tirwin's stereo/amp project

[tirwin]

This project comes straight from the "I just can't leave well enough alone" department.

It all started with this problem, which is painfully documented here:

Frustrated... fuel pump circuit. Help.

Don't bother reading all of that. I will spare you. Faulty factory alarm module was the source of the mystery ground that kept the fuel pump from running.

At the time, I fixed the issue by finding the wire connecting to pin 85 of the FP relay and disconnecting it. But I never knew for sure what was causing the mystery ground.

Well, that continued to bother me. So like a moth is attracted to a flame, I had to find out. I finally found the time to remove the fresh air blower plenum to access the alarm module. I traced the wire out and proved once and for all it was indeed a faulty alarm module. Alarm module was bypassed. Problem solved for good.

But with that fresh air plenum out of the way, all of a sudden the temptation was there to re-wire the stereo amp and relocate the subwoofer.

I guess it was around 2012 or 2013 that I re-did the interior and installed the stereo system.

The way I originally solved this problem was to use a piece of 1/2" MDF as a mounting surface for the amp and crossovers. I attached this to the fresh air blower cover by drilling holes through the supports and using some long carriage bolts with nylon spacers, washers and wing nuts.




The idea here was that I could just spin off the wing nuts to remove the mounting board if I ever need to access the area behind the dash or the smuggler's box. I left plenty of slack in the wiring so it did work, however it was still annoying because I couldn't take it out of the car to get it completely out of the way.

But it looked pretty clean and was it was functional.

Another drawback was where to put the sub. I had it mounted in the back seat, but I didn't really like it there. It got it in the way and it didn't look very clean.

Finally, there was one more important consideration. Since time immemorial, there has been a debate between good sound and weight savings.

If someone says you must choose between a Belgium dubel or German pilsner, what do you say?

Well, I decided to do what any rational person would do. Choose both!

[tirwin]

The amplifier, subwoofer and the mounting board are the primary contributors to additional weight.

I decided that I wanted to achieve a couple of things:

1) relocate the weight to better distribute it

2) design it such that it could be completely removed for track days and service

I kept thinking about where I could place the components and how I could secure things. I started searching the Pelican archives for inspiration.

Lo and behold, I came across this old thread by imcarthur.

Car Stereo Installation

He placed his amps in the nose of the car. Great idea!

Post #11 had the inspiration I needed. Brilliant solution.

He used a carriage bolt secured to the spare tire to mount the amp board.



The only flaw I could find in his thinking was he used SAE hardware that meant he had to keep keep a SAE wrench/spanner in the car at all time. That clearly won't do in a German car.

So I visited my local fastener store -- Threads for the South (great place!) and acquired an M12x80mm bolt, nuts and washers.

I found one of these on Amazon so I can just spin it off by hand. No tools required. Just insert the M12 nut in the plastic housing and voila!



FYI... if 9 more people are interested in this idea, you can send me $1 plus shipping costs and you can have your very own.

[tirwin]

M12x80 bolt installed on the spare tire.

[tirwin]

Sometimes when you go to tackle something like this, you really can't underestimate the need to prototype an idea.

I started with some cardboard and a made prototype pattern that I *thought* would work, but didn't.

The first issue I ran into was that my flexible cardboard prototype -- I'll call it Mark I because that's what Tony Stark does -- seemed to fit.

But when I built it out of 3/4" birch plywood, I ran into an interference on the left side. The angle of the spare tire is different than the angle of the nose. The cardboard was flexible enough that it appeared to work but obviously it didn't work. Next time I think I'll make my prototype out of 1/4" MDF or similar.

I'll call this piece Mark II. Why Mark II? Because II is 1 more than I. I know. You are simply in awe of my prowess.

Mark II suffered from various unforeseen issues. Here is a pic of the first attempt.


1) I covered it in some black auto carpet I had left over from another project. After piddling around with Mark II for a few days, I realized the carpet was going to hold dust and dirt so I decided I didn't like it.

2) I was going to have to make a cut on the left side to clear the side wall of the trunk. The angle of the proposed cut is shown here with tape.



3) When I placed the amp on the board, I didn't think about the 45º angle that the 4 AWG power and ground wires use. I was concerned about vibration and movement loosening these wires over time and I also didn't like the strain placed on the wires with no good way to secure them. I thought about cutting a notch in the board and using some strain relief molding but it didn't seem like a good solution either.



4) The amp board was sitting too high into the trunk which meant it was going to take up more of what little useful space there is in the trunk. I know it's not a terribly useful area but I just didn't like it.

5) As you can see in the picture above, I was attempting to route some of the wiring through the board to keep it clean. This wasn't going to work. The curves are too tight and the combination of techflex and shrink tubing limits the flexibility further. Plus I would've had to offset the board off the tire or the wires underneath the board would rub. Too much hassle. KISS - Keep It Simple, Stupid!

For all these reasons, I went back to the drawing board.

[tirwin]

This is the beginning of Mark III.

I decided to go with a wider and shorter design this time. 16" tall and 20" wide. No carpeting. Just paint it black. Keep all wiring on the front surface.

I think I forgot to mention why I ended up with 3/4" birch plywood. First, the MDF I had used previously was not holding up well to moisture. It had started expanding and generally looking like crap.

The birch plywood is actually lighter than the MDF and it seems to be a popular choice among car stereo installers. The only thing that would be better is PVC. It is expensive in comparison and I don't really have all the router bits to really do it right.



I used a rattle can paint top to mark the curves for the corners. Then I cut them with a jigsaw and sanded it all. The edges are sanded with a chamfer so there are no sharp corners.

Final sanding with 320 grit on the orbital. It looked so good I almost hated to paint it.

[tirwin]

I placed the Mark III version in the car for a test fit.

First task was to mark the location for the mounting hole and drill it.

Then I just loosely placed the components on the board to test the layout.



You may have noticed I'm using a quick disconnect for the power and ground. (and for the other connections too. more on that later.)

Here's a link to the disconnects on Amazon.

https://www.amazon.com/gp/product/B01KHQR0K4/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

You crimp the supplied ends onto 4AWG wire and then insert the crimped ends into the connector until they click in place. This would have been A LOT easier with a hydraulic crimper but I don't have one of those so I just had to crab up on it.



These are rated up to 175A which is plenty. The amp is fused as 2 x 30A for a total of 60A.

These also come with plugs for capping off the ends when not in use.

[tirwin]

A few coats of rattle can flat black...

I was initially worried about the paint quality because the humidity was up, but it turned out ok. Ideally, I would've waited until the weather was cooperating but I don't have a lot of time to work on the car these days, so I decided to push ahead.

[tirwin]

Cross-overs and amp secured to the Mark III board.



I used 1/2" nylon wire fasteners to secure the 4 AWG power and ground wire. I also put a couple of washers between quick disconnect and the board so it would have less interference when connecting.

I also added some simple black cabinet handles on each side of the amp. With the weight of the amp being off-center it was a little awkward to pick it up by the edges. With the handles on either side of the amp, it is easier to pick up because you're picking it up where the weight is located. It just makes it easier to position the hole over the carriage bolt.

[tirwin]

One key that I forgot to mention was my apparent wisdom (quite the rarity I'm afraid) of keeping plenty of length in the speaker wires and RCAs.

Thankfully, I had enough length to reach the front of the trunk so it wasn't necessary to re-run any of the wiring. I had already run 12 gauge speaker wire back in '12 or '13.

When I originally did the wiring I used the plastic tubing. At first it was ok but over time it looked cheap.

This time I decided to wrap all the wiring with a product called techflex.

Link to more info:

https://www.techflex.com

It comes in a variety of colors and sizes. It's readily available from Amazon.

I wrapped each speaker wire in 1/4" techflex and 1/8" for the remote wire. I used 1/2" on the 4 AWG power and ground wires.



I then wrapped the individual wires and the RCA cables in 3/4" tech flex split loom.

In order to make the wires between the cross-overs, speakers and sub where they could be easily disconnected I used these quick disconnect wire ends. Also available from Amazon.

MCIGICM 10 Pair XT60H (XT60 Upgrade) Male Female Bullet Connectors Power Plugs (10 Pair)



These require soldering so I had to break out the old soldering iron. I also used the wife's label maker and some clear shrink wrap.



Finished product - 4 speaker channels + 1 sub channel + remote lead.

[tirwin]

Working with the techflex can be a little tricky at first. When you cut it, it has a real tendency to fray. Some people suggest using a hot knife or heating a razor knife with a propane torch. You're basically cutting and melting/sealing the ends at once.

I found it's just as easy to cut and then use a grill lighter to quickly melt the ends.

One resource that I found super helpful was the Car Audio Fabrication channel on YouTube. This guy does really nice videos and includes a lot of great tips.

Here's the one he did on techflex.

[tirwin]

By this point, you're probably wondering about the details of my system. I'm really happy with the amp and components. The sub is meh. More on that later.

Here's a diagram of the wiring and the components for those of you who are interested. Big shout out to Pelican nineball. He helped me pick this out years ago. I haven't seen him around in a long time. Maybe he's still out there.



I'm super happy with the Hybrid Audio speakers. They are probably the best sounding speakers I've ever heard. The Alpine amp has a good SN ratio also so the sound is really clean.

[rennch]

Very nice looking install dude! (and don't listen to the inevitable "My music is in the engine compartment" goofballs.)

[tirwin]

That's it for now. I hope to get back to it tonight and make some more progress.

Stay tuned for more updates.

Things still on the to-do list:

1) clean up the wiring on the battery + and -
2) make the + and - 4 AWG wires from the battery to the disconnect
3) make (4) wires from the amp outputs to the crossover inputs - DONE
4) make (4) wires from the crossover outputs to the speakers with male quick disconnects
5) make (1) wire from the amp sub output to the sub with a male quick disconnect - DONE
6) make the remote wire from the AMP to the head unit with a male quick disconnect
7) set the high and low pass filters, crossover points and tune the amp gains

[tirwin]

Originally Posted by emptyo

Very nice looking install dude! (and don't listen to the inevitable "My music is in the engine compartment" goofballs.)

Thanks. I like to think I have the best of both worlds with this solution.

First, my exhaust is LOUD. Like 85-90 dB range. I have to wear earplugs on long road trips. I can crank this stereo up and have a great clean sound over the roar of the flat six.

And the best part is if I want to take the car to the track, I can take the whole thing out in just a few minutes. No weight. No fuss, no muss.

[ian c2]

Nice work tim

[Rawknees'Turbo]

Originally Posted by emptyo

Very nice looking install dude! (and don't listen to the inevitable "My music is in the engine compartment" goofballs.)

The people that say that likely don't put even 1K miles on their 911s per year. Listening to only exhaust, engine, wind and road noise (plus the roaring a/c blower fan, if one has a meatlocker system, like me ) gets old when the car is actually used on a regular basis, for transportation (the horror, I know! ).

Now all you need to complete your system is some appropriate tuneage, Tim - Slipknot, Rage of Light, Arch Enemy, Nightwish, The Agonist, etc, comes to mind! Let me know if I can be of further ASSistance, bro!

[rattlsnak]

Originally Posted by emptyo

Very nice looking install dude! (and don't listen to the inevitable "My music is in the engine compartment" goofballs.)

Probably would have been a heck of a lot quicker to cut a hole in your muffler! lol..

[tirwin]

Originally Posted by ian c2

Nice work tim

Thank you, sir

[tirwin]

Originally Posted by Rawknees'Turbo

The people that say that likely don't put even 1K miles on their 911s per year. Listening to only exhaust, engine, wind and road noise (plus the roaring a/c blower fan, if one has a meatlocker system, like me ) gets old when the car is actually used on a regular basis, for transportation (the horror, I know! ).

Originally Posted by Rawknees'Turbo

Now all you need to complete your system is some appropriate tuneage, Tim - Slipknot, Rage of Light, Arch Enemy, Nightwish, The Agonist, etc, comes to mind! Let me know if I can be of further ASSistance, bro!

I have to confess I only know Slipknot off that list. I was into metal back in high school. There are pictures somewhere.

Your series of videos of the ladies drumming is very nice though. Enjoyed those a lot.

This guy from TexASS is a little more my speed.

[tirwin]

Made a little progress last night.

I used wire ferrules and a crimp tool to make the connections for the push-down connectors on the crossovers and the amp outputs. Color-coded shrink tubing for + and -.



The Alpine amp uses these strange connections. You insert the wires into the housing and then there is a 1.5mm allen on each side that cranks down and tightens the wire ends in place. I've always thought the diagram on the amp leaves a lot to be desired. The connector is not keyed so it's easy to accidentally swap + and -. The connector plugs in vertically and the + and - symbols above each connection point on the amp reads left to right. Brilliant! No opportunity for error there.



Finished all the amp output wires. Wrapped each wire in tech flex. Zip-tied the bundle in place temporarily while work on the rest. I'll tidy up the whole thing once I finish the output wires and the lead for the remote.