Ed's 1990 Porsche 928S4: Audio System Upgrade

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November 1999

As I just finished upgrading the audio system on the car, I figured it was time for some more pictures.  I plan on providing appropriate annotations and/or commentary for these pictures in the near future.

Actually, there's still one thing to do (as of 01-Dec-1999): installing a couple of fans to keep the amp cool.  The raised deck has holes for them, but I haven't installed them yet.

Audio System Upgrade Information

This is just a quick-and-dirty summary of information about my recent audio system upgrade.  I don't have time to do anything better right now (01-Dec-1999), but plan to within the next week or two.

Installed Equipment

Clarion DRX9575Rz head unit (out of production; replaced by DRX9675z)	Clarion DEH7500z eq/DSP/crossover	Clarion CDC1255z 12-disc CD changer
Rockford Fosgate Punch 600a5 amp (out of production; replaced by Punch 600.5)	Lightning Audio Strike LS10TB 1F power capacitor	JL Audio 10W3-D2 subwoofer
MB Quart Referenz Premium PSC 210 component speakers for the front	MB Quart Referenz Premium PSC 316 component speakers for the rear	extra set of QM 160.78 Aufbau "surface mount spacers" to get the rear 6½" speakers to mount properly

Notable Features

• has raised three-piece rear deck to hide the sub, eq/DSP/crossover, amp, power cap (goal was to hide equipment where possible, not to show it, for both security and aesthetic reasons)
• subwoofer is mounted in custom wood and fiberglass enclosure inside the spare tire wheel; spare tire still present!
• raised rear deck and subwoofer are easily removed in less than five minutes for access to spare tire and battery
• tools are still easily accessible without having to remove rear deck (just lift and remove a narrow strip between the tool panel and the large left and right sides of the raised deck; this allows the tool panel to be accessed and removed)
• fans (not yet installed as of 01-Dec-1999) keep amp cool

Some General Notes and Observations

• The DRX9575Rz head unit may be a bit of a stylistic mismatch for the car (not exactly Teutonic, but not nearly as bad as some of the ridiculous units I've seen that throw a bunch of totally meaningless animation at you). I find it to be a very good unit, though, and find it to be very good ergonomically. Feature-wise (especially when combined with the DEH7500z eq/DSP/crossover), it's great.
• I didn't go to any great effort to make the hidden stuff pretty. The amp, eq/DSP/crossover, rear crossovers, power cap installation on the ½" MDF board on the right side of the hatch isn't exactly a work of art. Then again, who ever sees it?
• Speaker installation was tough, as every one of the MB Quart speakers had mounting holes in different locations than the OEM speakers, the tweeter grilles were much smaller than the OEMs, and the rear OEM 6½" speakers have very odd-shaped integrated rings that need to be used with the replacement speakers.  I plan on going into more detail on how to deal with all of this at a future date.  For now, I'll just hit a few high points. First, the MB Quart tweeter mounts and grilles are much smaller than the OEM ones. Since I didn't want to rebuild the door panels, I decided to cut holes in the OEM grilles and mount the MB Quarts in those holes. It worked and actually looks pretty slick. Cutting holes in the grilles wasn't easy. Don't try to use a hole saw like I did the first time; drill a hole and use a nibbling tool to expand it or use an appropriate size sheet metal hole punch if you can find/afford one. The other big problem was the rear 6½" speakers. As many others have done, I separated the OEM speakers from their integrated mounts using a Dremel (and appropriate cutting tool). Then put two "surface mount spacers" (with about 1/8" of the inside of the first one trimmed away with the Dremel so it overlaps the OEM ring by about 1/8") on top of the OEM ring, and finally a flush mount ring on top of that. Sounds clunky, but worked out pretty nicely (see the pictures for proof and a nice side view that shows the whole assembly).
• I came up with a rather clever (I thought) way to mount the front MB Quart 2-way crossovers in the door panels using the same mounting posts the OEM crossovers used. See the pictures for the details. If I remember correctly, those are 1½" flat corner braces and otherwise unused MB Quart clip nuts into which the crossovers eventually screwed.
• The rear MB Quart 3-way crossovers are too large to fit behind/under the rear 6½" speakers where I had hoped they'd fit, so they went under the rear deck with the amp and other big gear. Too bad, since this messed up my original plans to use the original speaker wiring and connectors. I wound up having to run separate wires from each component speaker to the rear crossovers.
• In case you're looking for it in the pictures and can't find it, the DRX9575Rz eq/DSP/crossover is mostly hidden because it's mounted under the rear MB Quart 3-way crossovers. Look carefully and you'll see part of it sticking out under where the wires attach to the crossovers.
• Fishing wire from the front of the car (head unit and front speakers) to the back where the amp and other equipment was mounted was a bitch (maybe I would have fared better had I figured out how to remove the rear interior panel).
• So far, I'm very pleased with the results. The bass is well balanced; I'm not into bass thumping, but rather true, flat response, a good quality 10" sub is just fine for my needs. The JL Audio 10W3 is made for a small enclosure and is well suited for the tire well application. The MB Quart PSC tweeters are phenomenal; cymbal crashes and such are incredibly lifelike.
• One thing really surprised me: for awhile, I was running the new front speakers (MB Quart PSC 210 components) using the OEM crossovers. When I finally got around to replacing the front crossovers with the proper MB Quart crossovers, the improvement was dramatic. I'm not quite sure why this is and didn't really think about it too much, but it really made me happy that the MB Quarts came with high quality crossovers.
• I'm a little disappointed in the Clarion DEH7500z eq/DSP.  It's kind of cool, feature-wise, but the DSP soundfield stuff (where you select different soundfields like Hall, JazzClub, Disco (ugh!), Dome, etc.) isn't really very good. I've found that I actually prefer leaving this DSP feature *off*. Maybe I just got spoiled on our home surround receivers (we've got a couple of Yamaha RX-V2095 home theater receivers driving two separate audio/video systems at home). Yamaha really does DSP right. I guess I could have tried to mount an RX-V2095 in the shark somehow...
• I've gathered some Clarion manuals, guides, and catalogs
• Rockford Fosgate Punch 600a5 Manual [PDF]

Pictures

A bunch of these pictures are really more related to the details of door panel removal than the audio system, but as I've had my door panels off a few times over the last couple of months for various reasons, I figured it was worth documenting.

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