About 4-Ohm Subwoofers
The ohm is a term to of measurement to describe the impedance of speakers (including subwoofers), to determine the resistance necessary for the voltage coming from the amplifier. Many subwoofers are rated at 4 ohms, but 2 and 8 ohms are also common. The subwoofer's ohm rating has no relation to sound or product quality, and is used solely for matching to suitable amplifiers and other speakers.
Other People Are Reading
-
Amplifier Ratings
-
Most amplifiers are designed to handle multiple ohm levels so as to be compatible with different speakers. The lower the speaker ohm rating the amp is connected too, the more power the amp produces. The higher the ohm rating of the speaker, the less power the amp produces. But amplifiers have limits, and the recommended ohm loads and power statements are printed on the amp chassis, or published in the owner's manual. Most amplifiers can safely handle speaker ohm loads between 4 and 16, with some amps able to go down to 2 ohms.
Speaker Ratings
-
Subwoofers are rated in ohms and power-handling capacity. A 4-ohm subwoofer rated at 400 watts is no different in sound quality than a 2- or 8-ohm subwoofer rated at 400 watts, except that the amplifier connecting the subwoofer must not exceed the power capacity of the speaker at stated amplifier ohm and power ratings. For example, if the amplifier produces more than 400 watts at 4 ohms, a 4-ohm subwoofer is in danger of being blown.
-
Speaker and Amplifier Matching
-
The real question becomes one of component matching. A 4-ohm subwoofer rated at 400 watts maximum capacity must be connected to an amplifier that will produce 400 watts or less with a 4-ohm speaker load. Always consult the owner's manuals of all components to determine the impedance and power specifications before purchasing or installing amps and speakers.
Multiple Subwoofers
-
Although individual subwoofer ohm ratings cannot be changed, connecting multiple subwoofers together will change the overall ohm rating. Plugging in two subwoofers to the left and right speaker terminals of an amplifier does not change the ohm load. Connecting two subwoofers in "series" (positive to negative and positive to negative speaker connections, connected to a single positive and negative amp terminals) will double the overall speaker ohm rating. Connecting in "parallel" (positive to positive and negative to negative speaker connections attached to single positive and negative amp terminals) will decrease the overall speaker ohm rating by half.
Dual-Subwoofer Wattage Calculations
-
Wattage for dual-subwoofers is determined by adding the power capacity of each speaker to derive the total. Two 400-watt subwoofers wired together in either series or parallel will have a total capacity of 800 watts.
-
References
Resources
- Photo Credit speaker tweeter woofer bass boom box sound waves image by david hughes from Fotolia.com
