Probably sounds dumb but...

[I Need a six...]

So I'm wondering, with amp heads and cabs, why does the head have specified wattage? I'm confused because if the head is 200 watts and it's run through an 8x10 1200 watt cab, what's that mean? I'm an amp noob, so please explain this to me. Get as detailed as you need, if I don't understand I'll ask, this really confuses me.

 

[waltdogg]

You can use any head with any cab as long as the impedance of the head and cab are matched. You just need to be sure you're not blowing up your cab with a head too powerful for it which can be remedied simply by rolling back on the bass control or the volume and knowing your cab's volume limits. You also should be careful not to get a cab that's horribly inefficient with a lower wattage head, you might find your yourself pushing your head to the redline because the speakers just can't move enough air with less power.

 

[I Need a six...]

You can use any head with any cab as long as the impedance of the head and cab are matched. You just need to be sure you're not blowing up your cab with a head too powerful for it which can be remedied simply by rolling back on the bass control or the volume and knowing your cab's volume limits. You also should be careful not to get a cab that's horribly inefficient with a lower wattage head, you might find your yourself pushing your head to the redline because the speakers just can't move enough air with less power.

Right, so if you run a 200 watt head through a 1200 watt cab, it's going to be louder than through a 400 watt cab? In other words the wattage of the head is like a guideline of sorts?

 

[waltdogg]

Cab wattage doesn't dictate "loudness." Speaker area and how efficiently those speakers translate electrical signals into cone movement are what dictate how loud your rig will be. I have a 200 watt GK head. It will always be a 200 watt head but it will sound louder through a cab with a lot of matching speakers a la Ampeg 8x10 or a cab with extremely efficient speakers a la fEARful and other boutique cabs at lower settings than in would with a cab with less speakers or speakers that aren't very efficient. With those cabs you'll need to turn up more for more loudness.

 

[pie_man_25]

Not really no. The amplifier head contains the electronic components that supply the electrical power, and the speaker cabinet as the name implies contains speakers that turn this electrical power into sound by moving a cone that pushes air around.

Some heads can only supply power safely to a 4 ohm minimum impedance or higher, as long as you're using the right impedance your head is fine.

In addition to impedance values, speakers and heads have power ratings. A head that supplies 300 watts at eight ohms of impedance could supply that 300 watts to a cabinet rated for either 200 or 1200 watts of power handling equally easily provided they're both 8 ohms of impedance. However, with the 200 watt cabinet, you could damage the speaker if you're not careful by putting too much power into them, as opposed to the 1200 watt speaker which handles more power. Heads are rated to supply a given amount of power in watts at a given impedance load, and speakers are rated to handle a given power load and are also rated to have a given impedance.

Some speakers might be high in sensitivity which would make them louder at a lower power level but may trade this off for lower power handling or less low bass capabilities, while others might have a lower sensitivity and therefore be quieter at a given power level but may also have higher power handing and more low end capabilities. This is all a gross simplification, but I hope that this explains things well enough.

 

[B-string]

You have 200 ounces of fluid (amp watts) you can put them into a 1200 ounce container (speaker cab), you still have only 200 ounces.

 

[I Need a six...]

Not really no. The amplifier head contains the electronic components that supply the electrical power, and the speaker cabinet as the name implies contains speakers that turn this electrical power into sound by moving a cone that pushes air around.

Some heads can only supply power safely to a 4 ohm minimum impedance or higher, as long as you're using the right impedance your head is fine.

In addition to impedance values, speakers and heads have power ratings. A head that supplies 300 watts at eight ohms of impedance could supply that 300 watts to a cabinet rated for either 200 or 1200 watts of power handling equally easily provided they're both 8 ohms of impedance. However, with the 200 watt cabinet, you could damage the speaker if you're not careful by putting too much power into them, as opposed to the 1200 watt speaker which handles more power. Heads are rated to supply a given amount of power in watts at a given impedance load, and speakers are rated to handle a given power load and are also rated to have a given impedance.

Some speakers might be high in sensitivity which would make them louder at a lower power level but may trade this off for lower power handling or less low bass capabilities, while others might have a lower sensitivity and therefore be quieter at a given power level but may also have higher power handing and more low end capabilities. This is all a gross simplification, but I hope that this explains things well enough.

I understand so far, but what I don't really understand is why get a head with greater wattage? If a 500 watt head can damage a 400 watt cab at high volume, why not just run a smaller head? I know you've probably explained that but I just don't understand.

 

[waltdogg]

Typical practice is to go on the safe side but say, just say, you find a head and cab you love but they are mismatched where the head is more powerful than your cab. Not much you can do about that because no other rig gives you the sound you want. So, in that situation you simply be mindful of your speakers' handling capabilities by listening and watching for speaker stress.

 

[I Need a six...]

Typical practice is to go on the safe side but say, just say, you find a head and cab you love but they are mismatched where the head is more powerful than your cab. Not much you can do about that because no other rig gives you the sound you want. So be mindful of your speakers' handling capabilities by listening and watching for speaker stress.

Right, that's not an issue( yet ) but is there a specific advantage to a head with greater wattage? If your running through the same cab and power levels Aren't an issue. For example let's say I have a 200 watt head run through a 1200 watt Cab ( that thing would be huge ) what advantage if any would I get by trading out to a 500 or 1000 watt head?

 

[silky smoove]

Amp wattage is the peak power output (typically). Cab wattage is the combined thermal capacity of the drivers. Simple as that.

 

[Downunderwonder]

Headroom. That's the extra loudness you have up your sleeve for occasional emphasis.

When you have no headroom, life is boring. A wise man said ''without quiet there is no loud''. Big problem in rock bands is guitardists who have small weiner syndrome. If they aren't the loudest thing always they pack a sad until they get a louder rig.

If you don't want to play that game your 400w amp into a pair of 2x10 will be fine for most stages.

 

[Korladis]

So I'm wondering, with amp heads and cabs, why does the head have specified wattage? I'm confused because if the head is 200 watts and it's run through an 8x10 1200 watt cab, what's that mean? I'm an amp noob, so please explain this to me. Get as detailed as you need, if I don't understand I'll ask, this really confuses me.

The head takes voltage from your electrical socket, and uses it to amplify the signal sent from your bass. This means it sends power to the cab. 200 watts of power in this case (without distorting the signal).

The cab accepts power from the head, power that causes the drivers (the speaker cones) to move back and forth. This sound causes a pressure wave in the air, which we call sound.

The cab saying it is 1200 watts means that it can accept up to 1200 watts from the head. The cab does not generate power, it merely receives it.

 

[I Need a six...]

The head takes voltage from your electrical socket, and uses it to amplify the signal sent from your bass. This means it sends power to the cab. 200 watts of power in this case (without distorting the signal).

The cab accepts power from the head, power that causes the drivers (the speaker cones) to move back and forth. This sound causes a pressure wave in the air, which we call sound.

The cab saying it is 1200 watts means that it can accept up to 1200 watts from the head. The cab does not generate power, it merely receives it.

right that's helpful. But here's what I still don't quite get, what's the advantage to a larger watt head? I'm sure It's been explained but it hasn't clicked yet.

 

[Downunderwonder]

I understand so far, but what I don't really understand is why get a head with greater wattage? If a 500 watt head can damage a 400 watt cab at high volume, why not just run a smaller head? I know you've probably explained that but I just don't understand.

The reason for the bigger amp is if you were thinking of doubling up on cabs like 2x10 or 1x15, then the load on each cab is less and you get 6dB of extra headroom.

 

[BazzTard]

I understand so far, but what I don't really understand is why get a head with greater wattage?

I think you are asking why get a larger wattage head than the cab can handle? Well usually you don't, unless you are adding a second cab.

If you had two 400watt cabs then you could safely deliver 400watts to each cab,meaning you could use an 800watt head. But say you are just practicing with the one cab, then yes,you have to wind back the volume on the 800watt head so you don't blow the 400watt cab. I am totally ignoring impedance here.

 

[Downunderwonder]

In days gone by you only got the full preamp feature set on the big'n.

 

[Downunderwonder]

No, no you don't understand. This question you ask confirms it.

You get a head with greater wattage when you want to be LOUDER. A 500watt head produces more power than a 100watt head going into the same load.

with the proviso that the cab you have is capable of doing something useful with the extra power. Often the first biggest rig improvement is the cab situation. Then you might have a use for more power.

 

[I Need a six...]

The reason for the bigger amp is if you were thinking of doubling up on cabs like 2x10 or 1x15, then the load on each cab is less and you get 6dB of extra headroom.

Oh ok, can you give me more detail if there's more to it?

 

[I Need a six...]

Thanks guys I'm understanding it now, more input is still ok though, elaborate even further.

 

[moody]

I understand so far, but what I don't really understand is why get a head with greater wattage? If a 500 watt head can damage a 400 watt cab at high volume, why not just run a smaller head? I know you've probably explained that but I just don't understand.

Unfortunately even a 200watt head can damage a 400 watt cab at high volume. It can depend on how you use it.

A lower power handling cab (say 200) can in fact handle occasional peaks of higher wattage (say 300) - as long as it isn't beyond it's physical limitations (voice coil jumps out or cone rips) and is allowed to cool afterwards. continual use at that same level would kill the speaker.

A larger power amp can be run at a higher volume level cleanly without distortion.

A cleaner signal near the peak handling of the speaker will be handled more easily than a distorted square wave near the peak handling of the speaker.

A square wave equates to the speaker not moving much while a lot of power is running into the voice coil. The speaker relies on movement of the voice coil to stay cool. To much on the absolute limits of the speaker and the varnish holding the voice coil together will melt and you have a dead speaker.

All this equates to overpowering, not underpowering. There is no such thing as underpowering. But you should get at least as big an amp as you need and speakers that can reproduce the volume that you need.