2 cabs - what amp output ohms?

[ShredFetus]

I've got a Marshall 9100 tube power amp and each channel has two speaker outputs, for a possible total of four cabs. I can switch the output of each channel (2 cabs per channel) between 16ohms and 8 ohms. My question is:

If there are two loads running of a channel switched to 16 ohms, does it effectively become 8ohms of total output per channel? Even though the switch is set to 16ohms? Or are the ohms consistant whether you have one or two cabs connected?

Argh!

This came to my attention when looking through my mates Peavey 51150II manual and it says switch the output to 8ohms for two 16ohm cabs.

Have I been ruining anything by running one channel with the switch at 8ohms with two outputs into a stereo 8ohm per side jcm900 box?

Argh again!

 

[ShredFetus]

Re: 2 cabs - what amp output ohms?

I know some of you have the answer to this! Maybe it's just the way I wrote the question haha... I tend to over explain a bit.

I've got a gig on tomorrow & it would help to know so I dont fry my amp on stage!!! :bowdown:

 

[Gearjoneser]

Re: 2 cabs - what amp output ohms?

Since the amp is stereo, I think you should have it set for 16 with 2 16 ohm cabs. Each side is a seperate amp, so it's switch is telling each side that it needs to see 16 ohms. I'm not positive, but if it were a mono head, you'd probably want it on 8, with 2 16 ohm cabs.

The best idea is to go to their website, and download the manual for that amp. It'll most likely tell you what to do with 2 cabs.

 

[ShredFetus]

Re: 2 cabs - what amp output ohms?

Thanks GJ, I think I get the idea from what you said, but heres a pic anyway, sorry I couldnt post it earlier.

So from what you said I can't use 2 8ohm cabs in the situation because my amp doesn't swtich to 4 ohms?