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Hi there, I'm new to this forum so treat me gently!
I have a Carlsbro 50 TOP Evo which I want to change the output valves on.
It has a bias test point on the rear and access to a pot to change the value.
Problem is, there are three test points; one common and one each for the two EL34 valves, but only one pot.
I've managed to match two Svetlana Winged C valves so that they read 34.8mv and 35.5mv which is a lot closer than the old JJs were in there but I need to know what value to set them.
I'm reading that with plate voltage at 440v and at 70% the ma setting should be 40.
Can I just set them to that on the basis of equivalence with mv using a 1 ohm resistor (I've no idea if this is what Carlsbro have used).
The fact that there is only one pot, does that mean I'm still looking at a value of 40mv and not doubling this for two valves?
Any help would be much appreciated.
Cheers
I have a Carlsbro 50 TOP Evo which I want to change the output valves on.
It has a bias test point on the rear and access to a pot to change the value.
Problem is, there are three test points; one common and one each for the two EL34 valves, but only one pot.
I've managed to match two Svetlana Winged C valves so that they read 34.8mv and 35.5mv which is a lot closer than the old JJs were in there but I need to know what value to set them.
I'm reading that with plate voltage at 440v and at 70% the ma setting should be 40.
Can I just set them to that on the basis of equivalence with mv using a 1 ohm resistor (I've no idea if this is what Carlsbro have used).
The fact that there is only one pot, does that mean I'm still looking at a value of 40mv and not doubling this for two valves?
Any help would be much appreciated.
Cheers