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Re: Practical upper limit of grid-stopper resistance on pentode amps? - Can large stopper 'soften' clipping?

Posted by sajti on November 26, 2000 at 06:43:51:
Grid stopper has one important function: Eliminate the HF oscillation, caused by inductivity of the wire, and leakage capacitance. Especially paralel connected, and push-pull amplifiers, where the valves connected together. This gridstoppers must be applied directly to the valve socket with short leads.
This resistor can't be large because of the input capacitance of the valve -> cut the top of the audio range
This resistor can't be too small -> don't eliminate the oscillation.
I apply 1k for the preamp valves, and 100 ohms for output. Triode connected pentodes often need screen stopping resistor, eliminate ocillation resulted by the connected plate and screen.
I use the lowest possible resistors.
Sajti