Quote:
Originally Posted by LimitedSlip
The following diagram shows how the dash and door speakers are wired. The dash tweeter and mid-range speakers are both 4 ohms. These two speakers are also essentially wired in parallel with the input to the trunk amp. Together, this presents a 2 ohm load to the HU (assuming the input impedance of the trunk amp is somewhat higher than 4 ohms - which is likely). So, the HU front speaker outputs are driving all six speakers with an amp between the head unit and the door speakers. This means that with factory wiring, whatever adjustments (tone, balance, delay, etc.) that you apply to the front HU output will be applied to all six speakers (Not ideal). If you want to deal with the dash and door speakers individually the best approach would be to run new wiring from the HU to the doors thus bypassing the factory amp in the trunk (FYI: Running new door wires is a bit of a challenge).
The rear side panel speakers are driven separately, directly from the HU and are identical to the dash midrange units with two exceptions:
1. The mounting brackets.
2. The fronts have an additional low-pass filter capacitor to block the high frequencies that the tweeters should handle.
(Thanks to @ MugsBRZ for the speaker pictures.) |
Actually, those capacitors on the dash OEM mid-range drivers are acting as HIGH-PASS filters to filter out LOW frequencies at about 4kHz @ 6db/octave. This is so the mid-range drivers aren't overdriven into distortion by attempting to play frequencies that the OEM door speakers were intended to.
Those OEM mid-range drivers should naturally roll off around the same frequency that the tweeters are designed to begin playing sound. The high-pass filters for the tweeters are rated at about 14.7 kHz @ 6db/octave.
Also, when you have separates in your system, they are normally rated as a set. For instance: a 4-ohm tweeter matched to a 4-ohm woofer in a matched set is rated at 4-ohms. The filters are what keep the set of speakers' impedance value at 4 ohms. To further explain this, if you had a 4-ohm 6" driver in parallel with another 4-ohm 6" driver with no filtration to act as a crossover for this set, you would have a 2-ohm load....on the other hand, if you were to add a high-pass filter at....let's say.... 5kHz to the first speaker, and a low-pass filter to the second speaker also at 5kHz, then that set would be rated at 4 ohms because the first speaker can't play much above the crossover point of 5kHz, and the other speaker can't play much below the crossover point of 5kHz. This would result in the total impedance value of the set to be 4 ohms.