Porsche wired the speakers wrong...Nice...

Hey guys! I was just replacing the factory speakers and wow what a surprise. Both back speakers were wired wrong! The tweeter is soldered wrong! Also two of them have capacitor on plus side, one on minus.... The front speaker was OK though. Am I crazy or did the do such a mistake from the factory? See:

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Maybe the rears in series are to offload the amp? And maybe it doesn't matter what side the capacitor is on? I don�t know, just speculating here.

Technically it's not correct. However, I'm really trying to wrap my head around the significance of everything from 1.5 KHz to 20 KHz being out of polarity from two speakers facing each other about 1 meter apart. The listener is separated from direct signal by the seats. The sound waves are bouncing around in the cabin reflecting off of glass and being absorbed by carpeting in sonically unrefined ways on top of that. Then add in road noise and calculate the front speakers combination of wave fronts and I'm questioning the significance. Surprisingly, or not surprisingly, this happens all the time in commercial audio. You'd think this wouldn't be a problem, but the first thing we do when we get a brand new PA system out of the box is check polarity. It makes me wonder what else is being flipped on all the other electronic devices in everything we own. Best,

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Best practices is to put the capacitor on the + side. However, because it's an AC signal it could go on either side. This is all best practices that we're talking about. Obviously this stereo was functioning for a couple of decades, assuming it came out of a 996, and the people in the seats enjoyed the music.

Speakers hooked up out of phase (polarity opposite each other) will cancel each other out. Not to an inaudible extent but it will sound much worse. Out of phase woofers will completely kill the bass response.

But for tweeters, it most likely doesn't make an audible difference. They typically work from around 2 kHz. Sounds travels 340 m/s so a 2 kHz wave has 2000 phase flips in that distance, so one every 17 centimeters. Unless the distance between the tweeters is just a few cm, there won't be any meaningful phase cancellation.

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So do you think this is from factory "we know, but it is OK"? I would be interested to see if others have the same "issue", if somebody still has factory speakers built in.....

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Yes, Porsche used reverse phasing for the rear speakers on the HiFI option. I have the schematic from the OEM shop manual and it even notes it. I personally don't like the idea of phase reversal in audio systems; therefore, I corrected mine with a multimeter. However, if you're wanting the stock setup, the rear speakers are exactly 180˚ out of phase.

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Now isn't that interesting. so those indeed are correct. Somebody thought that would make it sound better. There are so many variables and so much constructive and destructive interference going on at high frequencies from four locations in a small space I don't see how it would ever make a difference. IMO.

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It's not quite that simple. The capacitor is in fact acting as a 6 dB/octave high pass filter which causes a 90 degree phase shift at the cross over point, the reversed connection adds another 180 degrees for a total of 270 degrees of phase shift. The rear tweeters are closer to the ears than the fronts, at some particular frequency a pulse from both tweeters 'should' arrive at the ear at the same time in theory, good luck with the reality of the interior of a car with all of the reflective surfaces. More complex cross overs induce different phase shifts so it is not as simple as merely ensuring all positives and negatives are connected to the corresponding terminals on the speakers. I would leave them as per the OEM shop manual, OTH you likely will not even hear the difference in a car, try an experiment if you wish.

Interesting thread. I remembered there being something I found odd when I was upgrading a few years ago but until now had forgotten that it was that the rears were out of phase. I went with Focal speakers and if I had to do it over, I wouldn't spend that kind of money again. The interior acoustics of the car just don't warrant it and I don't listen to the stereo that much anyway.

99-01 with M490 sound has the rear speaker wires, wired 180* OUT of phase from the factory for some reason. Installed replacement speakers will also be 180* out of phase as well, unless they are re-phased with a cross pinned adapter or install speaker wires backwards

One argument that can be made for out of phase bass drivers is that cancellation happens at the midpoint the most. The listener behind the wheel is nowhere near the midpoint.

I am also in the middle of changing out the speakers. I already have an aftermarket Sony headunit. Sounds like because I will be removing the capacitors/tweeters, the speakers will go from 270deg out of phase to 180deg out of phase using the wiring adapters I have. Or should get the rears in phase by switching the pins on my wiring adapters? Would love to know what the brains-trust thinks. Thanks in advance.

I would leave the wiring the same as it was from the factory. It was out of phase for a reason, and I would assume the reason has to do with the �small room� effect of bass in your car and your positioning in that small room.