bass stack

[lloydbent]

I have 2 cabinets, a 250w 8 ohm and a 200w 8 ohm. I stack them on top of eachother, and will use a hartke ha3500 head, which is rathed at 350w at 4 ohm.
Am i right in thiking that would, in effect, run as a 350w head into a 450w (watts of both cabs added together) cab at 4 ohms (2 8ohm cabs in parallel = 4ohm impedance)
Is that all correct?
Cheers

Edited February 11, 2011 by lloydbent

[alexclaber]

Yes, except they're in parallel, hence the 4 ohm nominal load. More importantly, assuming the two cabs are very similar, by using a pair you've doubled your excursion-limited power handling and you've increased your lower frequency sensitivity by 3dB due to acoustic coupling.

[deepbass5]

Yep you havegot it, but bear in mind for future link ups, that it is the impedance that governs the power consumed not the wattage, thats just a limit at which damage may occur. This will not actualy allow you up to 450 watts just because you think you are adding a 200 + 250. They are both 8 ohms so share the power equilly which is good but you will still be limited to the lower rated cab in this case 200 watt. so 400 watts would be as high as you would dare want to push it. Alex didn't mention this because you are unlikely to get up there and these are close enough to make little difference. I only mention this as I have seen similar questions on here where someone is adding a 100w and a 300 watt cab if these are the same impedance this set up would be limited to the 100 watt cab. So together could handle 200W a 100 through each.

[alexclaber]

I wouldn't worry about thermal power handling differentials. I would put whichever cab distorts first when you crank the lows (usually the smaller or cheaper one) on top so you hear it complaining if you push it too hard.