Hello,
I plan to make my very first tube amp.
I bought two hammond 1609 and a bunch of 6p15/sv83 (as they are very cheap).
The main difference (beside internal wiring) with el84 is that the g2 voltage is "maximum 150V".
Here and there on the interweb I see a lot of people using them exactly like el84, in ultra linear, with the g2 at a higher voltage than the anode (more than 300V). And they didn't complain about something.
So, my question is, what is the worst thing that can happen if a tube really deeply fail ? I guess it can short, and melt the weakest point in the path from B+ to the ground (the transformer primary?)
Would I see the screen glow before failing ?
Quite often, on UL configuration, the screen is connected directly to the transformer, what about using a resistor or a zener to lower the voltage?
I dont mind destroying some few tube experimenting, but I'd love to know how to limit/prevent damages.
Afterward if I am happy with my amp, I'll buy some fancy $15ish proper El84 🙂
Other question, what fails when no load is connected to the secondary of the OT? The secondary becomes a simple inductance and the tension can rise beyond limit? It might destroy the tube or the bypass cathode cap?
Thank you very much 🙂
I plan to make my very first tube amp.
I bought two hammond 1609 and a bunch of 6p15/sv83 (as they are very cheap).
The main difference (beside internal wiring) with el84 is that the g2 voltage is "maximum 150V".
Here and there on the interweb I see a lot of people using them exactly like el84, in ultra linear, with the g2 at a higher voltage than the anode (more than 300V). And they didn't complain about something.
So, my question is, what is the worst thing that can happen if a tube really deeply fail ? I guess it can short, and melt the weakest point in the path from B+ to the ground (the transformer primary?)
Would I see the screen glow before failing ?
Quite often, on UL configuration, the screen is connected directly to the transformer, what about using a resistor or a zener to lower the voltage?
I dont mind destroying some few tube experimenting, but I'd love to know how to limit/prevent damages.
Afterward if I am happy with my amp, I'll buy some fancy $15ish proper El84 🙂
Other question, what fails when no load is connected to the secondary of the OT? The secondary becomes a simple inductance and the tension can rise beyond limit? It might destroy the tube or the bypass cathode cap?
Thank you very much 🙂
Melting grids can cause shorts, which is like wiring the plate and cathode together. Ideally you want a low wattage resistance to act as a fuse from cathode to ground that will open up under these conditions so the output transformer doesn't overheat and fail.
I don't think the 6P14P has the screen grid voltage limitation, you might look into grabbing some of those.
I don't think the 6P14P has the screen grid voltage limitation, you might look into grabbing some of those.
Oh, yes of course! I am really confused by those tube naming systems. I thought the p meant that you can wire the heaters in series.
Yes, those are 6P15P-er (6Π15Π-ep in russian). Does a good "how to read a tube name" exists somewhere ? Which explains what each letter/digit means for each system ?
According to the Svetlana datasheet of the SV83 the maximum g2 voltage is 200 V.
Attached you find some info on using the SV83 in amplifiers designed for the EL84, written by Eric Barbour, who used to work for Svetlana.
Attachments
You probably should ougtta ask TubeLab George, whose motto is "I blow things up so you don't have to"
