ohm question Marshall jcm800 with 2 cabs 1@8 /1@16 ?

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Ohm question Marshall jcm800 with 2 cabs 1@8 /1@16 ?

I need to run my mesa cab (8ohms) and a marshall cab (16 ohms)at the same time off of a jcm800 100 watt head. What should the head be on 4 ohms???

I will also like to run my voodoo cab (8 ohms) and my mesa cab (8 ohms) of of the same head. What ohms on the amp switch? these 2 together only not including anything else. Just 2 cabs at a time.

[Rich_S]

Re: ohm question Marshall jcm800 with 2 cabs 1@8 /1@16 ?

The 8 & 16 combination works out to 5.33 ohms. Since tube amps prefer impedance lower rather than higher, I'd use the 8-ohm setting. You won't hurt anything using the 4-ohm setting, though.

Keep in mind that the power won't be divided equally in this case. 2/3 (or 67 watts) will go to the 8-ohm cab. The remaining 1/3 (33 watts) will go to the 16-ohm cab. Make sure each cab can handle the power that will be flowing to it.

In the case of the two 8-ohm cabs, use the amp's 4-ohm setting.

[suislidE03]

Re: ohm question Marshall jcm800 with 2 cabs 1@8 /1@16 ?

I was going to ask a similar question.. if i have a 8 ohm cab and a 4 ohm, could i run the amp at 4 ohms and not kill it?

[Brow]

Re: ohm question Marshall jcm800 with 2 cabs 1@8 /1@16 ?

If using 2 cabs of different ohmage ratings, the Marshall manual states to set the amp at 'Half the ohmage of the lowest rated cabinet'.

For example, if using 1 @ 16 ohm and 1 @ 8 ohm, half of the lowest rated cab would be 4ohms

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Re: ohm question Marshall jcm800 with 2 cabs 1@8 /1@16 ?

Very helpfull thanks.