The Power Load
There are many ways a musician can ruin their gear. Plug something in the wrong way and bang, it can be gone. A basic understanding of electronics is needed in order to not fry things. What’s this word Ohm that appears? And Watts, is that Reggie?
The Ohm is a unit of electrical resistance. The Watt is a unit of power.
Enter Jim Anderson - The Dragon. The beloved Crocodile engineer guru and sound wise master. (Who says there has been Crocodile talk as of late, but that’s real estate, and that can go on and on.)
Jim, can you make Ohms and Watts make sense?
Jim: The Ohm is resistance. Think of it like the diameter of a water pipe. The smaller the pipe, the more resistance it has. And Watts is power. I guess you could say for this analogy, it’s water pressure. But they’re two totally different ratings. The resistance is applicable to a speaker load. The resistance on a circuit tells you how much of the power it can soak up. 8 Ohms is different that saying it can handle 800 Watts.
Ohms and Watts can be related because of certain formulas. It has to do with the way electrical circuits work. It all goes back to 1827 with George Ohm’s law. He’s the cat who figured out all this shit out.
181 years later, the Lights bassist Jeff Albertson poses an Ohm – Watt conundrum:
I have 450 Watt head and an 8 Ohm 2X15 cabinet. I know they go together cause the salesmen told me so. But what if I wanted to run a 1X15 cab or a 4X10 cab? Those things can be rated at 4 Ohms separately or 8 Ohms when chained together. I would have no clue if what I was hooking up is going to blow my amp or not. I have been playing bass for over fifteen years. These things still baffle me.
Jim, can you help a man out? Can you un-baffle Jeff?
Jim: Impedance, impedance, impedance. It’s all about matching. It wouldn’t matter what he’s hooking up as long as the impedance is the same. Depending on whether the resistive loads are in series or parallel, that changes things. If he hooked them up one way, it could be a 16 Ohm or an 8 Ohm load. He needs to know what the amp wants and then he can hook up whatever accordingly.
Let me back up for a second. When you’re talking about a load on an amplifier, it needs to have some place for the power to go. And it goes to a resistor, which is how much power it can handle.
The power that you’re applying to the resistor gets turned into heat, like a space heater. A space heater is a resistor; it’s dissipating the energy that’s going through it. That’s what a speaker’s voice coil will turn into if you stop it moving back and forth. The pushing back and forth, that’s how the speaker dissipates the energy. You know how on the back of some speakers, there’s a screen? Well, that’s ventilation for the heat. Without the speaker movement and ventilation, the electrical current will be too much and the voice coil will glow orange.
They do burn up, I’ve seen speakers catch on fire. I did sound one time at Myrtle Edwards Park for a heavy industrial noise band from Germany called Einstuerzende Neubauten, which means ‘collapsing new buildings.’ Part of what they try to do is destroy the P.A. One of their snare drums was a 4X8 piece of sheet steel which had to be mic’d. The guy beat the steel with chains. It was intense. After the show, I took the speakers apart to try and fix them and they burned a hole through the middle of the cone.
That wasn’t very nice of them to do.
It was part of their act though, destruction is cool! When there’s insurance.