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Originally Posted by Viewmaster
. I shall try various light bulbs but I do seem to recall that when I first used 60w bulbs they reached max brightness well before my variac was up to 240v, so switched to higher wattage.
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Hi Albert, ahah. It's worth noting what that might mean about grid current -- I've made another comment below. Obviously the bulbs aren't in the mains circuit, so their brightness doesn't
directly depend on the variac voltage...but you could almost use this test to ensure that you're not passing too much grid current.
Quote:
Originally Posted by Viewmaster
was nervous about what might happen to my GU81s if the 60w blew
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If the bulbs blow, the feedback coil will be o/c. The circuit will stop oscillating and there is no other path for grid current.
It's possible that your valves are biassed rather above their recommended grid current as it is (this is just going from memory, I haven't re-checked the data-sheet) so it's worth doing the experiment.
Nothing bad will happen to the valves.
Quote:
Originally Posted by Viewmaster
BTW, I am getting an ozone mask...…
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Joking apart, really worth having well-ventilated space/ a fan/ as there is tons of ozone in this set up.
Quote:
Originally Posted by Viewmaster
with EHT, RF and ozone dangers it's safer and better audio quality just to listen to a CD!
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True 'dat. But with these sorts of builds, there's so much investment in £££, time, and learning curve, that it's never obvious when to jump off!
