Mixing different OHM speakers...

[harpinon]

I am putting together a 2 x 12 cab for my Pure 64 head. I have several speakers and two on the way.
When trying these out, is there a serious issue with mixing 4's and 8's or 8's and 16's OHM-wise?

 

[riffmeister]

The lower Ohm speaker will receive more power and be louder (if the two speakers are of similar efficiency).

Wired in parallel here is how you calculate the total load:

(A x B)/(A + B)