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Plugging 3 8ohm Cabs to 4 ohm Amp.
- Thread starter Armando Trevino
- Start date
You ARE risking blowing a 4ohm head with a 2.67 ohm (I think) load. Be glad you got away with it, but I wouldn't continue the practice.
If having your cabs at ear level is what you're after, go ahead and stack all 3 but just plug in to the top two. Or bring a milk crate or some other stand.
If having your cabs at ear level is what you're after, go ahead and stack all 3 but just plug in to the top two. Or bring a milk crate or some other stand.
Run a second amp. Or maybe add a fourth 112 and make a custom cable linking the two parallel pairs to the amp in series for an 8 Ohm load and more volume from the extra driver.
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Yes, don't do it:
Questions are asked here on Talkbass regarding what the different cab ohm combinations are. Here is a chart that may be helpful:
===============================================
COMBINATIONS and OHMS ( Ω):
Four x 8Ω cabinets = 2Ω
Three x 8Ω= 2.66Ω
Two x 8Ω= 4Ω
Two x 4Ω= 2Ω
One 8Ω and One 4Ω cabinet = 2.66Ω
Two 8Ω and One 4Ω= 2Ω
One 2.66Ω and One 8Ω= 2Ω
Two x 2Ω= 1Ω
Three x 4Ω= 1.33Ω
Two x 4Ωand One 8Ω= 1.6Ω
One 2.66Ωand One 4Ω= 1.6Ω
Keep it up...the smell will be worth it!
Very bad idea since that amp is not 2ohm stable.
And even on its best day that amp is around 700 watts.
I would suggest upgrading to a Mesa Subway head.
And even on its best day that amp is around 700 watts.
I would suggest upgrading to a Mesa Subway head.
Sage advice!
Just yesterday I hooked up my Subway 115 and 210 (8 ohm cabs) along with an Ampeg Heritage SVT410HLF (4 ohm cab) just for giggles. That'll get LOUD! But running the Ampeg with the Subways was a downgrade in the tone dept, as could be expected. It was a fun experiment, regardless!
- Feb 12, 2006
- 61,010
- 5
- 220,849
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
Don’t do it, it’s a good way to damage an amp.
What part about 4 ohm minimum load did you not understand?
What part about 4 ohm minimum load did you not understand?
Thanks everyone. I got the answer I thought I was going to get. I must admit the first time I ran the 3 cabs I didn't even consider it. I was only thinking the wattage. Then next day a friend with the same amp head called me to ask me how it sounded and he let me know that the amp was only 4ohms and that it wasn't good. That's when I snapped what I did. No excuse I should have considered it. Now.... when the situation arose again at the same place, I remembered how good it sounded and that nothing happened to the amp. Yes I knew better and tried it again. Again it sounded great and no problem with my amp. But now I head your warnings and will not do this again or find a way to run a second amp for any additional cabs. Thanks everyone. First time treader.... 
Thanks everyone. I got the answer I thought I was going to get. I must admit the first time I ran the 3 cabs I didn't even consider it. I was only thinking the wattage. Then next day a friend with the same amp head called me to ask me how it sounded and he let me know that the amp was only 4ohms and that it wasn't good. That's when I snapped what I did. No excuse I should have considered it. Now.... when the situation arose again at the same place, I remembered how good it sounded and that nothing happened to the amp. Yes I knew better and tried it again. Again it sounded great and no problem with my amp. But now I head your warnings and will not do this again or find a way to run a second amp for any additional cabs. Thanks everyone. First time treader....
No need for a second amp. Like I said, just upgrade to a Mesa Subway. Any of the Subway 800 watt amps will produce more actual power than your Behringer and drive all 3 cabs with ease. You can even add a 4th cab if you want. Plus, the built in high pass filter on the Mesa amps will help those cabs greatly.
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I'm not overly knowledgeable about bass amps, but I know a Bugera is not a Behringer. Still can't run a 2.67 ohm load though...at least not safely.
Here’s a radical idea...
Keep doing EXACTLY what you’re doing, but don’t plug one of the cabinets in.
Keep doing EXACTLY what you’re doing, but don’t plug one of the cabinets in.
- Feb 12, 2006
- 61,010
- 5
- 220,849
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
2.67 ohms, 2.6 or 2.7 is simply rounding. I didn’t say anything to the contrary.
There are a few amps that will run a 2.7 Ohm load. Or you can slave another amp, if you have one, to run the third cab. Or use a light poweramp (with your head as a pre) to run the stack on "three cab" days. You could also trade the three 12s for two 15s.
Beyond that, when I played through one, the octave effect in the Bass Fly Rig you've posted seemed to me to eat a lot of cab-headroom and to benefit from an HPF -- don't know what the HPF built-into your head is like (I played the Fly Rig with another amp and cab), but you might find one helpful if you're pushing the cabs.
Beyond that, when I played through one, the octave effect in the Bass Fly Rig you've posted seemed to me to eat a lot of cab-headroom and to benefit from an HPF -- don't know what the HPF built-into your head is like (I played the Fly Rig with another amp and cab), but you might find one helpful if you're pushing the cabs.
Using a 4th cab as shown for 8 Ohm load is a great idea if you can do it. You will get MUCH more increased volume from the extra speaker than from the slight power increase you are getting. Double Watts is not Double loud - you can barely hear the difference but double the cone area DOES sound twice as loud.
And YES - you will blow the amp the first big peak you hit. Behringer power amps are so iffy I would never touch one. I'm an engineer - I know how they are marginally built.
And YES - you will blow the amp the first big peak you hit. Behringer power amps are so iffy I would never touch one. I'm an engineer - I know how they are marginally built.
The amp would go into protect mode/shutdown, long before it would get damaged.
It's still a risk, but seriously good amp protection has been built into amps for years.
Not all amps, but Bugera does.
Shutdown during a song is definitely something to avoid.
It's still a risk, but seriously good amp protection has been built into amps for years.
Not all amps, but Bugera does.
Shutdown during a song is definitely something to avoid.
Well, if the amp has good self-protection features built in, the best case is that it'll shut down. The worst case is you'll see the Magic Smoke come out of the amp. If it were me, I wouldn't go for either of those choices. Four ohm minimum load means just that.
