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

+1 @larryi agree, and most don't even realize they've had a voltage spike occur until one of the components isn't working and start troubleshooting backwards from there.  

@audition__audio If you check the specs of the Amplitrex it states it can supply 500 volts on the line.Like I said, it is the only tester I know of that can actually test the KT150's.

I agree with above, having owned tube gear since I was a little kid. I think you had tubes made on a Monday morning or Friday after lunch : )

It is a bit more than strange that Both amps died EXACTLY at the same time...

 

Hope you can get back on the road soon. Being without good sound sucks!!

 

All the best

grossman616,

I think the original poster explained that after one channel failed, he moved the tubes to the other monobloc amp and suffered the same failure. This means a bad tube in the first amp.  Whether or not that amps themselves are damaged is not clear, because he did not report trying the good set of tubes in either amp.  In any case, this is a good example for the practice of NOT swapping tubes when an amp goes down--you could be exporting damage to the other amp or channel if the tube failure is also causing damage.  The original poster also mentioned a faint burnt smell which pretty much rules out the failure being limited to the tubes themselves.  That smell means that, at the very least, a resistor blew (common mode of failure, my friend says cathode resistors also act as fuses, and does not consider that failure to be much more of a bother than changing fuses).

@Larryi - Lesson Learnt well, unlike Tube preamp which is self biasing , I agree that swapping popped tubes could have damaged my Other Amp. 

It could be a blown fuse or a resistor, but damn this unit requires an experienced tech to even open it. unlike other tube amps I have seen, this unit is almost concealed. The Auris company in Serbia gave me " fantastic solution" take it to their service center in California, while I live in Canada. Upon calling the service center he said it would be cheaper for him to fly to Canada, as both units crated weigh almost  100Kgs. Canadian distributor spoke to me and asked me to take it to Edmonton 300 Kms away to their dealer. I am going this morning and will keep you all  posted. I once again appreciate all you guys for your input and advise.

How do I post pictures?