"Pop" from sub when shutting system off

[dusty2221]

Any quick advice? I added the relay to my remote turn on lead, and since then, when the HU is turned off either by the switch, or by the power button itself on the HU, about 3 seconds after the sub "pops" or "thumps" Only the sub is doing this. Everything else is fine.

It's loud enough to make you nearly jump out of the boat when you don't expect it.

[EarmarkMarine]

dusty,
Switch your amplifier crossovers temporarily from highpass to fullrange on the other amplifiers/channels to verify the noise is not in all amplifiers. If its only in a single amplifier then the turn-on/off delay circuit or input muting circuit is defective in that particular amplifier. If it shows up in all amplifiers then its a problem with one of the source electronics or your wiring scheme.
At the root of the issue is that an amplifier input should be automatically muted so that it doesn't remain on to reproduce the sudden shut-off or power-down of the source electronics. If you think about it, its pretty easy to diagnose the cause by the process of isolation and elimination. You can also use a manual switch to temporarily and manually control the amplifier turn-on/off circuit and the sequence relating to the source electronics powering down.

David
Earmark Marine

[EarmarkMarine]

Btw, be sure to verify that the sub amp is actually shutting down.

David
Earmark Marine

[New Guy]

Dusty I think that it is because you are cutting the signal to the amp (rca's) before it is actually shutting the amp off.

Oops I didn't see that David posted

[mmandley]

I had this problem running the Stock boat deck. Then when i upgraded to Exile it poped a couple times and Exile redid the shut down circuit to add a longer delay. I think it has something to do with the instant off of the Deck and the amps arnt powering down slowly and so you get this loud POP.

It sucks and needs to be fixed as this can damage the speakers

[EarmarkMarine]

FYI, we do have an external adjustable circuit to correct an amplifier but I hesitate to recommend it until the problem is properly diagnosed.

David
Earmark Marine

[dusty2221]

If I remove the relay and run straight from the hu remote, there is no pop. Knowing that, david, would you assume its caused by the relay I have? In a quick search, I recall seeing something about 2 different speed, or something similar, relating to how quick it turns off. Hmmm. I'm not sure what my best starting point is.

Secondarily, I added a small 12v fan to move some fresh air, and now have a slight fan noise in the speakers. It is powered off the same remote, yet I ran an independent ground back to one of my stereo batts. I thought doing this would prevent the hum. What should I move? I double checked, and the system has zero humm when the fan is removed.

[EarmarkMarine]

Dusty,
Once you use a relay, everything including an EQ or other processor should be triggered by the relay also. Not the ignition, accessory or constant supply but only the remote trigger. All components should then share the same constant supply point. Same with the grounds. Then make sure the relay is correctly wired. You have the #30 workload input and the #87 workload output. Make sure to use this polarity. Then you have the #86 and 85 trigger circuit (pos. & neg.) that is tripped by the remote out lead on your source unit. The components of these two circuits must be totally isolated and cannot mix. Re-trace all these steps in your wiring. Draw out a schematic for clarity. I've never had a standard horn relay introduce the noise or pop when everything is correctly wired. PAC and similar DC fans do not introduce electrical noise. Is the voltage up to par during these tests? Different components do have different turn on/off thresholds.

David
Earmark Marine