The difference between good and bad natural distortion in speakers
Speaker cutaway. Illustration from Celestion, used with permission.
Let’s start with the understanding that a good guitar tone is subjective. What I might consider the Holy Grail tone might not do it for another player. But all tones good and bad have a purpose and a place, and you should know how to achieve the tone you’re looking for. To do this you need to understand how a speaker works and how all the parts translate to your sound. First ask yourself: How loud do I need to be before the speaker starts breaking up? What kind of low-end response do I need to achieve? How smooth or midrangey do I need the speaker to be?
These are very important things to know about your gear, because they can help you determine if your speakers are efficient enough for your needs, or made from the right materials for the sound you’re tying to get. Keep in mind that all amplifiers and speakers distort, but knowing when and how it happens is the trick to getting good distortion.
For example, let’s say you have a 20-watt tube amplifier that breaks up too fast and you wish it would stay cleaner at a higher volume. This is considered bad distortion, but is this the amp’s fault? Do you need more wattage? No. Before you run out and spend more money than you have too, try changing the speaker first. But which one is the right choice? What specs should you be looking for?
Know that power rating does not always determine the amount of break up. Breakup is mostly influenced by the cone. Break-up occurs quicker in a thinner, lighter-weight cone, but some speakers have a heavier cone which produces a slower break up.
What you need to compare is the sensitivity or SPL ratings. SPL, Sound Pressure Level, is a measurement for volume in reference to the human ear. SPL is always expressed in decibels, or “dB.” A speaker specified at 98dB will provide SPL of 98dB when 1 watt of power is applied and the listener is 1 meter directly in front of the speaker. Potentially 30 watts will achieve 117dB of output on a speaker that has a sensitivity of 98dB (that’s a 3dB increase for every doubling of power). (Refer to “Speakers: 40% of Your Tone,” June 2009, for more information about how wattage translates to volume.)
A higher power rating typically means a larger voice coil. Speakers with a larger voice coil tend to provide a more pronounced low end with less top-end extension. But there are other factors to consider.
Choose your magnets carefully. Do you go with alnico or ceramic? Each have different magnetic properties and costs associated with them. Alnico is a composite of aluminum, nickel, and cobalt, and is more expensive. Alnico is commonly thought to produce the “Vintage Tone,” and has a reputation for sounding compressed. Ceramic is cheaper and the most commonly used material. If you’re comparing speakers that have the same magnetic flux, but generated from different magnet compositions, you probably won’t notice a difference in tonality.
Neodymium seems to be the wave of the future, especially with the reduced weight and overall costs declining. Neo produces the most magnetic flux per ounce, making it ideal for use in multiple speaker cabinets to maintain performance while reducing handling and overall weight. Bigger magnets are more efficient, which translates to more output at a given power.
Consider the dust cap. The differences in size, shape, weight and the material of the dust cap significantly affect the top end. A small, conical cap can give you a little more sizzle on the top end, but a felt material produces a smoother top end. This information alone can help define your search and keep you from buying multiple speakers until you find the right one.
If your desire is to clean up or smooth out the tone of your combo amp, a higher wattage speaker with a felt dust cap may be exactly what you need. The key to good distortion is knowing when and how you are producing it. Bad distortion happens when you don’t want it and can’t figure out how to get rid of it.
That’s it for now, but stay tuned—part two of our discussion will cover the other end of the spectrum: Adding distortion and low end to a high-gain amplifier. Is your speaker reproducing what the amp can produce?
For more than 15 years Tony has been a music industry professional, conducting clinics and in-store training seminars world-wide for Peavey, Washburn, Eden Amps and Parker Guitars, as well as involvement in product development. He’s also an experienced performing musician.