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Hypothetical 3 cab rig

tgriley62

tgriley62

Jan 25, 2011
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S.E. Mo
#1
I have been trying to figure out how to set up a 3 cab rig based on 15" drivers, with all the drivers getting the same amount of watts & the only thing I can think of is this setup. If you were to daisy chain two 8 ohm 115's and then use one 4 ohm 215 cab each driver would get the same amount of watts. Also I know you would need a 2ohm stable head for this to work. Is this correct?
 
#4
Just always wanted to know how to set up an odd # of drivers without one cab getting more power than the others. I know even if you use the same size drivers but in two different cabs you will not be getting the most out of one. Example if you use a 4x10 with a 2x10 the 2x10 will be getting more power than the 4x10. Plus I just happen to like 15" drivers & think 3 would be killer
 
#5
tgriley62 said:
I know even if you use the same size drivers but in two different cabs you will not be getting the most out of one. Example if you use a 4x10 with a 2x10 the 2x10 will be getting more power than the 4x10.
Click to expand...

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... :hmm:

MM
 
#6
MysticMichael said:
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... :hmm:

MM
Click to expand...

Thanks. Would each cab get the same amount of power though?
 
#8
tgriley62 said:
Thanks. Would each cab get the same amount of power though?
Click to expand...

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
 
#9
MysticMichael said:
...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...
Click to expand...

Yes, they all get the same power.

MysticMichael said:
...It's a matter of relative impedances...by using an 8-ohm 2x10 with a 4-ohm 4x10...or an 8-ohm 1x15 with a 4-ohm 2x15...
Click to expand...

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. :cool:
 
#12
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.
 
#13
#17
Jim Carr said:
This may be of interest: 2 ohm bass amps (not sure how current it is)
Click to expand...

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... :atoz:

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... :hmm:

MM
 
#18
So if I did run three 8 ohm 115's would all three cabs be dasiy chained to each other (A) or would two be connected with the third cab using the other output on the head (B)

A: head---cab---cab---cab

B: head---cab--cab
\----cab
 
#19
tgriley62 said:
So if I did run three 8 ohm 115's would all three cabs be dasiy chained to each other (A) or would two be connected with the third cab using the other output on the head (B)

A: head---cab---cab---cab

B: head---cab--cab
\----cab
Click to expand...

Assuming the two outputs on the head are NOT separate channels, schemes A and B are actually the same.
 
#20
tgriley62 said:
Thanks. I actualy have that 2ohm head chart printed out. But I do have one other question concerning budget rigs. I may have the chance to join a group with 2 guitarist and drummer, playing classic rock i.e. REO, Doobie brothers type music and was wondering how 3 115's with a 300w head would do
Click to expand...

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?
 

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