Stangtime's simple yet satisfying stereo build.

[StangTime]

Well this has been a long time coming. I have built this system in stages over a long period of time. Some of you may have seen these pics before. I wanted to have all the info in one thread and will edit this post as I add more info. At the bottom of this post you will find attachments for some of the CAD drawings I created when I built this system. Feel free to use these and alter for your own system. This build is applicable to the 2018 and up S550 model 9 channel OEM system.

The plan was to build a great sounding, simple-yet-satisfying, system that wouldn't break the bank. The OEM system would be gutted beyond the head unit. Replace the fake 3-way OEM speaker system with a quality, 2-way speaker kit. Keeping it simple with a solid front sound stage, no rear speakers, no dash speaker, no upper door speakers. The head unit signals would run to the spare tire well. A DSP for EQ and time alignment would handle signal processing. The corrected audio signals will go to a 5-channel amp to power everything: The front stage and a removable single 10" subwoofer located behind the rear seats. Did I say it was simple?

Equipment list:
Front stage: Hertz MPK165P.3 Pro
Subwoofer: JL Audio HO110RG-W3v3
DSP: Hertz H8 DSP
Controller: Hertz DRC HE
Amplifier (5 channel): Hertz HCP 5D

Link to the system wiring diagram: 5-Channel System Wiring

First step: Used Forscan to flatten the output of the head unit so that there is no funky molestation of the audio signal. Note that Ford still applies a variable "loudness" contour to the volume level that gradually decreases as you turn the volume up from 0 to 15 on the dial.

Forscan code in APIM module:
727-01-02 00xx - First two digits set to 0. This disables any EQ Processing, bass roll-off etc. (tone controls will still function as normal)

Interfacing to the head unit:
I made a breakout box for audio signals and speaker wire returns. Completely plug-&-play using Molex sockets, no cutting of any factory wires. Got audio going to my DSP now. Yes, that is Cat6 cable you see for the signal wires. STP (shielded twisted pair) + Metra Speedwire. All wrapped in Tessa tape from beginning to end for a rattle free install. I painstakingly soldered crimp socket pins to all the wires. Slid heat-shrink on, and then inserted the pins onto the short pins of the connectors. Then soldered and shrunk the heat-shrink. The small black wire connects the shields of the signal lines to GND on the brown plug. The connectors all lock together.

I cut a long rectangular hole in a plastic project case and used strain reliefs for the cable exits. Filled the connector area with epoxy.

Then I contorted myself to get under the dash and pull the 9 channel OEM amp out. Removed the amp from the mounting plate and attached my break-out box with some self drilling screws.

Contortion #2 getting the plate mounted back under the dash and connected. Not easy being 6 feet tall and trying to work in this space.

For some deeper information you can rear my other thread here: Wiring guide for non b&o premium audio systems. No LOC required.

Battery Connection:
A KnuKonceptz 4AWG aluminum clad COPPER wire was run down the passenger side away from the audio signals. Fully wrapped in Tessa tape all the way.

4AWG Wire ferrules. Go on the end of the power wires. They protect the strands when you crank down on the terminal clamping screws. These are Uxcell part# E25-16

Disconnected and removed the battery and tray. Drilled a hole using a step drill just below the cabin air intake. This is the perfect spot as it puts the wire in a very accessible location just above the passenger carpet. The hole is drilled directly across from the threaded nut below the cabin air intake.

A PCV valve grommet sealed the hole and protects the wire. Some Butyl rubber around the wire to prevent water getting in. I may change this in the future to use a proper Nema 6 grade bushing. I routed the power wire to the left to avoid the waterfall spout on the right. The cowl rain tray dumps water into this area so I wanted to avoid it. I drooped the wire downward before going through the firewall so any water that gets on it would have a chance to drip off before the grommet.

I applied wire ferrules appropriate for 4AWG wire onto all ends of the power cable and re-installed the battery. The KnuKonceptz terminals work great with the ferrules. Some red heat-shink insulates the terminal. I flat-block sanded the clamp parts removing the black coating on the mating surfaces (very important) for good conduction. Attached the new terminal with the top clamp nut and trimmed the red rubber to fit over the new assembly.

Fuse holder installed (without the fuse!). It looks like a strange position but this was determined the best place after much humming and hawing. The power cable drops down under the negative lead down the side of the battery box.

Trimmed the battery cover a bit to clear the new power wire and fuse holder.

Next up: Speaker install and DSP controller.

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[StangTime]

All about the mid-bass:
My plan was to use Metra adapters for the door speakers but when I started measuring I discovered the Hertz 6.5" mid-bass drivers would be smacking against the door panels. So made my own from 1/2" PVC sheet.

Link to CAD drawing for the adapter ring: 6.5" Hertz spacer

Improved version for 3D printing. Includes drip shield protector.

3D CAD file ZIP download: 3D Printed Spacer Design

Assembled speaker with drip shield and cut up the OEM spacer to use the plug for easy interfacing to the door wiring.

Preparing the door cavity:
The doors on the Mustang are like huge tin cans and resonate badly. Sound deadening fixes that. I added Killmat to the outer metal trying to cover at least 75%.

More Killmat on the outer and directly behind the mid-bass driver cavity. I used the piece I cut out of the hole and applied it as an extra layer behind the driver.

Installed the driver and plugged it in.

Removed the 3.5" upper door driver. Kept the plastic mount and later I stuffed a closed cell foam disc into the hole to seal it and prevent sound from coming through door panel grille.

Added more deadener to the rest of the door panel and re-installed the vapor barrier.

Finally added my own DIY "Fast Ring" foam. This seals the door panel to the face of the mid-bass driver for better performance.

This foam ring caused a bit of a fitment problem with the door panel. FOr whatever reason, Ford did not make the door grille and the speakers concentric. So out comes the utility knife to do some trimming.

Before (passenger side):

After:

Tweeter install:
To replace the tweeters I removed the A-pillars. Getting them off wasn't hard, putting them back... well let's just say I filled up the swear jar. I'll discuss a different approach at the end.
The OEM tweeters were removed from their cradles and the connectors were cut from the magnets. Separation was done by clipping the leads and slowly separating the backplate from the magnet with a sharp knife working my way around. I wanted to re-use the connectors on my new tweeters so I could just plug and play. Epoxied the connector plate to the back of my new tweeters and soldered the wires to the terminals.

Then I cut the rear mounting posts off and used a Dremel sanding drum tool to gradually open the mounting hole until the tweeters fit through. I did this is small increments and kept trying to kit the tweeter after every pass with the Dremel ad I didn't want to end up with the hole too big. The fit is tight but not permanent.

The new tweeters in their new home. They can be pulled out with a trim removal tool and quickly unplugged if need be. Getting the A-Pillar installed was not something I ever want to do again.

Alternate method for tweeter replacement (2 person method):
So having learned a lesson, I helped another member replace his tweeters and we didn't remove the A-pillars from the dash. We simply pulled the top out away from the head liner and worked from the backside. Having someone hold the A-pillar away from the car while the other person works from the other side standing outside the car. The tweeter mounts can be carefully cut with a Dremel cut-off wheel and removed. Open the mounting hole carefully while sitting inside the car. Use the Dremel to open up the hole slowly and carefully while the other person holds a vacuum hose to collect the dust.

DSP Controller:
The Hertz DSP came with a little control unit for adjusting levels and switching DSP presets. I had initially installed it in the center under the toggle switches but here it was not the best. I had to reach around the stick shift to press the buttons so I ended up ordering a new panel and mounted it over the USB port.
Cut a hole for the wiring.

Cleared out some plastic with some careful Dremel work and a vacuum to contain the dust.

Controller mounted.

But if the car was in third gear it was difficult to use there. So I ordered a new center panel due to the previous hole I had put in it. On the new panel I notched the left side. Then purposefully covered the soon to be disabled USB port. Now the controller is in easy reach, no matter what gear I am in. There's a method to my madness...

Since I had now covered the USB port and was no longer able to use it I ordered this dual port for the armrest storage area: Dual USB module interface

Amp rack and subwoofer install is up next.

 

[StangTime]

The junk in the trunk:
All of the rear interior was removed and a liberal application of Killmat was applied. Two layers were applied to the wheel well area. Extra deadener was required because of the resonant nature of the well. A a single layer was applied to all other large sheet metal parts.

The grounding point:
A 6mm section of threaded rod and a knurled nut where used as a means to make the ground connection to the amp. Paint was removed with a wire wheel brush. The threads on the left will be used the hold the amp board down.

Measurements were made for the wheel well and drawn in CAD. With a partition for a small storage area at the rear for detailing supplies, battery cables or whatever. Amp board was made from 1/2" plywood with a beveled cut to match the contour of the sheet metal. Vertical supports added and a cutout for the tire inflator kit.
Link to amp rack CAD drawing: Amp Rack Board PDF

Test fitting the amp rack and grounding hardware. The ground bolt passes through the board. The bolt on the left is holding the amp rack down. It was too long, so later on I shortened it to not need the extra nut.

Covering the amp rack with carpet. 3M contact spray used here. The carpet was cut and wrapped over the edge and the excess was trimmed off.

Screwed the components to the rack. Put some old interconnects to good use.

Mounting the subwoofer:
I wanted to use a pre-made sub enclosure. Zenclosures would not ship to Canada. So I purchased a pre-made sub box. JL audio had one that was nearly perfect and it was highly regarded as an excellent sub, the HO110RG-W3v3. The problem with a box is how do you secure it? I'm not a fan of subwoofers banging around inside the trunk.

So I ended up using something I found by accident while looking for ideas online. A company in Australia makes these plastic locking connectors called Striplox. They are used primarily for locking furniture together or mounting things to the wall. I decided on the Striplox Clip 50 Connector
The small ones that I used can support around 200lbs each. I used a total of 4, fastened to the trunk floor where the sheet metal was flat and available under my sub box. Checked under the car for clearances. After a lot of planning, measuring, measuring and more measuring, I came up with an idea. Drew up the sub box in CAD.

Striplox bottoms "receivers" shown here with PVC spacers that I made so the box would clear the carpet and the wiring. The Striplox have a locking tab for permanent installation or optionally the tab can be removed for non-permanent installation.

I made a CAD template to center punch the locations. Then realized I needed to make an adjustment to my locations once in the car.

I then removed the sound deadening where the blocks would be mounted to ensure they would mount flat against the sheet metal. Then drilled holes through the sheet metal at the punch marks. 4mm Rivnuts were inserted and clenched through the floor. Then bolted the spacer/Striplox stacks to the floor with M4 flat head Grade 10.9 machine screws for added strength. Under the car, I covered the exposed Rivnuts with rubber boots and sealed them with silicone to protect from the elements. The amp rack was test fit to determine the finished wire lengths and was temporarily connected for system testing.

The removable trunk carpet panel over the spare tire well had to be slotted so the panel could be removed and installed without removing the subwoofer box. So I scored the back of the plastic trunk floor with a utility knife so it would hinge just in front of the sub box for ease of access to the amp and DSP and wiring. Making the floor hinge was also the only way to allow the panel to be taken out or put into the trunk as the sub was now in the way.

The bottom Striplox, called "receivers", open side face the rear seats. Carpet was cut out around the Striplox. The removable trunk carpet panel was test fit in place. With the sub out of the trunk, I still have a flat floor.

I used the CAD template again on the bottom of the HO110 sub box to line up the Striplox "cleats" that mate up with the Striplox "receivers". Pilot holes were drilled so the screws wouldn't go off mark. A total of 12 coarse thread #8 x 3/4" MDF screws were used.

The box is placed in the trunk and lined up on the Striplox. To lock the subwoofer in place, a little push from inside the car toward the rear. Folding up the rear seats locks in the sub preventing it from sliding in any direction. Attempting to move the sub forcibly rocks the whole car. It's not going anywhere.

Here, the power and subwoofer cables can be seen running under the box. The Striplox on top of the PVC spacer.

The amp rack is now back in the car after the Killmat was covered from the left-over carpet. Speaker wires and power terminations are completed. Wire ferrules used on all terminations. Fuse re-installed into the fuse block at the battery.

Connection for the subwoofer complete. The blue nylon braid sleeve is just for show on the exposed portion of the wire.

Finished up by securing all wiring and placing the tire inflator in it's new location. The little black box below the DSP is simply a voltage converter with a small delay that I made. It converts the 6V audio enable signal to 12V. Low voltage and audio signals are run on the left side and all power is on the right.

Sliding the hinging trunk floor forward under the sub box.

The finished look. (Please ignore the USB cable, I was doing some system tuning on the laptop.)

After using the stereo for some time I could hear the subwoofer was causing the parcel shelf to rattle and buzz against the rear window. You could literally see it flapping about. A sign that the sound pressure could not get from the trunk into the car easily. Putting the seats down, the parcel shelf would stop rattling. Audio measurements confirmed about a 3 to 5db loss in bass. I did not want to keep the seats down so I removed the parcel shelf. I bought a hollow punch set and used the 8mm size to punch out the thick carpet over the holes that were already in the panel. Removed the pathetic Ford speakers and zip tied the connectors in case I need to hook them up in the future. You can't see the holes when sitting in the car and due to the window tint they are difficult to see from outside the car. To prevent any movement of the parcel shelf, I stuffed foam blocks between the rear deck sheet metal and the rear of the shelf closest to the window. Easiest way was to go up through the speaker holes. This is a cheap and easy fix to allow the subwoofer (or rear speakers if you have them) to breath. I can feel the sub now, not just hear it. Definite improvement and the parcel shelf no longer moves.

I'm extremely pleased with how this all turned out and how good it sounds. The flexibility of having a DSP with time alignment and EQ for each speaker really allows you to make the system sound incredible. I have been tweaking the system ever since and it sounds better and better.

 

[Gnatsum21]

THANK YOU!

 

[Gfswindle]

Watching this thread. Your molex connector project box is outstanding. Mind telling where you got these plugs from? I currently have my dsr1 in place of the b&o Amp and I'd like to follow what you've done and place it on my Amp rack.

Edit - nvm I'm an idiot, of course my dsr interface harness had these connectors. But you've given me a great idea.

 

[Lifeownedme]

Nice. Subbed.

 

[Clintro]

Looks good!!!

I am getting ready to run wires in the a pillar, looks like I should just pull the top and snake instead of completely removing.

 

[Evolvd]

Looking good! A great small installation sounds much better than an ok large one.

 

[StangTime]

Updated with the final installment. See post #3

 

[Torinate]

That's awesome Todd!

Can't wait to hear it while i'm testing out steering wheel!!

 

[Socal Stangman]

I’ve been following your threads and like you I’m an audio guy. I just did an Alpine 9” Halo HU and I’m loving it. I really wanted to keep the system simple but I want to go HI Res so I’ll be gutting it all as well. I want to go back thru and read all this, what I’ve seen is very impressive. I do have a question though. Since you only did fronts, why only a 2 way set up? I’m sorry if you addressed this I didn’t read this whole thing yet.

 

[StangTime]

I’ve been following your threads and like you I’m an audio guy. I just did an Alpine 9” Halo HU and I’m loving it. I really wanted to keep the system simple but I want to go HI Res so I’ll be gutting it all as well. I want to go back thru and read all this, what I’ve seen is very impressive. I do have a question though. Since you only did fronts, why only a 2 way set up? I’m sorry if you addressed this I didn’t read this whole thing yet.

A couple of reasons why I went with a 2-way system. I did consider the 3-way Mille Pro setup but when measuring for driver fitment, I found out the midrange location in the door is not isolated from the main door cavity. The back pressure wave of the mid-bass will affect the midrange cone and cause distortion. I considered building a chamber for the midrange but there is simply no room due to the door design. So I looked for a midrange with a sealed back. There are not many of these on the market and those that exist were not a good fit.

A 3-way adds complexity and cost. I would have required a 7 channel amplifier or an additional 2 channel amplifier. The Mille Pro 3-way was also way overpriced compared to the 2-way.

The Hertz MP25.5 tweeter has a low fs (resonant frequency) it can have a crossover point as low as 2000hz. They blend very well with the MP165P.3 mid-bass which also prevents the mid-bass from beaming.

 

[Socal Stangman]

Ok cool. So then you are running these fully active then correct?

 

[demon67]

Incredible. Excellent work!!

 

[Cathul]

You don't have a PDF of the CAD drawings for the Striplox, right?

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