spender

When I bought my 2003 C4S last fall, the audio system had already been extensively (and very nicely) upgraded - a Pioneer Avic Z3 with GPS, iPod, and Bluetooth had been installed (very very cleanly), along with an Alpine MRP-F250 amp (40 watts RMS x 4) in the frunk (Crutchfield on their website says that this is their all-time best selling and best reviewed car amplifier). (I'll post some pictures later today.) The old Porsche amp (under the passenger seat) was apparently just removed.

The one thing that was apparently not touched was the speakers - my car came with the 6 speaker "hi fi" system (the 2 dash and 2 backseat speakers are the non-Bose Nokia "components", as well as the mini-subs in the 2 doors). The system, as it now stands, has great functionality and does everything I want (it overall has more functionality than the factory nav system in my friend's 2011 C4s), but doesn't sound as good as it should - most likely due to the factory speakers. I listen to a wide variety of music, and while a full sound is important to me, I'm definitely not one of those kids with the sideways caps that wants car-shaking bass.

I've recently decided to switch out the factory dash and backseat speakers with Infinity Kappa 42.9i 4" speakers, these are very well reviewed as pretty much the best 4" speaker you can get without going crazy on price.

However, once I put these speakers in, I am not sure how to fine tune my amp. I don't know how the 6 speakers were connected to the Alpine 4 channel amps, but I think that the front speakers are on channels 1&2 by themselves, and the backseat speakers and the door subs are together on channel 3&4 (there are only 8 speaker wires leaving the amp, so there must be some kind of a splitter/crossover downstream from the amp). As it stands, channels 1&2 have the HP filter turned on at the amp, and channels 3&4 have the LP and Bass EQ turned on - so I am again assuming that the door subs are on channels 3&4.

Frankly, I'm not really willing to start taking things apart to try to figure out how the speakers were wired to the amp - anyone have any suggestions for me as to how I can figure this out? I'm going to try playing around with the fader controls on the head unit this afternoon with a really bass-heavy song.

Also, once I do figure this out, anyone have any suggestions as to how I can fine-tune the amp?

spender

Here's some pictures (from the original dealer advert), I'll post some better and higher-resolution ones later on:

spender

Here's the wiring diagram from the 996 manual, showing the various speaker hook ups for the "hi fi" package with digital sound. It looks straightforward enough, except for that part about the rear speakers having their "phase shifted by 180 degrees" (i.e. the connections are reversed, but only for the two rears).

I know a tiny bit about why you do phase shifts on speakers, but would love to hear from someone who has insight on this specific phase shift in the 996. Thanks!

jeneric996

Your system will be difficult to decipher unless you have the specs from your aftermarket setup. As you mentioned you can play with the fader/balance. Alternatively, you can disconnect the speaker outputs from the amp one by one and see which speakers are affected.

Another way (old school style) is to disconnect the outputs at the amp and one-by-one test each positive and negative wire with a 9-volt battery. Have someone in the trunk apply the low voltage and you can listen to which speaker moves.

As you also mentioned, I suspect your amp’s 1 and 2 run the dash and rears while 3 and 4 run the doors. However, the aftermarket installer could have used the power from the headunit to run the rears.

Another concern is whether the speakers are in series or parallel which will affect the load (ohm) ratings. This occurs when you have two speakers connected to one channel. You generally put two speakers in series to increase the ohms and parallel to decrease the ohms.

Remember to mark your wires and take a pic before you unplug and test the wires.

spender

This is very helpful info and good suggestions, jeneric996, thanks! Given the clean installation that the previous installer did, I'm loath to start opening the dash and so on. I think your idea of disconnecting cables at the amplifier is a good one.

I hadn't considered that the amplifier in the Avic Z3 head unit might be getting used to drive the door subs. According to its specification manual, the Z3 has power of 50W x 4 (22W RMS), or 50W x 2 and 70W for a subwoofer. So there is certainly more than enough power there to drive the door subs, especially if the Alpine amp is doing all the work for the dash and rear speakers. The head unit itself has a hardware setup page that allows the rear output / preout to be set to "Subwoofer" as well. The Z3 has a gazillion hardware settings and whatnot, so this should (in theory) make it easier to map out how the system is installed (or it could just confuse me more).

This morning, in playing with the fader, I was able to discern two key things. Firstly, fading all the way to the front, or all the way to the rear, did not appear to affect the door subs. Secondly, if I turn off the "Sub Woofer" control on or off at the head unit, it does turn the door subs off completely. So this tells me that the door subs are most likely wired directly to the head unit (I am pretty sure that if they were going through the Alpine amp that I wouldn't be able to turn them off completely at the head unit). I guess that what is confusing me here is that channel 3/4 on the subwoofer is set up as though it is powering a sub - it has the LP (low pass) filter on, a crossover setting of 75Hz, and the "Bass Eq" function turned on. If am able to figure out that the amp is powering the subwoofer on its own, I would assume that the settings for the amp should be the same for all channels - as the dash and rear speakers are the same - but maybe the Alpine amp's settings have just been configured incorrectly.

I think the only way I will be able to confirm is this is exactly what is happening is if I unhook all the speaker cables from the amp, and it results in only the door subs still making noise.

RF5BPilot

What's the purpose of phase shifting the rear speakers?

jeneric996

It sounds like the headunit’s sub RCAs go to the amp’s 3 and 4 channel and then to the doors. The factory door speakers are mid/subwoofers. You mentioned the amp’s 3/4 are set to LP.

I am less unsure about your dash and rear setup. You mentioned full fade front and rear; thus, they are using separate channels. Check balance (left to right).
The system might be: channel 1 drives the fronts in parallel and channel 2 drives the rears in parallel. This will decrease the ohms and provide more power. If your speakers are at 4 ohms, placing them in parallel will drop to 2 ohms. The amp can handle this.

I am currently using my dash and rears with no pass setting (full). I used to have them on HP (high pass) but it did not sound rich/full. Since you changed your speakers, experiment with the HP and no pass settings. You may also want to increase the LP (for the doors) to around 200 to 250 Hz (or even up to 300 Hz) to get more mid bass frequencies.

spender

Further to my last note, and as suggested by jeneric996, I experimented by taking various wires off the amp - and what I found sort of surprised me.

Turns out that Channels 1&2 of the amp are wired to the front speakers only, and channels 3&4 go to the door subs. The big surprise is that the rear speakers are running off the amplifier in the head unit itself - when all the outputs were removed from the amplifier, I was surprised to still hear sound coming from the rear speakers when I turned the car on! This does not strike me as ideal, and I'm not sure why they did it this way. Seems to me that it will be a big challenge to get the front and rear properly balanced. and phased.

The other thing I thought was odd was that the (+) connector on channel 2 was not hooked up - although it was stripped, it was just tucked under the connector in a fashion that appeared deliberate. After my little experiment described above, I decided to hook it up to see what would happen. I immediately noticed that the front speakers are quite a bit louder than the rears - so I'm guessing that the installer may have deliberately disabled Channel 2 on the amp - but I'm just guessing...

jeneric996

Sounds good. You generally want the sound to be in the front center section/area rather than in the rear. Hence, the main reason the rear speakers have weaker power to them for just a fill. You can even get by with cheaper speakers in the rear. You can then adjust the fader to your liking.

I set up mine with my Alpine PDX-5, 5-channel: 1/2 drives the dash on full, 3/4 drives the doors on LP @ about 380 Hz, subout drives the Bose box in parallel LP @ about 140 Hz , and the headunit's power drives the rear. Sounds better than stock but far from my old school days; a/d/s amp & speakers all around, Kicker solobaric sub, and a Denon CD headunit with a Precision Power active crossover.

My next upgrade will most likely be the dash speakers. How do you like the Infinity 4"?

spender

Thanks again jeneric996 - your input has been invaluable. There really does not appear to be that much information out there about sound system upgrades for the 996.

I'm still curious about the reverse phasing of the rear speakers on the original wiring diagram. If this is done in the OEM hifi setup, should it not be done with an aftermarket system too? I guess I'm just curious as to why they did it this way, Porsche engineers usually have a good technical reason for doing things, and I would have thought it would be the same with this.

RF5BPilot

Normally, if a speaker is out of phase, it (in effect) has a lower volume. By intentionally running them out of phase, you can drive them harder, but the effect is still lower volume.

My guess is that the rears were efficient enough that when driven hard enough to make them sound good -- they overpowered the sound field. Reversing the phase let them be driven harder, producing richer sound, but (in effect) lowering the volume so they functioned more as fill sound rather than overpowering the sound field.

spender

My Infinity Kappas arrived yesterday, so I gave the upgrade a try last night. I have to say that rather than cut my speakers apart like in that Youtube video, I decided to give the "speaker rings kit" that is available on the net a try. I have to say that this was a big disappointment, and the "speaker rings" did not work well. I have done lots of interior and stereo work on every car I've owned, and this kit is simply too rough for my car. Even after spending hours with a dremel, I was unable to get the ring to fit (but the speakers look like they would have)... I spent about $100 to get a set of four of these rings into Canada, and I am sorely disappointed. My advice to anyone considering these is to save your money. I hate to badmouth a product that is sorely needed, but I would rather save my Rennlist brothers the aggravation of having to deal with these pieces of junk. Too bad Porsche has made it so difficult for its owners to upgrade their sound systems.

Anyway, on another note, when I removed the rear passenger speaker, I immediately noticed that there was a loose weld on the tweeter of the component speaker - the wire was connected but it could move (clearly this would have caused the bad connection and buzzing I occasionally heard). I re-soldered it, and I'll be darned if my system doesn't sound substantially better!

So, I'm returning the Infinitys, and am putting this project on hold for a while.

jeneric996

Sorry to hear about that, Spender, but thanks for sharing. I, too, would like to avoid hacking the factory stuff.

perryinva

Here are some pics of my Infinity Plate repalcements using the speaker grill blanks from Sunset. Extensive use of the Dremel to open the grill openings (little saw attachment) and to trim the plates to match the contours of the OE speakers. About 1/2 hour per speaker, once you knnow what to do. I used the 2 screw stand-offs, shortened appropriately, between the tweeter and woofer, and rubbery "hot glue" that I bought a ton of with a Ding King Dent Puller set. They are like a fast set RTV stick when done. The whole set sounds great, fits easily, and I still have the OE's if I ever want to swap out for whatever. I just made sure I left enough wire onthe connectors to splice/solder them back on if needed. I wrapped the crossovers in foam and inserted in the cavities so they wouldn't rattle around. Very pleased with the results. Study each pic carefully if you decide to copy them. Every cut is that shape for a reason, especially the extensive clearance around the 2 dash mounting screw holes. You need that much in order to fit flush with dash like the OE. Sorry for the inconsitent crappy pics, old camera.

jeneric996

Thanks, perryinva!