using multiple cabinets

[muttonchopsrule]

the thread about the 2x12 16 ohm cabinet got me wondering about exactly what's going when two cabinets are plugged into the same head.

i understand what happens to the impedence when speakers are wired in series, as opposed to if they're wired in parallel. but say you have a head that has two 16 ohm outputs, two 8 ohm outputs, and two 4 ohm outputs (hypothetically), and you have two 8 ohm cabinets, both of which you want wired up. which outputs would you use from the head? and when you use two different speaker outputs then would the two cabinets be in series or does the amp's circuitry put them in parallel?

[SlyFoxx]

Re: using multiple cabinets

Most of the time it's a parallel connection on the amp. But it's always good to check the manual. Some amps are just plain strange in how it's implemented and the silk screening on the back can sometimes be misleading at worst, counter intuitive at best.

[muttonchopsrule]

Re: using multiple cabinets

thats what i thought, about it being parallel. just wanted to make sure i wasn't just pulling it out of my ***, haha. thanks man.

[Gearjoneser]

Re: using multiple cabinets

Most likely the head would have a 4/8/16 selector, and two outputs running in parallel.

(2) 16 ohm cabs = 8 ohms selected on head.
(2) 8 ohm cabs = 4 ohms selected on head.

It'd be best not to use 2 4 ohm cabs, since most heads don't have 2 ohm settings.

It's also a good idea to NOT use 2 cabs that don't have the same ohms rating, since the lower one will be louder and pass more highs.

In general, most high gain amps run at 16 and 8, while clean combos run at 4.

If you ever decide to yank out the inner or outer tubes on a 100W amp, to bring it down to 50W, you've got to set the head selector at half of what the cab is.

Head with 2 tubes pulled out, set on 8 ohms, plugged into 16 ohm cab.

If you run a PA head to a cab, then run out of that cab into another cab, you're going to a series load, so the PA ohms output should be equal to the sum of the two cabs.

Hope that helps.