I'll give you folk the rundown here first.......

So I just bought a Crate 1200H half stack:

GT1200H 120W RMS Head 4 ohms
GT412SL 4x12 (100w each) 8 ohms

And obviously I'm only getting about half my power out of the head due to the fact that the impedance of my cab is 8 ohms and my head is 4 ohms. So the natural decision for me was to add another 8 ohm cabinet, run it in stereo with my original cabinet, and bring down my impedance to match my 4 ohm head, thus getting full power. This makes sense so far right?

So I added:

Behringer Ultrastack BG412F 4x12 (100w each) 8 Ohm Stero 16ohm Mono

So logically, if I run my Crate 1200h head which is 4 ohms, into both of these cabs, which are 8 ohms each, I should be running at full power (objectively how loud SHOULD this sound? Like, in my living room or something I shouldnt be able to run it at full power without knocking stuff off the walls?).

Now my issue here is that I don't really know very much about this sort of stuff, and it seems to me that my Crate head only has one output. But both of my cabinets have dual input jacks (for stereo purposes I would imagine) so how do I run this all together? Do I split the original output with a Male2FemFem adapter and then split that again for each cab? Seems to me that thats the only way I can do it but I'm not really sure. Seems like an awful lot of splitting. How do I connect my 4 ohm head to two stereo dual input 8 ohm cabinets? Am I way off base on all of this?

Anyways, HELP!!!!!!!!
You won't shake anything off your walls with that. Trade it for a valve combo. A 50watter will knock plenty of things around in your house.
Quote by rocknrollgod
well i can tall you this much do NOT get a marshall MG. becasue you will blow the speaker with duncans in the guitar. i know for experience.

Quote by Gutch220
Leave it to UGer's to argue over who "owns" a language

if the Behringer is 8 ohm stereo, and 16 mono, you're only going to be using half the cab running at the 8ohm stereo input. I think you can daisy chain the 2 cabs in parrallel, so if your 8 ohm crate cab has an output jack, you connect it to the Behringer's 8 ohm input, and it should be 4 ohms at the head. I would confirm this with an owner, but I think those cabs have a parrallel ouput.
"The fool doth think he is wise, but the wiseman knows himself to be a fool." - W.S.
amp clips
amp vids
your problem is your behringer, which your considering an 8 0hm cab is only 8 ohm in stereo and 16 ohms in mono. To match the 4 ohm output of your head you need to run 2 8 ohm MONO speakers or 2 8 ohm STEREO speakers, not 1 8 ohm mono and 1 8 ohm stereo.

Since the GT head is made for the GT cab, I dont understand why the ohms dont match up. Make sure your head or cab dont have switchable impedances. I will bet one of them does
Gibson SG Standard
Orange Rocker 30 combo
Fulltone OCD
EH Holy Grail
Yeah oddly enough the head and cab dont match. weird for a package deal. neither the head nor the crate cab have a switchable impedance.

The head only has a single output, and neither of the cabs have outputs, only dual inputs, another odd thing. It had occured to me that I could split my output from the head into 2 mono outputs, run one into the crate cab, and then split the other mono output again and run both of those leads into the behringer. Hmm. that gives me one 8ohm 4x12, and two 8 ohm 2x12s....does that even work? how would that effect my 4ohm heads output?

Would it be best for me just to run a stereo cable out of my crate head, and into both inputs on my behringer? thus using it like a stereo cab? 2 x12' speakers at 8ohms? that would allow me the full power of my 120w 4 ohm head?

that just leaves me with a an extra cab 4 x12 dual input cab. i guess i use it for something else then eh?

does that make sense though? running my 4 ohm head into the behringer, stereo, giving me two 8ohm 2x12s?

or does anyone know if the crate gt412st 4x12 cab has an output on it?
well, they sell that as a package right? It has to be able to hook up to the full stack. Are the dual inputs on the Crate cab wired in parallel? It's not a stereo cab right, it only has an 8 ohm impedance? If so, I still think you could daisy chain a cable to the 8 ohm input on the Behringer, and have it be in parallel. It would be only half the Behringer working, but it would be seeing the same load from both cabs that way. Have you tried emailing Crate customer support yet?
"The fool doth think he is wise, but the wiseman knows himself to be a fool." - W.S.
amp clips
amp vids
you cant flick a switch on the back of the head to make it run 8 ohms. thats wierd every head ive ever had has had a switch to change it from 4 to 8 to 16 ohms.

and its quite simple to setup a stack. if you have enouph room. take the straight cab put it where you want it. set the angle cab on top of the straight cab and the head goes on top. then you take 2 patch chords plug them into the back of the head and then into the back of the approprate cab.

sorry for any wrong spellings.
The crate cab is definately not stereo, just with the two inputs so parallel i assume. that makes sense that I could daisy chain them together, would i just use a stereo cable for that?

the other crate cab is definately wired for running the fullstack but its actually pretty expensive to buy it just on its own. i can either daisy chain the crate and the behringer (only running one 2x12 8ohm stereo channel) with a stereo cable, or i can run a stereo cable into the behringer cab, use both sides of the 4x12 (2 x 12 @ 8ohms) and thus get my full wattage. it seems to me to make more sense to just run stereo into the behringer, and say screw the crate. the only difference is that if i daisy chain them (again, stereo cable to do this?) then i get the 4 x12's @ 8ohms from the crate and the 2 x 12's @ 8ohms (leaving the other 2 x12's dead) totally 6 x12's. if i run just into the behringer, using both channels at 8ohms im only running 4 x 12's total. hmmm.

am i getting any of this? lol
when you are daisy chaining, you use a regular speaker cable. That's specifically speaker cable though, it's thicker than regular instrument cable. It should say "speaker cable" on the actual cable usually. That goes for any cab you hook to the head.

The Crate's output isn't in stereo. There is only one output anyway right? You would need some kind of Y splitter that was wired in parallel if you are trying to run into each 8ohm input on the Behringer, and wind up with 4 ohms seen at the head.
"The fool doth think he is wise, but the wiseman knows himself to be a fool." - W.S.
amp clips
amp vids
I have a y-splitter, that i can run from my head to presumably two inputs. would i then run two speaker cables to each input of the behringer? thus giving me two 2x12 8 ohm sets in stereo, matching my 4ohm head?

when you say daisy chain the speakers, is that like a speaker cable with multiple run offs? like a stereo cable (ie, more than one output)? or do you mean running one cable in, then another out?

yes, the head only has the one output, so if i ran a y-splitter, and then two stereo cables into each cab i should get the full power of the head.

why cant i just use regular instrument trs cables?
you can burn things up using instrument cable. Instrument cable is shielded, and a lot thinner wire than speaker cable. Speaker cable is meant to take the "powered" signal the head is sending to the cab. That's 100W of power man! Never run instrument cable in place of speaker cable. Make sure the Y you use isn't shielded, and is thick speaker wire.

You can wire it that way as long as it's unshielded speaker wire used for the Y. You don't want to use regular instrument cable anywhere that hooks between your cab and your amp head.

Think about it man, all the power your amp is producing is going thru that cable to your cabs. Instrument cable never sees any real powered signal going into the front of an amp.

When I say daisy chaining, I mean running 1 speaker cable to your crate cab from your amp head, then using the left over input on the Crate cab, and running another speaker cable to the 8ohm input on the Behringer.
"The fool doth think he is wise, but the wiseman knows himself to be a fool." - W.S.
amp clips
amp vids