4ohm amp into a 2.667 ohm load. Safe?

For a few minutes, low volume, probably yes. Long periods and your amp will overheat. When the manufacturer says "minimum 4ohm" they actually mean it.

 

I say you'll burn your amp up if it's only rated to go 4 ohms and you try to take it lower. Impedance does fluctuate while you're playing, but cabs also have an impedance when they're not doing anything, so if you take them down to a level the amp can't handle, then you'll either fry it or send it into protection mode shut down, if you're lucky that is. Those minimums are written on that amp for a reason.

 

NO! - You will destroy your output stage or output transformer. That is why the amps is rated 4 Ohms. The DC resistance of the speakers may be different than the impedance, but speaker ratings are pretty close when they are running audio through them.

 

Jim

First I'd want to know what brand of amp you're talking about. I wouldn't do it PERIOD just because. Manufactures put those load numbers on there for a reason. If it's a newer SS amp it will probably just go into protect mode and shut down till you run the correct load. If it's an older SS amp, I've seen them blow quick with the wrong load. Which in your case you say is not less than 4 ohms.

You mention 2.667 so I assume you have 1-8 ohm and 1-4 ohm cab and you want to run them both together, correct? Aint gonna happen if your amp only goes down to 4 ohms, and is it worth possibly torching your head?

You have to get rid of the 4 ohm cab for an 8 ohm cab or get a head that does 2 ohms. If those aren't options and cash was short, here's what I'd do and have done before.

Hit Craigslist or the paper and look for a decent rack mount stereo poweramp that you can run at 8 or 4 ohms. I've seen them for 200 bucks many times. Lots of DJ's dump amps. If you're lucky you can find one that you can bridge mono and get some high power out of it. Run that as a slave off the line out of your main amp and problem solved.

Keep Low

 

Typically, this is never a good idea, but it does depend on the amp. I've run a Mesa Walkabout into three 8ohm cabinets on many occasions and never had a problem and there are many threads on this amp running 2ohm loads, so it is well documented. Be very SURE you know what your amp is capable of before trying this!

 

Don't do it! I fried a GK 400RB output section thinking I had an 8-ohm load when it was actually 2 ohms. You can wire the speakers in series - but your amp will produce less power for a 12-ohm load and may have a lower overall volume despite the extra cone area from the extra cabs.

You will need to make or buy a connector box - here's some background:

http://colomar.com/Shavano/spkr_wiring_sp.html

Good luck.

 

While your amp may be able to handle the load, perhaps even for extended lengths of time, without knowing the model I cannot recommend this to anyone else as a safe endeavor. Run at your own risk.

 

Hi.

I wonder why there's a FAQ sticky about the subject...

Regards
Sam

 

Sound advice right there...



- georgestrings

 

Yes. Go right ahead. Since it's YOU, and YOU really want it, and want it bad, ignore all the manufacturers' ratings, and all the stuff in those pesky FAQs, and that stupid scientific nonsense, and just GO RIGHT AHEAD!

THAT'S THE SPIRIT!

 

What they said. There are particular instances where you can win this, but they are few. For example, I have an 8ohm 4x10, and a 4ohm 2x10. I want to use them together, for 6 10's. But, oops, that would be a 2.6ohm load. So I wired the 2x10 for 16ohms. Win, works great.

 

Great solution - every driver gets the same amount of power too! I bet you don't gig much with the 2x10" (16ohm) alone though?

 

Yes, they do. I installed a DPDT switch in the 2x10 to go between 4 and 16ohms.

 

Nice title Greenboy

 

No.

Not even if you really, really, really, want it to be ok.

 

Not even with a special dispensation from the Pope?

: {

<dreams shattered>

 

If you do decide to ignore the sage advice here on why this is a really bad idea, then when you blow your amp you must start a whiny amp blown thread so we can mock you.

 

Sounds like someone just got their junior magicians book, and is looking to conjure up the magic smoke

 

BAD! ummmmm.... Yeah, that's all I have to say. Bad...