software

This has had me wondering for years! And noboby has ever had a straight or
logical answer for me. Take your basic BF/SF Fender amp 64' to 81'.
(My princeton for example) I have a jack for a 8 ohm speaker and another
for a 8 ohm ext. cab. So if I add another 8 ohm speaker I'll be running a
4 ohm Load. Yes? The OT has no tap for a 4 ohm load. Yes? Doing such
a thing would stress my OT? Yes/no? If yes ... Why did fender design
it like this knowing it would cause a Impedence mismatch? Seems nobody
has complained in 40 years.

hmmm well if your princeton is anything llike the 5150 combo, heres how it works:
the internal speakers of the 5150 are at 16 ohms, and there is a jack for a 16ohm extension cab. the way it works is that, when you plug a 16 ohm cab(or any ohm cab) in the extension, the head automatically switches to an 8 ohm load(16 amp; 16 paralled = 8). Therefore you can run the amp 3 ways, in your case:
1. internal speakers at 8 ohms, or a cabinet at 8 ohms plugged into the internal jack,
2. internal speakers at 8 ohms, and an extension cab at 8 ohms, which would make the amp switch to 4 ohms and,
3. only plug a 4 ohm cab into the extension jack, and the amp will switch to 4 anyways.

again, this is the way it works for the 5150 combo, but there are only so many possiblities, so you should check the manual first.


Originally Posted by Warhearthmmm well if your princeton is anything llike the 5150 combo, .
Nope, Not at all. Your Peavey has to have a multible
tap transformer That internally switches when another jack is pluged in.
This is my point . Even old Marshall's gave you a Impedence selector
switch. Fender gave you the extra AC outlet in the back of the amp
that comes in handy at times. But with Impedence they kinda left ya
hanging.

Its also possible that the jack is wired to connect the extension in series rather than parallel.

Deleted the part that might have been a safety concern.