Re: HELP running multiple cabs - OHMS ???
I found this on the Bogner website in the manual.
NOTE for older Shivas made prior to 12/1/05: If you put the amp in play make sure you have a load or speaker cabinet hooked up, otherwise you could damage the output transformer and the power tubes. This older Shiva does not have an ohm selector, it has 3 speaker output jacks each labeled with an oval containing 2 numbers in it. One of the numbers in each oval is marked out with a black marker, so only the other number is important to you! If you hook up only one cabinet, the impedance (ohm value) of amp and cabinet should match: 4 into 4, 8 into 8 or 16 into 16. If you hook up two cabinets (they must have the same impedance, same ohm value). The total ohm value is half the value of one cabinet since they run parallel now: so two 16 ohm cabs plug into the two 8 ohm jacks, two 8 ohm cabs plug into the two 4 ohm jacks if your amp is wired with two 4 ohm speaker outputs of course, see the following for more details: The EL 34 Model has one 16 and two 8 ohm speaker outputs (the transformer has an internal 4 ohm tap also, so the outputs could be wired to 8 4 4 or 16 8 4 ohms if you wanted your amp customized)
NOTE for 6L6 Shiva's made June 2002 and newer are wired with one 16 and two 8 ohm speaker outputs, just like the EL34 models. Shiva 6L6 models made before June 2002 approx. do not have a 16 ohm tap. The older 6L6 Model have one 8 and two 4 ohm speaker outputs (the transformer has an internal 2 ohm tap also, so outputs could be wired to 4 2 2 or 8 4 2 ohms if you wanted your amp customized) Keep that in mind because most of the 4x12" cabinets are 16 ohms.
In other words, you need two 16 ohm cabs to use both 8 ohm jacks or what Bruce said. I have no idea where you get such a cable though.