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[Dave DND]

Without a doubt, one of the most confusing aspects of the Audio system in the Omega, is that of the BOSE system. There are many questions, rumours and half truths out there, so I thought I would put a few of these down here, in the hope that it may help you to understand the system.

Back in its day, the Omega BOSE system was indeed a stunning system to be heard, and had the benefits of extra subwoofers for a more rounded sound, and speakers that were designed to complement the interior of the car. This was all powered by a dedicated head unit and amplifier.

However, time has moved on, and it is the wish of many of you to want to alter or change some of the components of the BOSE system to bring it in line with the 21st century, and in doing so, many of you are encountering some problems.

Do I have BOSE fitted?
There are a few quick things to check – If you have subwoofers on the back shelf or a subwoofer in the quarter panel on the Estate, then it is an indication that you may indeed have the BOSE system. If you do not have these extra subwoofers then the answer is definitely not.

Head Units
Not all standard OEM head units are compatible with the BOSE system. Generally, the NCDxxxx and CCRTxxxx head units were the models of choice, although some models (not all) of CCR2006 could be programmed for BOSE outputs. The output of a BOSE enabled stereo is of a different voltage level to that of conventional car audio and this can lead to some compatibility issues that we shall discuss later.

Speakers
BOSE speakers are causing some real headaches on here. The main problem is that the impedance of them is only 2 Ohms, unlike conventional car audio that is rated at 4 Ohms. The other cause of concern apart from being a non-standard size, is that they are constructed from paper cones, which 20 years on have mostly bio-degraded making finding good quality second hand ones in short supply now. Should you wish to replace the BOSE speakers and retain the BOSE system, then you will need to find a suitable 2 Ohm replacement speaker, and very few people make those nowadays.

Amplifier
The BOSE amplifier was the heart of the system, and is generally speaking pretty reliable. It drove both the cabin speakers and the subwoofers. However, whilst around 60W per channel at 2 Ohms was quite an achievement 20 years ago, that would equate to a head unit of around 25W per channel nowadays, and a quick glance at modern head units will indicate that we have long passed that, with around 50W per channel now being the norm. It should also be noted that the input voltage requirements of the BOSE amplifier were also of a non standard level and range which is why BOSE would only work with certain OEM configured head units.

Subwoofers
The subwoofers seldom give any cause for concern, but would be sorely missed should you choose to remove them. It is doubtful whether the BOSE system would have achieved its reputation if these subwoofers were not present though, and it must be  pointed out that adding a discreet subwoofer to any system can significantly improve the sound.

Part II to follow

[Dave DND]

Replacement with an Aftermarket Head unit
Right, you have now read what the system comprises of, and you now want to change the head unit as you have realised that apart from a Cassette adapter or FM modulator, that you cannot connect your iPod or MP3 player, or maybe you just fancy something a little less archaic in its appearance and functionality. Before we go any further, I will refer to the FAQ section of the BOSE website, and give the definitive answer from the manufacturers before I explain why:

Q 7. Can I connect another radio to my BOSE® sound-system?

A No. Each BOSE® automotive music system is completely integrated, with every element custom engineered to work as a whole. If you install a new radio, the results could include decreased sound quality, incorrect bass and treble balance, distortion at high volumes, and a loss of bass at low volumes

OK, that’s what they say, and unfortunately they are right – but many of you will still try and will end up with a few different outcomes, some of which I shall describe here.

Because the Impedance of the BOSE system at 2 Ohms is half of what conventional car audio is designed to run at, and the voltage level outputs are significantly different, you may well end up with one of the following problems if you connect an aftermarket head unit:

No sound

- The head unit will go into a protection mode and not give any sound output as it has detected that the 2 Ohms speaker impedance is a short circuit.

- The internal amplifier of the head unit will start to smoke and possible catch fire as it has detected that the 2 Ohms speaker impedance is a short circuit. This will also burn out the BOSE amplifier and speakers if left connected.

Sound

- The sound quality is severely distorted as the head unit is overdriving the BOSE amplifier, and any distortion is a sign that damage is being done to the speakers and the BOSE amplifier.

- There is little or no volume control at lower levels – this is because the head unit is giving an incompatible signal to the BOSE amplifier. This will be made worse by head units that have a volume control that increments with a “click” of a button or rotary encoder as the gaps between the volume steps are too great an increment. This is not so noticeable with volume controls that have the old fashioned carbon track potentiometer that have a smoother volume control.

Conclusions
Hopefully you will now realise that the BOSE system was carefully designed to run as a balanced system and that due to the way it was designed using non standard components, that should you wish to replace any part of it, then you will have to replace the entire system in its entirety, as that is how it was put in. It was not an upgrade, it was a whole system that was installed in one hit.

It must also be noted, that should you wish to remove the BOSE system, then you will also have to do a fair bit of rewiring, so that the now redundant BOSE amplifier is bypassed.

So to summarise that all up, is that if you want to upgrade the head unit, then you will also have to upgrade the speakers, remove the amp, lose the subwoofers and do a bit of extra wiring, its certainly not going to be a 2 minute job.


My personal opinions
I have no problems with BOSE systems. Most of the BOSE systems in modern cars do indeed sound awesome, but that is largely down to materials that are currently available, The Omega BOSE system was a great system in its day, and was designed using materials and technologies that were available at the time, but that day was 20 years ago, and sadly has now passed. We no longer drive steam powered cars, as technology has moved us forwards. We no longer listen to a gramophone with a large trumpet. Well, the same can be said for car audio. Newer manufacturing processes now mean that paper cone speakers have been replaced with polypropylene and fibreglass ones, and sound reproduction technology has progressed significantly. We have more power to play with, as even the most basic modern head unit has twice as much as BOSE did 20 years ago. So whilst I appreciate the argument for originality amongst the purists in retaining the BOSE system, I am unable to accept retro-fitting the BOSE system as a viable upgrade when you consider what is commercially available today.