[earwig]

I been having problem of some noise in the background for years from this woofer and just had discovered the wires are reversed connected.Would that have done damage to the voice coil?

[Russell Dawkins]

If you mean the connections were reversed - no. That would just make the cone move in when it should be moving out - that's called reversing absolute polarity and it has absolutely no effect on the health or well-being of the woofer.

[markC]

Your bass must have been suffering terribly, as reverse polarity cancels bass.

[earwig]

Yes someone at the factory where the speaker was made must have soldered at the speaker terminals with the negative wire where it says( + )and positive wire where it say(-).So if the speakers are moving backwards when it hits a very low bass note it would make a funny awful raspy background noise.Mayby it slamed the cone inwards and the voice coil got itself damaged.No wonder it did that! Thank You very much now I know whats being bugging me for couple of years. 

[Russell Dawkins]

  ... uuhhh ... the only way this could contribute to bass driver damage would be if the speakers were in close proximity to each other and really canceling bass as a result and you were to turn up the volume grossly in an attempt to compensate - but this is all very theoretical and very unlikely.

As I said in my first answer "reversing the polarity of the woofer would have absolutely no effect on its health and well-being".

The cone of the bass driver wired in reverse polarity is no more likely to go further backwards when a "very low bass note" comes along than one wired correctly. It may go forwards when it should be going backwards, but that makes no difference and in any case it has nothing to do with damage to a voice coil by over driving.

My guess is that the voice coils have been over-heated and the adhesive has partially let go and the enamel has become black and crispy and thicker and you have a case of "voice coil rub" which is a common consequence of being intemperate with the juice. Both kinds.

Are you saying you have reversed the connections and the noise has disappeared?

[earwig]

Thank you! in any case I just now replaced the woofer(same make as original) making that rubbing sound and correctly wired the new woofer up and the speakers sound punchier than ever in bass. The noise is gone and the music is working out to sound much better too now that I corrected the problem.

[Russell Dawkins]

Did you reverse the connections on the old woofer and have the noise go away?

Did you check the woofer in the other cabinet to make sure it is connected the same way as the new woofer?

If the woofers are wired oppositely you will get out-of-phase bass which will have a big effect on the sound, especially if these are 2-way type speakers. 

You will also affect the sound negatively if the woofers are wired in a way which is the reverse of what the design engineer intended, in relation to the tweeter.

However, if you blew both tweeters out at the same time as you nearly fried the woofer, then there should be no problem, assuming the speakers are 2-way types.

Anyway, if the new woofer is just a generic replacement woofer and not an exact duplicate this is all academic and we are not really on the same page.

[JimJ]

Thank you! in any case I just now replaced the woofer making that rubbing sound and correctly wired the new woofer up and the speakers sound punchier than ever in bass. The noise is gone and the music is better too.

Just something to keep in mind, the way it was done might not have been "incorrect"...as wiring a driver in a speaker out of relative phase is commonly done. As the previous post mentions, opening up the other one would let you know definitively.

[markC]

Just to clarify. The bass would only cancell if 1 not both woofers were wired out of phase. I totally agree with Russell on the health of the woofer being wired out of phase or not.

[markC]

Just something to keep in mind, the way it was done might not have been "incorrect"...as wiring a driver in a speaker out of relative phase is commonly done. As the previous post mentions, opening up the other one would let you know definitively.

Quite true. It is, however, more common to wire tweeters out of phase rather than woofers.

[Russell Dawkins]

We don't know how what was referred to as the "negative wire" was identified as such, nor do we know the identities of the speakers or the amplifiers.
 
I have seen where demo speakers arrived at a store I worked in, having come through another dealer on a demo circuit, with the woofer of one of the speakers in inverted polarity. You could tell just by walking by them when they were playing. They were Martin Logans with cone woofers and at the time we wondered whether they came from the factory that way or if it had happened at the previous dealer.

In that case we assumed as you suggest; that the red input terminal went to the + side of the woofer and any intentional inversions would be in relation to a conventionally wired woofer.

[face]

Did you check the polarity of the woofer in your other speaker? 

Depending on the crossover slopes used, it's very possible that the woofer should have been wired out of phase.  By reversing it, there may appear to be more bass somewhere else, but you probably created a huge dip in frequency response at the crossover point.