Mixing a 16 ohm cabinet and a 2 ohm cabinet?

[Mr.Sharkfist]

I didn't see any posts about this specific cabinet setup I'm interested in currently. I got a 4x12 cabinet that runs at 16 ohms, and a 4x15 cabinet that runs at 2 ohms. I want to run both at the same time, my amp runs 16, 8, and 4 ohms minimum. I'm not a math guy so I dont know how these cabinets total out together. Can I run them together safely without any damage to my amp or cabs? I'll include my specific equipment if that may help. My amp is a Marshall 1992 LEM, it has a switch on the back that switches between 16,8, and 4 ohms. I run it into a 16 ohm Marshall JCM 800 4x12 bass cabinet. This works perfectly fine. However I also have a Acoustic Control Corp 408 4x15 bass cabinet that runs at 2 ohms. So I want to run them all together, how do these cabs add up together ohms wise? Thanks in advance.

 

[mmbongo]

Not nope, but heck nope. Your amp can't even handle a 2 ohm load, much less a 1.7 ohm load.

Also, are you aware that that equipment is meant for guitar and not bass?

 

[agedhorse]

Nope, and for a whole variety of reasons too.

 

[Roland GR 88]

If my old math skills are correct your amp will see 1.67 ohms with 89watts driving the Acoustic and only 11watts going to the Marshall.
Re-wiring you cabs might offer a solution depending on what's inside them and how they're wired. Both being old cabs I'd have a good look inside to ensure they haven't already been messed with and/or still sport the original speakers.
Celestian G-12 100's were prized for their power handling and may have been replaced if your Marshall originally had them.

 

[thetragichero]

you have two choices with your current equipment:

1. you can use just the 16 ohm cabinet on the 16ohm setting

or

2. IF the 2x15 contains two 4ohm speakers wired in parallel (which I am almost certain), you could wire the pair in series for an 8ohm load. you could then use just the 8ohm 2x15 on the 8ohm setting

 

[Stumbo]

What Roland said! Beat me to it.

What are the individual speaker ohm? Maybe you can rewire them.

 

[thetragichero]

4x12 at 16 ohms I believe can only be 4s (in series) or 16s (in series-parallel), so either 4 or 16 ohms from that (8 would be ideal)

 

[Bassamatic]

I know that this impedance thing is hard to understand, but jsut realize that when you parallel speakers, the combined result is always LOWER than the LOWEST impedance of any of the speakers. Since your lowest impedance speaker is 2 Ohms, the total will be less than that, and your amp cannot handle that at all.

Also be aware that the speaker with the lower impedance will get most of the power - it will not be divided equally, but in reverse proportion to the impedance. The 2 Ohm speaker will get 4 times the power of the 8 Ohm speaker, etc. That is another reason combining speakers of different impedance is usually not a good idea.

 

[DigitalMan]

Two things come to mind.

The world has no need for 2 or 16 ohms cabs. Ever. Rewire to 4 or 8 ohms before you are reported to the authorities.

Also, use separate power sources when powering cabs with different resistance *unless* they result in evening things out (e.g. an 8 ohm 2x10 plus a 4 ohm 4x10).

 

[thetragichero]

Also, use separate power sources when powering cabs with different resistance *unless* they result in evening things out (e.g. an 8 ohm 2x10 plus a 4 ohm 4x10).

with tube amp impedance, you match the load to the correct tap on the output transformer. These are almost universally 16, 8, or 4 for our purposes (i seem to remember mention of 2ohms on my father's deluxe reverb, but my brain is full of half-remembered things)
for solid state, you are looking to meet or exceed the minimum safe operating impedance of the power amp

for a tube amp, there is no way too get 4, 8, or 16 ohms from one 4 ohm and one 8 ohm cabinet, regardless of the number or size of the speakers in each enclosure

 

[Killed_by_Death]

Re-Wire both cabinets to 8 Ohms each, plug them both in & set it to 4 Ohms, done.

 

[JRA]

i think Killed_by_Death just killed it!

 

[vancamp]

i think Killed_by_Death just killed it!

Except it's not obvious that the 16 ohm cabinet can be rewired easily with those speakers to 8 ohm.

 

[agedhorse]

Except it's not obvious that the 16 ohm cabinet can be rewired easily with those speakers to 8 ohm.

Darn near impossible unless I'm missing something.

 

[JRA]

Except it's not obvious that the 16 ohm cabinet can be rewired easily with those speakers to 8 ohm.

Darn near impossible unless I'm missing something.

of course you're right. i withdraw my support of KBD in favor of a more cautious approach.

 

[JRA]

Killed_by_Death --- sorry, man....


whoops: you're right of course, i may swing back to supporting you after all!


i guess the OP may want to investigate and bring this matter to rest, eh?



Mr.Sharkfist : maybe it's time you shared some info: what are the impedances of all of those speakers/drivers?

edit: for more info

 

[mmbongo]

Killed_by_Death --- sorry, man....


whoops: you're right of course, i may swing back to supporting you after all!


i guess the OP may want to investigate and bring this matter to rest, eh?



Mr.Sharkfist : maybe it's time you shared some info: what are the impedances of all of those speakers/drivers?

edit: for more info

The OP seems to have checked out of this asylum

 

[BassmanPaul]

Re-Wire both cabinets to 8 Ohms each, plug them both in & set it to 4 Ohms, done.

If only it was as simple as that! There again, the posters on this site do the impossible every other day!!!

 

[Killed_by_Death]

Well, it's possible, but by leaving out two of the drivers:

Assuming they're all 16 Ohms you'd have to wire two of them in parallel for 8 Ohms, but then the efficiency of the cabinet will be diminished.

 

[bassinflorida]

I didn't see any posts about this specific cabinet setup I'm interested in currently. I got a 4x12 cabinet that runs at 16 ohms, and a 4x15 cabinet that runs at 2 ohms. I want to run both at the same time, my amp runs 16, 8, and 4 ohms minimum. I'm not a math guy so I dont know how these cabinets total out together. Can I run them together safely without any damage to my amp or cabs? I'll include my specific equipment if that may help. My amp is a Marshall 1992 LEM, it has a switch on the back that switches between 16,8, and 4 ohms. I run it into a 16 ohm Marshall JCM 800 4x12 bass cabinet. This works perfectly fine. However I also have a Acoustic Control Corp 408 4x15 bass cabinet that runs at 2 ohms. So I want to run them all together, how do these cabs add up together ohms wise? Thanks in advance.

I would 'say to you' don't do this,,,,,,, but you probably can not HEAR me.