Life of KT 150 Tubes

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

@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!!!!!

@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.

The best thing to do is not to wonder why both amplifiers failed at the same time.  The fact is that both amplifiers need repair, and the best approach to that is to fix each amplifier one at a time.  In the process of doing so, it may become obvious why they both failed at the same time, or you may never figure that out.  It makes no difference either way. 

A transformer coupled tube amplifier operates on certain basic rules.  The stress on the output tubes is determined by the plate voltage, the bias voltage, and the current drawn from plate to cathode.  The easiest thing that any good technician can do is to determine those parameters for your amplifiers.  If any of the 3 parameters is way out of specification, then you have a reason why the tube may have blown, and it's easy to fix.  For example, a coupling capacitor between the driver stage and the output tubes may have failed such that there is no bias voltage getting to the grid.  This causes the tube to draw maximum current and burn out rapidly.  Did you notice the tube glowing red instead of typical orange? I admit it is unlikely to lose a coupling capacitor simultaneously in two different amplifiers, but don't assume that both amplifiers failed for the same reason.  For another example, a plate resistor may have failed.  This would also cause excessive current draw, a brief red glow, and tube death.  I don't see why a competent tech won't look at the circuit, even without a schematic, just to test for these easily diagnosed issues and others like it.  If one guy won't look at it, try another.  Also, check on-line for a schematic.  Also, post this on a tube amplifier forum, e.g., TubeDIY Asylum, etc.

@Lewm-  As I mentioned,  I know both units have an issue. It could have been a tube popped, that is ruled out even with new tubes there is no Biasing.  

My issue is I don't  have an authorized tech near me . Spoken to couple of Vale Techs locally  they need schematics before they will open the unit, which Auris will not give. Emailed the distributer and they say take it to nearest dealer. There is only one dealer in Canada. He says "find out the culprit who popped the KT150". at least he could have said bring it over we will get it checked. This dealer did not sell the unit , he became the dealer much after I got the unit from distributor .

I am still waiting for the distributor to contact me.