Cabinet ohms with 2 tubes and 1 rectifier tube pulled quest:

[MichiganboySB]

Hi,
I broke a power tube so till I get a new set I pulled (2) inner tubes out and (1) rectifier tube. This is a Dual Rect btw. Each of my 4x12's are 8 ohm cabs... forget the formula for this. Do I connect each cab to a 4 ohm?I sure don't want to do any damage to any of this equipment I'm prone to dangerously experimenting with expensive gear.
Thx alot,
Ken

 

[MichiganboySB]

bump to the bumpity bump bump... I could sure use some help no? Last call fo alcohol

 

[MichiganboySB]

any smarter than me people out there?

 

[domct203]

With two tubes pulled you should drop the impedence at the amp by half of the actual speaker load. With both 8 ohm cabs hooked up you can't do that. Use one 8 ohm cab into the 4 ohm jack on the amp and the impedence will be somewhat corrected for two pulled tubes.

With all four tubes running then yes, each 8 ohm cab goes into the 4 ohm jacks on the amp.

I don't think using both cabs as usual ( 4 ohm ) with two pulled tubes for a short while will hurt the amp, it just might sound and feel a little different. Maybe someone else will comment there as well.

Dom

 

[Elpelotero]

i think you would something in that formula to be 2ohm, which Mesa's can't do.

Bass amps and cabs do it all the time, but not Mesa's.

You're going to have to sacrifice one of your cabs.

 

[ToneAddictJon]

???? Why would you pull out 2 tubes and still use 2 cabs??? Pushing that much air is gonna cause more volume than having the extra tubes in. I would just run one cab on 4 ohms.

 

[MichiganboySB]

I got it... thanks.
Ken

 

[clutch71]

Sweet flying V btw

+1 to what Toneaddiction said. I have a 4x12 and 2x12 Rectifier cab and I only run both when I can really rank the amp or when I feel like lugging all that stuff around.

 

[MichiganboySB]

Thanks Clutch,

(wonder if someone will trade me their Mark IV for this Budda Superdrive II 80

 

[rainsong86]

sorry to hijack the thread.. but I switch from the 50 and 100 watt modes of my dual rectifier roadster while the amp is still on (without changing cabs of course).. do these types of amps have some sort of function which corrects for impedance whenever it kicks out two of the power tubes and goes into 50 watt mode?.. also, is it safe to play with the 50/100 watt modes on a roadster channel or the progressive linkage knob on a road king while playing it?.. I sure hope it's not one of those deals where you're expected to turn off the amp before you change the wattage (like the Vox Valvetronix series)

 

[art_n_music]

Just got my first mesa, so can't say for them, but my Fender Twin does 25/100 switch on the fly.