Turn-off thump....... it won't go away.

[darkrider01]

I have tried everything I can imagine to get my sub to work properly with the factory radio. I mean it works, but when it turns off, there is a thump. The thump goes away if the amp gain is set to 0, but that really isn't acceptable.

Here are things I have tried:

1. Tapped into rear low level input signal at factory amp - wired to RCA's and used as sub-amp input. Tapped into Boston amp Remote wire - used as sub-amp remote turn-on.

2. Same as #1 but purchased a Metra "pop-stopper" that provides a 2 second turn off delay for the remote wire.

3. Same as #1 but purchased a Stinger Ground-Loop Isolater and placed between low level Boston amp input and sub-amp. The isolater has grounding wires, but I experienced a high-pitched escalating tone when they were connected.

4. Tapped into rear low-level input signal at factory amp - wired to input of AudioControl LC6i - output RCA's to amp. Used Boston amp remote wire directly to sub-amp.

5. Same as #4 but put Boston amp remote to LC6i and used remote out on LC6i to sub amp.

6. Same as #4 but used GTO signal sensing function of LC6i instead of the Boston amp remote wire.

7. Used rear 6x9's to provide signal input and used GTO signal sensing function of LC6i to provide sub-amp remote.

I'm really at a loss here. It looks like there are only 2 options to get rid of the thump. Option 1 is wire remote turn-on to cigarette lighter. Option 2 is aftermarket radio.

I just want it to be right.

Am I missing any other options? Thanks for any help!

[IDEALG]

the amp has to be turned off before the radio which you cant do in these cars. i have the same problem. i have an idea im working on to fix this and still keep our factory chimes

[ecko04]

*sigh* your pop is coming from your remote wire. There are actually 2 things you can do to rectify this nuisance.

1) Tap your remote from the factory remote wire AND
2) Wire 2 resistors in parallel (resistors should be of the same impedance...i.e. x2 1000ohm resistors)

Doing these 2 things together will make sure that 1) your amp still turns on when your radio is on and retains door chimes and turn on with the radio even though the key isn't in the ignition & 2) drops the voltage from the remote turn on wire to 6v, which should eliminate any popping.

[CamaroGeek]

Metra makes a part which handles this problem specifically, called the Axxess Trigger, available at Sonic among other places. The radio sends out two signals to control the amp - one is an active high enable, and the other is an active high mute (called Amp Control in schematics). You need to be using both signals together. I doubt if the Amp Control line is wired in non amp'ed cars, so that might be a challenge to get to at the back of the radio.

[darkrider01]

Originally Posted by ecko04

*sigh* your pop is coming from your remote wire. There are actually 2 things you can do to rectify this nuisance.

1) Tap your remote from the factory remote wire AND
2) Wire 2 resistors in parallel (resistors should be of the same impedance...i.e. x2 1000ohm resistors)

Doing these 2 things together will make sure that 1) your amp still turns on when your radio is on and retains door chimes and turn on with the radio even though the key isn't in the ignition & 2) drops the voltage from the remote turn on wire to 6v, which should eliminate any popping.

I'll give this a shot, though in my experience I have never seen a 12v remote wire cause turn-off pop. The "should" worries me though. "Should" has already cost me a pretty penny. At least resistors are cheap

Originally Posted by CamaroGeek

Metra makes a part which handles this problem specifically, called the Axxess Trigger, available at Sonic among other places. The radio sends out two signals to control the amp - one is an active high enable, and the other is an active high mute (called Amp Control in schematics). You need to be using both signals together. I doubt if the Amp Control line is wired in non amp'ed cars, so that might be a challenge to get to at the back of the radio.

I bet this could be achieved with a simple relay. If you used the mute circuit (assuming it's a 12V signal) it could be used to break the remote wire..... guess it's time to break out the multi-meter.

[CamaroGeek]

Originally Posted by darkrider01

I'll give this a shot, though in my experience I have never seen a 12v remote wire cause turn-off pop. The "should" worries me though. "Should" has already cost me a pretty penny. At least resistors are cheap



I bet this could be achieved with a simple relay. If you used the mute circuit (assuming it's a 12V signal) it could be used to break the remote wire..... guess it's time to break out the multi-meter.

You are correct, it could be done with a relay. The Amp Control signal is 5V when mute is active, so you would want to use the NC contacts. There are relays with fairly low current coils available, such as PB1061CT-ND at DigiKey.com. The Trigger piece is a general-use piece for delays, sequencing, ebrake emulation, etc., and the GMLAN amp control function is one of its uses. But a relay would be much cheaper.

[darkrider01]

Well, I have a wealth of new information.

1. My issue is not with the remote, though I'm sure I can solve it using the mute (amp control) and a relay.

2. If I have no RCA's plugged in, the amp doesn't make a peep when it turns off. It turns off silently, just like it should. It is only when I have a signal present, that I get the turn-off thump.

So it looks like my issue is in the input to my amp. Now what I can't understand is why this $200 AudioControl LC6i (read - expensive Line Output Converter) is allowing this thump through. I had the thump before I put the LC6i in place, and it is still present. I tried the LC6i in grounded, isolated, and 200 ohm modes for the grounding. On a suggestion from someone else, I tied all 4 input channels into the LC6i and then summed the output to see if it was a balancing issue (it still may be). Obviously, that didn't fix anything either.

So.....I'm still scratching my head and wiping away tears of ultimate frustration. I see little option now but to replace the factory head unit or abandon this dream forever and sell my equipment. I have never had this issue in any other vehicle. I just don't know what else to do.

[IDEALG]

steve at ******** has the answer pm him.

[ss_camaro_10]

i bought the sub thump wiring harness and i have no issues.

[Steve@Subthump]

it's all in the amp. some do it, some don't. there are different fixes that we use for amps that need assistance.

[darkrider01]

Originally Posted by IDEALG

steve at ******** has the answer pm him.

I PM'd Steve earlier, and he does say he has a solution. I respect Steve and trust his experience in this matter. I kinda feel like his solution is something I have already tried, but I haven't tried his exact solution. I'm going to try his exact solution anyway and buy some stuff from him tomorrow, but I figured I would at least explain further everything I have tried in case someone else is looking for info about this problem.

[Soundplus]

I too have been trouble with the turn off pop. I have tried the low voltage trigger that did not work.. I am very interested in hearing Steve's idea..

[Dznts]

http://********.com/Search-Results?k...=14&search_y=5

[darkrider01]

Originally Posted by Dznts

http://********.com/Search-Results?k...=14&search_y=5

I know my original post may have been TL;DR for most, but I have already tried a Stinger Ground Loop Isolator. Now the trick may be using the Ground Loop Isolator with the ******** harness. At any rate, it's only $7 for the audiopipe GLI which is a lot cheaper than some of the other solutions I have tried.

This is the Ground Loop Isolator that I have already tried....(link)