To avoid cutting the speaker wires in the door a wiring harness plug pigtail is available from Crutchfield:
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| Speaker wiring harness plug |
For the Premium system as in my car, I jettisoned the bass reflex boxes
under the door speaker covers and initially replaced them with 5-1/2” two-way aftermarket speakers in the door card speaker holes in conjunction with one-inch deep extension rings. The extension rings move the speaker out, closer to the grill on the original carpeted OEM speaker cover.
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| Bass Reflex Box |
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| Speaker Extension Rings |
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| Original OEM Premium Speaker Cover |
For the rear original Premium Sound speakers getting an original raw speaker component is done through a dealer. Online Sunnyside Porsche Parts seems to have good pricing on original speaker replacement parts with the original driver's attachment holes that line up with the original housing frame. I chose to instead replace the internal rear raw speaker driver with a generic aftermarket 4” coaxial one and disconnected the existing tweeter. I had to drill new speaker mounting holes in the existing rectangular assembly and calk the edges to seal the new speaker frame once the speaker was screwed to the fixture. Remounted on the rear deck the assembly looks OE stock now. Much like the OE speakers this rear speaker setup really adds only mid-high tones due to the acoustic limitations of the rear deck mounting position.
The Premium sound system has a bi-amplification setup for the door speakers, where one amp powers each woofer and another powers the combined midrange and tweeter speakers. On the face of it, this arrangement is a very high-end approach to car audio even today. The problem is that the stock Nokia power amp is so undersized it renders this approach moot.
The original Nokia amp also had an option for a Digital Signal Processor (DSP)
control panel located in one of the door pockets, a radically hi-tech item for its day. It was a very rare option whose value was questionable due to the low power output of the Nokia system.
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| Nokia DSP Control |
To really make a Premium System upgrade sing discard the bi-amplification approach and replace the original Nokia power amp under the seat with a more powerful aftermarket one.
A 4X75 Watt RMS per channel amp is good and easily fits completely under the seat, 4X150 Watt or more RMS is a lot better. More power does not translate directly into louder music, but it does significantly reduce distortion improving clarity at moderate volume levels. With all the engine sounds we have come to love in our 993 cabins having a system that can overtake these sounds and still provide good clarity is a big plus.
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| Original Nokia Amp. |
If I was to do it again I would use all the available space under the seat for a bigger two-channel amp powering the door speakers only and use any amp internal to the head or a second physically compact smaller power amp under the dash for the back as the back speakers really don't add much to the sound do to the limitations of their placement in the car.
Some really high-power amplifiers are packaged in a width that easily fits under
the passenger seat from left to right and can be placed so the amp's body extends reward into the back seat footwell. It can then be hidden under the carpet pad. The only limitation in amplifier size is the available space under the passenger seat extending rearward unless one wants to go to the complexity of relocating the power amp to the frunk.
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| Alpine brand aftermarket amp. |
Constant-on primary power for the power amp can be picked up under the seat. In my case, I added a fused heavy power wire directly from the car battery with the reasoning that an amp where all the channels combined pull a bit over 300 watts MAX any current limitations of the existing power wire may translate into reduced amplifier performance negating some of the advantages of the amplifier. Having now, years later, thought about it for a while, adding a dedicated power wire was probably overkill as amplifiers really run most of the time at a small fraction of their maximum output and only experience full output for a few milliseconds at a time.
If you want to avoid butchering the existing wiring harness or are not handy with a soldering iron Tore's website bergvillfx.com offers all sorts of hard-to-find 993 specific wiring harness adapters for audio upgrade projects. Crutchfield can also be a source for certain hard-to-find wiring harness adapters. Also here is a wiring harness kit at Discount Audio for replacing the Nokia amp without cutting any wires. If all else fails eBay is my go-to source of last resort for hard-to-find wiring harness connectors.
In my case, I cut off the original speaker frame's wiring harness sockets making them into wiring harness adapters avoiding cutting and soldering new terminations to the original speaker wiring harness in the doors. Similar to this, pre-made adapters are also available from Crutchfield and others. This page offers audio wiring detail for the 993.
The wiring diagram in the 993 Shop manual is clear and concise as to how the existing speakers are wired making it easy to tap new speakers or a replacement power amp into the existing wiring harness. The upgrade can cost less than $100 using four inexpensive two-way speakers or the sky is the limit through Best Buy, Crutchfield, or other suppliers depending on what level of sound quality you desire.
Car Seat removal – See: how to remove front seats without drama
To Sub-Woof or not, that is the question -- Getting clear sound and good bass response in a 993 audio system can be a challenge. As discussed above, even the original Premium Sound System is grossly underpowered. I put a 75 Watt X 4-channel Alpine power amp under the seat powering all four speaker positions
Having replaced the OE door speakers earlier and having lived with some nice two-way coaxial speakers in the doors for a while I was looking for ways to improve the smoothness of the bass sounds from the speakers.
Some have worked up very creative ways to add a subwoofer housing to smooth the bass. In all these cases one has to give up cabin space.
The BX10X is not an equalizer in the conventional sense. It recreates low-frequency harmonics lost in a 911 cabin space and sounds great! For general pop music and things such as acoustic guitar, it causes the bass to feel much smoother eliminating the boxed-in-like sound inherent in door-mounted speakers. I feel for general listening, it eliminates the need for a sub-woofer while transforming the sound for the better.
My initial experience with music with a hard beat was that the BX10X easily overdrives the 75-watt RMS per channel amps causing distortion. Having had it in the car a while I have now set my 10-year-old Alpine radio’s bass control center frequency from 100hz to 50hz and control the BX10X level using the standard bass control on the radio and found overdrive distortion to not be a big issue.
If your goal is to have powerful thumping low-rider worthy bass this solution is not for you, most likely a much larger power amp of greater than 150 Watts RMS per channel in conjunction with the BX10X or a separately powered subwoofer enclosure would be the ticket. Some newer head units incorporate features similar to the BX10X eliminating the need for this extra box.
Adding an auxiliary analog audio input for Bluetooth or satellite radio to your stock radio head:
Using an FM modulator or cassette adapter to create an analog auxiliary input for a file player, Bluetooth, or satellite radio can significantly diminish the quality of the sound produced. Depending on the quality of your audio source the best way to maximize sound quality is to have a direct analog audio input.
Continental branded radios:
Continental brand radio heads are quite popular for replacement units in the 993/964 Porsche. The primary attraction is that they have a front panel that looks somewhat period-correct for these cars.
Here is the Continental radio product line as of 2022:
https://productimageserver.com/literature/brochure/94436BR.pdf
It seems their radio heads do not offer line-level outputs to directly attach a power amplifier.
A small nuisance when using a smartphone for hands-free phone calls. It has been reported that with the Continental CDD 7416, there is a delay where the unit clips the first few seconds of a call when initiated. The workaround is to have some music on in the background on the unit.
Power Amp Adapters:Using a speaker-to-line level adapter to attach a power amp to almost any head that does not allow for a direct power amp connection introduces noise and distortion. This distortion in most cases will bewell above the threshold where one will be able to hear it and will cause listening fatigue at volumes high enough to cover the engine sounds in our cars.
The Blaupunkt Bremen SQR 46 DAB Radio Head:
This radio head has become quite popular as an aftermarket replacement for the 993/964. It is a good bit more expensive than some of the Continental offerings, it does look somewhat period correct for a 993/964, and most importantly it does have RCA style line level outputs to directly attach an external power amp. If you envision adding a power amp at any time in the future this is a popular unit to consider.
The Blaupunkt Frankfurt RCM 82 DAB is a newer product with updated functionality.
A partial list of features & updates includes:
- The newer Bluetooth version 5.x is supported making for more reliable music streaming connections;
- It is able to play audio files in the lossless FLAC format;
- It does not support the pre-2012 30-pin Apple devices however it works with newer devices with the lightning connector via a front or rear USB port;
- It carries forward the 4-channel RCA plug style preamp outputs and a usable 24 watts RMS per channel speaker output.
More on Blaupunkt car audio products can be found here:
The Porsche Classic Communication Management (PCCM) head.
It looks good in the dash and has a lot of functionality
Some other single DIN, Double DIN, and surface mount radio head options. Some require alternate mounting locations and methods:
In any event, whatever head/speaker or amp combinations you are considering here is a page with the needed wiring information to get things installed.
If you found this page informative return to the main page and bookmark it for future 993-related servicing, repair, and upgrading guidance & information. If it saved you some aggravation or even some coin consider a donation through the button on the top left margin of this page.
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