ne another and allows them to work efficiently.
Another feature you will see on many speakers is a port, which is merely an opening in the speaker which allows the long wavelengths of low frequencies to escape the cabinet and reinforces the speaker’s bass response. By including a port, the speaker will be able to reproduce bass at higher volumes than without it. Another method to increase a speaker’s bass response is to include a passive radiator, which has all the parts of a regular driver, except for a voice coil and magnet ans is not wired to an amplifier. The passive radiator moves back and forth with bass sound waves created by the other drivers and allows for more bass output from the speaker. A passive radiator can be preferable to a port in some cases because it doesn’t have the same tendency to turbulence or port noise. It also allows the speaker cabinet to remain small, which is an engineering method that we at Aperion use for our small footprint subs and center channels.
Finally speakers with more than one driver, that is nearly all loudspeakers, use crossover networks of circuitry to ensure that the different drivers play the frequencies for which they are designed. For instance in a two way speaker, which is a speaker with a tweeter and one or more woofers that play the same frequency range, the crossover will filter out low frequencies before the signal reaches the tweeter and then filter out high frequencies before they reach the woofer(s). This ensures that the drivers do not waste energy attempting to reproduce frequencies that are inaudible to our ears when produced by that driver. Commonly, capacitors are used to filter out lower frequencies and a coil or inductor is used to filter high frequencies. The crossover point is the frequency when one driver’s response falls off in decibels (dB) and another driver’s frequency response increases. You can think of the crossover point as the “hand off” of the sound from one driver to another. Using components to create an ideal crossover point for each driver is critical to ensure that the different drivers in a speaker blend together seamlessly while faithfully reproducing the full audio spectrum.
Audio Specs Explained
- What is Nominal Impedance? Impedance is a measure of resistance. All electrical devices resist the flow of electricity to some degree. Because they resist at some frequencies more than at others, engineers thought they would confuse the layperson. Thus they chose the word impedance instead of resistance. But the concept is the same. The nominal impedance (resistance) means “the lowest the impedance (resistance) will be at any frequency is not much lower than the spec listed.” This spec is unrelated to the quality of speaker performance but it can effect how much power your speaker draws from your receiver. The lower the impedance, the more power the speaker will draw from your receiver with the “volume” knob at a given position. Therefore if your speaker has a low nominal impedance spec, typically 4 ohms or lower, you will need a higher powered amplifier to drive it.
- What is Efficiency (also known as SPL)? The efficiency of a speaker is how loud it will play, in dB, when fed one watt of power and measured from one meter away. If a speaker is 10dB higher in efficiency than another, it will play twice as loud with the same amount of power. An increase of 3 dB means it will play just as loud with half the power. Don’t mistake efficiency for quality. In fact, many good speakers, like high performance cars, are low in efficiency.
- What is Sensitivity? This takes efficiency and adds the effect of impedance. If two speakers are the same in efficiency but one as half the impedance (resistance), it will play 3dB louder since it’s drawing twice the power from your amp (and that’s without touching the volume knob).
- What is Frequency Response? This is usually the most reliable indicator of a speaker’s sound quality. Unfortunately, it’s also the easiest spec to manipulate given that it depends on microphone placement, room placement, how the graph of t