question about ohms and cab setups

[adamdesoto]

ok, i have a roadster 2x12 thats 8 ohms and a mesa rectifier 2x12 thats 8 ohms but have only one 8 ohm speaker output. so i had the 8ohm cab goin into a 4ohm output but noticed that the on board 2x12s were pushin louder. then i wired both into the 4ohm outputs and it seemed to equal out the levels. is this normal and will it harm the amp to mismatch like this? i read that an 8 ohm into a 4 ohm is safe, but just wanted some feedback. thanks!

 

[parsky1]

You're supposed to plug two 8 ohm cabs into the two 4 ohm jacks. (I believe this is because in essence they are running in parallel)

A higher cab impedance than what the amp jack says is always a safe mismatch. Lower cab impedance than what the jack says = bad and will burn your power tubes out a lot faster.

 

[bigdan19]

ill second that ive got the same setup.
examples

stilletto ace head >2x12> 2x12
4 ohm - 4 ohm 8ohm 8ohm

its safe to mismatch in some cases as parsky1 mentioned and as youll see in the mesa handbook but its not really a good thing for your amp. i doubt it would be good for the speakers ever.

think of it this way, mesa boogie has set the amp independance to allow for some mistakes when connectiong. you can experiment using some of the handbook guides but u'll be up for a lot more tubes.

 

[adamdesoto]

cool. so the setup i'm running now is safe. thats good. thanks guys.