Intermittent loud turn off pop.

I played my car computer system for the first time today and while it sounds very good I am experiencing a loud intermittent turn offAttachment 13992 pop, it is loud enough that I am worried about the tweeters. This is an active 4-way system and as far as I can determine the grounds are good. I also disconnected the car computer and re-installed the Kenwood 2-din head unit that the car system replaced and with the Kenwood there was no pop.

I am using a Meanwell Dc-DC converter to isolate the car computer from the cars electrical system and there are the usual hot and ground terminals for in and out and there is also a ground that can be connected to the car frame and I'll try that tomorrow but in the mean while I am hoping someone might have suggestions about what might be going on.

Thanks,

That likely caused by a ground loop which is usually the culprit and can be very difficult to diagnose. Usually it’s a difference in potential between different ground locations the the cars body in relation to each other and often is made up through the RCA connections because they are also connected to ground through the amplifier chassis. Sometimes these can be rectified by keeping all the ground and power cables for each powered unit the same size and running all the grounds to the same location and making them as short as possible. Don’t let RCA cables cross power wiring if you can help it and sometimes you can delay the power on or off of amplifiers so they are staggering. Another culprit I have found is using a protective capacitor inline with a tweeter where sometimes this introduces a speaker pop and I don’t know why other than the capacitor unloads it’s stored up energy somehow.

Thanks for this informative reply. After reading this I spent the past few days double checking my grounds, the amplifiers and DSP are star grounded on a bolt in the boot while the SBC is grounded to the 12volt converter and the 12volt converter is grounded to a bolt in the front cabin. I replaced one ground wire that was of smaller gauge than the others. Today I'm going to mount the 12volt converter in the boot with the other gear and ground it to the main star ground. I'm nervous about removing the tweeter protection caps. as they have already saved my tweeters twice from a 3A.M. tuning session miss-adjustment while setting the DSP but I do have a cheap set of tweets that I am going to run in the system with the capacitors removed to check this out.

I'll report results when able.

Is the turn-off sequence different when you use the car radio vs the system with the power supply? If the car radio shuts off the amplifiers using the remote wire first, and then powers down the radio circuitry after, then you shouldn't have an off-pop

If the setup with your power supply shuts down the audio circuits in the sound card before turning off the amplifiers, then you might get some pops.

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Originally Posted by Donanon

Thanks for this informative reply. After reading this I spent the past few days double checking my grounds, the amplifiers and DSP are star grounded on a bolt in the boot while the SBC is grounded to the 12volt converter and the 12volt converter is grounded to a bolt in the front cabin. I replaced one ground wire that was of smaller gauge than the others. Today I'm going to mount the 12volt converter in the boot with the other gear and ground it to the main star ground. I'm nervous about removing the tweeter protection caps. as they have already saved my tweeters twice from a 3A.M. tuning session miss-adjustment while setting the DSP but I do have a cheap set of tweets that I am going to run in the system with the capacitors removed to check this out.

I'll report results when able.

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‘Just cycle the system with the tweeters disconnected and if the turn off pop goes away well then you found one culprit. You can use a very small glass fuse from parts express to protect the tweeters in lieu of the capacitor but to be honest I don’t know what value to use. I just know some home audio tweeters are protected this way.

Thanks for the replies. It's been a while since I replied to this thread as I have been chasing this turn off pop while also working on the install.


Justin Zazzi "Is the turn-off sequence different when you use the car radio vs the system with the power supply? If the car radio shuts off the amplifiers using the remote wire first, and then powers down the radio circuitry after, then you shouldn't have an off-pop If the setup with your power supply shuts down the audio circuits in the sound card before turning off the amplifiers, then you might get some pops"


In this system I am using a car computer and there is no car radio or other playback device in the vehicle. I have all devices and amplifiers connected to a Bosch relay which is energized by the cigarette lighter at the car fuse box. As far as I can tell the whole system shuts down simultaneously when the relay is de-energized. I still get the turn off pop.


JCsAudio"Just cycle the system with the tweeters disconnected and if the turn off pop goes away well then you found one culprit. You can use a very small glass fuse from parts express to protect the tweeters in lieu of the capacitor but to be honest I don’t know what value to use. I just know some home audio tweeters are protected this way."


I disconnected the tweeters from the amplifier and the turn off pop is still there, thanks for the tip on using fuses as I might just do this when I do the install in my buddies car.

I think the pop might be coming from the DC converter and I should have run the system without it by now but I had lock on bias toward the rest of the system, tomorrow I'll remove it and run the system to see if it is the problem.

You could also try turning everything on then turning one thing off at a time. If you don't get a noise, turn that thing back on and turn off something else. Usually the turn on/off sequences are timed a little bit so that the radio turns off the amp, then the radio turns off so that any radio off-pop cannot be passed to the speaker because the amplifier is already off. Or something like that.

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Originally Posted by JCsAudio

‘Just cycle the system with the tweeters disconnected and if the turn off pop goes away well then you found one culprit. You can use a very small glass fuse from parts express to protect the tweeters in lieu of the capacitor but to be honest I don’t know what value to use. I just know some home audio tweeters are protected this way.

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Tweeters are usually a bit sensitive to low frequency content. So fixing the problem is probably better than using a fuse... and if the pop is also be happening on the other speakers, then it probably makes sense to get rid of the pop universally?