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Audio and Video Talk
Valves / Vacuum Tubes
Preamp/phase inverter simulation in LTSpice
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<blockquote data-quote="El Sid" data-source="post: 930801" data-attributes="member: 18550"><p>I changed the grid bias between -1,5V and -2,0V for the 300k load to see the effect on of positive grid bias. with a -2V bias and a 2V signal, the grid current (pink trace, right axis) is ?5μA. With a -1.5V bias and a 2V signal, it spikes to -25μA when the input signal exceeds 2V! So lesson learnt there - bias with enough headroom to prevent positive grid-cathode voltage.</p><p></p><p>-2V grid:</p><p><img src="https://i.imgur.com/3jUDwsC.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>-1.5v grid:</p><p><img src="https://i.imgur.com/hwiEi1W.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p></blockquote><p></p>
[QUOTE="El Sid, post: 930801, member: 18550"] I changed the grid bias between -1,5V and -2,0V for the 300k load to see the effect on of positive grid bias. with a -2V bias and a 2V signal, the grid current (pink trace, right axis) is ?5μA. With a -1.5V bias and a 2V signal, it spikes to -25μA when the input signal exceeds 2V! So lesson learnt there - bias with enough headroom to prevent positive grid-cathode voltage. -2V grid: [IMG]https://i.imgur.com/3jUDwsC.jpg[/IMG] -1.5v grid: [IMG]https://i.imgur.com/hwiEi1W.jpg[/IMG] [/QUOTE]
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Audio and Video Talk
Valves / Vacuum Tubes
Preamp/phase inverter simulation in LTSpice
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