A question for R.G. or anyone with speaker knowledge?

[boogietube]

Well, I  like the fact that R.G is saving this thread. I got a real kick out of the answers and learned a lot about speakers. I do have an old diploma in repairing computers (circa 1987 - the 8088 and 8086 cpu's-, haha) Anyway, I did study rc curves and understand impedance and reactive loads a bit.  I did think he was off his rocker. He called back and I feigned interest in what he was saying for a few moments...I then told him that the price was firm, and,  that from my knowledge, I was unaware of any test that could tell him the "shelf life" without first knowing the exact electrical characteristics of each speaker in the enclosure at the time of manufacture.  He didn't really say anything and later his friend called me and came over without a meter and purchaced the speakers (Yorkville PR315's) from me for full asking price. Strange that he didn't appear in person...I was looking forward to quoting some of the knowledgable answers that were presented here....would have been fun....

[Paul Marossy]

The same guy probably send his cables out to be 'broken in'

Ha ha. I bet they sound much better after they get "broken in". 

[George Giblet]

> He claims that a speaker will measure a lower resistance as it ages- and he can tell how long he will get out of a used speaker just with a resistance measurement

When you abuse speakers the windings can, and do, short to the winding next to it.  When that occurs the DC resistance drops and you can see it on a DMM.   You need to have a good idea what the DC resistance is suppose to be to make a decision.  Another scenario is say a quad box where you might find one of the drivers has a low DC resistance and you can speculate the drive has shorted turns.

An impedance measurement can tell you something more but not that much more -  an impedance measurement isn't going to tell you much more unless 1) you know that model of speaker well or 2) the speaker is badly damaged such that it causes a dramatic change in impedance.

Multilple abuses or severe abuse can make the DC resistance drop over time but the changes are more likely to occur at each instant of abuse,  not some gradual characteristic change over time!

As others pointed out there many things that can go wrong with a speaker.

[trendyironicname]

i wouldn't worry about it.  i doubt he'll be able to get his head out of his rear long enough to find his way to your house.

[R.G.]

...I then told him that the price was firm, and,  that from my knowledge, I was unaware of any test that could tell him the "shelf life" without first knowing the exact electrical characteristics of each speaker in the enclosure at the time of manufacture.  He didn't really say anything and later his friend called me and came over without a meter and purchaced the speakers (Yorkville PR315's) from me for full asking price. Strange that he didn't appear in person...I was looking forward to quoting some of the knowledgable answers that were presented here....would have been fun....

Too bad you didn't get a chance to tell him that you had taken his advice to heart and learned that on can "rejuvenate" speakers by chilling them in a chamber with dry ice over night, realigning the magnetic flux domains in the copper wire and relaxing the defects that build up with use. In fact you had done this treatment to the speakers and they were noticeably better sounding now, so the price had increased just a bit... 

[Mick Bailey]

I've recently had a pair of Peavey PA cabs and a powered mixer in for repair because the sound was distorting badly on one channel. First thing was to check the Scorpion 15" speakers - they had been stored in an outbuilding for the past two years. The voice coils measured ok across the terminals, but one speaker showed an intermittent short with the meter connected between one terminal and the speaker chassis, when the voice coil was moved gently by hand for a few millimetres.

I unbolted the magnet and the voice coil had been clearly rubbing in the gap, possibly due to damp affecting the cone. The wear was just enough to rub the enamel off the wire. Under power this was causing an intermittent shorting out of more than a third of the turns. Measurements showed that the voice coil had gone oval, as well as off-centre.

The other speaker didn't initially appear to show any fault, but the slightest downward pressure (with the speaker in its operating position) as the cone was moved showed an occasional short to chassis. Whilst the owner had not reported any problem with that particular speaker, it clearly indicated that there was a problem which would only get worse. I took the magnet off that speaker and the coil showed the very slightest abrasion to the winding as well as measuring oval.

Some research turned up that this is a fairly common problem with these speakers. It probably explains why so many companies sell replacement baskets for them.

Perhaps the guy is looking for this type of fault?

[FlyingZ]

...I then told him that the price was firm, and,  that from my knowledge, I was unaware of any test that could tell him the "shelf life" without first knowing the exact electrical characteristics of each speaker in the enclosure at the time of manufacture.  He didn't really say anything and later his friend called me and came over without a meter and purchaced the speakers (Yorkville PR315's) from me for full asking price. Strange that he didn't appear in person...I was looking forward to quoting some of the knowledgable answers that were presented here....would have been fun....

Too bad you didn't get a chance to tell him that you had taken his advice to heart and learned that on can "rejuvenate" speakers by chilling them in a chamber with dry ice over night, realigning the magnetic flux domains in the copper wire and relaxing the defects that build up with use. In fact you had done this treatment to the speakers and they were noticeably better sounding now, so the price had increased just a bit... 

Very nice, the hardest part would be keeping a straight face 

[Paul Marossy]

...I then told him that the price was firm, and,  that from my knowledge, I was unaware of any test that could tell him the "shelf life" without first knowing the exact electrical characteristics of each speaker in the enclosure at the time of manufacture.  He didn't really say anything and later his friend called me and came over without a meter and purchaced the speakers (Yorkville PR315's) from me for full asking price. Strange that he didn't appear in person...I was looking forward to quoting some of the knowledgable answers that were presented here....would have been fun....

Too bad you didn't get a chance to tell him that you had taken his advice to heart and learned that on can "rejuvenate" speakers by chilling them in a chamber with dry ice over night, realigning the magnetic flux domains in the copper wire and relaxing the defects that build up with use. In fact you had done this treatment to the speakers and they were noticeably better sounding now, so the price had increased just a bit... 

That's great!