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How to run two, 4 ohm cabs with a 4 ohm (max) head

Jimmy Stump

Jimmy Stump

Jan 27, 2010
682
195
Canada
#1
Sorry if this has been covered (as everything is here), but I couldn't find it in the amp FAQ sticky.

I'm considering a 2 x 10" setup with two cabs, each at 4 ohms which drops the load to 2 ohms. Problem is my head is a 4 ohm only and I'd like to keep it.

Can I buy a seperate power amp for this setup and somehow bypass the power supply in the head? If so, can someone give me a tip on a decent, lower cost power amp (not sure how much wattage is recommended @ 2 ohms?), and tell me how I would bypass the head's power?

Mucho gracias!
 
#2
you can run both cabs with your head, just not at the same time!

sorry but i think you would need to make some pretty drastic alterations, the poweramp idea you suggested would work as long as the poweramp was ok with a 2ohm load, but then your head would just be a bloody heavy preamp to carry around..
 
#3
Jimmy Stump said:
Sorry if this has been covered (as everything is here), but I couldn't find it in the amp FAQ sticky.

I'm considering a 2 x 10" setup with two cabs, each at 4 ohms which drops the load to 2 ohms. Problem is my head is a 4 ohm only and I'd like to keep it.

Can I buy a seperate power amp for this setup and somehow bypass the power supply in the head? If so, can someone give me a tip on a decent, lower cost power amp (not sure how much wattage is recommended @ 2 ohms?), and tell me how I would bypass the head's power?

Mucho gracias!
Click to expand...

Don't know much about the head you are using, but if it has a Preamp Out jack, you can use the head to drive one 210 cab and then run the Preamp Out to the input of another power amp, thereby using your amphead as a preamp to the power amp.

Personally I'd just buy a 2 ohm capable head. Carvin's newer amps go down to 2 ohms, or will drive two 4 ohm cabs separately as well (one 4 ohm cab on each side of the dual monoblock head).
 
#4
Your situation is identical to mine. I use the 2x10 format (Acme), I own four - all 4Ω. I only gig with a pair. I was using a Carvin DCM1000 to drive them one per channel. When I decided That I was getting too old to carry the amp I looked at lighter units.

I've bought a lot of stuff from Carvin so, as usual, I checked out their catalogue. Only one of their light weight power amps was in the power range I was wanting but it was just a little low. I did something that I've not done since the Sixties and bought one of their bass amps the BX1500. So far I am delighted with it. I run mine flat, no contour, no compressor and no Bi-amp. It sounds wonderful running one of my 2x10s on each channel for 450W per, 900W total.

If you've not bought from Carvin it's a pleasant experience. We Canuks have to pay more shipping than our stateside brothers BUT the items arrive at the door with ALL import duties and taxes paid. It's actually nice to get a visit from the UPS guy. :)

Check them out at carvin.com

Paul

P.S. I can pick up this amp in its tolexed sleeve with one finger - the little one!
 
#9
silvertones said:
Make a cable so they are wired in series = 8 ohms.
Click to expand...

Yep, a cable or make a box.

SeriesBox.jpg


Either would be so cheap to make that it would be silly not to try it and see if it will work for you.

:D

Joe.
 
#10
BassmanPaul said:
Your situation is identical to mine. I use the 2x10 format (Acme), I own four - all 4Ω. I only gig with a pair. I was using a Carvin DCM1000 to drive them one per channel. When I decided That I was getting too old to carry the amp I looked at lighter units.

I've bought a lot of stuff from Carvin so, as usual, I checked out their catalogue. Only one of their light weight power amps was in the power range I was wanting but it was just a little low. I did something that I've not done since the Sixties and bought one of their bass amps the BX1500. So far I am delighted with it. I run mine flat, no contour, no compressor and no Bi-amp. It sounds wonderful running one of my 2x10s on each channel for 450W per, 900W total.

If you've not bought from Carvin it's a pleasant experience. We Canuks have to pay more shipping than our stateside brothers BUT the items arrive at the door with ALL import duties and taxes paid. It's actually nice to get a visit from the UPS guy. :)

Check them out at carvin.com

Paul

P.S. I can pick up this amp in its tolexed sleeve with one finger - the little one!
Click to expand...

Just curious here, Paul. Why not go with one of the Carvin power amps, the light ones like the 1540L ?
 
#11
equal said:
Why not just get two 8 ohm cabs? It's not hard to find 8 ohm 210s!
Click to expand...

This is an ideal situation where two 8 ohm enclosures would be perfect. When run in tandem (parallel), the amp would "see" a 4 ohm load. Smaller gig / venue? No problem, just use a single 8 ohm enclosure. "But, Riis....an 8 ohm enclosure won't receive the amp's full power" to which I respond "so what?". You probably won't see a discernible difference at lower volumes, its easy on the amp, and (god forbid) if you actually need the extra volume, add the 2nd enclosure.

The upside is you can keep using your existing amp...which is why you posted this in the first place.

Riis
 
#12
Hey Lowtonejoe,
So if I had one of your "series boxes" it would allow me to run both of my 5.3 ohm Epifani 310 cabs with my Markbass LMT800 amp? The amp minimum is 4 ohms. If so, then how much will u charge for one? I need to be able to run them both with my LMT800 and I do NOT want to add a power amp to the mix. I have been very bummed trying to figure this rig/ohm situation out!

Thanks,
Steve
 
#14
jnewmark said:
Just curious here, Paul. Why not go with one of the Carvin power amps, the light ones like the 1540L ?
Click to expand...

Simple, too much power for my needs. Only the DCM1000L came close to the 350W at 4Ω per channel I was looking for. The BX1500 is still too powerful for what I want but I can work with it. I'm not a believer in driving my speakers with all the power I can get. My Acmes are 350W RMS each and I don't like to exceed that by much.

Paul
 
#15
series wiring will do the trick, but your amp wattage will decrease usually by one half, is it worth it? Wouldn't a single 410 cab work just as well for you?

you can buy just a power amp with a wattage and ohm rating you desire and use the preamp out section of your current amp for the tone controls and bass inputs etc. Most power amps are stereo so you can add more cabs if needed in the future.

If your interested in a power amp, there are many affordable fine amps by QSC, Crest, Crown, Peavey, and others in various wattage's. Checkout the power amp section at musicians friend.com for spec's and pricing.



Invalid Link Removed
 
#17
Consider the SWR Amplite. 400 watts @ 4 Ohms 4lbs poweramp that you can connect via a line out to your existing head. You can string as many of these these as you need to power your cabs. If you aren't that attached to your head (heehee) you could sell it and get a couple of these and a preamp.
 
#18
WarwickDude68 said:
Hey Lowtonejoe,
So if I had one of your "series boxes" it would allow me to run both of my 5.3 ohm Epifani 310 cabs with my Markbass LMT800 amp? The amp minimum is 4 ohms. If so, then how much will u charge for one? I need to be able to run them both with my LMT800 and I do NOT want to add a power amp to the mix. I have been very bummed trying to figure this rig/ohm situation out!

Thanks,
Steve
Click to expand...

The problem with using your 2 cabs in series, is that although you gain added speakers - you will also be cutting your power output in half. Therefore, no real gain, but an extra cab to carry.

Also, when running them in series - if one cab goes down, they both go down.
 

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