What really do you gain by going with a 4ohm vs 8ohm single cab?

[mrpackerguy]

Other than the obvious of being able to mate it with another 8ohm cabinet?

For some unknown reason, I recently convinced myself I needed the 4ohm version of the 12" walkabout cab to replace my 8ohm walkabout 12" cab, to really get the full juice out of the walkabout amp.

So, 4 ohm cab arrives this week. I do a side by side compare. There are slight tonal differences: at the same gain and tone settings on the bass and the walkabout amp, the 4ohm walkabout cab was grittier, harsher in the highs (same tweeter settings), nastier in the mids and low mids. By contrast, the 8ohm walkabout cab was more pillowy, fluffier, more "polite" in the highs and mids, but without really a loss in punchiness. Lows were comparable. Both sound really good, just in a little different ways.

With my bass and how I want my tone to sound, the 8ohm is winning out, though I haven't given up hope on the 4ohm cab yet. Really no appreciable volume difference, but the 4ohm cab breaks up quicker when the gain is engaged past 1:30.

So I wonder to myself, why did I think I needed the 4ohm walkabout cab?

[Interceptor]

Decibels are why there isn't that much difference.

The smallest amount of difference we can reliably detect is 1 dB.

Play around with this calculator: http://www.ringbell.co.uk/info/dbw.htm

Plug in the difference in rated Watts that your head has between 4 Ohms and 8 Ohms.

Jim

[greenboy]

Originally Posted by mrpackerguy

So I wonder to myself, why did I think I needed the 4ohm walkabout cab?

Because you weren't taking advice from people who actually understood what it was all about, like lomo? All these drivers almost everybody uses are limited by their excursion well before what any thermal ratings would indicate.

[BigOldHarry]

You don't get much. You GIVE UP flexibility to add more cabs, however.

[NecroticImbecil]

In most situations I wouldn't bother. If I thought I needed more volume out of a solid state amp, I'd add another 8 Ohm cab rather than switch to a 4 Ohm of the same size.

Now that my only solid state amp is just used as a V-drums monitor, I use 4 Ohm cabs because my main head only works with 4 Ohm loads, and my various others work with a 4 Ohm load among others.

[mrpackerguy]

Originally Posted by Interceptor

Decibels are why there isn't that much difference.

The smallest amount of difference we can reliably detect is 1 dB.

Play around with this calculator: http://www.ringbell.co.uk/info/dbw.htm

Plug in the difference in rated Watts that your head has between 4 Ohms and 8 Ohms.

Jim

Jim: I miss the bike in your avatar.

[KJung]

With a 112, you probably wouldn't even notice the difference volume-wise. With a big multridriver cabinet, and a relatively low power head, it can be a life changing experience.

Not a simple 'matters or doesn't matter'. And, more watts is about much more than just 3db extra volume (which is noticable). However, going from driving a lower powered amp into clipping or limiting versus having that low end end be much less compressed and open can be a really wonderful thing. However, it doesn't work in all situations. Low powered head and multidriver cab... BIG difference. High powered head (i.e., 500 watts+ at 8ohms) or a little single driver cab with a typical mid range bass driver... not so much.

In my A-Bing of my internal 4ohm Scout cab and an external Scout 8ohm 112, I didn't really notice much tonal difference at all. My guess is, the speaker needs to bread in just a touch more to widen the low end, and like others above have said, the extra wattage is probably pushing that single 112 beyond its limits when you really crank your amp.

[seanm]

I find that with 12s, the big difference is going from one to two.

[StuartV]

@OP: When you compared the two cabs, did you turn the volume up to where it was just starting to clip with the 8 ohm speaker? That's really the only place where I would expect to hear any difference. When it starts clipping with the 8 ohm speaker, it should still have a little further to go on the volume knob before it clips with the 4 ohm. (I'm assuming your amp is solid state - I don't actually know your amp)

And if the cab can't handle that much volume from your amp (i.e. if you can't turn it up that loud because the amp would blow the speaker first), then there really is no point in the 4 over the 8.

Also, if the sensitivity of the 4 isn't at least as high as the sensitivity of the 8, there is also probably no point in the 4 over the 8.

[billfitzmaurice]

Originally Posted by seanm

I find that with 12s, the big difference is going from one to two.

Most of that difference is the result of the doubled radiating efficiency of two drivers versus one. Real world, the maximum output increase of a 4 ohm load versus 8 ohm is 2dB, and that assumes the amp has to go to its full output capability to drive the speaker to its maximum capability. More often than not there's no difference due to the lower impedance alone.

[G2K]

Would the amp have to work harder with an 8 ohm cab vs the 4ohm cab?

[mrpackerguy]

Originally Posted by StuartV

@OP: When you compared the two cabs, did you turn the volume up to where it was just starting to clip with the 8 ohm speaker? That's really the only place where I would expect to hear any difference. When it starts clipping with the 8 ohm speaker, it should still have a little further to go on the volume knob before it clips with the 4 ohm. (I'm assuming your amp is solid state - I don't actually know your amp)

And if the cab can't handle that much volume from your amp (i.e. if you can't turn it up that loud because the amp would blow the speaker first), then there really is no point in the 4 over the 8.

Also, if the sensitivity of the 4 isn't at least as high as the sensitivity of the 8, there is also probably no point in the 4 over the 8.

No, but good thought. Using the Walkabout head.

[dmrogers]

Originally Posted by mrpackerguy

So I wonder to myself, why did I think I needed the 4ohm walkabout cab?

Good question. Just to show you how different people think,
If it would have been me with a walkabout and 1x12, my thought would have been:

How fast can I get another 1x12 to pair with what I already have.

I played for two or three years with a head into a single 12. It served me well for the gigs. When the circumstances changed, I realized the need for an additional cab to suit different venues. I mean, if the head is powerful enough to drive a cab at either 4 or 8 ohms, does it really make a difference?

[greenboy]

Originally Posted by Interceptor

Decibels are why there isn't that much difference.

The smallest amount of difference we can reliably detect is 1 dB.

Play around with this calculator: http://www.ringbell.co.uk/info/dbw.htm

Plug in the difference in rated Watts that your head has between 4 Ohms and 8 Ohms.

And as someone has noted, sometimes the 4-ohm driver version will have less sensitivity than the 8-ohm driver of that model.

But it's all largely immaterial. The Walkabout when driving the 4-ohm Twelve simply overwhelms it fairly early, with no net gain in SPL over the Walkabout running the 8-ohm Twelve.

While doubling 8-ohm drivers can easily give ~ 6 dB.

[billfitzmaurice]

Originally Posted by G2K

Would the amp have to work harder with an 8 ohm cab vs the 4ohm cab?

The opposite. A lower impedance load increases current draw, which creates more heat. That's why amps shut down if the impedance load is too low.

[delta7fred]

Originally Posted by mrpackerguy

So I wonder to myself, why did I think I needed the 4ohm walkabout cab?

Because you spend far too much time on TB reading threads about how wonderful 4 ohm cabs are because you can get more volume/power/heat/etc out of your rig (and not enough time in the wood shed).

[RickenBoogie]

+1 What really makes no practical sense, is that mesa automatically assumes everyone wants the 4 ohm version to "get all the 300 watts worth", when in fact, the 12" spkr cannot even handle all 300 watts. In most cases, and certainly in this one, the logical choice is the 8 ohm Walkabout Scout- which will give the spkr all it can take.

[esa372]

related thread:

4-Ohm load vs. 8-Ohm load - benefits to amp?

[kosmicwizard]

Originally Posted by mrpackerguy

Other than the obvious of being able to mate it with another 8ohm cabinet?

For some unknown reason, I recently convinced myself I needed the 4ohm version of the 12" walkabout cab to replace my 8ohm walkabout 12" cab, to really get the full juice out of the walkabout amp.

So, 4 ohm cab arrives this week. I do a side by side compare. There are slight tonal differences: at the same gain and tone settings on the bass and the walkabout amp, the 4ohm walkabout cab was grittier, harsher in the highs (same tweeter settings), nastier in the mids and low mids. By contrast, the 8ohm walkabout cab was more pillowy, fluffier, more "polite" in the highs and mids, but without really a loss in punchiness. Lows were comparable. Both sound really good, just in a little different ways.

With my bass and how I want my tone to sound, the 8ohm is winning out, though I haven't given up hope on the 4ohm cab yet. Really no appreciable volume difference, but the 4ohm cab breaks up quicker when the gain is engaged past 1:30.

So I wonder to myself, why did I think I needed the 4ohm walkabout cab?

I have no idea why you thought you needed the 4 Ohm ... truth is you didn't, and you have also screwed yourself over in regards to being able to have a modular setup ... With a 8 Ohm walkabout combo and an 8 Ohm extension cab you would have been set, I guess you spent more than you needed to arrive at this conclusion. It is Okay, all of us make mistakes. Cheers.

[Interceptor]

Originally Posted by greenboy

And as someone has noted, sometimes the 4-ohm driver version will have less sensitivity than the 8-ohm driver of that model.

But it's all largely immaterial. The Walkabout when driving the 4-ohm Twelve simply overwhelms it fairly early, with no net gain in SPL over the Walkabout running the 8-ohm Twelve.

While doubling 8-ohm drivers can easily give ~ 6 dB.

Put together what I was trying to say and what Greenboy states - the amp hasn't more than 2 dB more umph together with the fact the 4 Ohm cabinet has less efficiency, and you've got an unhappy camper.

One of the truly great engineers I worked with years ago used to say (at the most irritating time possible) the laws of physics are not a suggestion, they're law.