Hypothetical 3 cab rig

Yes, but why?

 

That is correct. But it's not the only such cab configuration that is possible. There is, for example, the possibility of running three (3) 1x15 cabs, each at 8 ohms, into a 2-ohm stable head.

In that scenario, each cab operates nominally at 2.67 ohms. Not a bad rig - at least in theory...

MM

 

It isn't a matter of the size of the drivers. It's a matter of relative impedances...

Strictly speaking, the 2x10 and the 4x10 would each be receiving the same amount of power - but each individual driver within the 2x10 would receive twice as much power as each individual driver within the 4x10. This all assumes, of course, that each cab has the same impedance rating. The way to get around that, of course, is to compensate with cab impedances, by using an 8-ohm 2x10 with a 4-ohm 4x10, for example. Or an 8-ohm 1x15 with a 4-ohm 2x15...

MM

 

Yes

 

Yes. Since each cab is rated at the same impedance level - 8 ohms - and each is running simultaneously from the same 2-ohm stable head, each cab will receive the same amount of wattage.

Note: This scenario presupposes your use of a mono-block (i.e. single amp) head. If using a stereo (i.e. dual-amp) head, things would become a bit more complex. You would have some some output-balancing to do...

MM

 

Yes, they all get the same power.

I use a 4 ohm Epifani UL1 410 with an 8 ohm Epifani UL1 210. The drivers not only all get equal power, they are identical drivers in cabinets designed and built by the same company. Works fine as a 610. I do have a couple 2 ohm capable heads.

 

This may be of interest: 2 ohm bass amps (not sure how current it is)

and this: http://www.talkbass.com/forum/f15/ohms-faq-144244/

 

Yes you would need a 2 ohm stable amp.

a 8ohm driver and 4ohm driver are still going to behave slightly different. Finding a single 4ohm 15 cabinet will be harder to find.
the sensitivity of 4ohm 15's is usually lower. At least among the common ones made by Eminence.

it would be easier to just run 3 matching 8ohm ohm drivers in Parallel. 3x8ohm parallel would be 2.6ohms.

 

With 3 sensitive 15 inch drivers you wouldnt need much power at all. 3 Kappalite 3015s would have a sensitivity close to that of 2 ampeg 810s. I would think a mesa walkabout would be a great fit.

 

How about a Fender 400PS fully loaded with the three 18" folded horn cabs?

 

what kinda calculation gives you that conclusion?

 

It's current as of three months ago - at least according to the information in the header. But there are some significant inaccuracies and omissions...

For example:

Missing is any mention of the Carvin B2000 - arguably the 800-pound gorilla of all 2-ohm stable bass heads currently in production.

Also missing is any mention of the Eden Nemesis RS700 & EN700, each rated at 700 watts @ 2 ohms, although both are now also out of production. Their predecessor - the Nemesis NA650 (also out of production) - is also 2-ohm stable (@650 watts)...but unfortunately shows up on the chart as the "RA700" - a model number that never existed in the Nemesis catalogue...

MM

 

Assuming the two outputs on the head are NOT separate channels, schemes A and B are actually the same.

 

It is pretty likely you will have way more than you need in terms of speakers. Why do you want 3 15s? Not all speakers are created equally.

There are single 15 inch drivers that can out perform a dozen 15s. It all depends on the type of driver, cabinet design/execution, and fit to the application.

What type of cabs and amp are you contemplating?