Driving two 4 ohm cabs with a 4ohm min. load head.

http://www.rainbowmusicshop.com/sherlock.html

Go to town.

 

Running 2 ohms is pretty harsh for an amp.

 

"I know it can be done..."

Sorry to burst your bubble, but you basically have two choices:

1) run the two cabs in parallel. End result: a 2 ohm load to amp, therefore a fried amp. No good.

2) Run the two cabs in series. Net result: a 8 ohm load to the amp. The amp will put out half its rated power, but will do so happily forever...You'll need to do special wiring.

Well, ok you have more choices:

3) Pick the best sounding cab and just use it. 4 ohms, amp is happy, full power.

4) Buy a couple of 8 ohm cabs.

5) Buy a new head.

Your solution is option #3. Live with it. (And go take an electronics class to learn Ohm's law.)

 

And exactly HOW do you propose to make your cabs 8 ohms?


Why don't you so a Search on this forum? Your same question gets posted at least twice a day. And we always post the same answers over and over.

If you know so much, just go do it.


P.S. I will answer my rhetorical question. You can't make a 4 ohm cab into an 8 ohm cab by "rewiring it". You can make it into a 16 ohm cabinet, but not an 8.

 

Nope. Short of reconing all the speakers to be 8 Ohms there's no way to connect two 4 Ohm cabs to total 4 Ohms.

If you saw it somewhere, it was wrong. Sorry.

 

I implictly meant internal wiring....
There isn't any way to do it short of changing the impedances of the drivers or changing Ohm's law.

With a 4 Ohm 412, you can rewire it to be 1 Ohm (all parallel) or 16 Ohms (all series). The only other combinations (two series pairs in parallel or two paralell pairs in series) result in 4 ohms.
With the 215, you can do 16 or 4.

 

OK one cab at a time. Lets start with the 2x15. It currently running a 4 ohm load, which means it has one of 2 things going on inside. It could have 2 x 8 ohm drivers wired in Parallel (likely), or it's may even have 2 x 2 ohm speakers wired in series (very unlikely). Assuming it's 2x8 ohm speakers, the ONLY other way to wire it is in series, the end result being 16 ohms. The only way to get 8 ohms out of this cab it to dissconnect one of the speakers...........

Now to the 4x10. This will almost certainly have 4 x 4 ohm speakers wired in a combination of series and parallel to get the 4 ohms final nominal impedance. With more speakers to play with, there are more wiring options available. None of em come to 8 ohms with all speakers connected.

Sorry, that's the laws of physics at work, and they don't change for anybody.

 

Nope! The closest you can get is mismatched : 6 ohm (2 spkrs parallel = 2 ohms connected parallel to the other 2 spkrs which are connected to each other in series,) or 10 ohms (2 spkrs parallel = 2 ohms connected series to the other 2 spkrs which are connected to each other in series)

- Frank.

 

6 ohms is only for the one cab so it only solves part of your problem. Not only that, the 4 speakers won't recieve an even distribution of watts so some will be softer than others..

Seriously, if you're happy to spend money on 4 new 12" speakers, it would be money better spent on a amp that can run at 2 ohms - that way you won't have to modify the cabs at all.

 

I hooked up my Mesa to 1)4ohm cab, and 2) 2-8OHM cabs for a total of 2 ohms. The cabs were 1-(1-15+4-10),2-a(1-18)and a(4-10). The sound was very sperad out and I did not like it. I went back to either cab config and it was much better focused and just as loud. I think you will not gain anything with what you got. Get another amp, or run one cab. The 4-12 is shot anyway.You could get a used PV mono block ext amp. That would make your setup big or real big so you can Korn out.

 

Sorry I was insensitive...I'll never reply to your posts again...