Loudspeakers in Bridge Mode

[losaavedra]

I have a Prosound PS8400DSP mixer/amplifier, that I use for guitar, delivering between 200W and 400W.

'Bridge Mode' for the Prosound anticipates an 8-16 Ohm Speaker into a particular 'Speaker Out' socket on the back of the unit.

The speakers I have are:

Two 8 Ohm 15" Eminence bass units rated at 350W each.
Two 8 Ohm 12" Celestion C12P-80 rated at 80W each.

My query is ...

Is it 'OK' to series the two 15" together then separately the two 12" together (giving 16 Ohms in each case) then parallel the results together to finally get one 8 Ohm combination to be fed from the Bridge Mode socket on the Prosound?

Alternatively I could series a 15" with a 12", then the other 15" with the other 12" then parallel those two 16 Ohms to arrive that way at a single 8 Ohm that would give the same general result.

I'd be less nervous about this sort of parallel/serial arrangement if all the speakers involved were the same, but as they are not I wonder if I'm risking some sort of damage doing what's described above, particularly to the lower rated 12" speakers, even though I'm unlikely to crank the Prosound up to anything like its full volume.

Hope someone can advise me on this.

[Inductor]

Either way seems right. but i would consider Re instead. check if the celestions have a higher R. If not connect them each with the Eminence, like you said later to have same power for each pair.

Alternatively I could series a 15" with a 12", then the other 15" with the other 12" then parallel those two 16 Ohms to arrive that way at a single 8 Ohm that would give the same general result.