Testing Phase of Speakers

How can a make a test CD?

A little OT but figured you guys would be able to help…

I put a new cd player inmy car yesterday and the stock player I took out didn’t have any labels on any of the wires or the plug.
I had to snip the wires and connect the plug for the new deck.

Figured out all the wires except for the +ve/-ve for the front speakers.
I worked out the back ones by getting a mate to look at them from underneath through the boot whilst I touched the wires to a battery.
Can’t see the front ones as they are in teh door and I don’t wnt to take the door apart.

So we tested a couple of combinations and went with what we thought was the best.

My question (finally) is - what would be the best way to put a test CD together to test the phase of the speakers (left to right and front to back)?
I can generate different tones in Cool edit (wave shape and frequency) so I thought there must be some way to generate certain tones that would highlight phase problems and I could play them back through the car deck and see if they sound right.


If you record pink noise from cool edit onto a cd it should sound “bass light” if the speakers are out of phase, not sure if it will tell you the whole story with four speakers but its worth a try.

A simple idea borrowed from the 70’s “Stereo Test” of the Finnish national broadcasting company:

Record some speech (human ear is very sensitive to human voice, understandably) as stereo, panned dead center. Then switch the phase of the other channel for a part of the recording (where the speaker clearly indicates what’s happening).

If the speakers are in phase, the first part should sound, well, normal. The second part should sound like it’s coming from a very indistinct direction.

Thanks for the suggestions guys.
That idea of actually recoring something out of phase is a good idea Mwah.
So simple and will save me havine to swap the leads around to test


Yep, Mwah has a great suggestion.

Any good music source, with cymbals and voice, should work if it’s mono. Make mono waves of your favorite stuff (stereo format - everything dead centered), and burn them on a CD. When you play it the sound should appear to come from the middle of the speakers. If it sounds like it’s from the speakers themselves - out left and right, or front and back - they the speakers are out of phase. Move around to get your head in the middle of the speakers. The difference is usually very obvious. Work with just two speakers at a time. If it’s not too obvious flip the polarity of one speaker and listen again.

It’s hard to hear phase when the source is just a sine wave, or the frequencies low or high, but pink noise is generally ok. Music you are familiar with is better.

Also, keep in mind that some folks can’t hear phase differences very well. If you are listening to a mono source and can’t tell the difference when only one of two speakers has had the phase flipped you might be one of those that needs another set of ears to do the listening. Folks deaf in one ear might not be able to hear the difference, but that doesn’t necessarily prevent them from doing great mixes.

One other thing to consider is if the speakers use a crossover. These can add phase shifts, but as long as both speakers are wired the same the method I suggested will work. When it won’t work is in two or three way systems that have a single mid or tweeter, or woofer, wired incorrectly in one speaker and it’s correct in the other. That would mean the woofers could be in phase but the tweeters out of phase. Flip just one speaker and the tweeters will be in phase and the woofers out. I bought a used pair of JBLs at a pawn shop that ended up being wired that way. It was really strange until I figured out what the problem was…so make sure the woofers and tweeters are wired correctly first.