Series versus Parallel question

[BassyBill]

I believe mulchor is answering a different question and he is right.

Ignoring power differences from the amp at different cabinet impedences,

When a 4 ohm and a 8 ohm cab are connected in parallel, the 4 ohm cab gets 2/3 of the power coming from the amp, the 8 ohm cab gets half as much (1/3 of the power).

When a 4 ohm and a 8 ohm cab are connected in series, the 4 ohm cab gets 1/3 of the power coming from the amp, the 8 ohm cab gets twice as much (2/3 of the power).

This is correct - my apologies, I'd misread two earlier posts in the thread and didn't engage my brain. Serves me right for posting too early in the morning!

(My earlier post referred to the two cabs in the OP, btw, and was correct as far as those two cabs go.)

 

[BassyBill]

I was actually going to ask a very similar question this morning.

I have an Ampeg SVT 2 Pro which only supports 2 or 4 Ohm loads. I have 2 Aguilar cabs that are each 8 Ohms. Normally, I connect each one directly to one of the 2 speaker jacks on the amp, and set the amp impedance selector switch to 4 Ohms.

But, I also have a Peavey Pro 410 cab, which is 4 Ohms.

I was thinking, if I want more volume than I get from just the two Aggie cabs, I can daisy chain the two Aggie cabs, so they're both being driven by one of the speaker output jacks from the amp, and then I can connect the Peavey cab to the other speaker jack on the amp. Then set the amp impedance selector switch to 2 Ohms.

Right? This should be "safe" as far as the rated specs of the amp and all 3 cabs, right? (All 3 cabs are rated for at least 300W, which is what the amp is rated at)

Yes - connecting the two eight ohm cabs to one speaker output as you describe will present 4 ohms to that output. Then connecting the 4 ohm cab to the other output will give you an overall 2 ohm load, so if the amp is rated for that you should be fine according to the specs in your post.