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Re: Ella Output Impedance

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If you leave the NFB loop connected only to the 8ohm tap it will still function with a load connected to a separate 4ohm tap. There is still a voltage across the full OPT secondary, and this is the source of the feedback signal (ie the speakers are not part of the feedback loop). The current for the speaker is then drawn from the 4ohm tap.

I have disconnected the feedback loop only as a personal choice, since I have drastically modified the circuit from the original design anyway. If you want to keep it as designed, then leave it in. I found it unneccesary when the output tubes were triodes or triode-strapped pentodes. This is DIY, afterall, so I enjoy that freedom to customize it to my liking.

Great amp platform, btw. Even after scratch building a SE 300B amp, I still love the Ella.

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