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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

Showing 3 responses by audition__audio

audition__audio
1,640 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. 

audition__audio
1,640 posts
 

The Amplitrex is not going to give a KT150 an adequate test. Better than most other older testers but still it doesnt have the juice. 

Very few tube sellers are willing to test these higher voltage tube correctly as it requires a much higher than normal investment. I checked into a custom made rig and when I finally found a competent builder that was willing the price was just too high for a tube which is more of a commodity and can always be found cheaper than what I would have to charge.

audition__audio
1,640 posts
 

Are you sure that the Amplitrex can supply 500? I thought it only had 400. I am going to check this it out and if you are correct this may be a solution which would necessitate buying an Amplitrex for power tubes. I compared the Amplitrex with my Triplett 3444 and the similarity of results were very surprising on 9 pins and many octals. What I didnt like about the Amplitrex was the amount of time required to test.

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