Successful Aftermarket install on 07 CS w/Bose

Hey All, I want to think Trieullionaire from Euro MotorSpeed for answering questions and the quality of his dash kit for making this install possible. I have an 07 CS with the Bose System , here are the aftermarket parts I had installed. Kenwood DNX 7120 GPS /DVD System Kenwood KAC-8404 4 Channel 600W Amp Kenwood KCA-XM100 XM Satellite Radio Interface Box Kenwood KCA-IP300V USB/ Ipod Adapter Cord Crossfire XC8K Amp Wiring Kit XM Mini-Tuner CNP-2000 Euro MotorSpeed Cayman Custom Double Din Bezel Kit I was definitely a little nervous about my CS’s existence after reading numerous pessimistic posts about integrating aftermarket Double-Din systems into the Bose system . I did some research in the local Little Rock, AR area and settled on the guys at Auto Audio. ( Auto Audio Powered Site ). These guys were very professional and have a lot of experience with European high-end vehicles. I took the CS in yesterday and the install took them about 6 hours, you gotta love same-day service. The guys at Auto Audio bypassed the Bose amp, and actually removed it, not for any reason, simply to reduce weight. They also had no problem integrating the Kenwood deck using Euro MotorSpeeds wiring harness which prevented any wire-cutting. They did not do any “drilling” or “cutting” on my CS so that I can return to a complete factory look. Both the XM and GPS antennas were placed on my dash in the corner which is illustrated in the pictures attached. The USB/Ipod cords were ran into the glove-box. The Bose Sub with internal amp is controlled through the Deck, while the door speakers are wired through the Kenwood Amp which is velocred to the bottom of my front boot. The Kenwood amp supports 2 Ohm signals which fixed that Bose problem. I did lose the use of the center-speaker because I did not want to pay the cost of adding it to the system, Auto Audio’s guys said it was possible, but costly. I am very happy with the system, it gives me the ability to integrate my Ipod controls through the touch-screen or simply hook up an external hard-drive. The DVD play is nice for my girlfriend on trips to her parent’s house. The Kenwood navigation has been very good because it is fully Garmin supported. Garmin provides updates to the system in form of both DVD and through the SD slot on the system. Sound clarity is improved, and the utility of the system is excellent. The look is excellent. Bart

nice looking install... think i'm now ready to pull the trigger on mine and go the same route.

Forgot the picture of the Amp in the boot.

Install looks very clean & well done....I like it and am thinking about going your route. If you don't mind me asking, what was the cost?

Do you really need a new amp? i thought there is built in amp in the system

If I understand correctly the only Bose items still in use are the speakers. I was told they could NOT be used with other systems because they are only 0.5 ohm. If that's true was it worth getting that option ?

There is, but it uses a fiber optic MOST bus (Media Oriented System Transport) to communicate with the head unit. There aren't any head units in the aftermarket that work with the MOST bus. So if you're going to replace your head unit, the amp is going to have to be replaced as well.

I've read this a couple of times, but I find it very hard to believe. A 0.5 Ohm speaker is very impractical and would be very difficult to power. This is likely the result of someone putting a VOM across a speaker and reading it's 'resistance' at 0.5 ohms. But this is not an accurate way to determine a speaker's 'impedance'. Resistance is consistent and simple. Impedance is not. Impedance is an effective resistance taking all of the loudspeakers characteristics (capacitance, inductance and resistance) and it's operating frequency into account. A simple VOM test will only read it's resistance. To effectively measure a speaker's Impedance, an AC voltage, preferably white noise that spans the entire audible spectrum, needs to be applied to the speaker and a current measurement should be taken. Impedance will be equal to that Voltage divided by that Current. A speakers impedance will vary greatly across it's frequency range, dropping as low as a couple of Ohms and drifting as high as 50-70 Ohms at it's resonant frequency. Sorry, I had a geek moment there. Bottom line is, I doubt that the speakers are 0.5 Ohms. However , that doesn't mean they will be easy to use with aftermarket amplifications. The factory system has several function specific speakers; i.e. - Subwoofer, woofer, midrange and tweeters. Each of these speakers is designed to work in a narrow range of the audio spectrum. There is a crossover inside the BOSE amplifier that cuts the audio spectrum up into pieces that are appropriate for each speakers. So a replacement crossover will need to be added to make the system sound correct, and to protect the speakers from destruction. (Bart, I'd love to hear how your shop jumped this hurdle.) In summary, though the sounds system in a Cayman can be replaced, doing so properly is not easy or inexpensive.

I am considering the same unit for my 07 CS, it's my first choice after considering Eclipse, Pioneer , Alpine. I am interested in a reply to the issue Gator Bite raised about the crossover and how the install shop delat with it. I am also wondering how Bart D likes it after using it since install. I have read that the interfaces for the Radio, iPod , bluetooth are not intuitive and must often be accessed through layers of confusing menus.

I thought that the factory Bose amp had to be retained as it is part of the MOST bus loop/termination? It can be bypassed in terms of not being required as part of the audio system but is needed to maintain the MOST bus. I am missing something? How did the installer bypass and remove the factory amp?

He removed it by taking the head unit with it. It's all or nothing. The only systems that work on the MOST bus are the audio components. So if you take the head, you will have to replace the amp and changer (if equipped) too. That's what this guy did. He gutted the whole system and only used the speakers, which are not dependant on the MOST bus.

Gator Bite, just to perpetuate your geek moment for a moment there is at least one speaker I know of that had an impedance below 1 ohm and approached 0.5 ohm. The old Apogee Scintilla. Had a reputation for being hard to drive. Go figure. I'd be very surprised if Bose used speakers that fell much below 2 ohms unless it was outside of the frequency range they were going to be used for. It makes the amps expensive. Not typically what you'd expect for a factory application. Of course this frequency range could be exposed once the Bose amp and it's dedicated crossover was removed. This could create an unpleasant surprise.

And what size wire would be necessary for such a driver? Something much bigger than would be practical in a door boot. Very good point. I mistakenly said that white noise should be applied. In actuality, white noise should be passed through a band pass filter that limits the output to the speakers operating range, and then currect draw should be recorded. It is quite possible that outside of that operating range the speaker may have a super low impedance.

I've worked with Bose automotive audio systems a few times. Their speakers are low impedence 1 ohm speakers which are matched to their amplifiers. When you use a regular amplifier designed for 4 or 6 ohms on Bose speakers you get an impedance mismatch which makes the speaker's volume lower. A typical aftermarket amplifier doesn't have the correct setup to drive the speaker correctly.The output circuit is just the wrong value needed to drive them, either not enough output voltage or amperage the system isn't "balanced" . Bose speakers use larger magnets than regular 4 or 6 ohm speakers. Sound is part psychological but from what I gather from Bose 's design, their sound systems have the capability of sounding more accurate because of the larger magnets and dual voice coils in their speakers. It is possible to use an aftermarket amp on Bose speakers , but it has to be able to drive 1 ohm (or less if your Bose system has more than 4 speakers) loads on multiple channels. Those type of amplfiers are quite expensive. The overall wattage of a Bose system isn't much I think, this helps save fuel because of its light load on the car's alternator compared to higher wattage audio systems. I've been thinking of downgrading to a non-MOST Bose system that has an aux-in. Bose uses similar components across all auto makes and models, the main differences are cosmetic: shape, connector shape, wire colors. You can build an aftermarket system superior to the Bose system , but you would have to spend quite a bit of money. All your speakers must have the same tonal quality/model-line or it will sound like ****.

Need to find out would it be possible to keep the Bose / PCM headunit and just replace the amp and speakers? Or maybe just keep the bose amp so it does not affect the MOST bus and just tap into the headunit for source for the new amp?

I have to respectfully disagree. I have also worked with many BOSE systems. In fact, I've probably interfaced with and/or gutted hundreds of them in my 10 years as a mobile electronics installer. I've found the BOSE system in the Cayman very different for the many BOSE systems that I've worked with. The more typical BOSE system has it's amplifiers located in an integrated speaker enclosure. In this configuration, using a low impedance driver is more conceivable because wire length and resistance isn't as much of a factor. None of the BOSE drivers in the Cayman have a dual voice coil. None of them have integrated amplifiers. There are no output transformers in any modern day automotive amplifiers, including the BOSE amp in our Caymans. BOSE built their reputation on using psychoacoustics phenomenon to make small drivers sound big. They spent a lot of time understanding how the human ear identifies and connects with different frequencies, imaging and sound stage. They learned that if they altered the phase and amplitude of certain harmonics relative to their base harmonic, they could fool the human ear into thinking it's hearing a much deeper frequency than it actually is. This manipulation required a special pre-amplifier / signal processor and it's how they made their old 901s, which contained nine 4 inch drivers, which sounded like much larger speakers that had 10 an 12 inch woofers. The 901s didn't have woofers, mids or tweeters. Just nine 4 inch drivers and a signal processor / equalizer. I didn't like them, but most people did. To me, I noticed the lack of subsonic punch that you felt with your body, not with your ears. The BOSE system in our Cayman does not follow the BOSE roots. We have more conventional Sub Woofers, Woofers, Mids and Tweeters. The system in our car is a much more conventional system plus a signal processor used to provide surround processing (**** in my opinion). Our amplifier is located in our front truck. Twenty speaker wires run from that amplifier to each speaker. Those wires are 18 AWG. The rear speakers are approximately 8 feet away from the amplifier. Two conductors makes it 16 feet of wire to feed the rear speakers. If you shorted those wires at the speaker and measured their resistance, you'd probably find that they have 0.3 to 0.6 Ohms of resistance. If the speaker had an impedance of 0.5 Ohms, that means half of the amplifier's power would be wasted on loss across the wires. I don't believe for a minute that the speakers in our Cayman are 0.5 or 1.0 Ohms. Until someone actually measures them, the debate will continue. Once the snow melts and the sun comes around, I will test mine and report the results in excruciating detail here for anyone interested.

Using a regular DC impedence tester won't properly measure a speaker's impedence. You have to use an AC impedence tester. When you mesaure a speaker using just a regular DC impedence meter it will show up a little lower than the actual value shown on the meter by about 0.5 ohms or more... I measured all the bose speakers that I worked with at the time with an ac impedence meter and it measured 1 ohm for all the ones I've tested. This was on regular non-integrated amp speakers that all the systems I 've worked with on with across different acura / lexus /infinity cars. You can buy a digital AC impedence tester for 200 dollars i you want to verify yourself. You won't know if a speaker is dual voice coil unless you take it apart. The ones I have taken apart had dual voice coils. If you have some cayman bose speakers laying around, you can probably take it apart and put it back together for more verification. I meant circuit not transformer and I have corrected it sorry to confuse you.

Help.... Its a mess..... Did anyone keep a record of what the wiring was for the bose system? Heres what I am up to..... I have the Bose Sub out and it has 2 bigger power wires and 3 smaller wires, so the question here is: What wires to I connect to a speaker level to from my new Pioneer system to still use this powered Bose sub? I am thinking.... Either there is a shared ground and left and right speaker signals or there is only one speaker (-&+) and the third smaller wire is for turning on the powered bose sub like and "acc" or "amp on" +12v lead. Any ideas? My next post will be how to connect my amp to the Bose speakers So over my head!

Re: Help.... Its a mess..... Where you ever able to figure out the wires. I am going to attempt to install a Double Din Kenwood HU this weekend in my 2004 911 C4S Bose (Most fiber system) and am going to try bypassing the fiber Bose amp but wanted to know if the existing Bose speaker would sound OK with just the HU powering them or if I got an another amp would the speakers still sound Ok with the difference of resistance? Also, has anyone played with adding resistors to the mix to try to match the impedance? Thanks. Joe