Tranformers

[Robin]

So, you went with another OT instead of a 125ESE? I’m not familiar with that sort of wiring scheme for a OT so double check my advice. A single 6V6 in single-ended, class A operation with a 8 ohm load would like around 5k (5000) ohms on the primary. The exact value is not critical, it looks like you could get 5000 – 5500 ohms with that OT and that should work. That should get you around 4 watts of power with the 6V6.

[beelzebum]

It looks like the way you are supposed to connect the primary is, if you want the 3k load, then only use the two taps that are labeled 3k and ignore the rest. Same goes if you only want the 2.5k. Just connect one of the taps to your plate and the other to your B+. Even the website you had referenced earlier on seemed unclear as to what the center tap would be used for. If you want a 5k primary then use the 2.5k taps, and then on the secondary, connect your 8 ohm speaker to the 4 ohm tap. This will give you 5k at the primary.

[beelzebum]

I see on the home page it is showing my last post with a simple image that has now been deleted. That is because for some reason as soon as i posted it, the image all got smashed to the left of the screen.

[Humle]

Thanks for the good answers!

If I want to put a 6L6, EL34 or KY66
How do I do that?

Should I use another tap for the secondary output when I use them?

[beelzebum]

For a 6L6, the load should usually between 4k and 5k. so the same connections as the 6v6 should be fine. An EL34 is different, its load is a bit less. so for EL34’s you would want the tube connected to either the 2.5k, or the 3k taps and on the secondary and just attach your 8 ohm speaker to the 8 ohm load. to make it easy to switch between all of them, connect the primary to the 2.5k, and on the secondary you can put a switch to change the secondaries from 4 to 8 ohm. This way you will be able to switch the primary impedance between 2.5k and 5k depending on what tube you decide to use.

[Humle]

Many thanks for your help!

This is my first attempt, so has much to learn.!

[Robin]

If you use the layout from the book you’ll have the two output values you need for all those tubes (depending on the speaker load). You could also delete the switch and just wire up one output jack for 4 ohms and one for 8 ohms, That will work for most all the combinations of tubes and speaker loads. That’s what I’m doing with the new Two Stroke head I building.

[Humle]

sounds like a good way to do it!

Thanks

[Author]

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