8 ohms to 4 ohms? Can it be done?

[CosmicRay]

Hey Now - Happy & Healthy New Year to all!

Perhaps some one knows if an 8 ohm cab can be EASILY converted
to a 4 ohm cab.

I have an Epifani 410UL @ 8 ohms, that I would like to be switched to a 4 ohm cab.

I used to hook this and another 8 ohm cab together to give me the 4 ohms,
but I only use this cab now and would like to get the extra wattage out of my amp.

Any advice, help, insight would be appreciated.
Thanks!

-Ray

[Beej]

In a word, no. It would be most lovely, but in most cases its not a realistic possibility. You'll find good explanations behind the science of why not by searching the Amps forum on this site. Generally speaking, you'll be better off finding a 4ohm cab that you like instead...

[dmusic148]

No. You can wire it to 2 or 32 ohms, but not 4.

[scottbass]

No. Your cab has four 8-ohm drivers in parallel-series. There is no way to rewire them to get an overall impedance of 4 ohms. You can replace all the drivers with 4-ohm drivers in the same parallel-series configuration, or you can replace all the drivers with 16-ohm drivers wired parallel-parallel. Neither of those solutions is easy - or inexpensive!

You COULD put an 8-ohm power resistor in parallel with your 8-ohm cabinet to yield an overall impedance of 4 ohms, but then half of your amplifier's output power would be running through that resistor and would just be converted to heat. And what's the point of that?

[dmusic148]

Also, 'getting the extra wattage' is usually an exercise in futility.

[Stumbo]

Originally Posted by dmusic148

Also, 'getting the extra wattage' is usually an exercise in futility.

+1

Seems like you want to get the volume you had with 2 speaker cabs out of one speaker cab by changing the ohms.

FYI, there's no "magic" like that available.

Bottom line is, you get more volume by moving more "air" (more speakers) than with bump in wattage.

Maybe you could wire your speakers into two 8ohm pairs with separate input jacks. Then add an internal divider and then report each internal cabinet. But that's not easy to do. YMMV (don't try this at home).

That would get you 4 ohms per pair. The problem is, you're still moving the same amount of air. Also, each pair would handle half the wattage it used to and probably be blown in short order.

Like I said, no "magic".

Better to save your cash and buy another cab just like the one you have so each cab will be moving the same amount of air and pushing the same freqs.

[CosmicRay]

Thanks for all the insights everyone offered. I kind of thought it couldn't be done, but just wanted to confirm.
So, using a 4 ohm cab will not give me more volume than an 8 ohm cab?
I assumed I would get more wattage resulting in more power, hence more volume.
Not correct?

[CosmicRay]

Originally Posted by dmusic148

Also, 'getting the extra wattage' is usually an exercise in futility.

In what way?

[KJung]

Originally Posted by Stumbo

+1

Seems like you want to get the volume you had with 2 speaker cabs out of one speaker cab by changing the ohms.

FYI, there's no "magic" like that available.

Bottom line is, you get more volume by moving more "air" (more speakers) than with bump in wattage.

Maybe you could wire your speakers into two 8ohm pairs with separate input jacks. Then add an internal divider and then report each internal cabinet. But that's not easy to do. YMMV (don't try this at home).

That would get you 4 ohms per pair. The problem is, you're still moving the same amount of air. Also, each pair would handle half the wattage it used to and probably be blown in short order.

Like I said, no "magic".

Better to save your cash and buy another cab just like the one you have so each cab will be moving the same amount of air and pushing the same freqs.

It is not as simple as this, and it always kills me when guys post 'a bump in wattage doesn't matter' in absolute terms.

With an amp that is pumping out 500 watts into 8ohms and 750 into 4ohms (as an example), and with a 210, the additional wattage going from an 8ohm 210 to a 4ohm 210 would not be very noticable at all, since you have plenty of wattage available to drive that little cab to its full potential at 8ohms.

In the OP's case, a relatively low wattage head putting out about 300 watts into 8ohms, into a large cab that can easily handle more wattage, and it can make a HUGE difference going to 'full power at 4ohms)... not so much in absolute volume (although you'll squeeze out a couple more db's), but in headroom, clean, open, non compressed low end, and even transients.

An LMII running at 4ohms into an Epi410UL is a VERY different thing than running it into an 8ohm 410UL (and yes, I've done both).

Going from a single cab to two identical cabs will give you about 3db more in general, and going from 8ohms to 4ohms will give you an additional 2db. Since db's are on a log scale, that is HUGE.

So, saying wattage doesn't matter is just as much garbage as saying going from 8 to 4 always matters. It depends on the cab SPL, the cabs ability to handle more power in an absolute sense (thermal and xmax, etc.), and the absolute power level you start with (i.e., are you going from 'too much' to 'way too much', or are you going from 'not quite enough' to 'enough')

[KJung]

Originally Posted by CosmicRay

Thanks for all the insights everyone offered. I kind of thought it couldn't be done, but just wanted to confirm.
So, using a 4 ohm cab will not give me more volume than an 8 ohm cab?
I assumed I would get more wattage resulting in more power, hence more volume.
Not correct?

See post 9

[CosmicRay]

I see Epifani is coming out with their " UL Dist" series that allows switching to either 4 or 8 ohms.
Nice item, but I don't have an extra $1500.00 to spend on a cab.

[KJung]

Originally Posted by CosmicRay

I see Epifani is coming out with their " UL Dist" series that allows switching to either 4 or 8 ohms.
Nice item, but I don't have an extra $1500.00 to spend on a cab.

Yeah, those are massively overpriced, and typical of Epifani, way late from the promised ship date. Also, from what I understand, and from the Bass Player review, that switching system does not work exactly as you would think. The cabs with more drivers actually result in lower SPL when switched to 4ohms, which defeats the whole purpose.

Better to plan correctly when making a cab purchase in the first place (which I realize is sometimes hard to do).

[CosmicRay]

Originally Posted by KJung

See post 9

So, if I understand you correctly, using the LMT 800 will be "louder"
if ran through a 4 ohm {Epi 410UL for ex.} than an 8 ohm {Epi 410UL for ex.} cab.
Yes?

[KJung]

Originally Posted by CosmicRay

So, if I understand you correctly, using the LMT 800 will be "louder"
if ran through a 4 ohm {Epi 410UL for ex.} than an 8 ohm {Epi 410UL for ex.} cab.
Yes?

That seems to be in the gray area, since the high powered LMT800 (I originally thought you had the LMIII) puts out a substantial amount of wattage (500 watts) into 8ohms.

So, IMO, given that you are running as many watts as an F1 or LMII/III into 4ohms with your LMT800 into 8ohms, that should kick pretty hard. Yes, with that big cab that likes power, it will kick just a touch harder at 4ohms, but you won't notice as much difference as you would with a lower powered amp like the LMII or Shuttle 6.0, etc.

My guess is, given (as I mentioned above) the high amount of absolute power you are starting with at 8ohms with that particular head, you would be wasting your time and money swapping your 8ohm Epi for a 4ohm model. You should be just fine with that match-up.

Turn it up and be happy!

K

[CosmicRay]

Since I posted this question, I was on the Avatar's website.
They have a 410UL starting @ $450 that is available in either
4 or 8 ohms.
Yes, planning on using the same cab for all situations just sometimes does not work out the way we anticipate.
Perhaps the Epi 410UL will be placed on the auction block...

[KJung]

Originally Posted by CosmicRay

Since I posted this question, I was on the Avatar's website.
They have a 410UL starting @ $450 that is available in either
4 or 8 ohms.
Yes, planning on using the same cab for all situations just sometimes does not work out the way we anticipate.
Perhaps the Epi 410UL will be placed on the auction block...

Careful. Avatar's are decent cabs, but they ain't Epi UL's. What you would be gaining due to the increase in wattage you might lose in SPL and overall even tone.

Again, with your high powered amp, the difference between 4 and 8ohms in the high SPL 410UL will be small, and not worth the cost nor trouble. If you had a lower powered amp, or if the 410UL was lower SPL (i.e., needing a lot of watts to open up like some of the early Bergantino cabs or Acme's), it might be a different story.

Going from a 410UL to an Avatar 410 makes me weep a little.

[CosmicRay]

Originally Posted by KJung

That seems to be in the gray area, since the high powered LMT800 puts out a substantial amount of wattage (500 watts) into 8ohms.

So, IMO, given that you are running as many watts as an F1 or LMII/III into 4ohms with your LMT800 into 8ohms, that should kick pretty hard. Yes, with that big cab that likes power, it will kick just a touch harder at 4ohms, but you won't notice as much difference as you would with a lower powered amp like the LMII or Shuttle 6.0, etc.

My guess is, given (as I mentioned above) the high amount of absolute power you are starting with at 8ohms with that particular head, you would be wasting your time and money swapping your 8ohm Epi for a 4ohm model. You should be just fine with that match-up.

Turn it up and be happy!

K

Thanks! Much obliged!
I'll let the whim of the week fade away....

[KJung]

Originally Posted by CosmicRay

Thanks! Much obliged!
I'll let the whim of the week fade away....

Here's something to think about IF that match-up isn't working for you tonewise (kind of changing the subject here). I had an SD800 with my 410UL for a while (similar voicing to your LMT800), and while it was just loud as the bejeebers, I found the deep low end of the 800 series voicing, and the somewhat boosted upper mids and brightness of that head resulted in my rig not 'punching' like I wanted it to (and like it does with my LMII or F1... it is a 4ohm cab... but that's a moot point for the topic of this post).

So, volume-wise, you should be just fine. However, if the NATURE of your tone is bothering you... specifically if you rig seems bit bottom heavy (deep bass) and a bit harsh up top, without warm punch (I'm not saying that is the case, but just what I found with that match-up for my tone goals), you might eventually consider the Bergantino AE410. That cab seems to be made for the MB 800 series to my ear, and while you would have to dial back the upper mids a bit to even out the voicing of that match-up, the upper mid control on the LMT800 is in the perfect place to remove the 'gank' that is a little much with that matchup. And, it is a 4ohm cab, so you get a little more juice as a bonus.

Compared to the 410UL, the AE410 is tighter, more grindy, punchier and all around more 'snarly'... which could be a good or bad thing, depending on what you are going for. It will tighten up and punch up the low end of that particular head though IMO and IME.

Good luck! Play that rig for a while. It takes 10-20 gigs for me to really know what the heck I'm hearing with a new match-up!

[CosmicRay]

Ok, I appreciate your opinion and thanks.
I think it's more of headroom factor. Seems that on one, or maybe two, of those "smaller" gigs, I had to punch it up somewhat, then I noticed the clip light blinking away... I had
something turned up too much....
But I will use this configuration on some of my upcoming gigs and see how it goes.
Thanks again for the Berg AE410 info.
I see you're not a fan of Avatar....? what about Aguilar? I know they're not cheap either.
I own a 212 & 112 - sound really nice.

[KJung]

Originally Posted by CosmicRay

Ok, I appreciate your opinion and thanks.
I think it's more of headroom factor. Seems that on one, or maybe two, of those "smaller" gigs, I had to punch it up somewhat, then I noticed the clip light blinking away... I had
something turned up too much....
But I will use this configuration on some of my upcoming gigs and see how it goes.
Thanks again for the Berg AE410 info.
I see you're not a fan of Avatar....? what about Aguilar? I know they're not cheap either.
I own a 212 & 112 - sound really nice.

Ah, you are misinterpreting the clip light. The clip light on the Markbass heads is an INPUT clip light, not an indication that you are running out of headroom at the power amp stage. If that input clip light comes on, you will totally quash your input signal, making it sound like you are running out of headroom.

Just turn down your input gain a slight amount, and make sure that clip light never comes on (it is nicely designed to tell you when you are in trouble, so all you need to do is set the input so it never comes on). The best way to do this is to turn your master volume way down so you don't hurt your ears or speakers, and pound on the open E (or B string if you play a 5) harder than you would ever play on a gig. Turn the input gain down to just below the level the input clip light comes on, and you are set.