extension speaker impedance question and general wiring question

[mikepukmel]

Hi All.
The stock Fender Deluxe/Deluxe Reverb has two output jacks, one "main" and one "extension". The OT's are for an 8 ohm speaker.
So if I plug a single 8 ohm speaker into the main (shorting) output jack, everything is matched.

But the extension jack is parallel, so if I plug another 8 ohm speaker into that, won't the total now be 4 ohms?

1)
Was this amp (and similar) meant to use two 16's if you intend to use both the main jack and the extension jack?

2)
Since the main jack is shorting, what would happen if you happened to have a speaker plugged into the extension but nothing in the main jack?

3) If the shorting jack was ditched and 3 jacks wired, e.g. one 4, one 8 and one 16, would something bad happen if I had no extension jack but two speakers plugged into 2 different taps?
Thanks!

[The Dude]

1) If the jacks are parallel, two 8 ohm speakers will give you a 4 ohm load.
2) If you plug a speaker into the extension jack only, you will get little/no sound and the OT secondary will still be shorted via the jack. Not recommended.
3) If you ditch the shorting jack and wire 3 jacks, you still should not run multiple taps simultaneously unless you double the speaker impedance of each tap. You are still loading the secondary differently than expected even though you are using more than one tap.

[olddawg]

Don't plug speakers into different taps. In general tube amps will allow a "one level" mismatch, i.e. 8 ohm to 4, 16 ohm to 8 etc. running an 8 ohm extension cab in parallel with the 8 ohm internal speaker will be fine.

[g1]

Fender didn't fuss over mismatching like some do these days. A one-step mismatch was considered ok like olddawg said.
Some brands seem more finicky about mismatches, I would say it has much to do with how conservatively the OT's are rated.

[The Dude]

...... I would say it has much to do with how conservatively the OT's are rated.

That, and how hard you run it. If you're one of those guys who dimes the amp every time......

[mikepukmel]

Thanks everyone!