If I've got a 300-watt, all tube head, and I run it to two 4-ohm 8x10 cabinets, will each cab be getting 150 watts or 300? I know that it would dish out 300 watts at 2, 4, or 8 ohms, I was just curious as to how a multi-cab setup would work.

I had a gig on Saturday night where the bassist from another band was running his Ampeg Classic into two fridges, and he was freaking LOUD. With my set, I used the same two cabinets, but ran my Ampeg SVT4 in dual-mono so each cab was getting 490 watts. We appeared to have the same amount of volume, but something isn't adding up. How do all-tube amps deal with multi-cab setups??
"Comedy's a dead art form. Now tragedy, that's funny." -Bender Bending Rodriguez
right... but how would the work-load be divided up? I'm still trying to understand why tube heads work at the same wattage at three different resistance loads.

One 4 ohm 8x10 cab would kick 300 watts into the air. Two 8x10s would amount to 2 ohms resistance, so the amp would still be pushing the same 300 watts, just over a wider surface area? like, 150 watts per cabinet?
"Comedy's a dead art form. Now tragedy, that's funny." -Bender Bending Rodriguez
physics states that if it is the same wattage at different ohms then the voltage or current would be different which it shouldn't be since it will run at 120 volts regardless and the current shouldn't really change, you try doing that and you will probably miss up your head. Also are you running those cabs parallel or in a series.
All-tube heads like mine have an impedence selector switch. Mine will put out 300 watts at either 2 or 4 ohms. You just need to choose which.
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well if it has a selector than it depends on if you are running a series or parallel setup

Parallel will be 300 on both just make the head work harder, thats 2 ohms
Series will be 150 ob both and that should be at 4 ohms.
Last edited by Tcero12 at Dec 12, 2007,
All-tube heads sound a lot louder, a lot friggin louder, has to do with amplification physics. Remember, when I played at a bass expo, i used Quantum 600watt all tube into 8x10, and at 10 o'clock it was blowing my pants off with enormously clear sound, where as when I played my beloved GK solidstate, 750 watts, if I'm not mistaken, into 8x10 at 5 o'clock it didn't sound that loud...
Last edited by Bassilo at Dec 13, 2007,