Audio experts: question about turn on "thump"

Alright, so I'm pretty happy overall with my audio redux. Final setup on my 2017 crewmax SR5 non-JBL Entune premium include:

Rockford Fosgate Prime R600x5 amp
Audio Control LCQ1
Infinity Kappa 60.11cs front components
Rockford Fosgate 2-ways in the rear doors
2 hertz 10" subs in a box behind the rear seat
disconnect of the dash tweeters and center channel.

I followed closely the install and setup outlined by @TundraTex - especially for the RF amp and LCQ wiring. Overall the sound is tremendous and with much fussing and messing around with the amp and EQ bands on the LCQ1, I'm extremely pleased with the clarity of the sound, especially the Infinity Kappa components. I downloaded an RTA and pink noise app from the iTunes store and it was a yuuuuge help in setting up the LCQ.

My only remaining issue is a turn-on "thump" that I experience when the equipment powers on. All of my research leads me to believe that the amp is turning on before the LCQ1 fully boots up, which leads to the "thump". Additional research indicates many folks have solved this as a result of a ground issue. With that knowledge, I set about trying to diagnose the ground issue first.

I first checked and re-sanded the ground spot for the amp. It's a solid chassis ground in the driver's door trough and installed with 4g wire. The thump still persists. Next, I ran a temp ground line from the amp grounding spot over to the LCQ1 and tied it into the ground at the LCQ1 from the J144, 10-pin adapter. Still thumped at turn on. Next, I re-configured the 12v constant and 12v accessory leads on the j144 harness from using pin 9 to using pin 3, 12v acc, for turn on and pin 4, 12v constant, for 12v power. Still thumped. Note that the LCQ1 works fine in this configuration with pin 9 in J144 left unused. Still thumped.

So, I'm stumped. I went to the Rockford manual and it notes that in the case of a turn on thump that a remote delay timer needs to be used inline with the remote turn on lead. A conversation with both technical support at Audio Control and Crutchfield pointed me to grounds as the most likely concern with Crutchfield not able to provide any knowledge or assistance with a remote turn on lead.

Has anyone here had any experience with a turn on thump and a remote delay module? Or, any other ideas? If so, point me in the right direction.

thanks!

 

My first inclination was the ground as well. How far away is the ground from the amp? Both my amp and lc7i are installed under the passenger seat and grounded underneath. I’m assuming if your ground is on the driver’s side, the amp is installed over there as well. I know the LC1 is larger, so you may not have been able to fit both under the same seat.

Maybe try a 2ga, or even 1/0 and see if that helps

 

Thanks for the response. You're right, the amp is under the driver's seat and the LCQ is under the passenger seat. The 4g ground is no more than 12-14" long, at most.

Mike

 

Mike, sounds like your ground is fine. I don't have a thump with my system. Check your GTO jumper under the cover of the LCQ-1. It is usually shipped in the on position and uses signal on the audio channel 1 to turn on - essentially bypassing the remote in signal. If you're using the remote in, you don't need GTO. So try setting the GTO jumper to the "Defeat" position and see if that helps.

There's also a ground isolation jumper that's used to help reduce alternator whine. Try the alternate 200 ohm and off positions to see if that helps. In the factory position it essentially isolates the chassis ground and relies on the wired ground input only.

EDIT: Just re-read your OP and since your system works without J144 Pin 9 connected, that tells me your GTO is enabled. If you left pin 9 disconnected, you'll need to connect it again when you disable GTO.

Tex

 

So still working to figure this out. Oddly, when I pulled the cover off my LCQ, I didn't have a jumper on the GTO circuit at all, meaning the three upright prongs were empty for that slot. I confirmed this by calling Audio Control to make sure I was looking at the correct position on the circuit board. Thus, my remote in signal is essentially in defeat mode; they're sending out a jumper anyway to test either way.

Further, I removed the remote turn on lead from the amp to see what would happen when I powered up the system; I wanted to see what would happen when I took the amp out of the equation at power up and then added it back in several seconds later. Success, no thump. Once powered up without the amp, I quickly reinserted the remote-in lead to the amp and it turned on nice and quiet.

So, I'll try the GTO jumper when it comes in and see what signal sense does without the remote-in lead connected on the LCQ. If that's no good, I'll install a PAC Audio TR-4 delay timer inline on the remote lead in-between the LCQ out and the amp in.

Will report back findings.

Mike

 

I know I’m supposed to turn when my wife thumps me, I thought this thread might be about something like this.

 

Just to circle back on this thread, it seems that the LCQ1 was the source of both the hissing and the turn on thump.

I tried a number of different ground scenarios including changing the internal jumpers on the LCQ. I then added a PAC Audio TR-4, which is a turn on delay module. Still had the turn on thump.

I finally bit the bullet and bought a JL Audio Fix 86 as an alternative. Not only is the turn on thump gone, but so is the hissing noise. There is a bit of a learning curve on the Fix 86 but, the process of setting it up and calibrating it is a no-brainer. Further, tuning is done via a USB cable to my laptop which is a heck of a lot easier than reaching under the seat.

The Infinity Kappas, Hertz subs and RF r600x5 amp all sound great together now. The TuN software from JL allows for basic EQ tuning with more advanced tuning available with a TwK 88. For my uses, the Fix 86 and TuN 2.0 give me all I need.

I know that many folks have good success with the LCQ1 but, it just didn’t work well for me. I’ll have one for sale soon if anyone wants to give one a try!

 

I know it is too late now but I would have tried putting a capacitor across the power in and ground. That would turn on the power softly, eliminating the thump.

 

@MikeyMTBs, what harness did you use for your setup? Did you keep your stock HU?
thanks

 

I used this one from auto harness house. It comes with the mate to the j144/145 and all of the pins are in the right spot.

http://autoharnesshouse.com/41112.html

I am using the stock, 2017 SR5 non JBL head unit.

 

Will this work to wire an aftermarket amp in a JBL equipped truck? I’d be replacing the headunit as well.

 

Mine did the same thing. I checked all the grounds and didn’t find an issue so I went searching again on the internet. The problem was from all the components kicking on at the same time. You can either install a delayed relay or run a toggle switch for your amp. I ran a toggle switch and problem solved.

 

I hate to revive an old thread, but I am getting ready to replace the factory JBL amp, I replaced the HU last year with Pioneer avic-8400, Maestro RR/T01 harness. How did you end up wiring every thing?

 

Get a good amp install kit just greater than your amps wattage. If you plan on going bigger on the amp down the road then get a bigger amp kit. Installation is a breeze after that

 

I actually meant from the head unit to the amps. I want to use the pre amps on the Pioneer if possible, hopefully without having to buy and rewire new harnesses. I was also wondering how the dash speakers would be affected if I used the pre amps.