speaker pop at car shutdown

**andyman** · 12-07-2007, 12:04 PM

Here is a copy of a PM I sent out earlier.
I thought I would post it in the forum as well.

Thanks for reading it.

Hey Shakes,
Thanks for the many posts you have made in the past to the forum. I have gained a great deal of knowledge from guys like you on the forum.
I noticed you have not posted in awhile. I hope your still out there.

For some reason I have the opposite problem of your solution you posted below.

I have lilliput 701 with built in small amp.
When I turn the car off I get a loud speaker pop.
This 701 unit has audio in for pc input, but even in radio mode (701 feature) which stops the pc audio input and switches the the lilliput radio I still get the pop, so I think it has nothing to do with the pc portion of my setup.
The only thing I have come up with is when acc is powered off (turn car off) to lilliput radio then I do a constant to momentary pulse (momentary close circuit across pins 30 and 87 which runs to both sides of the face plate mute button) and also a power off delay on acc line to lilliput to give the momentary pulse circuit the time needed to mute the head unit before powering off the head unit.

Seems like there is an easier solution that would keep me from having to hack the face plate mute button.
Feels like I'm going around the world just to get 5 feet behind myself.

Any ideas would be great,
Thanks,
Andy

In Reply to your post 191697

the portion off the above post I am referring to:

excuse my ignorance but what do you mean by empeg?

anyway ... i don't think a capacitor will help you. for starters, in order to prevent speaker pop, you want your amp to turn off before, or at the same time as your sound card. if the sound card powers down first, you will get that wonderful pop. ... so doing anything to extend the amount of time the amp is on probably won't help.

even if that were the fix ... even a 1farad capacitor (those big ones you see in audio stores) would only provide you with power for a split second ... probably not even over one. search around in the threads regarding tank circuits and look for the equation Ricky posted a number of times.

you definately won't get any help from a cap you'll find at radio shack.

in my setup, i have my external usb soundcard and my amp's ignition wire both being fed from a relay, which is activated by the power cable coming off my ITPS. so the Soundcard and amp turn off at the same time. Additionaly, I have a EQ that my audio signal passes through which is hooked straight up to the ignition wire. So it turns off when the car turns off (45 seconds before the amp/soundcard turn off) so that also prevents the pop (no sound passes through the EQ when it's powerd off)

anyway ... i don't know your setup ... but find a way to turn your sc and amp off at the same time...

**TheGemInIMan** · 12-07-2007, 10:43 PM

You could try adding a thin miniature relay inside your Lilliput ...

Cut one of your speaker wires and attach to the relay switch contacts (N.O.) between the two wires ... Wired so that the when ACC is on it switches the relay on ... or whenever your Lilliput comes on ... you could use the 12v supply inside the unit itself ...

There are relays out there that are 5mm thick ... and thinner ... I don't know how much room you have in there ...

[media]http://img-europe.electrocomponents.com/images/RF231236-02.jpg[/media]

When the ACC goes off the relay will cut the speaker connection ... and vice versa ...

Just a thought ...

cheers,
Gem

**89ragtopgt** · 12-08-2007, 11:39 AM

i have an external usb sound card and it had a turn on pop and off. For the turn on i made a time delay relay for the amp turn on wire for 45 seconds. So when i turn on the car pc the puter boots and then within 45 seconds the amp turns on and no pop. for turn off i turn off the ignition on the car amp turns off before the operating system shuts down and then no pop.

**andyman** · 12-08-2007, 12:55 PM

My amp is built into the lilliput 701 monitor/ fm tuner.

When I cut the ignition my lilliput unit is powered off and at the same time a momentary relay pushes the shutdown button on carpc which then takes about 35 seconds for windows to shut pc down.
It seems like my problem is inverse of everyone elses.
My lilliput unit (which has the amp in it does turn off before the laptop carputer is powered down)
I'll add some delay between the amp/radio unit and the push of the laptop button, but I really don't think it will help since as of now the laptop does not power off for 35 seconds after ignition/ amp powers off.
I'll also try unhooking the audio cable from pc to lilliput unit and see if I still get the pop even using just the radio side of the lilliput amp/tuner unit.

???
am I making sense or just talking riddles? someone slap me and bring me out of the "speaker pop hell" I think I coined a new phrase there.

Thanks again,
Andy