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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?

vishu
helmholtzsoul
111 posts
 

I know this is silly. Did you blow a fuse? Are both MB on the same circuit? Maybe one lost a valve (tube) and that affected the other (a surge). I’ve blown tubes that blew the resistors for that valve. That has happened a few times. The rest of the time it was a blown fuse or one going bad from to many hard starts.. That little piece of thermal wire has a BIG responsibility.

I’ve seen 300Bs with 20,000 hours and were close to 100 years old. They had another 20,000 hours left.

1000 hours and 16K+, I’d hand deliver BOTH to the manufacture’s doorstep in Hades before they got away with that one. Serbia here I come.

decooney
2,337 posts
 

@vishu 1000hrs is premature.  

Which do you turn ON first, amps or preamp?

Which do you turn OFF first, amps or preamp?

Did you have a power outage/surge recently?

lloydc's avatar
lloydc
768 posts
 

You should buy US-made amps.  Now you know why.

vishu's avatar
vishu OP
28 posts
 

@Helmholtzsoul - Blowing the fuse is my first Guess, and next is blowing the resistor. To check the fuse  unit needs to be opened. Did talk to experienced vale tech, locally, he said he wouldn't even open it without schematics.  I  certainly wouldn't mind driving 300 kms to the only Dealer in Canada. I am sure the dealer would not give me the service Tech info, because I did not buy the unit from him. Auris has  responded they wouldn't give the schematics. 

 

@Decooney - I Turn Amp OFF first and ON last. No power outrage or surge.Naim separates is on the same circuit. Never used them simultaneously .Alway had bias set between  55mu-60mu as recommended  by Auris. I spoke to Tung-sol they said life is between 1000- 2000 hours. Thats is a big variation!!!!!

vishu's avatar
vishu OP
28 posts
 

@lLoydc -  "You should buy US-made amps". yes, if you are in North America and more so if you are in the US. I would say  before buying check for local authorized center. It is a personal preference that I like European , but comes with a price in North America.  I had issues with Dynaudio during warranty period. canada does not have Dynaudio  distributer  anymore. US distributer were amazingly good to replace a new set of speakers.

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