Ed's 1990 Porsche 928S4: Audio System
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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.
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)
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
Aufbau "surface mount spacers" to get the rear 6½" speakers to mount
- 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
- 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
- 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]
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
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