How many Watts for multiple cabinets

[ehinkley]

Good morning everyone.
Though I have played bass for years, I've always used a combo and never an amp head with separate cabinets. I am looking at stacking two cabinets, one 250W and the other 500W, and am having difficulty understanding the needed power calculations. I've been told that a 350-400W amp will be enough to supply both cabinets, but it would appear to my ignorant brain that 750W would be correct. Is that not the way it works? Thank you.

 

[colorblindbass]

id like some help on this one two,
can i do two 1000 watt cab's through a 450 watt head?

 

[seamonkey]

Rather than dive into this whole watts, impedance, power distribution thing - what is it you're trying to do? what kind of volume levels do you want to achieve? and why do you think you need two two different cabinets?

Colorblindbass - of course you can use a lower power amp than what your cabinets are rated (I recommend it). And you always have the option to turn down a high power amp to a lower volume.

 

[ehinkley]

I've always understood that underpowering speakers is almost worse than overpowering them. Am I wrong?
As far as the cabinets, I'm just looking at a couple of Avatar cabinets. One with 2 10s and one with 1 12.
It would be for small to medium club venues.

 

[kevinmoore73]

I've always understood that underpowering speakers is almost worse than overpowering them. Am I wrong?

Yes

 

[seamonkey]

I've always understood that underpowering speakers is almost worse than overpowering them. Am I wrong?
As far as the cabinets, I'm just looking at a couple of Avatar cabinets. One with 2 10s and one with 1 12.
It would be for small to medium club venues.

Underpowering is a myth.
Think of it this way, you have a volume knob - you don't crank the amp all the time so you're not running full power.

Then the argument dives into clipping - and how the amp can put out more than rated power when clipping. Turn it down if it doesn't sound right.

Voltage/current wise it's hard for a clipping amp to put out a whole lot more wattage than it's rated for. Unless the manufacturer has done some kind of super job on the power supply. Pretty rare.

Most cabinets can't put of any more volume after half their rated power anyhow. i.e. a 500w rated cabinet is going to enter into bass compression at 250w (typically).

 

[ehinkley]

Thank you for the replies. Let me ask a bottom line question as far as patching is concerned.
If I have an amp that is rated at 450W at 4ohms, would patching that into the 500W rated cabinet, and then patching that cabinet into the 250W rated cabinet work, or is that not a good idea? Again, pardon my ignorance in this matter.

 

[lug]

Thank you for the replies. Let me ask a bottom line question as far as patching is concerned.
If I have an amp that is rated at 450W at 4ohms, would patching that into the 500W rated cabinet, and then patching that cabinet into the 250W rated cabinet work, or is that not a good idea? Again, pardon my ignorance in this matter.

What are the two cabs rated in ohms?

 

[ehinkley]

Actually, the website shows 4 or 8 ohms for the 500 w cabinet, but doesn't show which they are relating the 500 w to.

 

[Geoff St. Germaine]

Your cabinet is either 4 or 8 ohms. Both the 4 and 8 ohm versions are spec'd to handle 500 W. You have to look on the back of your cabinet and hopefully the actual impedance of your cabinet is written there.

 

[ehinkley]

It says the cabinets can be ordered either at 4 or 8 ohm configuration at 500w.

 

[Geoff St. Germaine]

Ok, I see now that you don't have the cabs.

Ok, if both of the cabinets you get have the same impedance they will each receive equal power when hooked up in parallel to the amplifier. In that case you are going to be limited by the 250 W cabinet to the power you can supply to the system. I would still shoot for an amp with more than 500 W because you can always not turn the amp up all the way. Which cabs you get will depend on the minimum load impedance for the amp you buy. If you get one that has a minimum load impedance of 4 ohms, then I would suggest getting two 8 ohm cabs as when you have them both hooked up you will get maximum power from the amp. If you get an amp that can handle a 2 ohm minimum load then you can look at getting two 4 ohm cabinets.

What cabinets are you looking at?