07 Cayman - thoroughly confused about replacing Bose HU - leaving Bose speakers

All, sorry for yet another thread on this topic. so, I bought the Euro Motorspeed bezel kit, plus this: Add $25. Optional BOSE removal kit - If you are adding a new radio, but removing your BOSE amplifier, this kit will come with additional hardware to remove the BOSE amplifier. my intent was to replace the HU, and either let it drive the speakers or add a small amp (to drive the original speakers). I went to a local audio shop that had a Black Friday flyer and got talking about what I was up to. The guy there seemed knowledgeable... and said most of these Bose speakers are 1.5 ohm and require a special amp to handle that small load. If that is true it certainly makes sense, but I have seen nothing in scanning the threads off an on for months about problems swapping out the HU and keeping the original Bose speakers. I know I would lose the center channel and such, dont care about that. Any help is appreciated! thanks, YOLT

search is your friend http://www.planet-9.com/987-cayman-...7-cayman-boxster-electronics/56234-latest-head-unit-replacement-avic-120bt.html http://www.planet-9.com/987-cayman-...ayman-boxster-electronics/45494-cdr-24-w-bose-kenwood-dnx6960-self-install.html

I just got done replacing my head unit this evening with a Pioneer NEX 8000. I did use the Bose kit from Euro Motorspeed and left the Bose in place. The kit was super easy to install just very time consuming. Do yourself a favor and keep the bose . If you bought the Kit from Euro Motorspeed I would ask Loi if he could upgrade you to the retain Bose kit. I spoke with Loi 3 times during my install and he was very helpful.

I just recently replaced my H/U using the Bose integration kit. I put in the Parrot Asteroid Smart. Like ncthirteen said, it went pretty smoothly. If you do decide to replace the Bose amp then yes you will need to buy an amp that puts out low enough ohms. I wanted the ability to reverse everything if I ever sold the car. Hear is a another thread. http://www.planet-9.com/987-cayman-boxster-electronics/80561-parrot-asteroid-smart.html

Just get in touch with Loi, he is the best!

Hi, I replaced my Bose HU with an NEX8000 using Euro Motor Speed's kit. Was easy to install and Loi has been super helpful. My ongoing issue is the poor reception. We have confirmed the antenna booster is getting power. If I revert to old HU the reception is fine. With Pioneer it is terrible. We have swapped out the Pioneer , wires, antenna adapters, etc. Anyone have any ideas? Very frustrating! Thom

Hmm... I have an older Pioneer HU using Euromotospeed's kit. No issues with reception, but it may be where I live. Are you in an area that has weak reception for most of the stations you like?

How did you confirm the antenna booster is getting power. Did you apply power to it or are you assuming it's getting power via the radio harness?

I just plugged it into the harness. Here's another question / thought. I used the NAV-TV Most-Hur adapter so I could retain the Bose amp and speakers. In some instances of retrofits, I read about grounding issues without the adapter. Did you pull the Bose amp and go all analog? If so, could part of your problem be a grounding issue?

I used the Most-hur adapter to keep the original amps.

Still having this trouble. Loi has been really helpful and even asked me to send him my wiring harness so he could double check it. This Pioneer has the worst reception that is is pretty much unusable. Loi actually suggested trying a different HU. Can the Pioneer really be the issue? At this point the cd-24 is a better radio solution. I have considered taking it to a local car stereo place, but not sure they would know much more than all the info I have learned on this board and from Loi.

I have measured (professional Agilent 4 lead impedance instrument) the door speakers (Woofer & Mid-Tweeter) along with woofer TS parameters in my 2008 with BOSE & NAV. The woofer DCR measures 0.92 ohms and surprisingly the mid-tweeter measures at 1.96 (close enough to 2) ohms. (I have also measured the BOSE applied equalization (electrical at the speaker terminals) - but that is another story). I will try to explain why most amplifiers (much less head unit amplifiers) should not be used to drive the BOSE drivers. The power formula is P= V^2 / R. Since the car voltage is no greater than around 14 volts, even with BTL (differential) output, the power available is limited with a 4 ohm load. Most all external amplifier manufacturers incorporate a voltage boost in their amplifiers to raise the available supply voltage (the "V" in the formula) and therefore get increased power into 4 ohms. BOSE does not boost the supply voltage (this is the more costly method) but instead reduces the impedance of the driver (the "R" in the denominator of the formula). Now the current is used to provide the higher power (another way to express power : P= I^2 * R) You can see from the formula that reducing the driver impedance can also increase the power delivered to the driver via increased current. However, there are two problems with this approach..... 1. The amplifier is now required to deliver the needed current to drive these low impedance loads. Unless clearly stated on the amplifier that it has the capability (current) to drive such a high demand load, that amplifier should not be used on BOSE drivers. Some may report success but the amplifier is likely operating in it's current limit mode most of the time (lets call that the high distortion mode). 2. To conduct the higher current without appreciable losses, the thickness of the associated wires must increase significantly. Note that this includes the power wire originating at the battery (and ground) via fuses, switches, connectors etc. to the (high current) amplifier as well as the wires to the associated speakers. Consider for example, if the speaker impedance is 1 ohm, lots of power can be lost in the wires (and connectors) if they contribute just a 1/2 ohm. This is my fourth car that had the BOSE system built in and in all of those cases, the wire gauge insufficient and consequently introducing losses.

I believe, the importance of thick speaker wires is overestimatet I have replaced the original Porsche speakers with high power (high current consumption) speakers and high power amplifiers but kept the original (thin) speaker wires and I do not have any problems with it. Keep in mind, the resistance of an speaker wire e.g. 2m long and 0,75qmm thick (typicaly used in cars) is 0,0459 Ohm. This is appr. 5% of the impedance of the 1 Ohm speaker and appr. 1,25% of an typical 4 Ohm speaker. Increasing the thicknes of this wire would decrease the total resistance only very less / not significantly