Speakers are everywhere! They’re in your guitar or bass amp, they’re in your stage monitors and Front Of House systems, they’re in your headphones, your radio, your car, your recording monitors, even in the ceilings of stores and elevators to bring you that wonderful background music. C’mon, you know you love the AI-generated version of (insert favorite song here). Yeah, me neither, but that’s another topic altogether. Here we’re going to focus on musical instrument speakers and address a few interesting questions I’ve been asked.

What is the difference between the speaker wattage rating vs. db rating?

Apples and oranges here. The db rating of a speaker denotes how LOUD the speaker is. It is basically a measurement of the speaker’s efficiency. The typical test procedure is done by applying 1 watt to the speaker at a frequency of 1Khz and then measuring the sound level in db at a distance of 1 meter. This is a pretty consistent way of telling how loud one speaker will be compared to another speaker. Keep in mind that different frequencies will be reproduced at different levels by different speakers. This is the basic difference between what we call a "British" sounding speaker and an "American" sounding speaker. That said, the db rating is a good comparison point. Keep in mind however that the db curve is logarithmic, and that 3db equals TWICE the loudness. This means that a speaker with a rating of 100db will sound twice as loud as a speaker rated 97db with the same applied power. Knowing about the efficiency of a speaker can help you make a small amp louder or tame the beast!

The wattage rating of a speaker lets you know how much power the speaker will handle without damage, so unless you’re looking to push the speaker into creating its own distortion (and are ready to replace it quite frequently) the speaker should always be rated for at least as much power as your amplifier can produce.

What does a “voice coil” do?

A voice coil is a form of electro-magnet. The concept is very similar to a little science experiment that was around when I was a kid. If you take a large nail, wrap a good amount of insulated wire around it and connect it to a battery, the nail would then become a magnet! There’s a lot more theory here than I have space for, but basically the Voice Coil in a speaker is the winds of wire around the nail. Only the nail here is not a nail, but a magnetic pole that is surrounded by the voice coil, which IS actually many winds of wire. If you’ve ever touched a 9V battery to a speaker to see if the speaker is working, you’ll see that, depending on which way you connect the battery, the speaker cone will either move in or move out. That’s because the battery is DC and only has plus or minus voltage, so the magnetism of the voice coil will either attract or repel with respect to the polarity of the magnetic pole in the speaker. If you were to plug the speaker into an AC outlet (please DO NOT do this!) you would see the speaker move in and out at whatever the frequency of the voltage is in your area (60Hz in the US, but can be 60 or 50Hz elsewhere). SO, when we apply an audio voltage to the speaker, its movements replicate whatever frequencies it is being given.

How can you tell a stuck or blown voice coil?

Okay, we’ll go quickly back to using a 9V battery here. If you quickly connect a 9V battery to the speaker terminals and you hear a “click” but the speaker cone barely or doesn’t move at all, the speaker is stuck, quite possibly due to the voice coil getting too hot causing the winds to come loose and seize up the movement of the speaker. There could be other reasons why the speaker doesn’t move, but bottom line, if it doesn’t move, it’s bad. Now if you connect the battery and you hear nothing at all, more than likely the voice coil is open and again, the speaker is bad.

Does speaker paper affect the tone?

In a word, Yes. But there are many different ways that it can. The simplest of which is thickness. In general, I’d like to say that the thinner the paper, the brighter the speaker. Conversely, the thicker, the darker. But there are other ways the sound can be affected. Does the cone have ribs? How many? How big are they? Is the cone completely smooth with no ribs? Every aspect affects the sound of the speaker. Let’s go a step further. What is the paper made of? A while back speaker companies started to make speaker cones out of Hemp. My first experience with them years ago, I found them to be pretty dark, but probably very good for taming a bright amp. I even remember having discussions with people 30 years ago who were convinced that the new cones did not sound as good and probably would never sound as good as the cones in old speakers because the old cones were made of pulp from natural slow growth trees, and the new ones were made from quick growth forests, so the molecular structure was different! Thing is, we’ll never know. The speakers they were making then are now 30 years old, but what they were comparing them to are now 60 years old and the cones continue to dry out over time.

Speaking of time, mine’s up. Enjoy!