# Slight pop in the sub woofer when the amplifier turns on and off?



## rytekproject (Feb 25, 2011)

I tired to research and came to the conclusion that it might be a ground loop issue? Is there any way to trouble shoot this?
The speakers are run off deck power from a z120bt and the sub is run off of a PDX m6.
I have the sub amp is grounded to the chassis but the ground cable is temporarily a little long (maybe 4 feet of 4 gauge).


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## Moon Track (Mar 10, 2011)

Popping sound , it is possible , it comes from changing offset voltages in pre-amplification circuits. 
There are different amplifiers with different topology, it will be better to not have the sub grounded to the chassis if it wasn’t recommended by manual. You have a special ground terminal on the amplifier, why to risk, by checking the voltage converter for junction voltage thru speaker output.


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## Baada (Nov 28, 2010)

I assume that you mean you have the sub amp grounded to the chassis and not the sub itself. Correct?

It's not ground loop, which typically manifests itself as a continious whinning noise or similar. What you are experiencing is from a power surge during turn on of the one of the components. 

Are there anyother components other than the z120 and the PDX? Are you also using the blue/white wire to activate the vehicle's antennae or is it a fixed type? Is there anything else connected to the blue/white wire?


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## tyroneshoes (Mar 21, 2006)

Baada said:


> I assume that you mean you have the sub amp grounded to the chassis and not the sub itself. Correct?
> 
> It's not ground loop, which typically manifests itself as a continious whinning noise or similar. What you are experiencing is from a power surge during turn on of the one of the components.
> 
> Are there anyother components other than the z120 and the PDX? Are you also using the blue/white wire to activate the vehicle's antennae or is it a fixed type? Is there anything else connected to the blue/white wire?


Quick fix

PAC TR-7 Remote Turn-on Modules at Onlinecarstereo.com

turn on and off delay


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## finbar (Feb 1, 2009)

Have you tested for DC offset at the amp's speaker terminals?


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## rytekproject (Feb 25, 2011)

Baada said:


> I assume that you mean you have the sub amp grounded to the chassis and not the sub itself. Correct?


Yeah that was a typo. The amp is grounded. 



Baada said:


> Are there anyother components other than the z120 and the PDX? Are you also using the blue/white wire to activate the vehicle's antennae or is it a fixed type? Is there anything else connected to the blue/white wire?


I believe the antenna wire it only connected to the antenna remote lead but I will check. I'm not sure but this lead could be running to the pac tato as well. The ant is a fixed one. The only other components connected are a metra steering wheel control module and a Pac tato to connect the z120bt to the stock amp for now. Would turning the ant remote off fix it if this is the issue?



finbar said:


> Have you tested for DC offset at the amp's speaker terminals?


That was an interesting read, the output sounds fine then playing but who knows. I will try this too.


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## Baada (Nov 28, 2010)

If you only hear the pop in the sub my guess is the sub amp is turning on first and then the stock amp turns on and causes a little voltage spike which the sub amp picks up and you hear the pop. To verify this, disconnect the turn on wire for the stock amp and turn the vehicle on, if no more pop then you will need to delay the sub amp turn on, which as mentioned above the PAC can do for you. Good luck.


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## tw3nty_3 (Apr 11, 2011)

I may sound noob but isn't this normal? Especially when you first turn on the power to the deck. Because I have had that since to late 80's


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## finbar (Feb 1, 2009)

tw3nty_3 said:


> I may sound noob but isn't this normal? Especially when you first turn on the power to the deck. Because I have had that since to late 80's


Normal but undesirable. It is possible to have a system with no on/off noise.


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## Baada (Nov 28, 2010)

I think common is a better word than normal. It's not really a good thing though, especially if you have a severe case.


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## Mike_Dee (Mar 26, 2011)

*Re: Slight pop in the sub woofeInrush currentr when the amplifier turns on and off?*

Inrush current.


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## rhannahs (Mar 5, 2011)

I think I remember reading somewhere that it could be caused by your inputs, you're not using balanced differential inputs are you?


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## nervewrecker (Oct 5, 2009)

oh my, you too?

I was thinking it is my grounds, so I am in the process of double checking them. I will let you know what I come up with over the weekend. 

Is yours loud or very soft that you can barely hear?


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## minbari (Mar 3, 2011)

tw3nty_3 said:


> I may sound noob but isn't this normal? Especially when you first turn on the power to the deck. Because I have had that since to late 80's


its not normal and can be damaging. you should fix it before you blow up your speakers.

BTW, how does someone get banned with one post, lol?


to the OP, 

are you using the remote turn on from the HU for the amplifiers? if not, change that first. your HU usually has delays built in. it will turn on, get up and running and then 1/2 sec later turn on remote lines and such. this will eliminate any need for further troubleshooting.

another test you can try. pull your RCAs and then see if the turn on pop is there.


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## rytekproject (Feb 25, 2011)

When I changed to the Leviathan it stopped (maybe bc of its remote delay). My remote is from the HU, but I'm not really sure why it stopped. I'm going to be testing some new amps pretty soon and I will keep you updated with the progress.


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## minbari (Mar 3, 2011)

rytekproject said:


> When I changed to the Leviathan it stopped (maybe bc of its remote delay). My remote is from the HU, but I'm not really sure why it stopped. I'm going to be testing some new amps pretty soon and I will keep you updated with the progress.


well if it comes back there are two easy ways to fix it.

1) tr7 on the remote line to delay it more than the HU does already.
2) tr7 used to turn on relays that disconnect the speakers from the amplifiers with a delay.


ya, the ZEd stuff have a soft turnon circuit.


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