4 Ohm or 8 Ohm Cabs?

What's your rig?

It depends on your Amp.

 

Unless you plan to get a new amp that can go down to 2 ohms, get 8 ohm cabs. If I liked the cabs and I liked the GK (I assume you do), I'd check out a GK Legacy amp.

 

Being able to run both cabs at the same time will move a lot more air giving you more dB than one cab and more watts. Maybe @Wasnex will stop by.

 

Power is a function of voltage and current. Current flows better when resistance is lower, following Ohms law (W = V^2/ R)

As said above, depends of the ability of your amp to deliver the right current to cope with the resistance (Ohms)

All this to say it is how speaker/amp are coupled, there is no one better than the other.

 

Does GK's new line of amps do 2ohm?

 

My 'preference' would be to use the 'local shop in NJ' simply as a venue to purchase gear, and to take any recommendations from the owner with a grain of salt, as his 'information' is a bit questionable at best …

Might also want to look into a better understanding of the affects of speaker cabinet impedance after seeing a statement like '4 ohms require more power' ...

… as always, JMHO, and respectfully submitted … I would go further to say that the first paragraph of the OP shows a very good reason for those considering each to select 8 ohm over 4 ohm cabs if the user intends to run multiple cabs on a consistent basis … or even if there is a possibility of it in the future ...

 

There is some misinformation here.

Any given cabinet is a particular impedance, most typically 8 ohms or 4 ohms. 4 ohm cabinets do not require 'more' power. But an amplifier will usually put out more power into a lower impedance load.

According to the GK website the Legacy Series will be stable down to 2 ohms, which is the load your two 4 ohm cabinets will put on the amplifier if you use them both together. If you like your cabs I think the easier and more financially feasible option is to sell your amp and get an amp that will be safe and stable to use at 2 ohms, like the Legacy.

Those amps may not actually be more powerful at 2 ohms than 4 ohms, it depends on how GK configures their 'load capacity selection'. There isn't enough information on the website to answer that question.

As to what your local shop owner said, it's not an absolute that 4 ohms cabs are better for bass. Depends on the cabinets being used, in what combinations, their power handling, with what amp, etc.

Which model cabinets are you using?

 

If you take 2 ohm anps out of the picture then 4 ohm cabs are only useful singly.

The one cab has to provide all of your volume needs. There can be no modularity.

Your dealer is an idiot.

 

It depends very much on the specific amp and speakers. In the case of your specific amp, 2 x 4 ohm speakers is a non-starter.

 

Let's explore using one 4 ohm speaker or two 8 ohm speakers, because that is what the amp can handle.

If you double the speaker area and hold the total power constant you get +3dB in the low end from mutual coupling.

Basically two speakers will split the available power evenly. So the SPL of each speaker is 3dB less...but you gain 6dB from mutual couple. So the net is -3+6=+3dB.

This assumes all speakers have the same sensitivity rating.

 

I suppose one way of looking at it would be that if you are sure you will only ever use 1 cab then most amps will deliver more power to a 4ohm cab. This may not be a good thing of course. If you see yourself using multiple cabs then 8ohm cabs will probably give more options. There's also the consideration that tube amps are best run into the 'right' impedance but SS amps will happily deliver lower power into higher impedances.

 

It's always possible to slave a second amp for the second cabinet. That's how I drive 4x2x10, all 8 ohms. The Science Fair version of a fridge.

 

Firstly, what are your two 4ohm cabs? No good telling us without telling us, is it?

I'd, maybe, keep one and sell the other, depending upon your answer. Hoping one of them is a 2 X 12 that can handle 600 watts. If they happen to be something like a 4 x 10 that can only handle 200 watts, I'd sell them both. Really, if you ask a question, you need to supply the detail, if you want accurate informed help.

 

Generally speaking, you can think of your speakers as "pulling" power from the amp, not the amp "pushing" power to the speakers. The amp's wattage rating describes the maximum amount of power the speakers could pull from the amp. That maximum varies with the impedance (ohms rating) of the speaker cabs.

A 1000 watt amp with a 4ohm speaker load and the volume on "1" won't be providing 1000 watts to the speakers. It could provide "up to" 1000 watts maximum (roughly, depending on marketing hype and input signal levels). The 4 ohm load can "pull" up to 1000 watts maximum out of the amp if you crank it to 10 (that's how I think of it). An 8 ohm load on the same amp might only be able to pull 500 watts maximum.

I always run solid state amps; I understand tube amps are somewhat different - and I'm not real clear what the differences are. What I said above is my understanding of how solid state amps (and hybrid amps with a tube preamp section and a solid-state power section) behave.

I like a pair of 8-ohm cabinets. For loud gigs I can bring both and run a 4-ohm load, for quieter rooms I can bring one and run an 8-ohm load at lower wattage and volume. Flexible.

It's also good to have plenty of headroom. That means having a more powerful amp than you need for the job. Two reasons:
1) Most amps don't sound the same when you crank them. If you have to run your volume on 10 all the time, your bass knob (bass frequencies require more power than mids & treble) won't be very effective or might cause distortion. Your amp's tonal "sweet spot" is probably not at volume 10.
2) Accidents happen; input levels are also a factor in how much power gets pulled out of the amp. If you're already running close to your gear's limits, all it takes is one carelessly unplugged cord or dying battery to send a volume spike that could damage your amp as well as your speakers. Safer if your amp and speakers are not normally running close to their limits.

 

Especially if you ever want to run a stereo chorus effect

 

It's all about personal preference, a 4 ohm cab will give you power, but 2 8 ohm cabs will give you even more power, plus if its a small gig you can use one, or both if you like showing off

 

Go with 8 ohms.