Okay, so,
I have a tube head with a 130W output,
I have a 2 X 12 cabinet which I want to change the speakers in,
I'm want to change 1 speaker to a Celestion Vintage 30 (60W)
And 1 speaker to a Celestion G12K-100 (100W),
Both speakers will be connected in paralell and will each have an impedence of 8 ohms

My question is this:

Will the cabinet have a 160W power rating (combined value) or a 120W power rating (the rating of the lowest speaker times by 2)??????????

I really need to know this because if the power rating is 120W the Vintage 30 might blow due to my amp head...... Cheers for the help
okay. well.

First of all, you need to consider the impedance of the speakers. The G12K is 8 ohm, while the Vintage 30 is either 8 or 16 ohms. Assuming that both are 8 ohms, you can wire them to be a 4 or 16 ohm load. Does your amp output to either of those loads? It should, but it's worth checking.

Next, to get the cumulative power handling of a bunch of speakers, you can sum them. So the nominal power rating of the cabinet will be 160 W.

Finally, the nominal speaker power is usually conservative to avoid people blowing them out at the rated value. So you should be safe to overpower them by 10 W or 20 W... so you would really have to try hard to blow out the Vintage 30. And that's ONLY if you use the amp at FULL output, which somehow I think you never will...
Marshall amplifiers are the truest purveyors of rock and roll known to man.

"And give a man an amplifier and a synthesizer, and he doesn't become whoever, you know. He doesn't become us."

Holy crap, check this out!
Quote by Kazaza
Both speakers will be connected in paralell and will each have an impedence of 8 ohms

I already knew about impedance, this cab is gonna be 4ohms mono and 8 ohms stereo,
I just wanted to know about power, cheers for the response
Incorrect.

In stereo mode each channel will have a power rating according to the speaker connected. So 60W for one and 100W for the other.

In mono mode each speaker will draw power according to its impedance - the less impedance the speaker has the bigger fracture of the overall amplifier power it`ll take.
In your case both speakers will dissipate the same 1/2 of amplifier power fed to the cab, regardless of its power rating.
So your overall cab power rating = V30_rating * 2 = 120W. (since V30 is the less powerful one)

If you mistake it for 160W and try to fed those 160 Watts into the cab, both speakers will get its 80 Watts which is fine for G12 but is a trouble for V30.

It is true though that guitar speakers are very durable, so your amp fits your cab just fine. After all, I suppose that was the question

Cheers. Ace.
Yeah, I thought because P=VI that power would be proportional to impedance as well, cheers a lot for the post.
Quote by Kazaza
Yeah, I thought because P=VI that power would be proportional to impedance as well, cheers a lot for the post.

Sure thing. Play loud