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

mrpackerguy

mrpackerguy

Gold Supporting Member
Jul 3, 2004
4,694
3,185
Madison, Wisconsin
www.whozplaying.com
#1
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?
 
#2
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: Invalid Link Removed

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

Jim
 
#3
mrpackerguy said:
So I wonder to myself, why did I think I needed the 4ohm walkabout cab?
Click to expand...

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.
 
#5
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.
 
#7
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.
 
#9
@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.
 
#10
seanm said:
I find that with 12s, the big difference is going from one to two.
Click to expand...
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.
 
#12
StuartV said:
@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.
Click to expand...
No, but good thought. Using the Walkabout head.
 
#13
mrpackerguy said:
So I wonder to myself, why did I think I needed the 4ohm walkabout cab?
Click to expand...

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?
 
#14
Interceptor said:
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: Invalid Link Removed

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

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.
 
#17
+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.
 
#19
mrpackerguy said:
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?
Click to expand...

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.
 
#20
greenboy said:
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.
Click to expand...

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.
 

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