• The difference between 4-ohm and 8-ohm speakers all comes down to power.speaker image by Byron Moore from Fotolia.com
  
  Whether listening to the radio in the car, watching a movie at home or playing a guitar on stage, proper power usage and producing optimal sound from the equipment are fundamental in determining the fulfillment of the overall experience. A speaker converts electrical currents into sounds. Understanding the role that ohms play in this conversion process can aid in setting up the perfect audio system.
  
  

What are ohms?

• The two most common ohm ratings for speakers and amplifiers are four and eight ohms. Ohms refer to the resistance, or impedance, of currents of electricity as they pass through circuits. Ohms are used to determine the best method to connect speakers or to determine how much power can be drawn from an amp to a speaker. In other words, it refers to the amount of power that will flow through your speaker at a certain voltage. Four ohm speakers are less resistant than 8-ohm speakers. Thus, 4-ohm speakers will play louder than 8-ohm speakers. Impedance is set by the speaker manufacturer and cannot be altered. The ohm rating can be found on an identification plate located on a speaker's back panel.
  
  

Which is best?

• Four-ohm speakers are used in car audio, while 8-ohm speakers are generally the standard for home audio. Using 8-ohm speakers in most car audio systems will lead to damaged speakers. The power needs to be equal to the voltage times the current. In a car, voltage is low, which means the current needs to be higher. In order to achieve higher current, the impedance must be less. Additionally, 4-ohm speakers convert more of the available power into sound. On the other hand, home audio systems typically use 110 or 240 volts, so higher-resistance, lower-current 8-ohm speakers are more prevalent.
  
  

Can they be used together?

• Ohms and impedance do not relate to sound quality. The most important thing to remember is to use the same ohm rating on all speakers and amplifiers that will be connected to each other to prevent damage to the equipment. Connecting 4-ohm speakers to an 8-ohm amplifier can overdrive the amp, causing, at best, distortion of the sound quality and, at worst, damage to both the amplifier and the speakers. Yet 8-ohm speakers can be connected to a 4-ohm amplifier at the cost of wasting the potential power of the amp. When making a speaker purchase, take the ohm rating into consideration to achieve maximum performance.