worked for me on the remote wiring.Prob like $8 bucks and some spade connections at an auto store.Might be able to get a couple pieces of heat shrink as well at that price.The amp could possibly be having a seperating solder joint coming loose on the board as well.Prob wouldnt hurt to crack it open and take a look if its not under warranty

 

[THATpurpleKUSH 5,000+ posts]

I've seen a lot of people using relays to remedy the issue. I'm just stumped as to why everything was ok until we hooked up a different sub. It's not like the equipment being used is cheap- the h/u being the closest thing to "cheap."

The amp is most likely out of warranty so maybe we could open it up and see how it looks. The amp is sort of from the budget line of Diamond from what I can tell but Diamond is known for high quality so I'm not sure how it ranks compared to others.

 

[10k-watts]

Check the ground... happened to me years ago in my wife's car and I made the ground better and out stopped

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[Boomin_tahoe 5,000+ posts]

I would have to say a bad ground also....but checking could be looking at it or physically actually checking it, pull on it see if it moves and since you aren't there to verify it just rely on his word, could be different.

OR.....bad RCA's. Swap them out with another see if that helps any.