Currently Being ModeratedSep 20, 2012 12:02 AM (in response to evilmikehoo)Re: 212 combos and 412 cabs
In a simple one word answer, NO.
As you are most likely aware you would have mismatched impedance loads that would harm your equipment.
Most 4x12's are 16 ohm mono and most 2x12's are 8 or 4 ohm mono loads (d0n't worry about the stereo qualifications for now)
On your SpiderValve you can run only run one set of 8 ohm cabs, meaning two 2x12 cabs that are an 8 ohm load each(I just checked the amp back photos on here as I have the HD100mkii head).
The only way to run the speakers in your SpiderValave and a 4x12 at the same time would be to have an amp guru wire your 4x12 to be 8 ohm mono.
Wait a tick, I just noticed from the picture on here the speaker cable is plugged into the 4 ohm single meaning your amp must have two 8 ohm speakers making it a 4 ohm load. Sorry, I'm so used to seeing the two 16 ohm Vintage 30's in the back of my Mesa I took it for granted the SV used 16 ohm speakers as well. So in a sense you're screwed even more now with trying to do what you wanted. From what I can ascertain the only thing you could do would be to hook up your 4x12 by itself to your SpiderValve using the 8 ohm stereo inputs on your 4x12.
So to put it back into easier terms, no you can't run them all together on the SpiderValve, but you can run a 4x12 by itself if you wish using your amp just like an amp head.
Currently Being ModeratedOct 7, 2012 2:26 PM (in response to SSstormtrooper)Re: 212 combos and 412 cabs
I also have the spider valve1, But looking at mine, the 2x12s are pugged in as you say, to the 4 Ohm out B jack, but on inspecting the speakers, they are labeled 16 0hm! So shouldn't they be plugged into the 8 ohm jack? I don't think there is a way to wire two 16 ohm speakers to run as 4 ohms it there?
I bought the amp used from GC last week and now am wondering if they were plugged in wrong by the former owner. If so, I should plug them into the A jack (8 ohm) for normal use, but I could switch it to the B jack (4 ohm out) and add another 8 ohm cab to the second B jack, right? This configuration makes more since to me as you can add a cap and run the 2X12s with it.
Does anyone know if the factory originaly had these pugged into the A or B jack when purchased?
Currently Being ModeratedOct 8, 2012 6:19 AM (in response to EstringPicker)Re: 212 combos and 412 cabs
As far as I know, they should be plugged into the 8 ohm socket - mine is. Better find out what's goin' on there. Maybe the previous owner was using a cab and neglected to plug it back in the right way.