924/944/968 Frequently Asked Questions

924/944/968 Stereo FAQ

The following FAQ was created by Walter Spector, and was last updated 19 March 1999.

Most of the following information has been gleaned from personal experience in my '86 944. Additional information on differing models and features would be most appreciated. Please send additions and corrections to wws@sgi.com.

Factory Options

924, 83-85/1 944

The factory provided a location for a DIN-sized head unit in the center console. There is a center dash speaker location for use with mono radios. Cars delivered with stereo radios typically had a pair of speakers installed in the quarter panels on either side of the rear seat.

Morgan (ref 7) lists the following options available (few M codes – can anyone help clarify?):

Jan 1976

June 1976

Aug 1979 (924 Turbo)

Feb 1981

Starting in 1983 all cars were delivered with 4 speakers: a 4x6" speaker in each door, and a 4x6" speaker in each rear quarter panel on either side of the rear seat. An external fader control was located in the console for front/rear balance.

1983

85/2 944 onwards (4 speaker system)

There is space for a DIN-sized stereo with provisions for a small equalizer in the center console. As with the earlier cars, each door has a 4x6" speaker and there are a pair of 4x6" speakers in the rear quarters. An external fader control was provided for speaker balance.

The electronics and speakers were typically Blaupunkt. A typical U.S. 944 came with a Blaupunkt Monterey SQR 23 radio with cassette. The two front 4x6" speakers were Blaupunkt "whizzer cone" speakers and the rear speakers were 4x6" Blaupunkt coaxial speakers. An in-glass windshield active antenna replaced the fender-mounted antenna of prior years. This antenna system incorporates a Fuba preamplifier, located under the dash.

1985/2, 86

1987

1988

1989

1990

1991

In some post-'87 cars, the rear 4x6" speakers are mounted to an adapter plate. Removal of this adapter plate allows a 6 1/2" speaker to be mounted.

85/2 944 onwards (M490 10 speaker system, M493 8-speaker system)

This system consists of a better quality head unit with an equalizer/booster in dash. Each door contains 3 speakers - a 5-1/2" woofer and a 4" midrange mounted under the armrest with a small tweeter mounted above the power window controls. Each rear quarter contains 2 speakers - a 6 1/2" woofer and a nn" midrange.

1985/2, 1986

1987

1988

1989

1990

1991

The M493 option for the cabriolet was similar to the M490 option, but with 8 speakers rather than 10.

968

The car came with a six-speaker sound system. Dashboard layout and speaker locations are similar to the 85/2 and later 944.

Morgan (ref 7) lists the following options and chronology:

1992

1993

1994

Notes on Factory head units

AM/FM/Cassette - 2 audio channels

AM/FM/Cassette - 4 audio channels

AM/FM/CD - 4 audio channels

(Note to readers: Please help me complete the above table and the following descriptions!)

Blaupunkt Monterey SQR 23 (U.S. 944 '85 to '86)

The Monterey is a digitally tuned AM/FM stereo radio with a built-in cassette player. (The AM section also supports the European 'long wave' band. However LW is not used for broadcasting in the Americas.) The cassette player supports Dolby B encoded tapes.

The two built-in power amplifiers in the Monterey are rated at 9-10 watts output (RMS) each - at unspecified distortion - into a 2 ohm load.

Repairing the pushbuttons:

- Use chewing gum foil (add Al's email here...)

Blaupunkt Lexington SQR 45 (U.S. 944 with M490 10 speaker option)

The Lexington is a digitally tuned AM/FM stereo with built-in cassette player. The cassette player supports Dolby B encoded tapes.

There are four power amplifiers, however only the front two are used. The speaker level outputs are connected to a graphic equalizer located below the head unit.

Porsche CR-1 stereo

(How to key in the security code.)

Graphic equalizer/boosters (M490, M493)

A graphic equalizer/power booster is provided with the high-end 10-speaker systems. This is either a Blaupunkt BEA-80 or BEA-108. The equalizer/booster takes it's input from the two front channel speaker outputs of the head unit (the head unit's rear channel outputs are not used). The unit then contains four power amplifiers to drive each of the four speaker positions. So front/rear balance is controlled at the equalizer, rather than using the head unit or a separate fader control.

Note that the interface between the head unit and equalizer is at speaker level. Distortion is introduced due to extra amplification stages, compared to a quality aftermarket head unit using low-level interfacing to an equalizer. To mitigate this distortion, attention to setting the gain levels of the equalizer and the head unit is important.

(What is the difference between a BEA-80 and BEA-108? I presume 8 equalization bands vs. 10 bands? What are the per channel power ratings of these units?)

 

Stereo Replacement Tips

Radio removal

Blaupunkt radios can be pulled from the dash with a pair of U-shaped wire tools that fit into the small holes in the corners of the unit. Though most any car audio store will have these tools, they can also be fashioned from a bit of coat hanger wire.

Power connectors

The wiring diagram in the Haynes 944 manual is nearly useless. A better idea is to go to your dealer or a shop that has the factory service manuals and photocopy the pages for your exact car. Public libraries often carry the Mitchell's auto repair manuals. These are also a good source of accurate schematics.

Crutchfield (http://www.crutchfield.com) can provide adapter harnesses to avoid the need to cut up your wiring.

The six-pin connector commonly used in mid-80s has two large pins and four smaller ones:

A second set of power connectors are provided for the optional equalizer/amplifier:

Fader Control

A console-mounted front/rear fader control was provided with two-channel stereos. Since most quality stereos now have four audio channels with built-in fader controls the external fader control is not usually needed. Unplug the fader from the speaker wires, and then plug the new stereo straight into the speaker wires using 2-pin DIN sockets. If you remove the fader control, you can obtain a blank filler from Porsche - part number ###-###-### (85/2 and later cars).

Speaker connectors

Porsche uses 2-pin DIN plugs for the speaker wires. Most new stereos will only supply pigtails (wire with no connector) for connection to the speaker wires. To avoid cutting up the OEM plugs, buy a few DIN sockets and solder the pigtails to the sockets. Then just plug the new stereo straight into the wiring harness.

One source of 2-pin DIN sockets is Metra - who make a variety of car stereo interfacing products. The Metra 70-1693 contains a pair of 2-pin DIN sockets. If your new stereo has 4 audio channels, and you are bypassing the OEM fader control (or equalizer), you would need two of these Metra adapters. The Metra DIN sockets are stocked or can be ordered by most car stereo shops.

A few other sources of 2-pin DIN plugs and sockets:

The schematic in the Haynes manual for speaker wires is incorrect for later cars. The color codes used for the various speakers are:

Equalizer

The space below the stereo is used for an equalizer/booster in the M490 option. While it appears to be DIN sized, there are screws on the lower corners and inner clearance problems which prevent a full-height DIN-sized equalizer from fitting. So a half-height equalizer with some sort of cover plate below it (or around) it is probably your best bet.

CD Changers

To my knowledge, the factory has never supplied external CD changers for the 924/944 series. So custom mounting will be necessary. The most common location to mount a changer is in one of the rear cargo cubbies. Some 6-CD changers are small enough that they can actually fit in the front glove compartment.

(The 968 did have a CD changer option. Was it mounted in the rear cubbies?)

Power Amplifiers

To my knowledge, the factory has never supplied external power amplifiers for the 924/944 series. So custom mounting will be necessary. The most common location to mount external amplifiers is in one of the rear cargo cubbies. Other possible locations include the spare tire well, under the passenger seat, under the floor board (next to the DME), and under the dash. Not much room in these latter locations...

Fuse box access (85/2 944 on, 968)

Access to the underside of the fuse box for wiring in new circuits:

1.) DISCONNECT THE BATTERY, BOTH TERMINALS!

2.) Remove the fuse block cover.

3.) Loosen the two black thumb/screws.

4.) Using the thumb/screws, lift the fuse block.

5.) Slide the center lock (a black handle in the center of

the longer dimension of the fuse block) so that the connectors

can be pulled out.

 

Speaker Replacement Tips

Door Speakers (4 speaker systems)

The doors are usually provided with 4x6" oval cutouts with "European metric" style mounting. The factory 4x6 speakers are Blaupunkt full-range "whizzer-cone" speakers with a paper cone and foam surround. There is a rubber shield protecting the rear of the speaker from moisture. The paper cones on these speakers are very soft, so break up easily at high volumes. The foam surrounds provide very little excursion, which also contributes to poor sound at volume. The Xmax (maximum linear excursion) of these speakers must be very small. Also the foam surrounds become brittle with age and crack - further contributing to poor sound.

All cars, except the cabriolet, have a steel window track passing directly behind the door speaker area. This causes a serious restriction in available speaker depth. With the usual flat "waffle" style speaker grille (part number 477-867-081), this limits the depth available for replacement speakers to about 1-5/8".

Cabriolet owners are lucky - the smaller window allows the full depth of the door for speakers! I have heard of custom installs where 6.5" speakers have been installed. This obviously requires some trimming of metal and upholstery by the installer.

A second style of 4x6 mounting was used in some later cars. This is a two-piece assembly consisting of a thick plastic frame and a snap-on grille. The grille area is made of metal with a plastic surround. Using this grille, it is possible to mount speakers as deep as about 2". For example, an Audax VE4X6F0 mid/woofer, which is 52 mm deep, barely fits.

The parts list for the later grille assembly is:

944-555-149-00-01C Grille (2 needed)

944-555-159-00 Frame (2 needed)

477-035-375 Bushing (8 needed)

043-938-3 3.9x22 lens-head sheet metal screw (8 needed)

011-522-7 Washer (8 needed)

Note that the bushings are important to space the frame out far enough from the door panel to allow the grilles to snap on. Also note that the replacement speakers MUST be the European oval shape – not rectangular. The replacement speakers must also have a thin steel mounting frame like the OEM speaker - not a thick plastic one.

The least expensive approach to mounting a deeper 4x6" speaker may be to make a simple spacer out of, say, 1/2" MDF and use the flat waffle grilles. Spacing the speaker much further out than this is not possible as part of the grille is covered by the dash when the door is closed. (924 and early 944 have more clearance than later 944 and 968.)

If you are installing coaxial speakers, also make sure the tweeter does not protrude too far. For example, certain Infinity speakers have this problem. The JBL GTO-462d does not.

Last, many people have replaced the oval 4x6" speakers with ‘4x6 plate’ or round coaxial speakers. All other things being equal, which they aren’t, a 4x6 woofer should be more efficient at producing bass than a smaller round speaker. So if you do not plan to use a subwoofer, you may wish to stay with the oval form factor.

 

Door Speakers (10 speaker systems)

The ten-speaker system includes three speakers in each door. Two of these speakers, a 5 1/4" woofer and a 3 1/2" midrange, are mounted under the armrest. A small tweeter (1 5/8", 3/4" deep) is mounted higher in the door. These speakers are connected to a 3-way crossover network, which is also located in the door.

(How deep can replacements for the woofer and midrange speakers be?)

 

Front center speaker (924 and early 944 only)

In the early 1970s, when the 924 was first designed, mono radios were still quite common. So a single speaker was all that was needed. In most cars this location is now unused, though it might be usefully employed for specialized radio needs (e.g., cell phone, amateur radio, scanners, or CB radio).

A second possibility is to use this location to improve the sound staging of a stereo system. In the book Ultimate Auto Sound (ref 2), there are ideas for implementing a simple center channel concept. The author even includes construction details for a simple center channel mixer and bandpass filter.

 

Rear speakers (4 speaker systems)

The rear speakers are located next to the rear seats in the side panels. Once again, these are Blaupunkt 4x6" speakers. The units in my '86 944 were actually coaxial speakers - paper cones again but with a rubberized cloth surround and larger magnets than the front speakers. Despite the coaxial design, they are not very good sounding speakers. (What other factory 4x6" have people found in there?)

According to the Crutchfield catalog (http://www.crutchfield.com), the depth is restricted to 2". However this does not seem to be the case. At least 3" is available, allowing just about any aftermarket 4x6 to be used. Perhaps Crutchfield is thinking of the 924 – whose fenders do not bulge like the 944?

In some '87 and later cars, the 4x6" speakers are mounted to an adapter plate. Removal of this adapter plate will allow a 6.5" round speaker to be mounted. Be sure to check for this before purchasing replacement 4x6" speakers.

Removing the side panels to get to the speakers is not difficult, but takes some time and especially care. Do not attempt it when you are tired or in a hurry. Here are the steps:

1.) With the rear seat flattened down, unscrew the large

plastic screw and three capped screws holding the upper

portion of the panel on.

2.) Unscrew the two screws holding the bar that the rear

seat clamps into. (These may be very tight as they were

probably Locktited at the factory.)

3.) Lift the rear seat back. Unscrew the remaining two

capped screws.

4.) The rubber strip around the door edge simply pulls

off. Carefully pull it off to a point just above where the

side panel vinyl ends - next to the side window.

5.) CAREFULLY lift the side panel away from the quarter

panel. Use EXTREME CARE to avoid tearing the vinyl. The

edges of the vinyl have been glued to the metal, but may

be CAREFULLY pulled away.

6.) When you get to the area around the side window, CAREFULLY

and GENTLY pry the vinyl away from the metal and from under

the rubber window seal. Lots of 4 letter words help! Note

that the window was inserted at the factory AFTER the vinyl

was glued - so bits of the vinyl may actually be curled under

the window. Again - use EXTREME CARE to avoid tearing the

vinyl.

7.) The seatbelt does not need to be removed.

8.) The speaker is now exposed and may be removed by

unscrewing the four screws.

9.) Replacement is the reverse of disassembly. Tucking the

vinyl under the rubber window seal is the hard part of the

job. Pry a bit of the seal up at a time and neatly press the

vinyl under it. Again lots of 4-letter words help!

Rear Speakers (M490 10 speaker systems)

There are two speakers in the rear. These are a 6 1/2" woofer and a small midrange. Removing the 8 screws surrounding the speaker frame easily accesses the speakers.

Subwoofers

The factory did not supply subwoofers so custom installs are necessary. Ideas, which do not require cutting up the rear, carpet:

- A custom box in the hatchback (point at rear glass)

- Area above rear cubbies for custom enclosure

Ideas, which do require cutting up the rear, carpet:

- Use the spare tire compartment

- Use the rear cubbies

For several good and inexpensive ideas on subwoofer installations, see Ultimate Auto Sound (ref 2).

Antennas

Antennas (Part one - simple AM/FM reception)

The 924 and early 944 typically have antennas mounted in the driver side front fender. These are Hirschmann units and came in both manual and power versions. The Haynes manual (ref 4) has information on removal and replacement.

Starting with the 85/2 944, an in-glass windshield 'active' antenna system was used. Under the dash, between the glove box and the passenger side fender, there is a small preamplifier - made by Fuba. This amplifier is powered by a lead, which runs alongside the coax leading to the radio. It connects, through the wiring harness, to the 'power antenna' lead on the radio in order to get power whenever the radio is turned on.

Last, on some very late 968s, a small roof-mounted antenna was used. This is mounted just in front of the hatchback. It is also an 'active' Fuba-style antenna.

When installing an aftermarket radio on a car with an active antenna system, it seems to be a common problem to forget to apply power to the preamplifier. The following are the most common symptoms:

- Poor reception on FM - only a few strong stations will appear

- Virtually no reception on AM

Note that the preamp must be connected to a switched source to avoid running the battery down. Again, this is the 'power antenna' lead in the radio's wiring harness.

 

Antennas (Part 2 - Advanced Topics)

My 944 came with both the in-glass antenna and a Monterey radio with long-wave (LW) reception. Although LW is not used for broadcasting in the U.S., there are low-power aircraft and marine beacons. So some people without a life actually try to see how many of these beacons they can pick up. It turns out that the factory setup is quite deaf to LW with the in-glass antenna. I actually once parked about 50 feet from a maritime beacon and could not receive it!

Amateur radio operators may wonder about good places to install 'ham' antennas. One solution to the problem is to use the two ski-rack bolts, which are under the upper side of the hatchback. A mount can be fashioned from a bit of aluminum and is strong enough to support usable VHF/UHF (e.g., 144 and 440 MHz) antennas.

For amateur short-wave operation (and 11m CB radios), I've wondered how a magmount on the rear bumper would work. Using some copper shielding material to make a GOOD ground connection to the chassis would be important for efficient operation! An article in the December 1997 issue of QST (Ref 6) has some ideas for making effective use of a magmount at these frequencies.

Last, what if one wants to receive shortwave or longwave radio from the car, such as when using a car stereo like a Becker Mexico or similar Philips (and certain gray-market Sony) stereos? Attaching a small whip to a hatchback-side mount seems to work. One list member has successfully used the roof-mount active antenna from a 928 (part number 928-645-201-00) with the older and now-infamous Philips DC-777 radio. This roof antenna is also a Fuba-style unit. (Is this the same part as used in late 968s?)

 

Strange Noises

AM radio reception is especially sensitive to a variety of noises around the car. Three common areas of noise are:

- Raspy noises, which vary by engine RPM (ignition, fuel inj.)

- High pitched whine, varies by engine RPM (alternator)

- Clicks (wipers, turn signals, etc.)

Raspy noise - check plug wires. Many list members use Magnecor plug wires, which are designed to both maintain peak engine performance and minimize electrical interference. Magnecor has an optional CN25 version of their wires, which are especially designed for suppression at radio frequencies. (See http://www.magnecor.com for more information than you ever wanted to know about plug wires. Some cool pictures of racing engines too!) Make sure the rotor/cap are in good condition. Make sure that good 'resistor' spark plugs are in use.

Other areas to check for raspy noises include faulty fuel injectors, and improper bonding of the antenna or engine to the chassis. Of course if you have replaced your metal hood and fenders with carbon fiber parts, do not blame Porsche for poor shielding!

A high-pitched whine, which varies by engine speed – this problem is almost always caused by the alternator. Alternator problems seem rare on our cars. Individual repair parts are available; so total replacement of the alternator is not required.

A second cause of whining problems could be caused by 'ground loops' from external power amplifiers, CD changers, and the like. It is important to have a good common ground connection between all the units.

Clicks - caused by windshield wipers, turn signals, etc. If these are bothersome, try replacing the associated relay.

Auto Audio (ref 5) has a nice chart for tracking down and solving noise problems.

References

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