hooking two cabs to my rkII?

[nathan28]

Hey roadking users how to i hook up two 8ohm cabs to my roadking? Do i put them both in the 4ohm out slot of speaker a?

 

[Machine Gun]

1 in A and 1 in B - 4ohm jacks

 

[Detox]

1 in A and 1 in B - 4ohm jacks

And that's NOT exactly what the manual says...

 

[nathan28]

The manual saids if u hook them up that way and run the amp in the "a+b" mode it will drop the load to 2ohms and could fry the transformer. If i want both cabs on all the time, wouldnt i hook them one cab up to the 8ohm out b and one into the 8ohm out a.

I should be able to also put them dummy jack in b, and hook both cabs up to the 4ohm outputs on a. right? Please someone help this is confusing me badly.

 

[mrd]

The manual saids if u hook them up that way and run the amp in the "a+b" mode it will drop the load to 2ohms and could fry the transformer. If i want both cabs on all the time, wouldnt i hook them one cab up to the 8ohm out b and one into the 8ohm out a.

I should be able to also put them dummy jack in b, and hook both cabs up to the 4ohm outputs on a. right? Please someone help this is confusing me badly.

You are right. DO NOT hook up two 8ohm cabs like that. It won't fry the output transformer, but it WILL put a retarded strain on your power tubes and roast the **** out of them. I ran my head like that for a few months.. it sounds absolutely fuckin' great, but it burns those tubes like a hot knife through butter.

The proper way is to run BOTH cabs into either the two 4 ohms jacks in speaker A OR the two 4 ohm jacks in speaker B OR, 1 EACH into the 8ohm jacks in speaker A + B.

Like you said, running one 8 ohm cab into one 4 ohm jack in A and another 8 ohm cab into a 4 ohm jack in B will put a 2 ohm load on the head which will strain everything more than it's supposed to be strained.

Looks like you've read the manual just fine, everything you wrote in your post is right, so go ahead and jam it up with 2 cabs man.

 

[mrd]

1 in A and 1 in B - 4ohm jacks

And that's exactly what the manual says

Not to do, that is.

 

[Detox]

The manual saids if u hook them up that way and run the amp in the "a+b" mode it will drop the load to 2ohms and could fry the transformer. If i want both cabs on all the time, wouldnt i hook them one cab up to the 8ohm out b and one into the 8ohm out a.

I should be able to also put them dummy jack in b, and hook both cabs up to the 4ohm outputs on a. right? Please someone help this is confusing me badly.

I better read the manual again my self even though I don't have 2 cabs.
I seem to remember it all wrong... Sorry for my previous post!

 

[Fcal124]

Right from the manual:
NOTE: Do not use SPKR A+B selection when two 8 Ohm cabinets are each connected to the two 4 Ohm OUTPUTS of each Speaker Output Bank.

I take this to mean that you can't use the Spkr A+B when you have an 8 Ohm cabinet in both of the 4 Ohm outputs of each channel (4 cabinets).
Channel A & B are seperate channels and there should be no problem running them at the same time into 1 8 Ohm cabinet per channel.

Short answer................1 8 Ohm cabinet into channel A and 1 into channel B.
I'm still gonna call Mesa

 

[mrd]

Right from the manual:
NOTE: Do not use SPKR A+B selection when two 8 Ohm cabinets are each connected to the two 4 Ohm OUTPUTS of each Speaker Output Bank.

I take this to mean that you can't use the Spkr A+B when you have an 8 Ohm cabinet in both of the 4 Ohm outputs of each channel (4 cabinets).
Channel A & B are seperate channels and there should be no problem running them at the same time into 1 8 Ohm cabinet per channel.

Short answer................1 8 Ohm cabinet into channel A and 1 into channel B.
I'm still gonna call Mesa

No, that's wrong. Running 4 cabinets, 2 into each spkr A + B is fine, because it presents a proper load to the amp.

Running one 8 ohm cab into one 4 ohm jack in spkr A and one 8 ohm cab into one 4 ohm jack in spkr B (TWO cabs) is what is wrong, that presents a load of 2 ohms to the amp.

How is this so confusing? lol

It's common sense for anyone who has been using heads & cabs for more than a week.

 

[MetalMatt]

Now I'm confused! :lol: I think we need a sesame street drawing to help out.

 

[nathan28]

Ok guys i called mesa twice and talked to two different techs, they both said the same thing, and here it is:

They said, one 8 ohm cab in spk a 4ohm slot.

The other 8ohm cab in spk b 4ohm slot. Yes you can run both cabs the same time by using the spk a+b selector on the back.
------------------------------------------------------------------------
What you cant do is run 4 8ohm cabs like that.
You CANNOT put two 8ohm cabs in the two 4ohm slots in spk a and the same in spk b and then select the Spk a+b toggle to play all four cabs at the same time. That will cause a 2 ohm load.

Fcal124 is correct.(and yes that is exactly what the manual says)
You read it correct. I read it wrong.

mrd you are incorrect.
---------------------------------------

 

[Fcal124]

Thanks Nathan. Just got off the phone with a Mesa tech too.
I'm concerned because I have a RKII and 4X12 RK cab on order.
You can run A+B into two 8 Ohm Cabinets.(1 on each channel)
The Road King cabinet is set up to do just that. You can run either channel seperately, or both at the same time.
What you can't do, is run two 8 Ohm cabinets off of the same channel. Two 8 Ohm cabs on one 4 Ohm channel will drop the load to 2 Ohms. Since Channels A and B are seperate channels, there is no problem.
This is straight from the Mesa tech.

to quote MRD: Running one 8 ohm cab into one 4 ohm jack in spkr A and one 8 ohm cab into one 4 ohm jack in spkr B (TWO cabs) is what is wrong, that presents a load of 2 ohms to the amp

MRD, you're correct, if both of those cabs are on the same channel, but A & B are two seperate 4 Ohm channels.

 

[Machine Gun]

That is what Mesa told me. 1 8 ohm in 4 ohm jack A, 1 8 ohm in 4 ohm jack B. Not 2 cabs in A or 2 cabs in B or 2 8 ohm cabs in the 8 ohm jacks.

 

[mrd]

Ah screw it. I'm now more confused than ever. The point is, the Road King takes a beating either way, you can plug whatever the **** you want into it and it will be fine, you're just gunna roast your power tubes.

 

[mrd]

Reading this again... this is weird.

Does this mean that the RKII spkrA+B are linked vertically instead of separate?

I've always thought of them as two completely separate taps. Like on the Mark amps, from left to right you have 8ohm, 4ohm, 4ohm. If you want 1 8ohm cab, use the 8ohm tap. If you want 2 8ohm cabs, use the 2 4ohm taps. The RK is the same ****, it just has TWO of them. I always thought that as long as the load representation was proper on both SPKR A and SPKR B, it's fine. They aren't related. Are you guys saying that the problem only arises when both SPKRA+B are selected? IE: if you're using the 2 4ohm taps in SPKR A to drive 2 8 ohm cabs, but only have SPKR A selected, it's fine, but as soon as you do the same thing on SPKR B and then also select SPKR A+B, the amp will have a problem?

The manual must be worded strangely, because I've read that section over 10 times and I've always taken it to mean what I wrote above. Gah. :evil:

 

[Machine Gun]

Maybe we need another person to call Mesa. A little extra clarification never hurt anyone.

 

[MrMarkIII]

"Are you guys saying that the problem only arises when both SPKRA+B are selected? IE: if you're using the 2 4ohm taps in SPKR A to drive 2 8 ohm cabs, but only have SPKR A selected, it's fine, but as soon as you do the same thing on SPKR B and then also select SPKR A+B, the amp will have a problem?"

Yes.
"Speaker A + B" means all four 8 ohm cabs are now hooked up in parallel. Four eight ohm speakers (or cabs) connected in parallel equals a total load of two ohms.

 

[mrd]

OK so the two speaker outputs are linked... I guess for them to be separate, you would need two entirely separate output trannies, yeah? That seems a bit extreme.. thanks for the info though.

I bet you probably could still do it.. it would just chew up power tubes like a mad man.

 

[nathan28]

Hey guys i love this **** forum because there are some ppl on here that know their stuff!!! I know a good bit and most of it i have learned from these forums!!!lol. Thanks for the help again guys.

mrd it was messin with my head too, if only mesa put a diagram in the **** manual. Well they did put a diagram in the manual, it is for the regular rectos speaker outputs, not the roadking.lol. Thats something a non made in america company would do. Oh well mesa still makes the greatest amps ever.

 

[Fcal124]

Hey, at least their techs answer the phone right away. I wonder how many times they were asked this question?
It's amazing how there is nothing in the manual at all about hooking up a RKII head to a RKII cab.
Oh well, can't have everything................