[BoxK]

Please share for all.

Stock Sub Replacement with a BLAUPUNKT GTHS81 8" Amplified Subwoofer 320-Watts for $125
Objectives: 1. Improve the audio sound. 2. Be able to quickly and easily revert back to stock. 3. Keep costs down
Step 1: Remove old sub. Remove the latch cover by unscrewing the two large plastic screws on the inside of the sub area, below the latch. The cover will pop off easily with the screws out. Unplug the wiring connector from the sub, then unscrew the 4 10mm hex head screws holding the sub in place. The sub will lift out easily.

Step 2: Connect the existing wires to the preamp adapter. I used posi-tap connectors so that I didn't need to cut any wires on the stock sub wiring connector. As you can see from the photo below, the wiring connections to the adapter are: Brown - Grey, White - Grey/Black, Pink - White, Red - White/Black. I didn't need to use the brown ground wires on the adapter. I plugged the RCA cable into the adapter and routed the cable on the bottom side of the sub area. After the sub was in place, I also attached the adapter to the side of the sub area with some double sided Velcro.

Step 3: Connect the sub to power. I used a 12V 16AWG cigarette lighter power cord and cut off and stripped back the ends. I cut off an extra 6 inches from the cable and separated the red and black strands so that I could use the extra bit of red to turn on the sub. This was done by stripping both ends of the short red cable and plugging one end into the Remote (middle hole) and the other end into the 12v (bottom hole). Before plugging the short red cable into the 12v hole, I twisted the end together with the longer red cable from the cigarette lighter adapter. The black cable from the cigarette lighter adapter went into the Ground (top hole). I plugged the cigarette lighter adapter into the outlet on the left side of the trunk and routed the wire on the top side of the sub area. I tested the sub to make sure everything worked before moving on to the next step.

Step 4: Place the subwoofer. I used pieces of carpet to line the bottom of the sub area and the sides where the sub would sit. This allowed sub to sit snuggly in the space and also keep down any rattles. There is a port on the upper left side of the sub, so I made sure to keep the carpet away from that section. To assure the sub didn't move around while driving I used some 3/4" hanger strap and the hex screws from step 1 to attach the strap to the original mounting brackets. Underneath the strap I attached clear rubber bumpers (like what is used on cabinet doors), to provide extra tension and prevent any metal on metal between the strap and the subwoofer. It is easy to adjust the settings on the sub with it strapped in. Make sure the sub is set to "auto power on".

Step 5: Put the trunk back together. Reinstall the latch cover, sub space cover. I routed the power cable on the top left of the sub space cover to both hold it in place (as seen in the picture above) and to prevent it from being pinched. Fold the floor back over the area and enjoy.

Parts List:
Subwoofer
Preamp Adapter
Cigarette Lighter Power Adapter

In case you don't have any lying around:
Posi-tap connectors
RCA Cable
Hanger Strap
Rubber Bumpers

 

[BoxK]

This is an upgrade price I can live with. If I end up with the EV6, I'll be revisiting this thread and may come back with questions 😋

I'm happy to provide a parts list and pics if you decide you want more info.

 

[BoxK]

If the hum comes back, I will install the line converter.

I installed the line converter today, after the sub started humming again. I paid special attention to the situation before the humming started, though can't reproduce the hum by going through the same steps. The only correlation I have between the two times the sub started humming was that the trunk was opened and shut. Today the car was running when the trunk was opened and shut, then I drove 50 yards before shutting off the car. On the next startup, the hum began (trunk remained closed).
Anyway, I'll let you all know if I still have the problem with the line converter installed.

 

[BoxK]

Very thorough! I have a friend who could probably help me follow these steps. So did you leave the other speakers stock? Have you had any issues? How's the result after the sub install?

Sorry if any of this is redundant; lot of forum action these days.

Yes, all the other speakers are stock. I tuned both the sub and changed the tone settings in the car until I got the sound I was looking for. The new sub makes a big difference by filling in the low end the original sound system is missing.
As for issues, I have had none with the current setup, though I have a few "lessons learned". 1. I originally built a mount for the subwoofer that would connect to the brackets in the sub area. This made the subwoofer too high and put it right next to the plastic cover of the sub area. Putting the sub on the floor with carpet gave it more volume in the sub area to make better sound. 2. I also originally used the hi level inputs on the sub instead of the preamp adapter. This led to an occasional hum from the subwoofer when the car would start up. Moving to the preamp adapter removed the hum and makes for a simpler install for most.

 

[BoxK]

I installed the line converter today, after the sub started humming again. I paid special attention to the situation before the humming started, though can't reproduce the hum by going through the same steps. The only correlation I have between the two times the sub started humming was that the trunk was opened and shut. Today the car was running when the trunk was opened and shut, then I drove 50 yards before shutting off the car. On the next startup, the hum began (trunk remained closed).
Anyway, I'll let you all know if I still have the problem with the line converter installed.

It's been 6 days since I installed the line converter and I have had no problems. The occasional sub hum is gone. I consider the install a success, especially to tune of $125.

 

[BoxK]

I recently completed my stock sub removal and install of a Blaupunkt GTHS81 based on the info in this thread. It was a big help since I am completely new to working with car subwoofers. I wanted the ability to easily reinstall the factory sub, just in case of problems down the road, so used positaps to hook into the wires for the factory sub. I strapped the sub in place using the factory mounts, with carpet underneath and on the side where it could touch metal. For power I used a 12v 16awg cigarette lighter outlet adapter and stripped the ends. Everything works and it sounds so much better.
I would definitely recommend the change, assuming I can figure out my one outstanding issue. About 1/3 of the time, when I turn the car on, the sub will hum and won’t stop until I pull the hi-lo input. It will play music with the hum and the hum will remain even if I power down the sub, until the hi-lo input is pulled out and replaced. After that it will work fine through multiple power on/offs, until it decides to hum again. It’s not loud, though is noticeable.
Any thoughts on how to fix the issue?

 

[BoxK]

I tried this and have the same issue still. It happened significantly less on the Blaupunkt subwoofer I tried than the MBQuartz sub. I had to return the Blaupunkt because the level control did not function, once I get a new sub I will probably get a line converter to see if that remedies it.

Please let us know how the line converter works out for you. I have one I was going to install, but I can't figure out how to make the hum appear. I have been in and out of the car over a dozen times today and not experienced a single issue with the sub. If the hum comes back, I will install the line converter.
The line converter I have has the option to connect ground wires. I am curious if I connect the ground wires from the converter to the same ground as the power line if that might help eliminate the hum. I'm a total neophyte, so is this is a bad idea?