# Turn Off Pop



## mattyjman (Aug 6, 2009)

What causes it? 

On this other forum, I have 1 person suggesting that it's the topology of class a/b amps. 

The other thinks it's the factory head unit. 

What could cause an issue like this? I'd like to get some gurus to provide some possible scenarios, since the other forum is short of gurus


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## Sine Swept (Sep 3, 2010)

The amp needs to turn off before the radio. Heres a premade jobby

STINGER SGN21 IGNITION OFF POP STOPPER FOR AMPS - SGN21


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## basshead (Sep 12, 2008)

Remove the RCA and use a jumper between the 12v and remote to see if it still pop, if it does it's the amp.


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## jtaudioacc (Apr 6, 2010)

like sine swept said, it's usually a timing issue. with just a radio and amp, the radio is usually turning off before the amp. the stinger piece works good most all of the time. but, you can emulate the timing or make sure by making sure the amp turns off first by playing with the wiring. then you just need something to emulate that and should be all good.


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## mattyjman (Aug 6, 2009)

ok, that's what i thought... 

so what does this stinger piece actually do? How's it work?


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## minbari (Mar 3, 2011)

basshead said:


> Remove the RCA and use a jumper between the 12v and remote to see if it still pop, if it does it's the amp.


this^^^

Eliminates everything except the amplifier. if it still does it, it is the amplfiier. if it doesnt, then the HU is causing it.


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## asota (Feb 7, 2011)

Do you have a relay in your turn-on circuit?


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## WhippingBoy (Dec 21, 2010)

mattyjman said:


> What causes it?
> 
> On this other forum, I have 1 person suggesting that it's the topology of class a/b amps.
> 
> ...


The pops are typically caused by the collapsing of the rail voltages as the amplifier powers down. Delaying the turn-off time to the amp should eliminate the audible pop. There's some suggestions on this site addressing this issue.


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## Maylar (Dec 6, 2012)

mattyjman said:


> What causes it?
> 
> On this other forum, I have 1 person suggesting that it's the topology of class a/b amps.
> 
> ...


Most amps today have "soft" turn on / off and don't pop.. but it's something that's easy to check.

You mention factory HU - are you using an active LOC? Or do you have any other device between the HU and amp like an EQ maybe?

Also, where do you get the remote from?


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## mattyjman (Aug 6, 2009)

asota said:


> Do you have a relay in your turn-on circuit?


i've been told that a relay doesn't help with the pop, but i still plan on using one, i think...



Maylar said:


> Most amps today have "soft" turn on / off and don't pop.. but it's something that's easy to check.
> 
> You mention factory HU - are you using an active LOC? Or do you have any other device between the HU and amp like an EQ maybe?
> 
> Also, where do you get the remote from?


this is camaro factory HU 2013, and the outputs are low level, so they are going straight to the bitone. the remote can be grabbed from the amp, but i'm thinking about using the cigarette lighter instead... 

most people on the forum have no idea what they are talking about, and i thought it was a early turn off thing, but wasn't certain. some amps have issues, some don't apparently...


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## asota (Feb 7, 2011)

A relay can cause a turn-off pop was my point but if you have none that can't be it.


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## mattyjman (Aug 6, 2009)

oh gotcha

here's a link to the thread where one member went through the most exhaustive efforts...

Aftermarket amplifier turn-off pop/click/thump...The Answers - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums - Camaro5.com


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## Sine Swept (Sep 3, 2010)

I found some useful hints - using a diode/ capacitor to add a delay to the turn off on your radio

The rec.audio.car FAQ

Scroll to the bottom and click on Electrical - section 2.2

I will also note that whenever you are adding a relay in your system to add a diode across the coil to prevent a voltage spike when the relay coil collapses (Some relays do have them built in)


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## jtaudioacc (Apr 6, 2010)

Sine Swept said:


> I found some useful hints - using a diode/ capacitor to add a delay to the turn off on your radio
> 
> The rec.audio.car FAQ
> 
> ...


holy usenet batman! lol

but i do love some alt.binaries.


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## TrickyRicky (Apr 5, 2009)

Some amplifiers use a relay on the speaker signal output. I notice these amps don't have a turn off pop at all.....only internally when the relay clicks.


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## Sine Swept (Sep 3, 2010)

Bringing the old into the light!


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## Maylar (Dec 6, 2012)

Typically what causes turn off pop is that the device just before the amp (bitone in your case?) outputs a pulse when its power or remote is removed. If the amp is still active at that point in time the pulse comes through as a pop or thump. I'm not familiar with the bit one, but my Audiocontrol EQL does it and it's rather annoying.

Solutions are to either delay the turn off of the EQ or put a relay in the audio lines between it and the amp. The relay disconnects the RCA signal when the remote turns off.


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## 14642 (May 19, 2008)

OK. Turn on and turn off pops are caused by a couple of things. Usually, it's a DC offset somewhere. Less frequently, some piece of gear makes a voltage spike when it turns off. The second is very uncommon these days. 

The DC offset is likely the problem. If you're using the low level output of a factory radio, even a VERY small offset will be turned into an audible pop after the level of the signal is increased by the preamp and then the amplifier. Since it's a DC offset that's causing the problem, it has to be removed. An LOC is effective for this because it has either some capacitors or transformers. An LOC won't work for you, because it also attenuates. A simple ground loop isolator will probably work.

A delay circuit on the radio will not help because you can't keep the radio on longer than the amp because the radio turns the amp off when it turns off. 

First, disconnect the output of the radio from the input of your bit one. Turn the radio off. If the pop is gone, then you have to eliminate the DC offset from the signal to the Bit One. Try the ground loop isolator. Or use an LOC and remove the resistors inside that provide the attenuation. 

If the pop is still there when you turn the radio off with the radio's outputs disconnected from the bit one, then remove the RCAs from the input of the amp. If it's gone, then it's the Bit One. In that case, adding a delay circuit to the Bit One and turning the amplifier off immediately when the radio turns off will fix it. 

If the pop is still there with no input connected to the amplifier, then it's the amp. You can fix this too by delaying the turn off of the amplifier, installing relays in the speaker outputs of the amp. The relays should be controlled by the remote lead of the radio (or the bit one) so they disconnect before the amp turns off.


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