What You Need to Know About Bass Amp Power Ratings

You may have noticed that the technical information on the back panel of your bass cabinet includes a “power rating” spec consisting of two different wattages, one labeled “continuous” and the other labeled “program", with the latter being twice the amount of the former.

Take a Fender Bassman 810 Neo cabinet, for example, which says “POWER RATING 1,000w continuous, 2,000w program” on the back. Or a Rumble 112 cabinet, which lists “500w program” and “250w continuous".

What does that mean? Why two different wattages? What’s the difference between the “continuous” rating and the larger “program” rating?

First of all, the whole subject of power ratings is devilishly complicated. We’re talking full-on guys-in-white-lab-coats science here, which, in all honesty, many bass players wouldn’t really need to delve into very deeply—if at all—in the normal day-to-day course of using of their gear. However, these dual power ratings do denote important aspects of the cab’s design and performance.

The two wattage ratings pertain to the speakers and the amount of power they can handle coming from an amplifier. The very definition of watts applies to average continuous power, and bass signals (and music in general) consist of peaks and valleys that, for short durations, are greater than the “average” level.

The “continuous” power rating is the lower wattage and the one more relevant to the day-to-day use of your speakers. It describes the amount of average power a speaker can more or less continuously handle without risking any harm to it—e.g., melting the voice coil or softening the adhesives that hold various parts together, etc.

Heat is the main issue here, and there’s a lot of thermal and other science at work—enough to fill a library. Suffice to say that the “continuous” power rating reflects the amount of power your speakers safely handle in the course of normal use. It’s half the wattage of the “program” rating, so it can be thought of as being like the 60 mph point on the speedometer of a car that’s capable of going 120 mph. Your normal everyday driving speeds are far closer to 60 mph than they are to 120 mph (the limit of the car’s capability), and, similarly, your bass cabinet’s “continuous” power rating is much closer to the amount of power actually used than to the seldom-used upper limit of its capability (the “program” rating).

So, here’s the useful part: When you’re matching cabinets to power amps, use the “continuous” rating as your guide. When doing so, keep in mind that the amplifier’s output power should ideally not exceed the cabinet’s “continuous” rating.

The “program” rating is the higher wattage— twice the “continuous” rating—because it refers to the maximum amount of peak power a speaker can safely handle for short durations. Again, it’s like the maximum speed your car can reach—although your vehicle is probably capable of a top speed around 120 mph, you never actually drive it that fast, and even if you did it would probably only be for a short burst.

When playing through your bass rig, it’s likely that you’re not always (if ever) pushing it to its peak power limit. The “program” wattage figure is thus like the “120 mph” mark on the speedometer of a car that you only ever drive at 75 mph or less (but if you need to briefly reach 85 or 90, you certainly can without harming the vehicle).

This is of course a very brief and highly un-scientific explanation of an enormously complex subject. Believe us, there’s a lot more to it. The descriptions and analogies mentioned here are only meant to give a rough idea of what these dual power ratings mean, and hopefully this simplified explanation gives you a good general idea of what’s going on.