How to use two or three cabs with one combo amp?

[Corbic]

Hey all, while I was reading a book for my school summer assignments, I had a good idea hit me: Why not have a second speaker cabinet for my amp with a different sounding speaker in it? Then a second idea, mostly inspired by Peter Frampton and Pat Travers, why not have a rotary speaker going along with it?

So then the final setup would look like this:

In my Crate V32, there will eventually be a G12H30 speaker.

I have a seperate 1x12 speaker cab with something like a Celestion Blue in it.

And then I have the new Motion Sounds 1x12 Rotary Speaker, with it's stock speaker.

So I have the amp to the left of me, the cab to the right of me, and the rotary in the center all looking like this.

AMP Rotary CAB
/ = \

The line represents how that speaker is pointed, and the equal sign means it's just facing straight.

So now, first of all, is this a good idea worth eventually trying or a stupid idea I should just scrap?

And then, how would one wire this whole thing up?

Thanks!

-Corbic

 

[embotone]

Re: How to use two or three cabs with one combo amp?

Assuming your speakers are all 8 ohm, you are going to end up with an impedance of 24 ohm, or 2.6 ohms, depending if you wire them serial or parallel. If your amp has only one 12" speaker, it probably has an 8 ohm output. If you did the 3speakers up parallel, run your amp into a Weber Z-matcher https://taweber.powweb.com/store/zmatch.htm
Set the input impedance to 8 ohm, the output impedance to 2.6 ohms.
Then, run the output into a 3 way splitter and then to the speakers. The way you wire up the splitter will determine if the speakers will be parallel or in series.
If you want to run your speakers in series, set the input to 5.3 ohms, and the output to 16 ohms.
If you don't know what I am talking about, get someone else to do it for you.
Bottom line, you should NOT run your amp straight into all three speakers, or you will probably blow your output transformer in the amp.

 

[Rich_S]

Re: How to use two or three cabs with one combo amp?

It looks like that amp has a fixed, 8-ohm output, so you're going to have a tough time getting the impedances matched. The Z-matcher would help a lot.

The other problem is balancing the relative volumes of the three speakers. Assuming you wired all three in parallel (and they're all 8 ohms) then the power would be split in equal thirds. Volume, however, would depend on speaker effiiency - a G12H30 would be louder than the others, because it is very efficient. So in this case, you'd have more than 2/3 of your volume "straight" and less than 1/3 "rotating". I doubt you'd even hear the Leslie.

You'd probably get a better mix, and an overall simpler system using just the combo with the G12H30, and the Motionsound without the additional cab. You could use 16-ohm speakers on both, but you'd need to have the Motionsound plugged in all the time.

Life's a pain with no output-imedance switch.

 

[devastone]

Re: How to use two or three cabs with one combo amp?

Doesn't the Motion Sound have a built in power amp? It's been a while since I've seen one so I don't remember exactly. If it does, you need to run a line out to it, not a speaker out.