Amplifier Upgrade for 2003 Carrera with PCMII & MOST Bus.

Okay so after days of research I have learned quite a bit about MOST (Media Orientated System Transport) System. The system is basically the same as a token ring Ethernet network. You can have many devices on the network that don�t necessarily talk to each other; they just share the same digital bus and if you disconnect one like Christmas lights they all go out. That seems to be the problem with respect to upgrading the amplifier. First of all I have not been able to find a MOST compatible amp for sale anywhere or even the mention of it. But even if there was it wouldn�t really matter because of the way the system works. The PCMII head unit has the address of the MOST compatible Bose amp programmed inside it. So if you were to install a new MOST Compatible amplifier it would not receive the signal from the head unit because it will have a different MOST Bus address. In the same way Computers on the internet all have different IP address. So I guess basically my question is can you connect the Bose amplifier in SERIES with another amp? On the Porsche website they talk about one 100-Watt switching amplifier with five additional 25-Watt linear amps. Can these linear amps be replaced? Oh yeah and i could be totally wrong about all of this.

i recently leased a tt with the bose radio. i tried to take my aftermarket amp from my previous porsche and add it to this car. both the dealer and an independent sterio shop that has tons of porsche experience told me that it is almost impossible to add non fiber optic compnents to the new car. whether this is entirely true or not, i can't tell you, but i left the sterio alone.

Keyvan, Please PM or email me for further information or to answer your questions. You may also search the archives, as I have posted on this topic before. I designed the MOST amplifier for Bose used in Porsche 986, 996, Cayenne. MOST is an interesting animal, conceived to allow for OEM integration of components. While the hardware is fairly straight forward, you are correct in that it is the software (primarily in the headunit) that makes it difficult to add a component without factory (Becker) software support. This is why it is doubtful that you will see an aftermarket MOST component for quite sometime. There are however interesting tricks which you can do, depending on how much work you want to do or what you want to accomplish. Please keep in mind that there are no longer wires (analog line level differential voltage signals) between the headunit and amplifier; so removing everything will also require substantial wiring to be added to the car between the passenger compartment and the front hood. MOST infotainment devices in the Pcars are very simple. The new 2004 Audi A8 is much more complicated with over a dozen devices on the ring. Next generation cars will have 20+ devices.

You've got PM Itc...I think, my browser timed out.

It is entirely possible to add components to the fiber optic system...but it has to be engineered properly. Talk to Rick Reus at Reus Audio in Orange, CA. He is IMHO the world's foremost expert on Porsche, Ferrari, and Mercedes audio systems. <a href="http://www.reusaudio.com" target="_blank">www.reusaudio.com</a> tell him Ryan Gaytan sent you. <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

Ryan, Could you please explain what "engineered properly" means? Also, do you know if in fact Reus has added a MOST device to the ring/network? Of course it is entirely possible, I do it for a living designing for Porsche (personal favorite), Audi (second favorite), Mercedes, GM, Nissan, Honda; however, without a substantial reverse engineering of the S/W protocol and/or Becker support, I do not believe that any installer in the US will be doing MOST systems anytime soon. If they did, I would certainly be impressed and interested.

I called them and they said that they keep the stock amp and reamplify the signal, can't sound that sound?

I dont know enough about technology to tell you if they can do a MOST system or not. But they did add amps and speakers to a 2001 MBZ S-Class fiber optic system and kept the stock head and CD changer. I asked him how he did it, and without revealing secrets, he said that they fabricate their own parts to put into the fiber systems. <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

It would appear that what they are doing is picking off the signals inside the amplifier chassis at the internal amplifier's inputs; where at this point they are analog, thus easy to feed into another amplifier's inputs. Nice job Reus Audio. This is fairly straight forward to do and leaves the ring in tact; the headunit has no idea that the external amp exists, as it is simply talking to the MOST amp. I still do not believe they are actively inserting a new device/node into the ring; from the user's perspective, the new amp/speakers have been 'added' to the ring and controlled by the existing headunit. There is the issue of the audio hequalization internal to the Bose MOST amplifier, but that is a topic for another day.

does engineered correctly mean that you have to spend a large amount of money, out of proportion to the upgrade that you are trying to make. in my situation, i was trying to upgrade my head unit and add more amplification. what they told me was that without spending tons of money, it was impossible. if you have to spend thousands of dollars in software/labor to install an $800 headunit, then it is useless to try.