Well, last I heard, Doug was going to be offline until later this week. So you probably won't get an answer from him any time soon. But I think I can help, though.

I just happened to have experienced a phase problem day before yesterday, and I can tell you exactly what it sounds like.

Here's what happened: I just bought a new car, and I'm in the process of transferring all of the components that I ripped out of my old car. I'm doing it in little stages. The first step was to replace the cheap factory 6x9 rear-deck speakers with my bitchin' aftermarket 6x9's.

Well, the factory wiring on the speakers was not labeled +/-, and the color-coding didn't help, either. The factory speakers were likewise not labeled, and I don't have one of those handy-dandy Crutchfield wiring harnesses which takes care of the problem for me.

In the end, I'll be wiring my own amplifiers directly to my own speakers, so I'm not concerned with being able to wire them correctly when that time comes (all of my aftermarket components are properly labeled). But just for that evening, all I wanted to do was to get the factory radio working through those aftermarket rear deck speakers. So I figured, "as long as I get the phase between the left and right rear speakers the same, the worst that can happen is a phase difference between the fronts and the rears, and that's not as bad because the delay time difference screws up the phase between fronts and rears anyway".

So I just plugged in the wires, crossed my fingers, and turned on the radio. I set the fader all the way to the rear and played with the balance. Almost instantly I could tell that the phase was reversed on one of the speakers. I didn't need a special test track or a constant-frequency tone. Here's how:

The radio was tuned to a Jazz station, and there was a lot of plucked acoustic bass in the song. When the balance was in the middle, I could hardly hear the bass. The incorrect phase on one of the speakers caused the bass to cancel itself out when both speakers were playing the same bass notes. When I set the balance hard left or hard right, the bass came through loud and clear. I checked my wiring, and sure enough, I had wired one of the two rear speakers backwards. Switching the wiring on that speaker fixed the problem instantly.

In theory, if the fronts and the rears were similar in timbre, you could do the same thing in a 4-channel setup. But usually, they're not, so you might be out of luck in that case.

I assume that your problem is similar to mine, in that you're using the factory speakers and the factory speaker wires, and they aren't clearly labeled. One way to figure it out is as follows: Buy an aftermarket wiring harness for the head unit (mine is on order right now, which is why I couldn't do this yet). The aftermarket wiring harness should match up to your factory wiring plug in the dash perfectly, and it will have the speaker wires labeled +/- properly. Then, look at the color-coding of the wires coming out of the back of that factory plug. Those colors should be the same as the wires leading to the factory speaker connectors. Use that as your guide.

As far as your complaint that you're not getting "good separation", that can be caused by a lot of problems, not just phase. Incorrect wiring, an amplifier set to mono subwoofer mode, or simply the fact that in-car audio traditionally doesn't have good separation can all be the cause.

Now you also said that the sound is dead and boomy. That could be phase, or again, it could be any number of other problems. If this is your first time hooking up the Empeg, you may be surprised that its default EQ settings are totally flat. There is no bass or treble control, and the loudness is off by default. Many aftermarket stereos have their outputs tweaked a little bit, even at the default settings. So if you compare a flat-set Sony CD player to a flat-set Empeg, the CD player will probably have a bit more bass and treble there by default. After you fix your phase, play with the Empeg's EQ a bit and see what you think.

Tony Fabris
Empeg #144