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I put the final two layers on the choke and temperately closed the amp up as it will be finally done, laying all cables right and so on. The loaded MF channel now has 0.8mV RMS. So, forget about any noise.

Playing the amp today a bit I have formed the following area of my dissatisfaction. They are not the dissatisfactions but rather the things that I would like to improve before I end up this project.

1)      The filament voltages. The fix resistors that I use are not good as different brands suck different currents and I have a few tens of volt fluctuation with different tubes. It might be not a big deal but I do not like it. So, why I do not have the two 50W rheostat, like in tube testers, of the step attenuators where I will be able to drive my voltage up and down. If someone knows what I where buy such a thing please let me know.

2)      The output transformer. The 2.5V tubes and 4V tubes work perfectly with the same operation point but it is obvious to me now that all of my 2.5V tubes sound less loaded then all of my 4V tube. I have a transformer 20:1 that is fine but it is clear that the 2.5V tubes with 800R on plate and 4V tubes with 1250R on plate would need 5:1 difference in loading ratio.  I do not know which one is right at this point but it is obvious that in order the 2.5V tubes and 4V tubes sound the “same” this load must be normalized. So, it is highly likely that another counf for my OPT will be called upon…

Otherwise it looks like the amps are at the final lane…

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