full stack ohms question

gimmesometruth27

hey i just have a quick question.

i recently purchased a 1974 marshall jmp super lead head and am wanting to run it as part of a full stack. i have 2 marshall 1960 AV and BV cabs with vintage 30s in them. i used to use a jcm 900 head and stack them but i have not run them as a full stack in a few years because i got a matchless head that could only power one cab so i quit using a stack. i remember when i did use a full stack i had to change the ohms on either the head or on the cabs and i can not remember for the life of me which i am supposed to switch.

i was planning on using the head and cabs at 16 ohms, but for some reason i am thinking i am supposed to switch both cabs to 8 ohms, but i might be wrong. i don't want to do that and end up screwing up my new (to me)vintage head. any info is really appreciated. thanks.

ianvomsaal

Make sure both cabinets are switched to Mono. Since you're hooking two 16 Ohm cabinets to your
super lead head in parallel, R1 (16-ohm) and R2 (16-ohm): 1/RT = 1/16 + 1/16, RT = 8 ohms

Two 16 ohm cabs = 8 ohms (if they are wired in parallel)

Read this if you want to truly understand: http://www.sweetwater.com/expert-center/techtips/d--01/14/2005

gimmesometruth27

thanks for the info ian!! works like a charm. now i have to see about getting a damn attenuator because its a non master volume head and i am having trouble getting power tube breakup with the channels jumped and the volume on 3.....its always something lol...