Road King 2x12 Cab

[jnoel64]

Please forgive me for asking such a stupid question, but I am not used to my Road King 1 yet....
I have the 2x12 Road King cab that accompanies the head. I'm not entirely sure of the correct method of connecting the head to the cab. I have read in the manual to NOT use the A+B selector on the channel strips if only using one cab. Yet the cab itself has A, B or A+B. I would like both speakers to operate simultaneously. Can someone please explain exactly how I connect them properly? I know how unbelievably stupid this sounds, but honestly, the manual doesn't cover this thoroughly enough that is very straight-forward....thanks for your patience and understanding!

 

[bandit2013]

You can use a single speaker line, connect to the a/b (4 ohm jack) which places both speakers in parallel. Just make sure you have the bias set for 4 ohms (sorry thinking RA100), use one of the 4 ohm output jacks on A. Keep the jumper on the b side. Just make sure all channels will select the A output.

If you have another cabinet, you can use the B output. You probably could split the cab using the A and B inputs. You will need two cables to do it. 8 ohm jack on A, 8 ohm jack on B. May be a bit much for each speaker.

In light of the Road King, say you have the Road King 412, half of it has V30 and the other has MC90. It would make sense to split that type of cab for the different tones provided by each speaker.

 

[rocknroll9225]

Just make sure you have the bias set for 4 ohms (sorry thinking RA100), use one of the 4 ohm output jacks on A.

Sorry to go off topic for a quick minute here, but I kind of felt the need to correct this - selecting between 4 and 8 ohms has nothing to do with the bias, it switches between two different taps on the secondary coil of the output transformer. The bias sets the amount of idle current running through the power tubes so they'll operate correctly within the voltage rails. Two totally different things. Everything else you said was correct though.

Carry on

 

[bandit2013]

I said bias, :shock: I must be brain dead. :lol: Perhaps "LOAD" would be the better term. Impedance or impotence, one of which may be considered a medical condition and the other is part imaginary depending on the phase angle. Yep, bias, bias, bias.... 8) my bad.

 

[rocknroll9225]

No worries, man haha. Just figured I'd clear that up. But yeah, as far as the OP, if you want to switch between the V30 and C90 in the cab, plug the speaker A 8 ohm out into one 8 ohm side of the cab, and the B 8 ohm out into the other 8 ohm side of the cab. If you're doing it this way though, you really shouldn't run the amp with more than 2 power tubes at a time. In reality you could run it with more, but you'll have to be careful not to crank the volume too high. If you want to be able safely use all of the power options on the head, I'd recommend either getting a road king 4x12 or 2 separate guitar cabs.

 

[Stratocaster]

Part of my reply in this post...

http://forum.grailtone.com/viewtopic.php?f=24&t=59002

...You should be using the single available 8-16 ohm 'A' output from the amp, and connect this to the single 'A' input of the speaker cabinet.
You should then connect the single available 8-16 ohm 'B' output from the amp, and connect this to the single 'B' input of the speaker cabinet.

Per the manual, never select A+B if you have two separate cabinets plugged in (occupying both 4 ohm outputs from amp), as the resulting impedance is too low for sustained tube life (drives it down to 2 ohms).

Again - A+B is absolutely safe when you have a single connection to 'A', and a single connection to 'B' (as long as each connection is at 8-16 ohms).
It's when you have TWO connection each to 'A' and 'B' (via the TWO 4 ohm outputs per A or B) that you have a detrimental condition.

So as a final thought for you, the correct way to connect TWO RK 4x12 cabs is to use both of the 4 ohm outputs per channel from the amp.
You'd connect one of the 4 ohm connections from channel 'A' of the amp to your top cabinet (in a stack) 'A' input. You'd connect the second 4 ohm 'A' output from the amp to your lower cabinet 'A' connection.
You'd repeat for 'B' connection.
You'd set your channel strips up to be A, or B....but never A+B.

Strat