IB Slammin Posted January 22, 2004 Share Posted January 22, 2004 All the parts were in and I started the '75 Cornwall project Saturday AM. Install the 511b / 902-16A atop the CWs. Pulled the crossovers and K-77s, plug the hole, replaced wiring, mounted the K-77, sealed the box. Ready to test fire and do some A/B stuff between the K-55, 902-16A, and 902- with an 8ohm diaphragm, all on the Altec 511-b. Only 4 or 5 cuts into it......Something failed. The left channel K-33E. I pressed on the diaphragm and it was frozen. I must assume that the voice coil melted in the gap. I was using normal volume. (high) Blown after 29 years. Ok, the Lux SS produced a large instantaneous peak. Monster Clip. Will the clip indicaters never flashed and I have pushed the '75s much, much harder in the past with no problem. I can accept the fact that I blew a woofer. But, if I simply over powered it, why didn't it take the tweeter and mid driver first? Doesn't add up to me. Was the K-33 just worn out. (like me) thanks, tc Quote Link to comment Share on other sites More sharing options...
sfogg Posted January 22, 2004 Share Posted January 22, 2004 " But, if I simply over powered it, why didn't it take the tweeter and mid driver first? Doesn't add up to me. Was the K-33 just worn out. (like me)" Hook a multi-meter up to your amp and check it for DC on its outputs. If something fried in your amp they tend to put out DC which your crossover will route to your woofers. Hence they burn out and not the rest of the system. Shawn Quote Link to comment Share on other sites More sharing options...
WMcD Posted January 22, 2004 Share Posted January 22, 2004 I blew a woofer. I think part of the problem was that I had been playing Telarc disks with infrasonics. It might be that those low frequencies at high levels cause the amp to generate d.c. On the other hand, the woofer was probably bottoming out. I heard some crackling noise just before the woofer died. So it might have been heat plus mechanical overload. Gil Quote Link to comment Share on other sites More sharing options...
D-MAN Posted January 22, 2004 Share Posted January 22, 2004 There are a couple of reasons that the woofer could bite it: 1) there is a physical obstruction in the air gap. This is the bain of DYI, sawdust or some other obstruction although typically you would (or should) first HEAR bad things before it truly fried. But not always. 2) the insulation on the woofer voice coil wire will eventually fail due to age, that is why most older tube amps require new transformers (they fry) when heated up after a long dormant period. The definitive test involves an Ohmeter check. If the voice coil measures anything other than 3+ Ohms then it is either shorted or open. If open it may be due to an obstruction or scraping. If shorted, probably an insulation failure. (Those are guesses). Whether obstructed motion or age-induced insulation failure, it would explain the reason that the mid and tweeter remained unaffected by the source signal which most likely was within nominal operational conditions and had nothing to do with the woofer biting the dust. DM Quote Link to comment Share on other sites More sharing options...
WMcD Posted January 22, 2004 Share Posted January 22, 2004 Further to this subject, I have a lot of doubts about speaker ratings re power. I look at 20 watt light bulbs, and how hot they get. Then I look at the voice coils. It is difficult to believe the voice coils could take this, continuous. Gil Quote Link to comment Share on other sites More sharing options...
hoggy Posted January 22, 2004 Share Posted January 22, 2004 I'm not electrically inclined and know very little about watts, ampredge etc, but I think it's the ampredge(spelling) that's the heat culprit, but I'm probably completely wrong. It's like volts, it's not the volts but the amps that kill ya. Ok you electricians out there what's the deal? hoggy Quote Link to comment Share on other sites More sharing options...
formica Posted January 23, 2004 Share Posted January 23, 2004 P = V * I Or if you prefer the Power (watts) is the multiplication of Voltage (volts) and Current (or amperage measured in Amps ). Rob Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted January 23, 2004 Author Share Posted January 23, 2004 ---------------- On 1/23/2004 2:06:06 PM formica wrote: P = V * I Or if you prefer the Power (watts) is the multiplication of Voltage (volts) and Current (or amperage measured in Amps ). Rob ---------------- Rob, I understand the the formula. Does that mean that you agree with the DC spike routed thru the cross over down to the woofer theory? I checked the output with a cheap meter and showed no DC voltage. Could a particular source material push the amp down to direct current? thanks, Terry Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted January 23, 2004 Author Share Posted January 23, 2004 ---------------- On 1/22/2004 8:40:38 PM William F. Gil McDermott wrote: I blew a woofer. I think part of the problem was that I had been playing Telarc disks with infrasonics. It might be that those low frequencies at high levels cause the amp to generate d.c. On the other hand, the woofer was probably bottoming out. I heard some crackling noise just before the woofer died. So it might have been heat plus mechanical overload. Gil ---------------- Gil, I am leaning toward the bottoming out theory. I was playing some bass loaded material. I put a cheap Rat-Shack meter on the channel and detected no DC. I would think that it came source, but the preamp infrasonic filter in always "in". I will slap another K-33 in this weekend and see if I can't eat another one. (Ahhhha!!!) I will get back to you. Thanks, Terry Quote Link to comment Share on other sites More sharing options...
D-MAN Posted January 23, 2004 Share Posted January 23, 2004 Just a guess, but I would think that if you were "slappin" the cone against the motor board hard enough to prevent cone movement to the point that it was going to overheat, you would definately hear it slap before it eventually fried the VC... but then again, who knows, that would be some LOUD stuff anyway, so you may not hear it first... I would also guess that the cone itself would display some marks of the compression against the motor board in such a case... but then again, who knows... Its the age of the woofer that I am keying in on. Things get weird when you (and your speakers) get old! DM Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted January 23, 2004 Author Share Posted January 23, 2004 ---------------- On 1/23/2004 8:28:41 PM D-MAN wrote: Just a guess, but I would think that if you were "slappin" the cone against the motor board hard enough to prevent cone movement to the point that it was going to overheat, you would definately hear it slap before it eventually fried the VC... but then again, who knows, that would be some LOUD stuff anyway, so you may not hear it first... I would also guess that the cone itself would display some marks of the compression against the motor board in such a case... but then again, who knows... Its the age of the woofer that I am keying in on. Things get weird when you (and your speakers) get old! DM ---------------- Thanks DM. I hope that you are right about the old age thing. I was doing a demo on the 511-Bs and was concentrating on the mids. I consider myself to be an astute listener and would like to think that I would have noticed something banging hard enough to fry the VC. None the less, just got the other K-33 mounted and will know soon. I will let you know. Regards, Terry Quote Link to comment Share on other sites More sharing options...
3dzapper Posted January 23, 2004 Share Posted January 23, 2004 TC, It's obviously a defective K-33! How dare Klipsch sell a woofer that only lasts 29 years! The nerve! It probably was that speakers time to go. I don't think that you would have bottomed out a K-33 and still be in the same room and hearing. A little cone sag or former coil warp; wires just touching the magnet by a few atoms; wear thru the laquer; toast. I keep wondering if after all these years if I should rotate the K-33s in the Khorns? Would the benefits outweight the chance of damaging them? Rick Quote Link to comment Share on other sites More sharing options...
formica Posted January 23, 2004 Share Posted January 23, 2004 ---------------- On 1/23/2004 7:09:21 PM IB Slammin wrote: Rob, I understand the the formula. Does that mean that you agree with the DC spike routed thru the cross over down to the woofer theory? ---------------- Sorry about that Terry, I was kinda answering hoggy's question, and it wasn't really directed to your fried woofer. There was a recent discussion here about an amp's clipped signal resembling a DC current, but there was no consensus. I'd think (like already mentioned) that it was probably more of a combination of dried lacquer on the VC and the significant power fed to it that caused it to have a premature thermal failure. Do you already have a spare woofer? Later... Rob Quote Link to comment Share on other sites More sharing options...
djk Posted January 24, 2004 Share Posted January 24, 2004 "Just a guess, but I would think that if you were "slappin" the cone against the motor board hard enough to prevent cone movement to the point that it was going to overheat, you would definately hear it " Maybe you could cut a hole in the motorboard about 14" diameter, that way the cone couldn't hit it. Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted January 24, 2004 Author Share Posted January 24, 2004 ---------------- On 1/24/2004 3:30:47 AM djk wrote: "Just a guess, but I would think that if you were "slappin" the cone against the motor board hard enough to prevent cone movement to the point that it was going to overheat, you would definately hear it " Maybe you could cut a hole in the motorboard about 14" diameter, that way the cone couldn't hit it. ---------------- Do What?!?! Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted January 24, 2004 Author Share Posted January 24, 2004 Rob, Rick, and all, I put another K-33 in and tested. Gave them a good workout for about 2hrs; amps had every opportunity to miss-behave and all is well. All of us have our time, and it was time for the old woofer to join Mr. Klipsch. I guess that I overacted a bit. I have had several klipsch (1971) and never blew one. I just couldnt believe that it would go in its prime of life! Anyway, I got to evaluate the 511b/902-16As. OMG!!!!! Farewell to the stock CWs. Many thanks to all. Terry Quote Link to comment Share on other sites More sharing options...
djk Posted January 24, 2004 Share Posted January 24, 2004 "Do What?!?!" It already has a 14" hole in the front, its a Cornwall (the cone can't hit the motorboard). Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted January 24, 2004 Author Share Posted January 24, 2004 ---------------- On 1/24/2004 7:38:06 PM djk wrote: "Do What?!?!" It already has a 14" hole in the front, its a Cornwall (the cone can't hit the motorboard). ---------------- Well, yah,... no shick. I am aware that it is a Cornwall. In 1973 when I ordered my first pair, I remember ordering Klipsch Cornwalls. In 1975, when I ordered the second pair...lets see...I believe that I ordered Cornwalls again. My 75's and '73 vert's both have a 14" opening and I would suspect that they all have a 14" opening. What is this motorboard slapping business? What are you talking about? Is this a joke? Terry Quote Link to comment Share on other sites More sharing options...
djk Posted January 25, 2004 Share Posted January 25, 2004 "Is this a joke?" Yeah, its on D-man, he's the one that made the motorboard remark. The woofer can only hit the board its mounted on in the Klipschorn/Belle/LaScala. Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted January 25, 2004 Author Share Posted January 25, 2004 ---------------- On 1/25/2004 8:19:36 AM djk wrote: "Is this a joke?" Yeah, its on D-man, he's the one that made the motorboard remark. The woofer can only hit the board its mounted on in the Klipschorn/Belle/LaScala. ---------------- Darn! Now that I am doing a few mods...I was hoping that you guys were going to suggest that I fire the K-33s thru a slot! Ha Thanks, Terry Quote Link to comment Share on other sites More sharing options...
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