2. amps-preamps
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Anybody blow a ceramic woofer with an OTL amp?

I would appreciate anybody's experience with transients (such as a tube blowing) in an OTL amp that results in breaking the ceramic driver in a Kharma 3.2. I just had this happen to me - a driver tube blew, terrible noise from the woofer and it broke. The Kharma distributor said this was only the second he had heard of with an Atma-Sphere amp, but that it was much more likely with an OTL amp because of the lack of transformer. Ralph is interested in the frequency with which this occurs, as he feels it only happens with ceramic woofers, which are much more likely to blow than non-ceramics. Have any other OTL owners had this happen to Kharmas? I guess the lesson is to keep testing tubes or keep a careful eye on them to prevent this happening, but I would like to know if this was a freak happening or more common than has been generally accepted? Judging from the number of Tenor-Kharma combos out there, it should be more common than I thought if the combination of OTL and ceramic woofers is a problematic one.
springbok10
larryi
3,993 posts
 
I am a bit leery of OTL's. I know that if a tube does fail, they will not actually pass D.C. because they are coupled by a capacitor, but still, I worry. A friend borrowed a Joule Electra OTL and it was subject to intermittent popping. On his horn system, popping meant a sound that rattled windows and could send someone into cardiac arrest.
tireguy
1,964 posts
 
Cinematic_systems- The drivers used are not stock accuton drivers, kharma modifies them in house. So your right its not expensive but it can be time consuming and difficult to find the right replacement driver.
trelja
3,223 posts
 
Not to be a wiseguy, Honest1, but if you read the next sentence, "Then, the whole thing repeats.", you will find the answer to your question...
howie
230 posts
 
This is very disconcerting to hear. I've read how much you enjoy the sound of the Kharma and Atma-Sphere combo. I was just digging up the thread where Tireguy *cough* was telling some stories about blown drivers :P and I see that you've already found it.

I trust what Jtinn said fully. If your speakers did not have ceramic drivers, it might not have blown, but it probably would have been damaged without you knowing it (not sure which is better). It is nevertheless a cause for concern since it can happen, but like anything else, there's a great deal of luck and chance/freak occurence involved. How many times have we read of a bad review sample? Considering the relatively small number of reviews and perhaps the importance of these reviews, you would think that the frequency in which a bad review sample is sent would be small but it isn't.

I've been lucky so far with my 3.2s. I don't normally play at great volumes but do turn up the volume now and then. I don't have extensive experience with tube amps but did for a time run a pair of Bryston 7Bs SSTs on them, so the ceramic drivers can definitely handle lots of power.

Keep us up to date on the process of getting your speakers fixed.
tireguy
1,964 posts
 
Howie- As I understand it the issue is not power handling but distortion/amp cliping which causes the driver failure.
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