Hello all,

The lummerland express was my first build and has been wonderfull for quite some time. Now I wanted to try something different: I want to be able to use both ecc99's and 12au7's so my first thought was making the secondaries of the OT switchable.

for a 8 ohm connection I would need yellow/white for ecc99 and yellow/orange for 12au7

Would this cause me a problem since they would both use the yellow secondary?

After hooking it up I was quite surprised I could measure continuity between all three of the secondaries in either position of the switch. Is this possible to do? I can really use your help guys!

Thanks in regard!

Hi JesseJJ, welcome to the Forum.

I also had that idea a while back but decided to build something else so I dumped it. However, I think it should be possible to put the different secondaries on a switch as you did. It's normal that your DMM told you continuity between the different taps as they're basically just a wire wound over a magnet. So they'll just have a few Ohms of DC resistance. BUT for an AC signal there is an impedance which is way higher.
You want to make sure that the unused tap is really an "open" end in the respective switch position. And don't switch while running the amp!

Thanks for your reply!

How would you recon I make sure it is really a open end in each switch position?

Thanks a lot!

Hi Jesse,

well, just make sure the switch works well and as expected. You should be fine then. Let us know how it works  :topjob: