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?

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The OP says that one tube in each amplifier “popped”. That is not the exit mode of tubes that wear out. Normally a tube that is dying due to long use will just begin to sound bad and eventually become impossible to bias properly until the user finally notices a problem and replaces it. Although catastrophic failure does occasionally occur, most commonly at start-up, the amplifier needs to be evaluated.

I appreciate all your input and advise. Some of you seem so technically sound probably you wouldn’t hesitate to open. While I was communicating with you all Manufacturer emailed me back that he will help me out , he cc’d the distributor to find a Tech for me. If nothing happens then I would venture into opening it.Wonder why they make such great amps , market it without having tech support. I have had amps that lasted me for decades.With The Russian war it is so hard to find KT150, it’s solely made in Russia. 2000 hours life is fair. That would last me around 3 years with using my Naim separates . I have opened up Audio Valve from Germany few times. Newer had major issue , changed tubes and fixed point to point soldering. Auris is a beast , hard to open.

All of you have provide me great support and advise. Thank you guys.

@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?