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Hi CountachQV (and any others) - I'm UK based but, with help from the thread and members here, including from Mitch but with particular thanks to John Aplin (who helped me offline, as well as through his posts here) I have also carried out the conversion. I got snagged-up in two particular areas that you might want to know about. Anyway, a number of tips.
Firstly, make sure you get the right type of PCM 3.1. One from a 981 Boxster/Cayman or 991 will do (they are virtually identical). As you're US based, get one that is US specific (the small rectangular label on the side of the unit will tell you if the unit is for the US or is world-wide spec). By looking at the larger label on the underside of the PCM you can see the spec of the unit - to check that it has nav (remember that there is a PCM version without!), whether there is a telephone module needed (you don't particularly need this; all PCMs have inbuilt BT capability) and - importantly - whether there is a digital/XM tuner built in as well as FM. I'll come back to this... Be aware also that PCMs built after November 2011 (I think that's the date; it's around then) have a built-in hard drive to give you Jukebox capability, so all other things being equal, these later units are a better bet than the earlier ones; the build date is also shown on the smaller label. As you probably know, PCM's are advertised on eBay but a tip is also to look for 981s and 991s that are being broken after accident damage - so hunt out written-off cars and talk directly with breaker yards (online) as well as look on eBay.
Physically fitting the unit is straightforward, as per the notes here. You've picked-up on the need for two mics and the options of GPS antenna placement. You can choose whether or not to hook up the full USB socket or just stick with the AUX as per the standard car. In my experience, without coding you will end up with just FM radio, CD and USB capability; any other functionality (so BT phone and streaming, navigation, digital/XM radio, etc) will be blocked after a few minutes of operation unless the car/unit is recoded.
In relation to coding I had simply first class support from the chap I bought my codes from, Nikita, who is based it seems in Russia. Clear pricing, totally reliable and very, very quick (when I needed an additional code he sent it by return of mail even before I had made payment via PayPal). Happy to recommend him and to supply his contact details via PM. Once you have the codes, your dealer will need to enter them using PIWIS and activate them for the car; it seems to be a bit of a two-way process with the car initially rejecting the new components until it's been told that everything's OK. A bit like a medical transplant op, I guess! The codes are VIN-specific, unique to your car and I ended-up needing a number of codes - one to allow the PCM unit to be recognised and activated (which, from memory, allowed BT phone and streaming to come back), one for navigation (to allow access to your regional maps) and one for the digital/XM radio. Because I wanted everything to look 'factory' I also got the code for the correct 'boot screen' - nothing more embarrasing than being in, say, a Boxster and having a GT3RS screen-logo appear on start up (well, probably having it happen the other way round would be worse).
Now for the two problem areas. And this has taken me ages...
Firstly, radio performance. You'll have read that FM performance is reduced with the retrofit when compared to the full PCM factory fit, even if you fit the full 'FM Diversity Controller' to combine the two antenna feeds into a single wire for plugging in to the back of the PCM. (By the way, wiring-up the 12V power supply to the Diversity Controller from the Quadlock connector on the back of the PCM is virtually impossible to figure-out and do until you know how, then it's all very straightforward - again I can help if anyone's stuck, including providing the part number for the power-supply lead that is needed and which is nigh-impossible to uncover, even from Porsche). But in my experience, performance on FM is reduced to being only borderline acceptable, particularly in traffic or city environments. That said, another chap (hi Craig!) based in South Africa has gone down this route and reports that everything is fine, so you take your chances!
Anyway, I finally managed to get to the bottom of this. It transpires that factory-fit PCM uses an FM diversity system which relies on four antennas that are part of the factory spec - two located (embedded) in the LH of the windscreen and two on the RHS (you can see the antennas embedded in the glass, close to the A-posts) - and the signals from each pair of these antennas are routed to the PCM firstly through an Antenna Amplifiers (there are two of them in PCM spec cars, one mounted on each of the LH and RH A-posts respectively) to the Diversity Controller and then on to the single antenna input socket (a Fakra socket) on the back of PCM. With base CDR cars, there is only one pair of antennas which are embedded in the RH of the windscreen, and the signals from this pair are routed directly to the CRD head unit through a single (and unique, base spec-specific) Antenna Amplifier that is mounted on the RH A-post only. So essentially when you retrofit a PCM you are trying to make it work through a different antenna configuration (only two antennas and a single, base spec specific amplifier) from the system that it was designed to work with (two pairs of antennas, each with its own dedicated amplifier). No wonder it only sort-of works...
How to work around? Well, short of replacing the windscreen for one with the four antennas and then fitting the two dedicated Antenna Amplifiers (and I have considered this!) I decided to replace the FM-only PCM unit I had bought through eBay with another one, again sourced through eBay, that included the digital tuner (DAB) module. I then just added a simple DAB screen-mounted antenna and all was well; a 30 minute installation to get perfect radio after months (on and off) of working to perfect the FM installation. I know that you don't have DAB in the States but you do have satellite/XM - my tip is to make sure you go for it!
And then the final area of concern... When converting from base CDR (which has amplification built-in to the head unit), be aware that the audio output from the PCM is essentially low-level (line-level) and probably peaks at about 4V or 5V max. So it won't properly drive a standard OEM upgdrade/aftermarket audio amp and you need to find an amp that will take line-level (low-level) inputs. I used a Hertz D-Power 4 amp; I know that Jon Aplin used a BLAM unit - others are available, of course. But here's the thing; although I haven't managed to get formal confirmation, it seems that the audio output from the PCM is not 'flat' and so, by simply amplifying that and feeding it through the standard speakers, the results are a bit 'meh'. Listenable - but only just. Remember that the PCM units are usually connected either to a SPP (ASK) amplifier, or to a Bose amp, or to a Burmester amp and I suspect (actually, I believe) that each of these amps also contains some signal processing capability (built-in eq) so that the output from the amp is flat (flatish - you get my drift) even though the input to it, from the PCM, is far from that.
How to fix - well, I have finally nailed this just in the past few days; I added a small DSP processor (an Axton A500 DSP - look it up) that sits next to the amp and processes the signals from the PCM before they go in to the power amp. This unit has a 7-band equaliser built in and also some time alignment capability (like magic - really effective) and it is all worked via BT from your phone - very neat. At last, I seem to have high quality sound!
Un dernier point sur les haut-parleurs et les amplificateurs. Si vous avez une base ou une installation SPP, sachez que les tweeters avant sont câblés en parallèle aux woofers montés sur la porte (si vous avez uniquement l'audio de la base) ou aux médiums montés sur la porte (si vous avez SPP) et cela signifie qu'ils présentent une charge de seulement 2 ohms à l'ampli (chaque haut-parleur a une impédance nominale de 4 ohms; lorsqu'ils sont câblés en parallèle, ils se combinent pour produire une charge de 2 ohms) vous devez donc vous assurer que l'ampli de puissance choisi est évalué pour être sûr (c.-à-d. : stable et sans surchauffe ni déclenchement) jusqu'à 2 ohms. Certains amplis le sont, mais d'après mon expérience, la plupart ne le sont pas - choisissez donc avec soin.
Bonne chance avec ça. Le fil de discussion ici m'a été d'une grande aide et j'espère que ces notes supplémentaires vous aideront, vous et d'autres, à vous lancer dans cette voie de mise à niveau vraiment intéressante.
James
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Bonjour Monsieur, puis je installer un PCM 3.1 d'une Panamera sur une 991 équipée d'origine d'un CDR31 ? Merci pour votre réponse. Cordialement.
