In case anyone is interested,. a matched pair of new valves were fitted an hour ago, and all is back to high decibel normal.
I conjecture that the grid probably came loose from its pin...
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7 years ago
Any (electronic) valve freaks out there?
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7 years ago
The normal cause is a grid to cathode short, caused by the cathode coating falling off.
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7 years ago
I guess that's possible. In which case a good shaking might have fixed it?
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7 years ago
Not IME, the clearances are very small and a degree of welding may have taken place. FWIW, I still have an AVO valve tester, which was in working order last time I used it, which is some years ago.
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7 years ago
Pah, cheap. I need to get around to buying a pair of matched quads :(
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7 years ago
Blimey that's 200 watts!
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7 years ago
Long time ago now since i used bottles but leaky coupling caps were a prime cause of trouble as were leaky cathode bypass electros...
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7 years ago
95W RMS per channel ... 15W RMS per channel in Class A. Velleman K4000, feeding a pair of Mission 752s.
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7 years ago
Neither of those the case here.
1/. The fault moved with the valve, so caps exonerated. 2/. No cathode resistor and bypass in use. Negative grid bias supplied by a rectified part of the heater circuit.- Vote on answer
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7 years ago
. Id rather have a fistful of power FETS meself, for hi fi.
Bottles are good for guitars because they distort.
The furthest distance from the original sound, that's the definition of a good rock guitar amp.
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7 years ago
Which should be considered an instrument in its own right;?...
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7 years ago
Well its PART of an instrument. It is the 'soundboard' of the electric guitar, so to speak.
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7 years ago
Fair enough, each to his own.
Solid state does too. The difference is that valve distortion has a "nice" sound while silicon doesn't.
:)
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7 years ago
Complete rubbish really.
FETS are very similar to valves actually.
The reason transistors sund harsher under overload is because they can have - lacking and output transformer, and being cheap enough to have lots - far more feedback applied than valves, so when they clip, they tend to clip hard, but that's a function of the design, not the silicon.