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Life of KT 150 Tubes

Auris audio Mono Block -Forte 150 uses Two KT150 for power output for each monos, Very strangely a both amps popped the KT 150 same time. I can vouch it had less than 1000 hours in 2 years as I have NAIM NAC 252/NAP 300 in the same room. I tested the tubes and one is 100% dead and the rest have very marginal life. With great difficulty I have ordered four new tubes. Would any of you know why this would have happened, in the sense bath amps not working at the same time? I am trying to get hold of Auris in Serbia. Even a good Valve tech will not open the unit without schematics and Auris wouldn’t provide one. I am in Canada. There are 2 authorized service center in the US. When crated both amp weighs 94 Kgs.Not easy to ship. I tried with a borrowed set of TUBES , there is no Biasing at all,mA reads 0, but there is signal coming in and VU display lights up. 

Lesson learnt well not to buy equipment that is hard to service. I bought this even before there was a dealer in canada. I tried contacting the distributor Motet in Toronto. They are telling me to contact Dealer in Edmonton 300Km away. He never sold me the unit, why would he have any interest if he didn’t make any money on this unit? The unit cost $16,800 USD. Any advise what I should do?

128x128vishu
vishu's avatar
vishu OP
28 posts
 

@jasonbourne52-   “Forget those new design KT150 tubes! Only use 6550/KT88's. These have proven reliability - and a lot more affordable! JJ in Slovakia makes good ones.”

JJ6650 is 1.6 amps where as KT 150 is 2.3 Amps. I am sure it will work as I am down sizing. But wondering the SQ? Some one suggested KT120? 

Post removed 
curiousjim's avatar
curiousjim
4,731 posts
 

It really seems odd that one tube blew on each monoblock at the same time. Assuming the tubes are wired in series, was it the same tube that blew on both?

JD

audition__audio
1,494 posts
 

It isnt possible to determine tube life without the specifics of each application. As another points out, this tube is very difficult to test properly on any "suitcase" tester of which I am aware. To test properly you would need a custom rig. 1 to 2 thousand hours is a very short life span for power tubes. But considering that this tube is new production only, this just may the price you pay for no old stock variant. Some of my guitar amp clients claim that old stock Mullards are giving them over 10 years, while new production tubes last around a year. 

I dont think substitution of type is the answer. 

lewm
13,089 posts
 

Output tubes are usually wired in parallel, not in series.  Thus it is quite possible for one to fail while the others roll along. I have no idea why my previous post was deleted, but it was. Perhaps an overzealous censor.

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