Factory 2005+ Pioneer 6CD/MP3 unit with built in subwoofer outs
I posted previously on getting the Pioneer 6CD/MP3 player from a late Ranger and installing it after repairing it.
I have a EL8A-HP Bazooka tube in the truck, and I was running it off the rear speakers using the high level inputs on it.
But when I put in the Pioneer, it has an electronic crossover and subwoofer outs, so it did not have much bass at all getting to the main speakers. Turning the Bazooka tube all the way up gave some thump, but it was not right -- although the mids and highs were much improved by the Pioneer head unit.
Today I wired up the subwoofer output from the Pioneer head unit and man what a difference. I used the low level inputs of the Bazooka for this since there's not enough drive for the "speaker level" high level inputs.
Now, if you are going to do this, be advised that Ford did this right, unlike most audio companies INCLUDING some high end ones. This could make it a bit tricky to get a clean signal to your subwoofer amp, but I'll suggest some ways why and also why RCA connections stink for car or professional audio.
Too many audio systems use what is called "unbalanced" audio, where one of the wires carrying the signal is also ground. This is in contrast to "balanced" audio where ground is only a shield, and the signal is carried by two wires neither one of which is ground. This is how professional audio is done.
The beauty of a balanced input is that noise that hits both wires gets cancelled in the amplifier. A signal must be present at opposite polarities between the two wires to be amplified, but environmental and ground noise hits both wires with the same polarity and gets cancelled on the receiving end. Refer to a tutorial on balance audio somewhere if you need more understanding -- but it works, lol.
Bazooka's inputs are actually "balanced" inputs that do not reference ground which is a good thing. So you can hook directly into them. They don't "care' if you ground one side, but they don't require it.
But if you try to connect this to some amplifiers where the ring of the RCA is ground, you may have a problem. Some amps actually are balanced inputs but have RCA connections, so it doesn't matter, just like the Bazooka.
Let me show you what I'm talking about. Here is the subwoofer output connector pinout from the Ford head units for some years now (see diagram at bottom from an Explorer). This is the view looking into the connector on the HARNESS. The connector on the headunit is the "mirror image" of this one.
Pins 1 and 2 are the mono subwoofer feed. Pin 2 is (+) polarity, and pin 1 is (-) polarity. Pin 3 is ground BUT IT'S ONLY A SHIELD. It should be connected at EITHER the head unit end OR the sub amplifier end but NOT BOTH (to prevent ground loops). Pin 4 is a "turn on" signal to the Ford factory subwoofer system but there's a catch: it's only a 5 or 6 volt (approximately) signal so if your sub amp needs a 12 volt turn-on signal that won't work. I'm using the "auto on" function on the Bazooka right now.
If you need to hook into an unbalanced input, you can use a "ground isolator" of the type that is a transformer. They work quite well and aren't expensive in general.
Thought I put this out in case anyone wants to use one of the headunits that has the electronic crossover with a non-factory subwoofer.
If you have 2 RCA inputs on your subwoofer amp, you may need to tie them together depending on if your amp is a mono amp or not. Mono amps may have two inputs, but they are just added together inside to make a mono signal. You only need one input jack on those amps.
Low bass is non-directional, so it's not an advantage to have a stereo sub mix, as you probably know (hence why most subwoofer systems are in fact mono in nature even if driven with stereo amps).
It's worth the trouble though: my little system sounds WAY better than it did and I'm quite happy to have the sub out on this unit. It sounds better than the older CD6 I had did with the sub running off the speakers, even though the speakers weren't bass-blocked or crossed-over in any way at the headunit.