8 Ohm speaker in Mojotone aa764 Vibro Champ?

[Magnuseklof]

Hi everybody, this is my first post, and probably a noob one.

My name is Magnus, photographer by trade, hobby guitarist and allround tinkerer.
I've built 3 tweed amps in the past, 5E3, 5F2a & a 5F1, they all turned out very nicely, more due to my ability to follow instructions than to any deeper electrical knowledge, but I'm learning...

I hope someone might help with this question:
Since the output transformer in Mojotone's AA764 Vibro Champ kit has taps for both 4 & 8 ohms, I wonder, is it possible to install an 8 ohm speaker instead of the traditional 4 ohm champ speaker or is there something else in the circuit that forbids this?

Very grateful for advice,

/Magnus

[Stevem]

No reason to not do that , in fact I changed out the output transformer in my Vibrochamp to the Mojo one for the specific reason of using a 8 ohm driver!

It let me stuff in a great sounding Jensen 10" driver into the Champs cabinet with some work.

Not only does this swap over open the door to you trying out more speakers , but the 8 ohm winding on the Transformer sounds better also since you are now using the full secondary winding, in fact the highest impeadance tap on any output transformer will always sound the best and also make for the lesser chance of blowing up the transformer!

[pompeiisneaks]

Yup you could also just put two jacks on the output area of the chassis and have one be a 4 ohm and the other 8 ohm, but you do need to wire things correctly for dual impedances. Or use a single one and buy one of those impedance selector switches.

In any case, you can just put some shrink tubing over the end of the unused 4 ohm lead to keep it electrically safe, and coil it up and put it somewhere away from the signal to avoid it injecting noise etc. and just use the 8 ohm.

~Phil

[Magnuseklof]

Thank you so much guys, I really appreciate your expertise!
Have a great weekend!

/Magnus