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As I'm waiting for my kit to arrive, I thought I would start gathering some tubes for the project.
What I have so far: 2x Valvo ECC83 from the 60ies, 1x Siemens ECC83 from 1967.

I don't understand now, what is it I have to keep in mind regarding power tubes and their bias for the 18 Watt. Is it correct that the tubes don't have to be biased, because it is a cathode biased tube amp? For that matter, can I buy any EL84 as far as they test in the good range of any tube tester (for example: 1x Brimar EL84 and 1x RFT EL84 and put those into the amp, even though those 2 won't be matched?)? I wanted to buy several EL84's from different brands (one from each brand) and play with them, but is that safe?
I have read some things regarding matched power tubes in the 18 Watt, and is it correct that if you take 2 different ones, that that should not be a problem and it could in a way improve the tone of the amp, as they are mismatched? So, is the goal to take two mismatched EL84s? I mean, can such a thing harm the amp?

Regarding the EZ81, can I buy any EZ81 as far as it tests good in a tube tester or what is it I have to keep in mind here (biasing?)?

Nice!


We adjust the bias in an approximate way by choice of the cathode resistor. Then the valves self-adjust. Generally, 150 ohms is a safe value for the cathode resistor.


As long as they aren't too far out from each other, then that's perfectly fine. If they are too far out you may get increased hum or even one of the pair overheating and red-plating. So I like to "match" by ear, just picking pairs that have the best tone. As you're in Croatia, you should look for old Tesla EL84s. They have fantastic tone!


It's safe provided they're not too far mismatched.


Yes, you can do that. Rectifiers don't have biasing.

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Great tones come in small glass jars!

Hey zaphod, thanks for your input! You helped a lot!

Regarding Tesla, I found some Tesla EZ81, boxed, never used, so I think I'll take some of those, also you can get RFT's for really reasonable prices.
About EL84, good you mentioned that. Will look for some that are not too far from each other!

I generally select pairs of EL84s for best tone and least hum. That's the matching I need.

_________________
Great tones come in small glass jars!