Not necessarily. The Amplitrex can supply 500 volts on the line, which as you say is not ideal, but it is the best out there. This would give one a better idea about the general health of the tube than any other tester i am aware of. Are you aware of a tester that can supply 600 volts? Custom made is probably not the answer for the reasons you state.
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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Hello Vishnu. The life of a tube depends on how hard it it driven. You mentioned that the other tubes tested weak. That means they were were working very hard. Does the amp have a power rating areound 100 watts or more? That's really pushing any pair of tubes. If it's only 50 - 60 watts, that's reasonable for those tubes. If the voltage supplied to the tubes is not over 400 volts, you could probablsy use 6550s or KT120s and live with a lower power output. If you can set the bias make it about 3/4 of what the original tubes called for. It should sound OK. If the voltage is over 400v (I'm guessing it is), look up the tube specks for whatever you replace them with. If they can take the voltage, try an easier to find tube. Remember, 100 watts is not twice as loud as 50W. It's only 3 db or so louder, hardly noticable. 100 watts sounds about three times as oud as 10 watts. That's the reason so many people are happy with 300B tube amps than don't even make it to ten watts (they can do more but sound rather bad). I wish you success. This is not a good time to need tubes. |
What an absolutely STUPID statement by @lloydc I have over 3500 hours on KT 150 tubes in my X200 by Audio Hungary (stupid)
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Faint burnt smell means something inside the amp went bad, probably a resistor burnt up. That could be caused by a tube going bad. Moving the bad tube to the other amp would then cause the other amp to go bad. I never do the switch tube around test for power tubes because that can damage the other amp (or channel in a stereo amp). It is far better, when something goes wrong with a tube amp, to first have the tubes tested. The sort of good news is that is that the most common failure-a resistor going bad-should be relatively easy to fix by a competent technician, even if the technician doesn't have the schematic. Perhaps you could persuade the technician to have a go even without the schematic. |
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