2. amps-preamps
  3. 192979-121025

Air Tight 300B Flame Out

I was listening to my Air Tight 300B amplifier (fed by a Lamm LL2.1 Deluxe preamp and driving Charney Maestro speakers) starting making popping noises through the speakers. By the time I got to the amp to look, the right channel 300B tube was lit up brightly and smoking. Obviously, I turned the amp off right away.

The 300B tubes are the new issue from Western Electric with maybe 100 hours on them.

Any ideas on what may have happened, next steps, and anyone that can service Air Tight on the west coast? The Lamm preamp is a recent addition. Wondering if the preamp somehow caused the problem?

  -GAR

gareents
allanblissett
163 posts
 

Use a cheaper tube to test, incase the amp is the problem. 

chenry's avatar
chenry
236 posts
 

Red plate, from the sound of it. Is there a failure on your bias board?

ghdprentice
7,462 posts
 

@carlsbad2

+1

Yep, occationally a tube goes out. Hopefully it did not take out a protective resistor... but it may have. That is why they are there. 

gareents OP
74 posts
 

Thanks all.

I have basically the same conclusion. I am thinking that the tube failed (arced), and the smoke was from a fried resistor. 

Rather than put in another tube, thinking that having the amp checked out by a tech is the best corse of action.

testpilot
977 posts
 

Some amplifiers use a sacrificial resistor to protect the amplifier when a tube fails.  In most instances, this is a simple fix although stressful when it happens to your $15k+ amp. 

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