Extension Cab Question (re: Ohms)

[Frank9]

I just got a nice 190L. It has two speaker outs. One is labeled just speaker and is 8 ohm. That's easy enough, I have an 8 ohm 4x12 plugged into it right now. The other out says external speaker and is labeled 4 ohm. Now does that mean that the total resistance be 4 ohms (two 8 ohms cabs in parallel) or should the extension speaker itself should be 4 ohms. I'm hoping it's the former as it's a lot easier to find 8 ohm cabs.

Thanks.

[PSYKO]

As long as total load does not exceed 4 ohms, you will be fine.  The amp has no way of "knowing" whether or not you have more than one cab, or that its a cab at all (it could be a four ohm light bulb for all it knows or cares!)  All it sees is an electrical load.  I'm not familiar with that particular amp, but I wouldnt recommend running both a 4 ohm and an 8 ohm load at the same time, as the two jacks may simply be wired in parallel.

[Frank9]

That's what I was hoping to hear. Thanks. Is there any way to tell if the outputs are wired in parallel without opening the thing up and having a look?

[loudthud]

See my post in the thread titled Sunn 2000S Guitar and Bass Heads.

[elektron]

Hi-- I have the service schematic for the 190L and I have a full stack 190L vintage 1973.. the cabs have each 4x10's and are each 8 ohms.  If you use 1-8 ohm cab it should be plugged into the 8 ohm jack... if you add a second 8 ohm cab it is in parallel with the first so the total is 4 ohms and that is the tap for the transformer (4 ohms).... hope this helps.

[Frank9]

Thanks again everyone. I pretty much figured that would be the case but I've pretty much fallen in love with this thing and it had no manuel so I didn't want to risk it without some advice.