How To Run Two Cabs Through One Amp?

[Old Garage-Bander]

Well, it will matter which amp he uses. First, the amp has to be 2-ohm capable. Second, if he's going to use each cab for different frequencies, he'll need an amp with bi-amp capabilities ( built-in crossover). There aren't too many amps that meet those criteria.

Of course, you are correct in all of that. And it was not my intent to lead him down the wrong road for an amp purchase. I simply suggested that he should try to see if the two cabs are going to sound good together, even though that is only a secondary concern for the OP. I didn't want to go all cab Nazi on the guy.

Carvin has several amps that will handle two ohm loads.

 

[BassmusM6674]

Honestly you would be better served to sell both of your not so amazing cabs and go out and buy a much nicer 4-10 and be done with it. Theoretically the cabs will sound OK together, but probably not. Also, to send lows to one and mids and highs to the other you would need a preamp, a crossover and a two channel power amplifier. If you are going to spend that kind of money, again, just go out and get one kick butt cab.

Well Said!

 

[rockinbilly]

The Bergantino "B" amp can handle a 2 ohm load and push 800 watts, but your gonna have to spend some money for it !!!

 

[JGbassman]

It will be a 2 Ohm load unless special cabling is used.

Yea I made a mistake. Corrected now.

 

[funkinbottom]

Carvin has several amps that will handle two ohm loads

This is true. The DCM1000 is on sale for 279 right now. I have a Carvin power amp. Quite versatile. 2 ohm capable all day long and loves it. Also in stereo mode(one cab per side), OP would at least have separate volume control over each cab. Although that doesn't address the cross over issue. And he would also need a pre amp . Just a thought.

 

[Fuzzonaut]

It doesn't need to be a 2 ohm amp, a cab merger would work too. They are like $50.

I used to own a Marshall 3540, it was built for biamping.
It can do 4 ohm on both sides.

 

[Ric5]

I've never done this before. I have two cabinets I want to stack. A behringer bb410(1200 watt/4 ohm) and a Peavy Black widow(600 watt/4 ohm/pushing an extra 400 watts after some work). First things first, I don't wanna blow any speakers. A close second in importance is tone. I want to be able to make these two cabs work beautifully together. Any recommendations for an amp head?

Get 2 cabs that are both 8 ohms and similar in size.

Pretty much all bass heads have 2 speaker jacks

 

[Rip Van Dan]

Honestly you would be better served to sell both of your not so amazing cabs and go out and buy a much nicer 4-10 and be done with it. Theoretically the cabs will sound OK together, but probably not. Also, to send lows to one and mids and highs to the other you would need a preamp, a crossover and a two channel power amplifier. If you are going to spend that kind of money, again, just go out and get one kick butt cab.

I used to run an acoustic B410 over a GK115blx and with a few adjustments got them to sound good together. Then I bought a DN410 cab by DNA, which sounds far better by itself as well as louder than that 410+115 stack did. My amp runs 4 ohm load per channel or bridged at 8 ohms, so I run it bridged into this one high-quality cab and all is right with the world.

Running your (referring to the OP here) two 4 ohm cabs, as others have said, will put a 2 ohm load on your amp and if your amp has a 4 ohm minimum load rating, it will burn up your amp unless the amps protection circuitry shuts off your amp in time. You can get a serial switch box or cables that run it in serial and then run an 8 ohm load on your amp (safe but less power), but normally amps outputs are parallel, which would yield a 2 ohm load So if you don't know what the minimum ohm rating is on your amp, find out BEFORE you hook both cabs up to it.

If you want to run it bi-amped (sends low part of signal to one cab and high part to the other cab), you don't need a cab with woofer in it for the highs. Basically I'm saying that with the full frequency speaker cabs we have now, you are wasting virtually all of one cab by just using the tweeter in one cab for the highs. This was a nice thing to be able to do in the 80's when we didn't really have full-range cabs, but virtually all decent bass cabs now are full range.

 

[canteenboy]

Thanks for all the info guys. It definitely made me rethink my approach. Gonna take the advice of the last post and find 2 8ohm cabs that work well together. I'll find a good amp to pair it with from there.

 

[morgan138]

But how will the total impedance of the cab be 4 ohms if all speakers are connected without the crossover?

Because when you combine speakers with a crossover, you don't calculate the total impedance the same way as if you were just running them in series or parallel. So it's not correct to assume that a 4 ohm crossed-over cab has an 8 ohm high side and an 8 ohm low one.

or make it sound awful because the unpowered 10s in there mess up the pneumatics inside the cab or make it sound great because the crossovered 18 becomes a nice sub, complimenting the 410 in a wonderful way.

Ah good point about the 10s...I don't remember if they're divided off from the 18. I do know that if you run just the 18, that 1820 sounds okay at least. Not sure if that means the 10s are in their own partition, or if the unpowered speaker factor just isn't a huge deal.

That 18 won't make a usable sub in any case, unless it has a replacement driver that loves that Peavey enclosure. It's a low powered speaker that doesn't put out a lot of deep bass.

That Peavey box = low midrange bump, combined with an upper midrange clang if you use the 10s
The Behringer box = scooped tone with some fairly low bass

 

[morgan138]

Thanks for all the info guys. It definitely made me rethink my approach. Gonna take the advice of the last post and find 2 8ohm cabs that work well together. I'll find a good amp to pair it with from there.

Good plan. I love Peavey in general, but those mixed-driver cabs (1820, 3620, 1516) were just not good designs at all. Plus, super bulky and heavy. A pair of matching 1x15s or 2x10s will do you much better!

 

[Rip Van Dan]

It doesn't need to be a 2 ohm amp, a cab merger would work too. They are like $50.

View attachment 1066903


I used to own a Marshall 3540, it was built for biamping.
It can do 4 ohm on both sides.

Bi-amping or Dual-Mono? They are different. If you have your cabs hooked up to separate channels and Bi-Amp engaged, then you are sending the lows form one channel to one cab and the highs through the other channel the other. And that's bi-amping.

If you do not have Bi-Amp engaged, then it sends 200-watts of full frequency signal to each cab. You're using both channels as individual amplifiers or what is sometimes called Dual-Mono mode. They are not the same thing. If you haven't run your amp with your speakers plugged into channel A and channel B outputs yet, you are in for a pleasant surprise when you do. You'll get much more volume because you are getting everything each cab has to offer instead of all from one cab and just the tweeter from the other one.

Typically the high side of the biamp puts out ~100-watts in Bi-Amp mode and the low side will put out whatever the max is for that side of the amp. Dual-mono on your Marshall puts out 200-watts at full-frequency per side. I have an Eden WT500/800 (modded to 800-watts bridged) and it runs 400-watts per side with a 4 ohm minimum load per side. However, it does not have bi-amp circuitry in it like the WT800 does. Dual-mono is a very nice way to run a different ohms load on one side without changing or influencing the ohms load on the other channel. A good "balance" knob (if there's one on you amp) then allows you to mix the sound from each side to get the balance of sound you like.

 

[Fuzzonaut]

Bi-amping or Dual-Mono? They are different. If you have your cabs hooked up to separate channels and Bi-Amp engaged, then you are sending the lows form one channel to one cab and the highs through the other channel the other. And that's bi-amping.

If you do not have Bi-Amp engaged, then it sends 200-watts of full frequency signal to each cab. You're using both channels as individual amplifiers or what is sometimes called Dual-Mono mode. They are not the same thing. If you haven't run your amp with your speakers plugged into channel A and channel B outputs yet, you are in for a pleasant surprise when you do. You'll get much more volume because you are getting everything each cab has to offer instead of all from one cab and just the tweeter from the other one.

Typically the high side of the biamp puts out ~100-watts in Bi-Amp mode and the low side will put out whatever the max is for that side of the amp. Dual-mono on your Marshall puts out 200-watts at full-frequency per side. I have an Eden WT500/800 (modded to 800-watts bridged) and it runs 400-watts per side with a 4 ohm minimum load per side. However, it does not have bi-amp circuitry in it like the WT800 does. Dual-mono is a very nice way to run a different ohms load on one side without changing or influencing the ohms load on the other channel. A good "balance" knob (if there's one on you amp) then allows you to mix the sound from each side to get the balance of sound you like.

The Marshall I mentioned does indeed both, bi-amping and dual mono - and Invalid Link Removed.
When bi-amping, you have separate volumes for low/high and you can set the crossover frequency with a knob that goes from 100 Hz to 1 Khz.
I used to bi-amp an Ampeg Isovent (2x10" & 2x15") with it.

 

[Gearhead17]

Thanks for all the info guys. It definitely made me rethink my approach. Gonna take the advice of the last post and find 2 8ohm cabs that work well together. I'll find a good amp to pair it with from there.

Two identical 8 ohm cabs are the way to go. If you want to do bi-amping or at least try it, it's going to be a lot more difficult to find something that you can easily obtain and/or try out. One person's "this rig worked for me" is another person's "this rig sounds awful". Most of us will say two identical cabs gives you everything you like about one cab plus MORE volume. I live within this camp from playing a bunch of shows and owning way too much gear.

 

[canteenboy]

I tried this setup. Sounds really good. I didn't crank it though, or run pedals. The Peavy has a new 18. It pushes 600 watts instead of the standard 200. Lows sound like they have potential on this cab. I'll have to see. I don't think this head(ampeg pf-350) is a great match. The Hartke also is a bit undesirable because it doesn't have a tweeter. First things first, can someone tell me if I'm going to damage gear with this setup?

 

[canteenboy]

Hartke xl series 4 10 is 8ohm. Peavy 1810 is 4ohm. Ampeg runs 250 watts at 8ohm and 350 watts at 4 ohm.

 

[TheOxRocks]

The Carvin BX1600 is bi-ampable, runs about 500w per channel at 4 ohms, can run at 2 ohms, has separate volumes for each channel and a great crossover. I have its older brother, the 1500, get GREAT sound and tone out of it, and have never had the master volume above 3 even in a loud club.

 

[morgan138]

First things first, can someone tell me if I'm going to damage gear with this setup?

Yeah, you're at risk for damaging or cooking that head. It's only rated to run as low as 4 ohms, and you're using two 4 ohm cabinets in parallel which is a 2 ohm total impedance. Generally only pretty heavy duty heads will safely run that low.

The Hartke also is a bit undesirable because it doesn't have a tweeter.

Do you specifically need a tweeter? In my experience they create as many problems as they solve. I'd consider a tweeter-less cab as the baseline, and then ask yourself if you need the kind of high-treble response a tweeter will get you.

 

[fhm555]

Here you go

BX1600 Dual Mono Block 1600W Bass Amp Head

 

[morgan138]

The Marshall I mentioned does indeed both, bi-amping and dual mono

Bi-amping with two identical power amps? That seems like a pretty weird idea, part of the point of bi-amping is to have more power on the low side since low frequencies need more wattage to sound as "loud" as high ones. Take a GK800RB, the lows get 300 watts and the highs get 100.

If you're bi-amping with 200+200, you'll be limited by having only 200 watts on the low side and you'll only use a fraction of the 200 watts you have on the high side. Kind of a waste...