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I think the filament circuit in Poseidon could be arranged differently. The left tube 12AX7 could get the filament to its 4 and 9 pins, while the right one could get it to its 5 and 9 pins. This way every six months you can swap the tubes not having to scrap the tracks off. What do you think?

Wiesiek Lipowski wrote:I think the filament circuit in Poseidon could be arranged differently. The left tube 12AX7 could get the filament to its 4 and 9 pins, while the right one could get it to its 5 and 9 pins. This way every six months you can swap the tubes not having to scrap the tracks off. What do you think?

This is implemented for the Poseidons but probably not documented anywhere. See how V1 has 10 pins? On one of the drivers the V1 socket can be rotated 180 degrees and the filament will be on 5 & 9 as you say - i.e. the whole other half triode will be used and you can rotate them regularly. Note that the 'X' between the ALT pin and pin 9 will also need to be cut (or else you'll be heating the unused triode). When you rotate 180, everything lines up (cathodes: 3 to 8, grids: 2 to 7, plates: 1 to 6).

Shannon

I know this possibility, of course. I only wanted to say there is another and easier way to use both the halves of the first tube here, and not having to cut anything. I wanted to avoid heating both sections as well, of course.
Thanks for your response, anyway.