Listening for speaker phase

Hi,

Someone told me a way of determining if there was a problem with the speakers being out of phase by using the faders and just listening to bass levels, but I can't remember it. Does anyone know how to do this? Do I need a test signal cd of some sort? And is there maybe a test signal that can be downloaded from the net (hahaha - for free, of course).

Thanks.

God, I don't know how many times I have gotten into a customer's car and found the speakers out of phase. And the customer didn't even know it!

Simply listening to the Bass while turning the balance and fader will work, but then you have to figure out which one is properly connected. Is it the left, or the right? It won't matter which one you switch, because then they will both be working in the same direction. But are they still correctly phased? Maybe, maybe not. And will they be in phase with the rest of the system?

The easy way to make sure is check the wires. But that can't always work unless you know the wires haven't been spliced somewhere. Check em at the amp or source, then at the speaker terminals.

My old time reliable method was to enlist the eyeball of a friend (or fellow installer, or the customer, or the salesperson, sometimes even the owner), taking a 9-volt battery (standard equipment in my tool box) and pop the speaker wires momentarily (with the wires disconnected from amp or head unit of course), having the eyeballer telling you which direction the speaker cone travels. Forward movement indicates correct polarity. Bend the positive(or negative) lead over to mark it for reference.

If you don't have an assistant, then use your ears. Taking your trusty 9 volt battery, then holding both L & R speaker leads at the same time touch them to the battery, listening to tonal depth of the popping noise. Do this a couple of times so your inner ear remembers. Then reverse one set of the speakers leads and repeat the popping. You will notice a difference in the depth of the pop. If it now sounds shallow, then the speakers are now out of phase. If it sounds deeper the second time, then the speakers are now "in-phase". At that time, I usually bend the positive lead over as a way to mark it, if I am not connecting it at that time.

Some people will say that using a 9 volt battery could blow the tweeters. I did it this way for years and never had that happen. The crossover network will block the DC.