Modern Music in a 308

After a solid month of Hell I finally got the sound system installed in my 308. The bottom-of-the-line Blaupunckt and 5" coax speakers weren't cutting it, especially with the top off and the windows down.

Considering the amount of fabrication required and interference fit of every component installed I decided to do the job myself to minimize any permanent alteration of the car. It was my intention to try to preserve the originality of the car as much as possible while installing the most powerful, high fidelity system I could to counteract the inherent noise that comes with an open, mid-engined car. This is a vast improvement for those drives to and from Canada as well as other long distance cruises.

Note; These cars were NOT designed for a sound system. There is no room on the doors for decent sized speakers due to the small designated areas restricted by the existing window tracks and mechanisms. There is no room for an amplifier unless you mount it in the rear trunk behind the engine, (not an option). There is hardly enough room to run the additional power supply and speaker wiring required under the dash.

In summary; The entire operation is a battle against inadequate room while NOT hacking the car to bits to make more of it!.

The first step was building an airtight enclosure for the sub-woofer. I pulled the passeger foot plate out and dismounted the Thermocouple control units and Timers. I then remounted the units to the forward bulkhead.Note; none of these units are operational due to the absence of Cats and the raw fume recovery system.

Over the top of these units I installed foil-faced, rubber sound mat. From there I built sides and a top to form a tapered box in the space that is behind where the passenger foot plate mounts.
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The next step was to fabricate the replacement for the passenger foot plate out of 1/4" plate aluminum that would act as the sub-woofer mount.
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With the mounting plate painted black and more sound mat applied to the inside to seal it to all four sides I filled the enclosure with 20 ounces "polyfill" to slow the air down inside the enclosure to better simulate an enclosure larger than what it really is. This was done to match the enclosure size requirements of the sub-woofer.
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The next step was to cram the polyfill into the hole and mount the sub.
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On to the amp installation.
Borrowing the idea from another Fchatter I decided to mount the amp inside the spare wheel up front. The proximity to the battery and the rest of the sound system dictated the location. It was the most logical one and the ONLY one.

I bought the most powerful amp I could that would fit in a 13" circle. I made a circular mounting plate out of .10", 2024 T0 aluminum and rimmed the edge with 3/8" gas line to protect the paint on the wheel. I laid out the amp "footprint" and carpeted the rest, top and bottom. I then mounted the amp to the plate with three wide strips of velcro. Because of the tight fit I could not utilize the mounting brackets or holes on the amp. I actually had to remove 1/8" from each corner of the amp for clearance.

The entire unit lifts out allowing the spare and battery to be removed without disconnecting the amp.

Also note; The RCA cables (blue) from the head unit and the speaker wires from the amp (bronze) are sleeved in thick-wall poly tubing to prevent cross-talk and interference from the power supplies throughout the car.
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It took an hour to cut the hole in the dash for the new head unit. It would have been nice to have been able to use the original "three hole" system but the new decks slide in from the front through a rectangular hole. The dash is made out of fiberglass so if and when some one more anal than I wanted to put it back stock it can be glassed in and recovered.
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On to the doors.
I put a layer of foil-faced rubber sound mat on the inner door skins to dampen vibration.

The original speaker holes measured out at 4 7/8" diameter and were in a square recess precluding the possibility of placing a larger speaker in the recess. The door isn't deep enough and the forward window track was in the way as well.

The only option open to installing a 6 1/2" speaker was to mount it to the face of the inner door skin spanning most of the original speaker recess, the attach points being at the front, top and bottom with the aft hole floating over the recess. A 1/4" nylon spacer was installed under the "floater" to stabilize the flange.

The speaker hole itself was enlarged with a forward bias to accomodate the larger magnet and basket while at the same time barely missing the forward window track. ZERO room for error.

The speakers utilize a center wired tweeter for a total of four connections to each speaker requiring a crossover that is mounted in the bottom of each door.

The door panels have a return flange around the edges that create a hollow space between the inner door skin and the door panel that accomodate the speaker flanges with room to spare.
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Wanting to use the stock speaker grills became a challenge when I found that the protective cage over the tweeter of each speaker stuck out 1/4" past the plane of the grill.

I spaced the grills out away from the door panels with 1/4" nylon spacers and longer screws. Because the grills were originally recessed into the panels there was room to space them out and still remain nearly flush with the panels.
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So I fired everything up to test out the system after a month of labor. It sounded good at low volume but as soon as I tried to push any power the amp would kick off momentarily then back on. The higher the volume the more often it would kick off. Needless to say I was rather disappointed and perplexed. I was afraid I might have fried something during my numerous power hook-ups and reroutes.

I drove the car down to the place where I bought the system and started testing. He found that the sub-woofer only had 1 ohm of resistance instead of the rated 4 ohms. DEFECTIVE! Meaning I had to tear it back out and replace it. A two hour job (don't ask me why).

Because the sub was a discontinued item I was upgraded to a more powerful speaker. The visual difference was obvious. I was EXTREMELY lucky that it bolted right in without further modifications. The other was a tight fit as it was.

An improvement from what I could see. Lemonade from lemons.

The new sub had a glowing blue LED center too! WOW! (No I didn't hook it up). The new one is on the left.
The sub is covered by carpet now and it doesn't seem to dimish the sound at all. The grill over the front will take a pretty heavy foot. This I found out by accident.
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This was the car from HELL. There is absolutely NO ROOM FOR ANYTHING! It took me a month to do this job working on it nearly every day for at least 4 hours each day!

If someone were to ask me to do their 308/328 I would not do it for anything less than 3k! Never again!

On the flip side, with the help of the knowledgable guys at Bry's in Marysville (Miseryville) I got a set of well matched components that work at their optimum performance at well under the maximum potential. The sound is pretty impressive for the the limitations I was held to in system size.

Here are the specifications;

Alpine 9823 Head unit (Free for my B'day)
includes
Barcus Berry Electronics processor
Bass engine
Bass band width control
Sub-woofer level control
18w X 4 RMS (Primary amp rating)

Alpine F-240 Four channel amp
Channels 1 & 2 for the doors and channels 3 & 4 bridged to power the sub-woofer.
50w X 4 RMS - 360 watts MAX

Alpine SPR-174A, 6 1/2" coaxial speakers in the doors.
40 watts RMS- 160 watts peak

Phoenix Gold Octane-R10 Sub-woofer
250 watts RMS-500 watts peak
(optional blue LED )

In retrospect,
An 8" sub-woofer would have saved me a weeks worth of work.
I should have hooked up the blue LED in the sub-woofer

 

Bring your favorite CD!

 

.............a secret government thing. Can't really talk about it.............

 

Being too big for my car and running the seats all the way back nixed the idea of amps behind the seats. It's a challenge just getting the top back there.

I am a little concerned about the heat up front but? Not many choices.

 

The foam was going to be the next part of the project so I went to Home Depot to pick some up and they didn't carry what I described. Numerous people have gotten theirs at Home Depot but it must be from the stores in warmer climates that carry it for home A/C installations.

I am not running that much power so I don't imagine I will be heating things up that much or straining the alternator, at least not as much amperage draw as running two cooling fans.

 

Wow, you must have some flat units. I can hardly get my hands under my seats, much less if someone were sitting in one.

I thought about amps behind the seats but I have other "junk" that I stick back there like a towel for wipe downs, a jacket, camera, 2.5 lb Halon extinguisher, FSR radio and sometimes a snack or two. In addition to that, a CD case.

 

Aaahhh. I just realized a difference in how I store my top. I can see where there would be room for an amp on the aft wall if the top is stored per the book with the outer surface of the top facing forward leaving a hollow between the top and the aft wall.

I store my top with the outer surface facing aft against the wall leaving a "cupped area behind the seats for more "junk".