#1
Okak so my heads max output(350 watt) is at 2 ohms. I have 2 4x12 cabs loaded with 8 ohm speakers with an 8 ohm load on each cab. My goal is to wire each cab to 4 ohms so when ran in series (amp-cab 1-cab 2) the load is 2 ohms. Can anyone help me with a diagram? I saw one online but its gone now and havnt seen a similar question on the forum. Here is a text diagram of what Im trying to do.

Amp- output 1------ cab1 (8ohm speakers, 4 ohm load)|
Output2 |
|------------------------------------------------------------------
Cab2 same as cab 1..... Total ohm load 2

Thanks in advance.
Jim root tele
5150
Blue Voodoo 4x12
#4
It can't be done so if there was a site then what it said was incorrect. You could rewire a single 4x12 to 2 ohms or to 32 ohms but they are the only other possibilities that share the power evenly between all the speakers.

In any case doing this would probably not be noticeably louder than what you have now. You need to double the power to get a 3dB increase in volume and this is only a little louder than what you have. In practice you won't get double the power into 2 ohms and most amps are less reliable into 2 ohms.

Finally if you are a guitarist then you don't need 350W ever. This might help http://www.ultimate-guitar.com/columns/gear_maintenance/making_it_loud.html
#5
It can't be done so if there was a site then what it said was incorrect. ...........QUOTE]
Umm. O.k. Sites up ^^ there, give it a crack yerself. ( second link ) Certainly not IDEAl wiring, but it's there and explains "how" to get them to 3 ohms.
He can easily double up his cabs he has now and end up at 2 ohms, but he wants to keep what he's got.
One solution is switching out all the speakers for 4 ohm speakers instead of 8.
BTW- amps nowadays are sometimes rated at 2 ohm safe, just like the one I have here at the house. says it right on the back of the head and I've run it at 2 ohms. So :P
Not claiming to be an expert, but I build cabs with multiple speaker types and crossovers. Getting the ohms correct at the jack can sometimes call for creative thinking. Never say something "can't" be done.
yeah I said it. What.
Quote by LeviMan_2001
So in the end, be careful, but even still it's not THAT easy to get killed to death.
#6
Okay cool. I was trying to avoid getting new speakers but it looks like thats the best option right now. Btw at 4ohms my head is rated for 2ohms as ideal. Only reason im trying to get to that is a lot of the shows I play dontvmic cabs. If that were the case id just run my blue voodoo cab, eminence designed model, which is at 4 ohms and thevcab my headvwas designed for but 2 of them. Unfortunitly its a bitch and a half to find these cabs these days.
Jim root tele
5150
Blue Voodoo 4x12
#8
Btw at 350 watts im looking at 110 decibles. Enough to melt the edible paties right off any groupie.
Jim root tele
5150
Blue Voodoo 4x12
#9
Like I said it can't be done with the power shared evenly between the speakers. The '3 ohm circuit' puts 75% of the power through two speakers and will be quieter than leaving them alone. Unless this is a 550W 4x12 you could end up blowing the speakers taking most of the power.

Sorry hope doesn't often triumph over Physics.

Your decibel calculations are wrong too I'm afraid, my daughter has nicked my calculator but 350W is roughly +24dB which means your cab would be roughly 86dB/W making them quieter than most hi-fi's. A Marshall for example would be roughly 102dB/w and give a peak of 126dB with 350W.

Amp manufacturers often claim crazy power ratings by giving the power into 2 ohms but the current this demands can't be provided over the long term as the power supplies built in to the amps can't cope and the output circuits overheat meaning this is a short term peak only. They stop the amp from breaking down by having protection circuits. At two ohms the resistance of the cables and speaker connectors becomes significant and you lose power this way too. Don't fall for advertising jazz.

the difference between 22oW and 350 is only just noticeable and in practice you won't get it anyway.
Last edited by Phil Starr at Mar 27, 2011,