Aimed strictly at those who wish to retain the stock head unit, some modifications were developed to allow some additional functionality.

At the moment this mod is only applicable to the Blaupunkt system fitted to VY and VZ Commodore/Monaro models, but development is underway to expand this. Modern automotive systems are becoming more and more integrated with the vehicle, not only functinally but aesthetically. Many - like myself - are of the opinion that whilst improvements can be made, among the main criteria is that the appearance and overall functionality not be interfered with.

Firstly because this unit (and the majority of other factory systems) doesn't provide low level (RCA) signal outputs, a buffer circuit was developed for the four channels, to allow external amplifiers to be used whilst protecting the head unit circuitry from loading effects or external fault conditions. This of course can be done with LOCs, or "Line Output Converters", but this isn't the way to go if you're after real sound quality. LOCs merely attenuate the speaker outputs (reduce the voltage) so that they can be used to feed the line level inputs to the amp. The main drawback here is that by then the signal has already passed through the onboard power amplifier chips in the head unit, and that's where the distortion is introduced - by using these you're simply amplifying an already distorted signal. Far better to give your system the best chance by feeding clean signals to the external amps. The output buffer modification does exactly this, by picking the signals up inside the head unit after all the signal conditioning stages, but before the power stage - essentially a "pre-amp out" for those familiar with that term.


Subsequently a further circuit was developed to fill another void in these systems - the ability to inject a signal from an "Auxilliary" device (such as a MP3 player or other portable audio) and switch this through the system, rather than using the FM modulator method, which has mixed results to say the least. Some get it working OK, but even then we're limited by the standards which govern FM transmissions - relating to audio frequency response, dynamic range, pre-emphasis/de-emphasis, etc. This mod injects the output from the portable device at the input stages of the head unit, allowing full volume/tone/eq controls, and maintaining a direct wired link to allow all the frequency response and dynamic range your portable player can produce.
To activate the Aux Input the device is plugged into a 3.5mm socket (placed where you choose) and a push-button switch is pressed. This causes the existing source (radio or CD player) to be muted and the injected signal is piped through. Note that the selected source is still active, but is simply overridden. (an "Antenna Inhibit" facility is included to drive the electric antenna down when the Aux is active in radio mode to prevent wind noise.

---> Click here for Price Listings on Stereo Mods <---

Combo Kit

The photo at left shows the Blaupunkt system unit from a VY/VZ Commodore with both the line output and auxilliary input mods installed - a "Combo". The two PCBs (Printed Circuit Boards) can be seen supported above the main unit board, with the wiring connections made as required. In the case of these systems an additional connector arrangement was developed to overcome the problem of practically zero space behind the unit to access any connections. These units employ a slide-in cradle with a captive socket for the main harness connections, therefore a similar scheme was developed to enable the new connections to be made with a minimum of fuss, and more importantly with no impact on the overall functionality. In the top left of the photo this connector body can be seen attached to the existing connector block. The mating pins are attached to the cradle, with a pair of "figure 8" shielded cables (with RCA line sockets mounted) running down to the lower left side of the centre console, the object being to use standard RCA cables to extend to wherever the amplifier(s) will be mounted. The amp remote output also runs to this point, to be extended in a similar way to control the power state of the amp subsystem. For the input mod, a longer cable is attached to feed via the console to the switch and socket mounting positions. It's around a metre in length, so easily reaches to the usual mounting positions.

AUX Input Buttons

A factory style backlit switch to activate the Aux Input has also been crafted which snaps into the console behind the window switch position. This polishes the installation, giving a truly "off-the-line" look.

This installation doesn't show the 3.5mm socket (for connection to the Auxiliary device), but this can be placed where chosen. If mounted directly adjacent to the switch in one of the blank button caps, the cable is of sufficient length to reach, however if mounted elsewhere (such as inside the console storage bin) then a short extension plug-to-socket cable must be fitted. This is preferred over extending the wiring, so that the centre panel can still be removed from the car should it be required - connectors are simply unplugged. If the cable is extended, then suddenly the panel becomes "tied" to the car with the cabling. Extension adaptor cables are available on request.

Car Audio Downloads

Stereo mods full install guide (approx 3.75MB) This document is an earlier revision of the full installation guide for the Line out and Aux in modifications.


Stereo Removal / Refitting guide (approx 1.3MB) A guide for those needing to remove and re-fit the head unit only - example, for a "partial install" job.


Factory AUX switch fitment guide (approx 500KB) The procedure for mounting the factory style activation switch for the Aux Input.


Stereo mods price list - For pricing and kit option information for the stereo system mods.