I had my first tube go the other day (a KT120 in a push-pull amp). It took out the fuse, which I didn't notice till after I ordered some spare tubes.
Fortunately the amp came with a pair of spare fuses. But my question is: do they usually take out the fuse when they go? (And I should have a spare fuse per spare tube?) Or is it a rare occurrence?
FWIW, the tube did a spectacular purple plasma display on it's way out.
Thanks,
Jeff.
Fortunately the amp came with a pair of spare fuses. But my question is: do they usually take out the fuse when they go? (And I should have a spare fuse per spare tube?) Or is it a rare occurrence?
FWIW, the tube did a spectacular purple plasma display on it's way out.
Thanks,
Jeff.
The fuse simply did its job and protected the rest of the circuitry in the amp.
It's not exactly a rare occurrence for an output tube to fail, but you shouldn't personally encounter it very often.
By all means keep a supply of spare fuses of the required type and rating.
I'm sure you are aware that when one of the pair of push-pull tubes fails, then its partner should also be replaced?
Depending on the design of the amplifier, the output tubes may then require to be re biased. Which make and model of amp do you have?
It's not exactly a rare occurrence for an output tube to fail, but you shouldn't personally encounter it very often.
By all means keep a supply of spare fuses of the required type and rating.
I'm sure you are aware that when one of the pair of push-pull tubes fails, then its partner should also be replaced?
Depending on the design of the amplifier, the output tubes may then require to be re biased. Which make and model of amp do you have?
It's a Rogue Audio Cronus Magnum II. I did re-bias, but I didn't replace the partner.
Unfortunately I re-biased the partner before noticing that the fuse was blown (so it had no one to share the current source with). I re-biased again after replacing the fuse, but because of that I don't know if the bias changed on the partner tube or not. (The bias of the other two tubes were still spot-on.)
Unfortunately I re-biased the partner before noticing that the fuse was blown (so it had no one to share the current source with). I re-biased again after replacing the fuse, but because of that I don't know if the bias changed on the partner tube or not. (The bias of the other two tubes were still spot-on.)
For interested parties, here's a nice review of Jeff's amp:
Rogue Audio Cronus Magnum II review | What Hi-Fi?
Rogue Audio Cronus Magnum II review | What Hi-Fi?
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