My 1987 Porsche 928 S4, 5 speed - Sound System Page
Sound
System
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My first disappointment, and I do understand that this car was not build for audiophile's musical experience, was flatness of the sound. Once I have noticed that stock ITT speakers had cone frames were made out of plastic - that was it. So, once I was sure I could not live with that I started putting the concept together. Since I was not about to spend $4,000 to $6,000 for installation, in addition to $2,000 for the system, I had to try to undertake this task on my own.
This is the final result
Foam cover with black carpet
Cutouts for amplifiers cooling
Top plywood panels wrapped in black leatherette
Quarter-turn fasteners used to secure upper panels to the rack
The pages linked below show the details on what system consists of and how it was built. It took me 2 years what would have taken Unique Whips (Speed Channel) two days. But I know I had more fun.
Construction steps:
Other 928 Sound Systems:
Exhaustive List Of Car Audio Manufacturers:
With advise of Kirk Neal (of Ampmanaudio - unfortunately not in business any more), I have selected the following system components:
- CDT Audio Professional HD-642 3-Way System for the front (6.5" Mid-base, 4" Mid-range, 1" tweeter and 60dB "Phase Perfect" cross-over),
- CDT-6 (replaced by HD-6) 6.5" mid-base speakers are used for rear fill,
- Old Eclipse 56050 (2000 model - company is out of business) 6 CD in-dash changer (GREAT SOUND BUT VERY UNRELIABLE - FAILED AFTER LESS THAN 2 YEARS (AND PRESENTLY OUT OF BUSINESS), - 1ST CD LASER FAILED, THEN REMOTE WOULD NOT TURN AMPS OFF - SCRAPPED AND REPLACED WITH TEMP JVC FOR TESTING OF HD RADIO - SEE BELOW):
Changer Mechanism
ECLIPSE COMMANDER Ready
ESN (ECLIPSE Security Network)
Equalizer/DSP Sound Processor Control (optional)
6 in-dash CD Changer with Daisy Chain linking
8-times over sampling digital filter & dual 1-bit D/A converter
CD Text-Ready
Integrated Optics Pick-Up Unit
Digital Servo System (DSS)
Enhanced error-correction capability
The ECLIPSE Memory Buffer
Highly Balanced Oil Damper
High Quality Film Capacitor
ECLIPSE STARTUNER IV
24 Station Presets (18FM/6AM) & Preset Scan
High-Voltage (5V) & Low-Impedance (55 Ohms) Output
ASM (Auto Station Memory)
Free-Flow Signal Circuit
Copper-Shielded Chassis
Audiophile Components
Independent Bass/Mid/Treble Memory for Each Source
3 Pairs of RCA Pre-Amp Outputs
Non-Fading RCA Pre-Out Terminals for Subwoofer
NOB (No Ordinary Button) Rotary Volume Encoder
High-Visibility VF Display
ECLIPSE LAN Advanced Data Link System
Remote
My second receiver: JVC HDR-1 - I selected this unit only as a temporary replacement head unit (HU) to test HD radio capability. It costs less than Fujitsu Ten Service Department asks for opening failed Eclipse's box ($160 minimum charge). I ma still deliberating which of "big three", Sony or Pioneer head units to select, to have presets buttons in the front, bass/treble controls at the knob, and in spite of poor availability of good HD signal, I still would like to have build-in HD tuner:
Kenwood high end units are closest to what I was looking for (such as Kenwood Excelon KDC-X996: used to have 5 V level outputs (better noise rejection than 4V units) - but current units deliver only 4V outputs, it has built-in HD radio, and Kenwood has the best technical support (all e-mails are answered exhaustively!!). The problems include high glare and poor visibility in daylight, no station preset buttons in the front (it takes 3 steps to change station while driving!) and NO treble/bass controls at the knob available which makes any sound adjustments while driving impractical (5 or 7 steps operation to change setting via EQ);
Alpine units, such as the latest CDE-HD138BT (as of Dec 2012), the output level is still limited to 4 V, vs. 5V found in old Eclipse and some Pioneer and Sony units, it has HD tuner, has outside pre-select buttons and it has easy access to bass/treble controls with single button operation - so far No. 1 choice candidate;
Pioneer units, such as DEH-80PER, are the only high-end units with 5V outputs, but still have no preset buttons on the outside, and has no built in HD tuner;
Sony units, such as Sony MEX-GS600BT (Crutchfield), do have 5V outputs and external station preset select buttons, but have no built-in HD tuner; and finally
Eclipse - now out of business, used to have the best sound quality, but were very unreliable (infamous INFO3 error code does not mean that the head is dirty - as tech support would make you believe - but that the laser head is out of alignment which could be fixed for minimum of $160), it had no build-in HD tuner, and the high end units are extremely over priced, while tech support was clueless and never replied to the calls or e-mails (unlike Kenwood).
Head Unit - Amplifier Matching - the Basic Car Audio Electronics is the best site I have found. This page explains the significance of matching Head Unit output voltage level with amplifier input sensitivity. It has great tutorials on all basics car audio electronics. In my case, I should be able to use Alpine 4V output unit, my 5V amps gain range to be adjusted to approximately 4V position to generate max rated power at max Head Unit volume.
Power Output: 200W Max. (50W X 4),20X 4 (RMS)
Built-In HD Radio Tuner with Multi-Cast Capability
Ready For I-pod *
Sat Radio Ready
MP3/WMA Compatible with ID3/WMA Tag
CD/CD-R/CD-RW Compatible
DiAS Digital Tuner
Digital 7-Band iEQ
Gold-Plated Front and Rear Line Output Terminals
Gold Plated Subwoofer Output Terminals with Level/Frequency
Control Rotary Encoder Multi-Control
2.5 V output level for front and rear; 2.0 V for subwoofer
Wireless Remote Control
* Using KD-PD100 I-pod Adapter
Remote
Unfortunately, this is $160 unit vs. over $800 Eclipse for a reason:
Subwoofer control range is limited (8 steps vs. 20 of Eclipse),
Illumination colors are not selectable (as in newest Eclipse designs and some of Kenwood's),
No treble/bass controls at main knob (this is the same problem with very high end Kenwood units) - one has to use EQ to change those frequencies (4 step operation - not doable while driving),
2.5 V output level, vs. 5 V of Eclipse, makes this unit more susceptible to an alternator noise,
Key problem: HD radio is great ONLY when unit locks on to HD signal - which is hardly ever. The technology as is - is not capable of maintaining HD signal within the FM signal range (HD signal is superimposed on FM waves and decoded by HD tuner). Refer to this blog for latest on this troubled design.
Conclusions:
HD idea is great, but it does not work reliably. HD unit has 20-20,000 Hz frequency response and is superior to 40-15,000 Hz range of conventional FM broadcast. When unit locks on HD signal, I can hear clear and significant frequency range expansion on both ends. Base becomes deeper and there is no static noise.
Multicasting stations are great. On the same FM setting, one can select two or more alternate broadcasts! Again, depending on station transmitter proximity, 20 - 30 seconds after tuning in, for stations located 20 miles away in clear no obstruction path, ,those secondary broadcasts will typically drop off completely - silence. Only on primary broadcasts, units reverts to FM when HD signal is lost.
In present state of technology it is only reliable in a very limited range as supported by referenced above blog and my experience.
Only when transmission/tuner design changes will be made, HD would have proven to be a superior way to listen to a free car radio, however to be fully appreciated it must be listened to high end sound system.
If HD is not your thing, then Kenwood (4V) or Alpine (4 V) should be great choices. If one needs 5V outputs, only Pioneer and Sony can offer such head units.
If you want no mechanical rotating parts for greater reliability - then Kenwood KIV series unit is for you!
If You want a subscription service and do not mind drilling hole in the roof for external antenna - than clearly Satellite Radio is for you. I want to have clean looking roof, that is why I am reluctant to get it. Also, paying extra $10/moths does not appeal to me too much.
My current 2-DIN Receiver with 5V output signal level: Kenwood Excelon DNX995S with NAV and Bluetooth:
To make it fit the the trim panel around stick shift was shortened and clock was eliminated.
The factory receiver bezel was used for now - with future custom frame to be made to make smooth transition to the center console trim.
Specifications |
0.4kW |
0.6kW |
Maximum Power |
|
|
Power into 1 Ohm |
365 W x 2 |
440 W x 2 |
Power into 2 Ohms |
200 W x 2 | 200 x 2 |
RMS Power into 4 Ohms |
70 W x2 | 95 W x2 |
RMS power in Tri Mode |
70 x 2 + 140 W |
95 x 2 + 180 W |
Distortion at nominal power |
0.08% THD | 0.08% THD |
Signal to noise ratio |
98 dB unwtd. | 96 dB unwtd. |
Low pass cross-over |
40-180 Hz, 24dB/oct. | 40-180 Hz, 24dB/oct. |
Frequency range |
12Hz - 20 kHz (-1dB) | 12Hz - 20 kHz (-1dB) |
Input sensitivity range |
0.1 - 5 V | 0.1 - 5 V |
Dimensions |
150 x 300 x 53 mm | 150 x 300 x 53 mm |
Weight |
2.4 kG | 2.5 kG |
ESX Q 2751 subwoofer monoblock amplifier:
Specifications |
Q2751 |
Rated Power |
|
Power into 2 Ohm |
450 W |
Power into 4 Ohms |
274 W |
Distortion at nominal power |
0.05% THD |
High pass cross-over (subsonic) |
7 - 42 Hz, 24 dB/oct. |
Low pass cross-over |
38 -195 Hz, 24dB/oct. |
Frequency range |
7 Hz - 200 Hz (-6dB) |
Input sensitivity |
9 V |
Damping factor @ 20 Hz |
500 |
Bass boost (variable) |
0 to + 18 dB/Fo 43 Hz |
Phase response |
Lagging 10° @ 20 k Hz |
High pass cross-over (line out) |
7 - 42 Hz, 24 dB/oct. |
Dimensions |
232 x 260 x 73 mm |
Part Numbers for all Stinger interconnects/blocks/cables Part Numbers are shown in the links shown above and in the System schematic diagram