cab specs for a tech dummy

[pbass2]

Hi,
I'm looking to add an ext cab to my combo(Markbass CMD 121P). I'm a bit of a dummy with matching cabs to heads or combos--been using just a combo for a looooong time. Trying to go used and cheap as it probably will get used only once in a while.
I know I need an 8ohm cab(so then my combo will be putting out 500w into the 4 ohm total). The Markbass ext. cabs are rated at 400w RMS. When looking at used cabs by other manufacturers, what would the range of acceptable power rating be? Is there a danger in going too low(many 8ohm 1x15s I'm seeing are rated at 250w)? Or is it just not that exact a science, and I just have to try 'em out? Any enlightenment appreciated!

 

[greenboy]

Lower RMS ratings for cabs shouldn't affect you too much since (if I understand you correctly) you'll be splitting the power amp of the combo between the extension cab and the combo's. Some things to think about: do you tend to boost EQ at certain frequencies? Do you use lower tunings (a low B string or whatever)? Choose cabs for tonal preferences, ability to produce sound without speaker distress (farting) and other needs and you'll do just fine. If you can't audition a lot of cabs be aware that specsmanship runs rampant in the bass cab industry - so experience goes a long way in this endeavor.

Sometimes that might be your experience which can only be had by having tried lots of things, other times it may be the feedback you see here on the forums, which is often wide, diverse, and even conflicting.

But just get the ohms right and you are well on your way to building some gear choosing chops!

 

[pbass2]

Thanks. yeah, playng all four string currently, the lowest I go is drop D, but I do favor as bottom heavy a sound as possible. I'm thinking a 15" will compliment the 12" nicely. Had some nicer cabs offered to me, but for my purposes I "think" I can stay pretty cheap and just find a beater 15" to add a little girth.

 

[greenboy]

Yeah, either a typical 115 or 112 or 212 could do that. If you feel you are missing some upper mids definition a typical 210 cab might be the way to go.