Hey Now
I have an Engl Fireball and a Framus Cobra that I am running through a Marshall 4x12 cab (stereo/300W/900 series). I just picked up the Cobra, and usually have one of the two shut completely off while I play the other. Today I was trying to compare tones, so both were on. I was playing through the Cobra while the Fireball was on standby, and when I switched the Fireball completely off, I noticed that the Cobra suddenly had more volume, punch and drive. I was looking at picking up an ABY pedal so I could run both heads at the same time, but I assume that I'll have the problem of decreased volume etc. by doing this. I was under the assumption that with a stereo cab this wasn't a problem (running two heads through the one cab). Am I doing something wrong? Anyone have this problem or be able to explain why this is happening? The cab itself seems to be working as it should (Cobra through the left two speakers, Fireball through the right two), and both heads are running at 8 OHMs, and the cab is switched to stereo at 8 OHMs per side.
Any help would be appreciated!

i used to run 2 heads thru one cab. I didn't have that problem, but i did use something similar to the switchbone, it was a framptone amp switcher. The fireball could just be more powerfull? Sorry i cant be much help

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Possibly the greatest thread title ever.

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^hahah, for a split second I read 2 girls/1 cup.

You have to understand that different amps have different volume tapers, a Fireball with the master volume at 12 o clock might not be exactly as loud as the Cobra with the volume also at 12 o clock, even if they are both the same wattage and working at the same Ohmage(also, these amps put out different wattages right?). You might have to have the fireball's volume up a bit higher to match the cobra.

Just tweak the master volumes accordingly til you get em paired. Probably easier( as well as better sounding and more fun) if you buy another cab to go with it though.

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Wasn't sure if anyone would get the '2 Girls/1 Cup' reference... that's awesome.

There is definitely a difference in the 2 amps volume wise, and if run together there will have to be some tweaking to accomodate this. The problem I had was that I was playing through the Cobra while the Fireball was turned on, but on standby. I turned the power on the Fireball off completely, and then noticed that there was a gradual volume increase in the Cobra, without touching any of its settings... more grind and punch.

Thanks for the input however...

sounds like you need a better power supply. Are both amps plugged into the same wall? :P

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... both are plugged into a Furman power conditioner. I'll try using two separate outlets, and see what happens.
Thanks for the input.

the only other thing i could think of is if some wires are crossed... which is possible because marshall stereo isnt exactly true separated stereo.

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It might be that the speakers in the cab are wired in parallel horizontally instead of vertically? Like each "side" of speakers is actually the top and bottom speakers instead of the left and right side, so if the Cobra sounds like it's louder and punchier it might be using the 2 top speakers that project more sound at your head?

Edit: I think it might have something to do with the load from the amps, have you tried running the amps into the opposite sides of the cab?

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Thanks again for the tips guys.
The cab is split into left/right stereo - and the inputs on the rear match what's coming out of the front. It's definitely not that the Cobra 'appeared' to be louder, it was. So much in fact that I had to turn down the master volume, and also turn the bass and presence down some. I am in agreement that it must have something to do with the load on the amp. I was reading some reviews on A/B/Y boxes, and see that (the ones I was researching, Morley ABY and Radial Switchbone) always refer to 'two amps/two speaker cabs' when switching between the two. The Radial Headbone is apparently used to switch between two heads into one cab, however there isn't a 'Y' function on it (it makes it very clear in the user manual that it keeps the exact same load on the amp when switching between heads). I am under the assumption that I cannot use both heads at the same time through the same speaker cab, and having both on (even if one is only on standby) still makes the load unstable to the other amp.
Thanks again for the help!

What are you using to split your signal currently? Or are you just running one at a time?

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The Morley ABY isn't that great, you get a little crosstalk between the two split sides, which is a bit naff, especially if your amps are both cranked.

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So far I'm just running each at one time, Cobra left, Fireball right. I usually have one completely off when playing the other, but the other day I kept the Fireball on standby so it would warm up while I was playing the Cobra. That's when I noticed the problem. I remember reading that with the Fireball (or any Engl with the Power tube monitors) some signal still makes it though when the amp is on standby. Maybe this creates some type of load imbalance, causing the drop in power in the Cobra...? Seeing as I haven't found an apparatus that allows for running two heads into one cab at the same time (ABY box), I'm assuming that it's not possible - especially since the Radial Headbone stresses that there is no change in the load to the heads when switching between whatever two sources you use.
As for the Morley ABY box, I agree... haven't read to many good reviews about it. Apparently plays havoc with your tone, isn't true bypass, along with what you had already mentioned.
Thanks again guys.

You might wanna Rewire your cab for a true stereo operation.

I use a Radial Bigshot ABY with no complaints.

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