Speaker Impedance Matching: Ohms & Speakers Explained
Now here’s a topic that may make even the most jaded audiophile run for cover: speaker impedance matching.
It’s also a popular topic for forum geeks to utilise when hassling naïve newcomers.
We don’t do that here, and if you do any research you’ll find that the answer is rather straightforward.
In as few words as possible, this article will clarify the idea of matching impedance in speakers and amplifiers, allowing you to go on to more engaging pursuits.
The Difference Between Resistance and Impedance
Okay, so you don’t have to be a rocket scientist to grasp this concept, so let’s put it this way,
The two terms used to indicate how challenging it is for electricity to flow across a circuit are “resistance” and “impedance.”
One’s resistance to the passage of electricity is quantified by this term. In order for electricity to go through a circuit, it must pass over what is essentially a bottleneck or a hurdle. Measured in ohms (), resistance is a constant that does not vary with either time or the frequency of the current.
However, impedance is a broader concept that includes the influence of inductors and capacitors on an electrical circuit. As with resistance, an impedance value is a complex number that may have both real and imaginary parts. As we’ve established, the resistance is the real part of the equation, while inductance and capacitance contribute the imaginary part, which represents the resistance to current. Unlike resistance, which remains constant regardless of frequency, the value of impedance varies according to the latter.
Current and Voltage
The amplified signal is sent to the speaker as an alternating current (AC) electrical current, which is measured in amps. As well, a voltage is used to “push” this current to the speaker.
First, according to Ohm’s law,
Impedance is the relationship between voltage and current, which is Current = Voltage ÷ Resistance
Consequently, either the voltage or the current must rise if the resistance decreases, putting more stress on the amplifier’s power supply.
To illustrate, the resistance drops while switching from 8-ohm to 4-ohm speakers connected to an amplifier.
When there is less of an impedance to the current, more power may flow through and be sent to the speakers, which may be more than the amplifier can handle.
Why Does Speaker Impedance Matter?
The coil in a speaker functions as a barrier to the passage of electricity from an audio source like a phone or computer when the speaker is connected to both. The speaker’s ability to withstand power is directly related to this resistance. Watts are used to measure power, whereas ohms are used to measure resistance. The impedance of the speaker must be matched to that of the audio source in order to prevent damage and distortion.
Speaker performance also depends on the reactance element of impedance, which is connected to the inductance and capacitance of the speaker. The frequency response, or how effectively the speaker propagates various frequencies, will be affected by the shift in impedance caused by the inductance at low frequencies and the capacitance at high frequencies.
The impedance of a speaker is a measurement of the internal components of the speaker (inductance and capacitance) and how they impact the speaker’s performance by resisting the passage of electricity. It’s crucial to match the speaker’s impedance to that of the audio source for optimal performance and to prevent any harm to the speaker.
A speaker’s rated impedance is something to keep an eye on while shopping for new home theatre speakers.
Because of their lower average resistance, 4-ohm speakers need more power to operate than 8-ohm speakers.
Nominal values are used to represent impedance, which means that the real impedance over time might be greater or lower than the average.
Speaker and Amplifier Impedance Matching
These are only words, so don’t be intimidated by them. Nothing too complicated, and we will make sure you understand everything in the simplest terms possible.
When the impedance of a speaker and amplifier are in sync, sound is reproduced with little distortion, and the lifespan of both components is prolonged.
Impedance, expressed in ohms, is a straightforward measurement of the level of resistance in a circuit to the flow of electricity. Speakers have input impedance, which is the resistance to electrical current flow at the speaker’s input, and amplifiers have output impedance, which is the resistance at the amplifier’s output.
Here’s an illustration: assume your amplifier has an output impedance of 4 ohms, and your speaker has an input impedance of 8 ohms. The impedance of the speaker is double that of the amplifier‘s output in this situation. Connecting the amplifier to the speaker causes it to “battle” against the speaker’s impedance, which may cause audible distortion and eventually destroy the amplifier.
However, if both the amplifier’s output impedance and the speaker’s input impedance are 8 ohms, then the amplifier and speaker are “matched” and may operate together well. Because of this, the amplifier will be able to provide the intended volume level without distorting the music or damaging the system.
To put it another way, if the resistance values at the output of the amplifier and the input of the speaker are near to or the same, then the amplifier and the speaker are impedance-matched. This safeguards the amplifier’s ability to provide the specified level of power to the speaker without distortion and protects both the speaker and the amplifier from failure.
You should pay attention to the amplifier’s impedance range while reading its specs.
If it says 4-8 ohms, it means the amplifier is compatible with the most popular household speaker impedance ratings of 4, 6, and 8 ohms.
Even though it specifies 6-8 ohms, 4-ohm speakers will still function with it.
However, the amplifier will shut down if the volume is turned up too high, which may happen if the space isn’t adequately sized for the speakers.
Should You Alter the AV Receiver’s Impedance?
When connecting speakers to an AV receiver, the impedance setting should be adjusted so that the two are compatible. This is due to the fact that a speaker’s impedance may modify the amount of power supplied by a receiver to the speaker. The receiver may not be able to provide the necessary amount of power if the impedance setting is not matched to the speakers, resulting in subpar audio or maybe even damaging the speakers or the receiver. You should refer to the user manuals for both your AV receiver and your speakers to determine the optimal impedance settings for optimal sound quality.
The speaker’s real impedance may be greater or lower than its nominal value, based on the audio frequency it receives over time.
If you are cautious with the amplifier’s volume, you should be alright.
However, regardless of the impedance of your speakers, it is recommended that you keep the default value of 8 ohms unchanged.
This video explains a little more about what we’ve discussed above.
In conclusion, it’s crucial to know how to adjust the AV receiver’s impedance setting so that the receiver’s power output is compatible with the speakers being utilised.
Most listeners won’t need to worry about this, however, since most current AV receivers can accommodate a broad variety of speaker impedances.
However, if you’re using speakers with a low or unique impedance or intend to run the amplifier at high levels for lengthy periods of time, it’s still a good idea to verify the suggested impedance settings for your particular receiver and speakers.
That’s it! You got it all right and now you know what is left for you to do, go have some fun, we say!