I have a Mk7 Alltrack, seen here - http://forums.vwvortex.com/showthread.php?9151346-Mageus-Alltrack-build. The Fender sound system is surprisingly decent, but since I’m an audio snob I decided to upgrade it. I started with the subwoofer, then changed out the front speakers, then decided to upgrade the amp. Following documents my build.
SUBWOOFER
The stock Fender subwoofer is a paltry 6.5” driver in a plastic enclosure that sits within the spare tire’s wheel. Needless to say it is underpowered and lacking in clarity, even after being packed with polyfill. People smarter than I have done technical evaluation of waveforms and suggest that the Fender crossover settings overlap the cabin woofers and sub, using the door woofers to help the sub out. This is borne out by my gross and fickle hearing.
I shamelessly copied this excellent idea from hybrid88 - http://forums.vwvortex.com/showthread.php?9015697-Alltrack-Subwoofer-Install&highlight=subwoofer. An MDF subwoofer box made of 2 concentric hexagons, the smaller which fits within the spare tire wheel, and the larger which rests on top of the tire (it’s not bolted down). I could have made cylinders using a circle router jig, but that would have been too tedious. The hexagons were easy to make with a table saw set at 30deg. It all fits under the stock floor. I’m not much into ‘boom boom’, but the new sub delivers markedly improved clarity of base along with hitting the lower frequencies.
I built a custom trunk floor with a cutout for the speaker and slots for ventilation of the amps. It’s made of laminated ¼” MDF (total height ½”), covered with speaker box carpet. It hinges just like the stock floor.
- hexagonal 0.9ft3 box from MDF
- 12” Alpine driver
- Alpine MRV-M500 single-channel amp
- run signal from subwoofer cable in trunk to speaker-level inputs on the amp (don’t need line-out convertor or turn-on wire)
- wire from amp out to banana plugs on the subwoofer
- power from the battery, through the firewall near the pedals, up the driver side, under the rear seat, and into the front of the trunk.
The subwoofer box, unfinished.
![]()
The subwoofer box, finished.
![]()
I tapped into the existing subwoofer cable. The stock driver is dual-coil. White wires positive, brown wires negative, yellow marker indicates line 1. I only used one of the pairs of wires, since my sub is single coil.
Custom trunk floor.
After cutting and priming the MDF
![]()
Carpeted. It hinges like the stock floor.
![]()
Installed
(Unfortunately, VW built the spare tire off center, so the hole doesn’t line up)
![]()
FRONT SPEAKERS
The stock Fender cabin speakers are decent. However, the tweeters don’t have the clarity of higher end speakers, and the woofers both lack base and are muddy. I installed a set of Focal PS165 V1 separates.
The 6.5” woofer fits almost perfectly in the door. It’s just slightly wider than the door hole, so I made ½” spacers. There is plenty of depth behind the metal for larger speakers. There is also plenty of room between the speaker and the door card, if your driver is tall or you need a thicker spacer. I tapped straight into the speaker harness. The stock front woofer is dual-coil, so I only used 1 pair of wires. I may add sound-deadening later. I left the rear speakers stock.
I replaced the tweeters in the A-pillars. I cut the stock mounting posts and hot-glued the new tweeters in.
The Focals sound great. However, the stock Fender amp applies major crossover and EQ filtering, which screws up the aftermarket speakers. Tweeters are way too bright, and the woofers cross over way too low. Since I’m using the stock wiring, I couldn’t use the Focal crossovers. Which led to my next project . . . see below.
![]()
AFTERMARKET AMP (FENDER VERSION)
The stock amp filtering has some issues:
- Tweeters get too much volume. Even with treble set to -7, the Focal tweeters are too bright.
- Woofers cross over too low and are low amplitude. The woofers carry hardly any mid frequencies, and cross over very low to cover the wimpy stock subwoofer. I have to increase base at the head unit, but then the woofers boom from carrying subwoofer frequencies.
- Subwoofer is probably attenuated to protect the wimpy stock driver.
I decided to keep the stock head unit and add aftermarket equalizer and amplification. Here is the flow-chart.
- MIB2 speaker level output ->
-> AudioControl LC7i line output convertor ->
-> Clarion EQS746 7-band equalizer ->
-> Alpine MRV-F300 4-channel amplifier ->
-> stock speaker wire harness coming out of Fender amp
I could have run speaker wire directly from the head unit to the amp’s speaker-level inputs, but I wanted to add equalization. So, I had to put an LOC in between.
Unfortunately, swapping out the Fender amp is not as easy as just pulling it out and plugging into the head unit.
- The MIB2 head unit communicates with the Fender amp via a fiber optic (MOST) cable. No way to tap the signal between the two.
- The MIB2 head unit has the new QuadLock connector. Speaker-level output pins are on the head unit, but the QuadLock plug is missing the insert for those pins.
- If one wants to use the speaker-level outputs from the head unit, one has to recode using VCDS.
- If one wants to use the existing speaker wiring, one has to tap into the 38 pin Fender amp harness, which is under the driver seat.
- The front woofers and the subwoofer are dual coil. If the aftermarket speakers are single coil, one has to use a single pair of wires.
That being said, I’ve been able to solve all of these issues.
The MIB2 head unit uses a newer version of the QuadLock connector. See here for details - https://www.golfmk7.com/forums/showthread.php?t=29694. It’s missing the tan colored 8-pin speaker-level-out section. This is part# 3B7-035-447, $25 at the dealer or from ECS - https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/8-pin-connector/3b7035447/ . Mouser has a similar part, but is not in stock. Now, you could tap into the pins directly like q2quest did, but the wires have to pass through the quadlock connector when hooking everything up, and are at risk of falling out. Those pins are much smaller than they look in the picture. I swallowed my pride and bought the $25 part.
![]()
I ran a 9-conductor 18ga cable from behind the head unit, behind the kick panel, under the door sill, and under the carpet to an opening under the passenger seat. It’s pretty easy to follow the stock wiring. I also ran an 18ga +12V wire from the driver-side fuse box across the dash, and grabbed ground from a point behind the passenger kick panel.
![]()
These all run into the line output converter under the seat. The LOC auto-senses the speaker-level signal to turn on, so it doesn’t need a remote wire. It supplies remote output for your amp. RCA cables carry front/rear/subwoofer channels under the carpet, down the door sill to the back, accompanied by a remote wire. I plan to add an equalizer once I figure out how to mount it next to the passenger seat.
![]()
You can’t run wires from the door sill directly to the side of the trunk because there are no openings in the sheet metal. The wires run under the rear seat to the area near the seat buckle, through the plastic trunk divider, and into the front of the trunk. I had to cut holes/slots in the plastic bar that crosses the front of the trunk.
![]()
![]()
Slots cut in the trunk divider bar
![]()
The front of the trunk is just right for the two amplifiers and wiring.
![]()
Another 9-conductor cable takes the output from the 4-channel amp down the driver side to under the driver seat. There, I connect to the Focal crossovers for the front woofer/tweeter, and tap into the stock speaker-wire harness. See below for my trick on how to tap into stock terminal connectors. The harness uses a 38-pin connector like this - http://forums.tdiclub.com/showthread.php?p=5013568#post5013568. However, they’ve changed the wiring. Using web references and a multi-meter, I figured out the Mk7 wiring.
Mk7 Fender amp harness pinout
1 red/green Vcc+
2 brown ground
3 brown/black front L woofer 2 (-)
4 brown subwoofer 1 (-)
5 brown/yellow subwoofer 2 (-)
6 brown red front R tweeter (-)
7 brown/white rear L (-)
8 brown/green rear R (-)
9 brown/purple front R woofer 1 (-)
10 brown/green front R woofer 2 (-)
11 brown/yellow front L tweeter (-)
12 red/yellow front L tweeter (+)
13 brown/silver front L woofer 1 (-)
14 red/silver front L woofer 1 (+)
15 red/black front L woofer 2 (+)
16 white subwoofer 1 (+)
17 white/yellow subwoofer 2 (+)
18 green/white front R tweeter (+)
19 red/white rear L (+)
20 blue/yellow rear R (+)
21 red/purple front R woofer 1 (+)
22 red/green front R woofer 2 (+)
23 - (not used)
24 -
25 -
27 -
28 -
29 -
30 -
31 green/yellow
32 brown/blue
33 blue/black
34 brown/black
35 -
36 -
37 -
38 light blue
Fender amp harness.
![]()
Focal crossovers wired to stock amp harness.
(I haven’t wired the rear speakers yet)
![]()
For power I ran 4ga cable from the battery as described above. Use a ring terminal on the battery terminal nut. You can’t remove that battery terminal nut, so you need to use a U terminal (or cut the ring terminal) and slide it onto the battery terminal. The wire goes under the rear seats, through a hole in the plastic trunk divider, and into a distribution block. Ground is tapped from the bolt on the middle LATCH anchor.
You have to recode the radio module to use the speaker-level outputs. Look here for details - https://www.golfmk7.com/forums/showthread.php?t=29694. Basically, you tell it to use the internal sound system.
REFERENCES
My forum thread for terminal connectors, pins, etc:
http://forums.vwvortex.com/showthre...onnectors-reference&p=112119721#post112119721
See this thread for detailed installation stereo upgrade instructions / pictures:
https://www.golfmk7.com/forums/showthread.php?t=38180
AutoInstruct has a bunch of tutorials:
- Sill panel removal - https://www.autoinstruct.com.au/manufacturer/volkswagen/mk7-golf/mk7-golf-sill-panel-trim-removal/
- head unit removal - https://www.autoinstruct.com.au/manufacturer/volkswagen/mk7-golf/mk7-golf-glovebox-headunit-removal/
- A-pillar trim removal - https://www.autoinstruct.com.au/manufacturer/volkswagen/mk7-golf/mk7-golf-a-pillar-trim-removal/
- front door card removal - https://www.autoinstruct.com.au/manufacturer/volkswagen/mk7-golf/mk7-front-door-trim-removal/
- run cable through firewall - https://www.autoinstruct.com.au/man...mk7-golf/running-cables-through-the-firewall/
SUBWOOFER
The stock Fender subwoofer is a paltry 6.5” driver in a plastic enclosure that sits within the spare tire’s wheel. Needless to say it is underpowered and lacking in clarity, even after being packed with polyfill. People smarter than I have done technical evaluation of waveforms and suggest that the Fender crossover settings overlap the cabin woofers and sub, using the door woofers to help the sub out. This is borne out by my gross and fickle hearing.
I shamelessly copied this excellent idea from hybrid88 - http://forums.vwvortex.com/showthread.php?9015697-Alltrack-Subwoofer-Install&highlight=subwoofer. An MDF subwoofer box made of 2 concentric hexagons, the smaller which fits within the spare tire wheel, and the larger which rests on top of the tire (it’s not bolted down). I could have made cylinders using a circle router jig, but that would have been too tedious. The hexagons were easy to make with a table saw set at 30deg. It all fits under the stock floor. I’m not much into ‘boom boom’, but the new sub delivers markedly improved clarity of base along with hitting the lower frequencies.
I built a custom trunk floor with a cutout for the speaker and slots for ventilation of the amps. It’s made of laminated ¼” MDF (total height ½”), covered with speaker box carpet. It hinges just like the stock floor.
- hexagonal 0.9ft3 box from MDF
- 12” Alpine driver
- Alpine MRV-M500 single-channel amp
- run signal from subwoofer cable in trunk to speaker-level inputs on the amp (don’t need line-out convertor or turn-on wire)
- wire from amp out to banana plugs on the subwoofer
- power from the battery, through the firewall near the pedals, up the driver side, under the rear seat, and into the front of the trunk.
The subwoofer box, unfinished.
The subwoofer box, finished.
I tapped into the existing subwoofer cable. The stock driver is dual-coil. White wires positive, brown wires negative, yellow marker indicates line 1. I only used one of the pairs of wires, since my sub is single coil.
Custom trunk floor.
After cutting and priming the MDF
Carpeted. It hinges like the stock floor.
Installed
(Unfortunately, VW built the spare tire off center, so the hole doesn’t line up)
FRONT SPEAKERS
The stock Fender cabin speakers are decent. However, the tweeters don’t have the clarity of higher end speakers, and the woofers both lack base and are muddy. I installed a set of Focal PS165 V1 separates.
The 6.5” woofer fits almost perfectly in the door. It’s just slightly wider than the door hole, so I made ½” spacers. There is plenty of depth behind the metal for larger speakers. There is also plenty of room between the speaker and the door card, if your driver is tall or you need a thicker spacer. I tapped straight into the speaker harness. The stock front woofer is dual-coil, so I only used 1 pair of wires. I may add sound-deadening later. I left the rear speakers stock.
I replaced the tweeters in the A-pillars. I cut the stock mounting posts and hot-glued the new tweeters in.
The Focals sound great. However, the stock Fender amp applies major crossover and EQ filtering, which screws up the aftermarket speakers. Tweeters are way too bright, and the woofers cross over way too low. Since I’m using the stock wiring, I couldn’t use the Focal crossovers. Which led to my next project . . . see below.
AFTERMARKET AMP (FENDER VERSION)
The stock amp filtering has some issues:
- Tweeters get too much volume. Even with treble set to -7, the Focal tweeters are too bright.
- Woofers cross over too low and are low amplitude. The woofers carry hardly any mid frequencies, and cross over very low to cover the wimpy stock subwoofer. I have to increase base at the head unit, but then the woofers boom from carrying subwoofer frequencies.
- Subwoofer is probably attenuated to protect the wimpy stock driver.
I decided to keep the stock head unit and add aftermarket equalizer and amplification. Here is the flow-chart.
- MIB2 speaker level output ->
-> AudioControl LC7i line output convertor ->
-> Clarion EQS746 7-band equalizer ->
-> Alpine MRV-F300 4-channel amplifier ->
-> stock speaker wire harness coming out of Fender amp
I could have run speaker wire directly from the head unit to the amp’s speaker-level inputs, but I wanted to add equalization. So, I had to put an LOC in between.
Unfortunately, swapping out the Fender amp is not as easy as just pulling it out and plugging into the head unit.
- The MIB2 head unit communicates with the Fender amp via a fiber optic (MOST) cable. No way to tap the signal between the two.
- The MIB2 head unit has the new QuadLock connector. Speaker-level output pins are on the head unit, but the QuadLock plug is missing the insert for those pins.
- If one wants to use the speaker-level outputs from the head unit, one has to recode using VCDS.
- If one wants to use the existing speaker wiring, one has to tap into the 38 pin Fender amp harness, which is under the driver seat.
- The front woofers and the subwoofer are dual coil. If the aftermarket speakers are single coil, one has to use a single pair of wires.
That being said, I’ve been able to solve all of these issues.
The MIB2 head unit uses a newer version of the QuadLock connector. See here for details - https://www.golfmk7.com/forums/showthread.php?t=29694. It’s missing the tan colored 8-pin speaker-level-out section. This is part# 3B7-035-447, $25 at the dealer or from ECS - https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/8-pin-connector/3b7035447/ . Mouser has a similar part, but is not in stock. Now, you could tap into the pins directly like q2quest did, but the wires have to pass through the quadlock connector when hooking everything up, and are at risk of falling out. Those pins are much smaller than they look in the picture. I swallowed my pride and bought the $25 part.
I ran a 9-conductor 18ga cable from behind the head unit, behind the kick panel, under the door sill, and under the carpet to an opening under the passenger seat. It’s pretty easy to follow the stock wiring. I also ran an 18ga +12V wire from the driver-side fuse box across the dash, and grabbed ground from a point behind the passenger kick panel.
These all run into the line output converter under the seat. The LOC auto-senses the speaker-level signal to turn on, so it doesn’t need a remote wire. It supplies remote output for your amp. RCA cables carry front/rear/subwoofer channels under the carpet, down the door sill to the back, accompanied by a remote wire. I plan to add an equalizer once I figure out how to mount it next to the passenger seat.
You can’t run wires from the door sill directly to the side of the trunk because there are no openings in the sheet metal. The wires run under the rear seat to the area near the seat buckle, through the plastic trunk divider, and into the front of the trunk. I had to cut holes/slots in the plastic bar that crosses the front of the trunk.
Slots cut in the trunk divider bar
The front of the trunk is just right for the two amplifiers and wiring.
Another 9-conductor cable takes the output from the 4-channel amp down the driver side to under the driver seat. There, I connect to the Focal crossovers for the front woofer/tweeter, and tap into the stock speaker-wire harness. See below for my trick on how to tap into stock terminal connectors. The harness uses a 38-pin connector like this - http://forums.tdiclub.com/showthread.php?p=5013568#post5013568. However, they’ve changed the wiring. Using web references and a multi-meter, I figured out the Mk7 wiring.
Mk7 Fender amp harness pinout
1 red/green Vcc+
2 brown ground
3 brown/black front L woofer 2 (-)
4 brown subwoofer 1 (-)
5 brown/yellow subwoofer 2 (-)
6 brown red front R tweeter (-)
7 brown/white rear L (-)
8 brown/green rear R (-)
9 brown/purple front R woofer 1 (-)
10 brown/green front R woofer 2 (-)
11 brown/yellow front L tweeter (-)
12 red/yellow front L tweeter (+)
13 brown/silver front L woofer 1 (-)
14 red/silver front L woofer 1 (+)
15 red/black front L woofer 2 (+)
16 white subwoofer 1 (+)
17 white/yellow subwoofer 2 (+)
18 green/white front R tweeter (+)
19 red/white rear L (+)
20 blue/yellow rear R (+)
21 red/purple front R woofer 1 (+)
22 red/green front R woofer 2 (+)
23 - (not used)
24 -
25 -
27 -
28 -
29 -
30 -
31 green/yellow
32 brown/blue
33 blue/black
34 brown/black
35 -
36 -
37 -
38 light blue
Fender amp harness.
Focal crossovers wired to stock amp harness.
(I haven’t wired the rear speakers yet)
For power I ran 4ga cable from the battery as described above. Use a ring terminal on the battery terminal nut. You can’t remove that battery terminal nut, so you need to use a U terminal (or cut the ring terminal) and slide it onto the battery terminal. The wire goes under the rear seats, through a hole in the plastic trunk divider, and into a distribution block. Ground is tapped from the bolt on the middle LATCH anchor.
You have to recode the radio module to use the speaker-level outputs. Look here for details - https://www.golfmk7.com/forums/showthread.php?t=29694. Basically, you tell it to use the internal sound system.
REFERENCES
My forum thread for terminal connectors, pins, etc:
http://forums.vwvortex.com/showthre...onnectors-reference&p=112119721#post112119721
See this thread for detailed installation stereo upgrade instructions / pictures:
https://www.golfmk7.com/forums/showthread.php?t=38180
AutoInstruct has a bunch of tutorials:
- Sill panel removal - https://www.autoinstruct.com.au/manufacturer/volkswagen/mk7-golf/mk7-golf-sill-panel-trim-removal/
- head unit removal - https://www.autoinstruct.com.au/manufacturer/volkswagen/mk7-golf/mk7-golf-glovebox-headunit-removal/
- A-pillar trim removal - https://www.autoinstruct.com.au/manufacturer/volkswagen/mk7-golf/mk7-golf-a-pillar-trim-removal/
- front door card removal - https://www.autoinstruct.com.au/manufacturer/volkswagen/mk7-golf/mk7-front-door-trim-removal/
- run cable through firewall - https://www.autoinstruct.com.au/man...mk7-golf/running-cables-through-the-firewall/
). This sheet is cross checked against the official wiring diagram that I wrote in my own way.
