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2 ohm vs 4 ohm

Table of Contents

2 ohm vs 4 ohm [Full Guide Updated 2023]

What is 2 ohm?

The ohm is the SI unit of electrical resistance. When it comes to subwoofers, the ohm rating indicates the electrical resistance of the subwoofer. A subwoofer with a lower ohm rating, such as 2 ohms, has lower electrical resistance, allowing more power to flow through it. As a result, 2-ohm subwoofers can produce louder sound compared to subwoofers with a higher ohm rating, like 4 ohms.

However, it’s important to note that while 2-ohm subwoofers may be louder, they can also be more power-hungry and may require a more robust amplifier to drive them effectively. Additionally, due to their lower impedance, 2-ohm subwoofers can be more demanding on the electrical system of the vehicle and may potentially lead to poorer sound quality if not properly powered.

Therefore, when choosing a subwoofer, it’s essential to consider factors such as the power requirements, amplifier compatibility, and overall system design to ensure optimal performance and sound quality.

What is 4 ohm?

A 4-ohm subwoofer has a higher electrical resistance compared to a 2-ohm subwoofer. This higher resistance means that it will draw less power from the amplifier and use less energy overall. As a result, 4-ohm subwoofers tend to be more efficient and can potentially last longer than subwoofers with lower resistance.

In terms of sound production, 4-ohm subwoofers may not be as loud as their 2-ohm counterparts. However, they are often characterized by producing a more compact and controlled sound. The sound quality of a 4-ohm subwoofer is generally considered to be better in terms of accuracy and precision, although the difference may not be easily noticeable to casual listeners.

The price of a 4-ohm subwoofer can vary depending on the brand and specific model chosen, ranging anywhere from $20 to $180 or more. It’s important to consider factors such as the intended use, desired sound characteristics, and overall system compatibility when selecting a subwoofer with a specific impedance rating.

Speaker’s Impedance

Speaker impedance refers to the measure of resistance that a speaker presents to an amplifier. In simpler terms, it determines how much pressure or load the speaker puts on the amplifier. The relationship between impedance and amplifier power is inverse or negative. This means that a lower impedance will draw higher power from the amplifier.

To explain further, a lower impedance indicates lower resistance in the current flow, allowing more current to pass through the speakers. To accommodate this increased current, the amplifier needs to supply more power. This is how speaker impedance affects the amplifier’s operation.

When it comes to car speakers, the maximum impedance you typically encounter is 4 ohms. This is largely due to the 12V power source used in cars. Another common choice for car speakers is 2-ohm speakers. Now, let’s illustrate the impact on the amplifier using an example.

Suppose your car has a 4-ohm speaker rated at 100W. In this case, the speaker will draw 100W of power from the amplifier. Even with a 100W amplifier, you can comfortably use 4-ohm speakers. On the other hand, if you have a 2-ohm speaker with the same power rating of 100W, it will require 200W from the amplifier to function properly. Attempting to use a 100W amplifier with a 2-ohm speaker will either prevent them from working together or potentially damage the amplifier.

This example demonstrates the impact of speaker impedance on the amplifier’s power requirements. It’s essential to consider these factors to ensure proper matching and compatibility between the speakers and the amplifier. Keep in mind that there are several other differences between speakers with different impedance ratings.


The Difference Between 2 ohm and 4-ohm Car Speakers

Here are the differences between 2-ohm and 4-ohm car speakers:

  • Resistance: The primary difference lies in the resistance value. A 2-ohm speaker has lower resistance, allowing more current to flow through it, while a 4-ohm speaker has higher resistance, allowing less current to pass. This affects various aspects such as sound quality, power consumption, and amplifier requirements.
  • Sound quality: Due to the difference in current flow, there is a noticeable distinction in sound quality. A 2-ohm speaker, receiving more power, can produce louder sounds. In contrast, a 4-ohm speaker draws less power, resulting in lower volume but increased control and potentially better sound quality. Achieving better sound quality with 2-ohm speakers may require adjusting settings and using a compatible amplifier.
  • Amplifier compatibility: 4-ohm speakers demand less power due to their higher resistance, making them generally safer for most car amplifiers. They are unlikely to damage the amplifier. However, 2-ohm speakers require more power, and using them with an amplifier not capable of meeting their requirements can cause overheating and potential damage. Therefore, it’s crucial to ensure your amplifier can handle the power requirements of 2-ohm speakers.
  • Cost: There is a significant price difference between 2-ohm and 4-ohm speakers. 2-ohm speakers are typically more expensive because they are designed to produce louder sounds, which is a desirable feature for many. Additionally, running 2-ohm speakers may require a more powerful amplifier, which can add to the overall cost. On the other hand, 4-ohm speakers are more affordable and compatible with a wider range of car amplifiers.
  • Durability: The durability of speakers depends on various factors, including their construction and quality. Theoretically, 4-ohm speakers may last longer than 2-ohm speakers. The higher resistance in 4-ohm speakers allows for a more controlled and precise flow of current, potentially reducing the strain on components. However, the durability ultimately depends on the specific speakers being used.

It’s important to consider these differences when choosing between 2-ohm and 4-ohm car speakers, as they impact sound output, compatibility, cost, and potentially longevity.

Can you use 4-ohm speakers with a 2-ohm amp?

You are correct in stating that a 4-ohm speaker can be used with a 2-ohm amplifier. A 2-ohm amplifier typically has more than enough power to provide to a 4-ohm speaker. In simple terms, if an amplifier is capable of handling 2-ohm speakers, it can easily handle a 4-ohm speaker without any issues.

However, the situation is different when you try to power a 2-ohm speaker with a 4-ohm amplifier. This scenario is not ideal and can lead to problems. To make it work, you would need 2-ohm speakers that require half the power of the 4-ohm speakers. For example, if you have two 120W 4-ohm speakers and want to use 2-ohm speakers, you would need two 60W 2-ohm speakers. Additionally, using lower-powered speakers may result in a decrease in sound quality.

Considering these factors, it may not be worth using 2-ohm speakers with a 4-ohm amplifier. It is generally recommended to match the impedance (ohm rating) of the speakers and amplifier for optimal performance and to avoid any potential issues.


What’s better, a 2ohm or 4ohm subwoofer?

The main difference between 2-ohm and 4-ohm subwoofers is their prices. Generally, 2-ohm subwoofers tend to be pricier compared to 4-ohm subwoofers. The price range for a 2-ohm subwoofer can vary between $50 and $200, depending on the brand and size you choose.

In terms of sound, there is a slight difference of about 2.5dB between 2-ohm and 4-ohm subwoofers. Some individuals may notice this difference, while others may not perceive it as significant. However, when both types of subwoofers are run at the same wattage, they will generally produce a similar quality of sound.

The relationship between watts and ohms is governed by mathematical formulas. Amplifiers provide the electrical pressure in a circuit, ohms measure the resistance or load against that pressure, and watts measure the power released as work. When one of these values changes, the others often adjust accordingly. For example, an amplifier that delivers 100 watts of power through a 4-ohm speaker will produce 200 watts through a 2-ohm speaker because it’s easier to push the reduced load.

It’s important to consider the impedance (ohm rating) when selecting subwoofers and matching them with an appropriate amplifier to ensure optimal performance and avoid potential issues.

2-Ohm Vs 4-Ohm Subwoofer: Which Is Better?

Subwoofers play a crucial role in car audio systems as they are designed to reproduce low frequencies, commonly known as bass, that regular speakers cannot effectively produce. Understanding terms like wattage, impedance, and resistance is important when dealing with subwoofers. In particular, resistance, measured in ohms (Ω), is a term that many people are unfamiliar with.

Resistance refers to the opposition encountered by an electric circuit to the flow of electric current. When it comes to subwoofers, they have a specific level of resistance to the audio signal they receive from a head unit or amplifier. Most subwoofers available today have a resistance rating of either 2 ohms or 4 ohms.

While your stereo or amplifier may work fine with either a 2-ohm or 4-ohm subwoofer, it is essential to understand which resistance rating would provide the best bass quality.

2 Ohm Subwoofer


Check 2 Ohm Subwoofer Price

When purchasing a subwoofer with a rating of 2 ohms, it indicates that the resistance level in its circuit is 2 ohms. A 2-ohm rating represents a lower resistance, allowing an amplifier to deliver more power to the subwoofer with less impedance. Consequently, the subwoofer can produce louder sound output.

However, it’s important to note that a 2-ohm subwoofer consumes more power due to its lower resistance. This increased power consumption may result in a decrease in bass quality. It is necessary to ensure that the amplifier powering the 2-ohm subwoofer can handle the power requirements effectively to avoid potential issues.

4 Ohm Subwoofer

A subwoofer with a resistance rating of 4 ohms indeed has higher resistance compared to a 2-ohm subwoofer. This higher resistance restricts the flow of current from the amplifier to the subwoofer, resulting in lower sound output and less loud bass.

However, the advantage of a 4-ohm subwoofer is that it consumes less power from the amplifier due to its higher resistance. This can be beneficial for the overall power efficiency of the audio system.

Despite producing less volume, a 4-ohm subwoofer can still deliver higher-quality bass. The higher resistance allows for more controlled and precise current flow, leading to a more focused and compact sound reproduction. This can result in a more refined and detailed bass experience, even though it may not be as loud as a subwoofer with lower resistance.


Check 4 Ohm Subwoofer Price

What if you have multiple Subwoofers?

When using multiple subwoofers in your car, the way you wire them will determine their overall resistance. You have two options: series wiring and parallel wiring.

Series wiring involves connecting the subwoofers one after the other, with the negative terminal of one subwoofer connected to the positive terminal of the next subwoofer. In this configuration, the resistance of each subwoofer adds up. For example, if you wire two subwoofers in series, each with a resistance of 2 ohms, the total resistance will be the sum of their resistances, which is 2 + 2, resulting in a total resistance of 4 ohms.

Parallel wiring, on the other hand, involves connecting the terminals of one subwoofer to the corresponding terminals of the other subwoofer. The positive terminals are wired together, and the negative terminals are also wired together. In this configuration, the total resistance is calculated differently. If you wire two subwoofers in parallel, each with a resistance of 2 ohms, the total resistance is calculated by dividing the resistance of one subwoofer by the total number of subwoofers. So in this case, it would be 2 ohms divided by 2, resulting in a total resistance of 1 ohm. Wiring subwoofers in parallel lowers the overall resistance.

It’s important to note that the final resistance value resulting from series or parallel wiring will affect the impedance seen by the amplifier. It’s crucial to match the impedance of the subwoofers to the capabilities of the amplifier to ensure proper power distribution and prevent any potential damage.

What if a subwoofer has dual voice coils?

Dual voice coil subwoofers offer additional flexibility when it comes to wiring options and overall resistance. Each voice coil in a dual voice coil subwoofer has its own set of terminals.

If you have a dual voice coil subwoofer where each voice coil has a resistance of 4 ohms, you have the choice to wire it in series or parallel, just like with single voice coil subwoofers.

If you wire the voice coils in series, the resistance of each voice coil adds up. So, in this case, the overall resistance would be 4 ohms + 4 ohms, resulting in an overall resistance of 8 ohms.

If you wire the voice coils in parallel, the overall resistance is calculated differently. The formula for calculating the total resistance of dual voice coil subwoofers in parallel is a bit different. Instead of dividing the resistance of one voice coil by the total number of coils, you treat the two voice coils as if they were a single coil with half the resistance. So, in this case, the overall resistance would be 4 ohms / 2, resulting in an overall resistance of 2 ohms.

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It’s important to consider the capabilities and specifications of your amplifier when choosing the wiring configuration for your dual voice coil subwoofer. Make sure the chosen configuration matches the amplifier’s capabilities to avoid any potential issues or damage.

So which is better between a 2 ohm and 4 ohm subwoofer?

When choosing between a 2-ohm and 4-ohm subwoofer, as well as considering how to wire multiple subwoofers, it ultimately comes down to your personal preferences and goals for the bass in your car audio system.

If you prefer moderate volume and prioritize the best quality bass, a 4-ohm subwoofer is a good choice. Wiring multiple subwoofers in series will increase the overall resistance, resulting in higher quality bass reproduction.

On the other hand, if you prioritize loudness and want the bass to be as loud as possible, a 2-ohm subwoofer paired with a compatible 2-ohm amplifier would be suitable. Wiring multiple subwoofers in series can still be beneficial for achieving lower overall resistance and increasing loudness.

Ultimately, it’s important to consider the specifications of your amplifier, the capabilities of your subwoofers, and your personal preferences when making these decisions.

What Is Impedance in Car Speakers?

Impedance refers to the overall opposition to the flow of alternating current (AC) in a speaker’s voice coil wire. Most car speakers are designed with impedance ratings of either 2 ohms or 4 ohms. It is uncommon to find car speakers or amplifiers with impedances higher than 4 ohms due to the low voltage of the car’s electrical system (typically 12 volts). However, there are exceptions like the Kicker CompRT 10″ subwoofer, which has a 1-ohm impedance. This subwoofer is ideal for situations where space is limited but you still desire powerful bass.

It’s important to note that when you see a speaker rated at 4 ohms, it doesn’t mean its impedance remains constant at 4 ohms. In reality, the impedance varies depending on the frequency of the audio signal being played. It can be as low as 0.3 ohms or as high as 30 ohms. Generally, the impedance will be higher for lower frequencies and lower for higher frequencies.

If you’re interested in the Kicker CompRT 10″ subwoofer or want to explore its capabilities and pricing, you can find it on Amazon or by following the provided link.

2 ohm v 4 ohm speakers

The 4-ohm value listed on a speaker represents its nominal impedance, which is an average of the various impedances the speaker is designed to work with. The impedance of a speaker affects the flow of current from the amplifier. With higher impedance, less current will flow from the amplifier. For example, if you have a 100W 4-ohm speaker, it will draw 100W from a 4-ohm amplifier. However, if you connect a 2-ohm speaker to the same amplifier, it will force the amplifier to produce 200W. This increased power demand can potentially overload the amplifier, leading to overheating or even damage.

It’s important to match the impedance ratings of speakers and amplifiers to ensure proper power distribution and prevent potential issues with overheating or damaging the equipment.

Kicker 1 ohm car subwoofer

Low impedance speakers can force amplifiers to work too hard.

when an amplifier is overloaded due to mismatched impedance, several consequences can occur. The amplifier’s fuse may blow or its protection circuit may activate, causing the amp to shut down in order to safeguard other components of the audio system. In more severe cases, the amplifier itself can be damaged or even rendered inoperable.

When designing a car audio system, it is important to consider the impedance matching between the speakers and amplifiers. However, due to the various installation types and configurations in car audio setups, it is not always feasible to have all components with the same impedance, such as 2 or 4 ohms. In the subsequent sections of this article, we will explore different impedance combinations and their implications in car audio systems.

Why Do Car Speakers Have Different Ohms?

The choice of impedance, whether 4 ohms or 2 ohms, for car speakers depends primarily on the desired sound quality and efficiency of the speakers. The voltage supplied to the speakers remains constant, while power and impedance are interconnected. In the case of coaxial speakers or a component system, the car amplifier recognizes the impedance of the entire set when connected to the crossover, rather than individual speakers, which may have different impedance ratings.

4 ohm speakers require less current from the amplifier compared to similar 2-ohm speakers. Higher impedance results in less distortion in the amplifier and a more stable current flow. However, modern amplifiers are increasingly capable of remaining stable while delivering significant power to speakers with low impedance.

The main advantage of lower impedance speakers is that they can receive more power from the amplifier, which is particularly important in a noisy car environment. The presence of road or wind noise needs to be compensated for by the improved performance of the speakers, and low impedance speakers tend to excel in this regard.

Can I Use 2 Ohm Amp With 4 Ohm Speakers or Vice Versa?

In most cases, it is recommended to match the impedance of speakers to that of the amplifier. If you have a 4-ohm amplifier, it is advisable to choose speakers with a 4-ohm impedance. However, in certain situations where the sound system has been carefully designed with calculated resistance values, it is possible to have speakers with different impedance ratings.

It is technically possible to connect 2-ohm speakers to a 4-ohm amplifier, but caution must be exercised to prevent damage. To ensure the amplifier is not overloaded, the 2-ohm speakers should have half the RMS power of the amplifier. Failing to do so can result in the amplifier being overwhelmed by the mismatched impedance, potentially causing the transistors to blow or other damage to occur.

For example, if you have a 2x120W amplifier operating at 4 ohms, you can pair it with either 120W 4-ohm speakers or 2x60W 2-ohm speakers. Both speaker configurations will draw the same current from the amplifier, but the 4-ohm speakers are likely to produce better sound quality.

Can I MIX 2 Ohm and 4 Ohm Speakers?

In most cases, the front and rear speakers in a car have the same impedance. However, there can be exceptions. While it is possible to install speakers of different brands, sizes, power ratings, and even impedance values, it is relatively rare to encounter such scenarios. Typically, when 4-ohm speakers are installed, they tend to have consistent impedance across the system.

However, if you choose to wire 4-ohm front speakers and 2-ohm rear speakers to a 4-channel amplifier, caution must be exercised to avoid overloading the amplifier’s transistors or causing damage. It is important to consider the power level of the 2-ohm speakers in order to maintain a safe operating range for the amplifier. Additionally, the volume levels of the speakers should be taken into account. Since 2-ohm speakers can play louder with the same power, combining them with 4-ohm speakers may result in the rear speakers overpowering the front speakers, leading to an imbalanced sound.

If you intend to have different impedance values for the front and rear speakers while using a single amplifier, it is recommended to ensure that the 4-ohm speakers have twice the power rating of the 2-ohm speakers. This helps in leveling out the amplifier’s output across all channels and maintaining a balanced sound. It is worth noting that managing different speaker impedance is easier when the amplifier is designed to support 2-ohm and 4-ohm configurations on different channels. In such cases, matching the power of the speakers to the maximum output of the amplifier will help ensure compatibility.

Nevertheless, the best and safest approach is to use speakers with the same impedance throughout the car audio system. This promotes system stability and minimizes the need for extensive adjustments to achieve optimal performance.


How to Connect a 2 Ohm vs 4 Ohm Subwoofer?

Subwoofers indeed differ from typical car speakers, particularly when it comes to impedance. It is common to find subwoofers with different impedance values, often lower than those of regular speakers. Subwoofers can have impedance ratings of 4, 2, or even 1 ohm in some cases. Additionally, they may feature either a single voice coil or dual voice coils, adding more complexity to the wiring options available.

The primary objective of subwoofers is to produce deep, powerful bass, and this requires a significant amount of power. Generally, subwoofers with lower impedance can handle more power and deliver louder bass. For instance, a 2-ohm subwoofer will produce louder bass compared to a 4-ohm subwoofer when both are powered with the same amount of power.

However, it’s important to note that the strength of the bass generated also depends on other factors, such as the type of enclosure used. The enclosure design, whether it’s a sealed enclosure, ported enclosure, or other variations, can greatly impact the overall bass response and quality.

2 ohm subwoofer wiring diagram source: RockfordFosgate

If you desire exceptionally loud bass in your car audio system, opting for a 2-ohm subwoofer and ensuring you have a robust power supply to provide sufficient current is a recommended approach. However, it’s important to consider that reducing impedance to achieve louder bass may result in a compromise in bass quality. In other words, you need to decide whether you prioritize the overall music quality or the sheer loudness of the bass.


4 ohm subwoofer wiring diagram source: RockfordFosgate

Similarly, subwoofers with dual voice coils offer additional flexibility in configuring the overall impedance. While physically you have a single speaker, the connection with the amplifier is similar to having two independent woofers. Depending on how you choose to wire the dual voice coil subwoofer, you can determine the overall resistance and impedance, which will affect the performance and compatibility with your amplifier.

Can I Replace 2 Ohm Speakers With 4 Ohm Speakers?

When replacing speakers in your car audio system, it’s generally safe to replace 2-ohm speakers with 4-ohm speakers (or vice versa). However, it’s important to be mindful of the power requirements of different impedance speakers. 4-ohm car speakers typically have a lower wattage rating compared to 2-ohm speakers because they are less efficient in converting electrical energy into sound.

When replacing speakers, it’s crucial to carefully check the impedance specifications, as new speakers may have different impedance values than the ones being replaced. Overlooking this aspect can lead to potential damage. For example, replacing 2-ohm speakers with 4-ohm speakers (or vice versa) that have the same power rating can overload the amplifier if it was not designed to handle lower impedance. This can result in overheating or other damage to the car audio system.

Conversely, increasing the speakers’ impedance will result in quieter sound output across all frequencies. While this change won’t cause damage to the system, it may not meet your desired audio expectations.

To ensure compatibility and optimal performance, it’s recommended to match the impedance of the new speakers as closely as possible to the original speakers or consult the manufacturer’s specifications and guidelines. This will help avoid potential issues and ensure a satisfactory audio experience.


Characteristics of a 2-ohm Subwoofer

The most important factor to consider when choosing a subwoofer is the impedance rating of your amplifier. You can typically find this information on the back of the amplifier. Once you know the impedance of your amplifier, you can select a subwoofer accordingly. The impedance, measured in ohms, indicates the amount of power that the speaker can convert into audio. It is a critical specification to consider when selecting a subwoofer.

It is true that subwoofers with lower electrical resistance (such as 2 ohms) tend to produce louder sound compared to those with higher resistance (such as 4 ohms). However, it does not mean that lower ohm speakers are inherently better than higher ohm speakers. The reason is that subwoofers with lower impedance are more likely to compromise sound quality compared to those with higher impedance because they consume less power.

When choosing a subwoofer, it’s essential to strike a balance between loudness and sound quality. It’s not just about selecting the lowest ohm rating for maximum volume. Consider your overall audio requirements and preferences to ensure that you choose a subwoofer that provides both the desired loudness and satisfactory sound quality.

Characteristics of a 4-ohm Subwoofer

Subwoofers with a 4-ohm impedance use less energy due to their higher electrical resistance. Consequently, they produce less sound compared to 2-ohm subwoofers. While 4-ohm speakers may sound quieter than those with lower impedance, they often deliver a more focused and impactful sound. Choosing between a 2-ohm and 4-ohm subwoofer depends on your priorities. If sound quality is your primary concern, then a 4-ohm speaker is the better option as it offers cleaner and more impactful audio. However, if you prioritize loudness, then a 2-ohm subwoofer would be more suitable.

It’s important to note that the difference between the two options is not extremely significant. When both 2-ohm and 4-ohm speakers are supplied with the same wattage, they can produce similar sound quality. The relationship between wattage and impedance means that if one of these values changes, the other will also adjust accordingly.

Is Higher Ohm Better for Subwoofers?

When setting up a subwoofer, two components are involved: the subwoofer itself and the amplifier. Both of these components have impedance specifications indicated. It’s a common misconception that higher impedance will automatically result in better sound quality for the subwoofer. However, the impedance of a subwoofer does not directly impact sound quality. The quality of sound primarily depends on the amplifier.

If the impedance of your subwoofer is not compatible with your amplifier, the sound quality may indeed suffer. It’s important for the impedance of the subwoofer to match the capabilities of the amplifier. Simply having a higher impedance does not guarantee superior subwoofer performance. The correlation between impedance and sound quality is minimal and often unnoticeable.

Connecting a subwoofer to an amplifier that doesn’t match its specifications won’t immediately cause it to explode. However, the amplifier may overheat and distort the audio it produces. This occurs when the subwoofer draws more electrical current than the power supply of the amplifier is designed to handle. As a result, the amplifier may shut down quickly, potentially causing damage.

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To avoid such issues, it’s crucial to ensure that the impedance of your subwoofer matches that of your amplifier. By doing so, you can prevent problems and ensure proper functioning. However, it’s important to note that issues may still arise if you push the volume too high. Always refer to the specifications of your amplifier to confirm its impedance compatibility with your subwoofer.

If the amplifier’s specifications indicate a range of 4 ohms to 8 ohms, it can support subwoofers with impedance values of 4, 6, and 8 ohms. Similarly, if the amplifier is designed for 6-ohm to 8-ohm speakers, you can connect a 4-ohm subwoofer to it, and it should work. However, if you plan to set the subwoofer at high volumes to achieve powerful sound in your room, there’s a risk of overloading the power supply. In such cases, the amplifier may shut down. Additionally, if the subwoofer is damaged before the amplifier shuts down, it can lead to further problems.

It’s important to consider the capacity of your amplifier to drive a subwoofer with low impedance, such as 2 ohms or 4 ohms, to ensure optimal performance and avoid potential issues.

DIAGRAM – 4 ohm vs 2 ohm subwoofer amp power

2 ohm vs 4 ohm subwoofer amp power diagramThe reason why matching a 2-ohm or 4-ohm subwoofer to your amplifier yields the best results lies in the relationship between voltage, power, current, and resistance. Ohm’s Law and Watt’s Law provide a simple way to understand this relationship between electrical resistance, voltage, and current. By combining and rearranging these laws, we can use a straightforward formula to calculate power delivered to an electrical resistive load like a speaker.
Formula for power voltage an resistance with speaker power

Why the right subwoofer Ohm load is important for amplifier power

The correct selection of the subwoofer’s Ohm load is crucial for optimizing the power output of the amplifier. Whether it’s a car audio system or a home stereo, the purpose of the amplifier is to amplify the small audio signal to a higher voltage capable of driving the speaker, overcoming its inherent resistance. While powering an 8-ohm speaker is typically not a challenge in a home audio setup, vehicles have limitations in providing high voltages.

Voltage, power, and speakers

Voltage, power, and speakers are interconnected factors. Increasing the output voltage allows for a greater current flow, resulting in higher power and louder sound. However, every audio device, such as a radio or amplifier, has its own limitations in terms of power output. When a higher speaker Ohm load is connected, it reduces the current flowing through the circuit, subsequently diminishing the power that can be delivered to the speaker. To fully harness the power capabilities of the amplifier, it is essential to match the subwoofer’s Ohm load to the minimum Ohms rating specified by the amplifier. While using a higher speaker impedance is not inherently problematic, it means that you won’t be able to fully utilize the power potential of the amplifier, thereby limiting the performance you can expect from your audio system.

How do I know what my amp’s minimum speaker Ohm rating is?

example of car amp minimum Ohms specification and max RMS power specification

The power specifications of an amplifier should be readily available from the manufacturer or retailer, typically provided on the packaging and in the owner’s manual. When reviewing these specifications, it is important to focus on the following key points:

  1. Pay attention to the RMS (Root Mean Square), continuous, or CEA-2006 power rating. Avoid being misled by “peak power” or “maximum” figures, as they may not accurately reflect the amplifier’s true capabilities. The RMS rating represents the reliable and continuous power output of the amplifier.
  2. Look for the CEA-2006 standard. This standard, established by the Consumer Electronics Association (CEA), ensures that the product meets the advertised specifications. Amplifiers from reputable manufacturers often provide these reliable set of specs.
  3. Take note of the minimum Ohms rating, also known as the amplifier’s stability rating, which indicates the lowest impedance the amp can handle per channel. This rating may vary depending on the channel mode (stereo, bridged, etc.) and should be considered when selecting speakers or subwoofers to ensure compatibility.

By focusing on the accurate RMS power rating and considering the amplifier’s minimum Ohms rating, you can make informed decisions when choosing an amplifier that matches your specific audio requirements.

Important note about bridging an amp for subwoofer use

Diagram showing a 4 channel car amplifier bridged to 2 channels

Before purchasing subwoofers, it’s important to consider that most bridgeable 2-channel or 4-channel amplifiers require a minimum speaker impedance of 4 ohms when operating in bridged mode. This requirement is related to how bridging functionality works.

When an amplifier is bridged, it combines two channels together in a push-pull configuration to deliver increased power to a single speaker. While many modern amplifiers can handle lower speaker impedance, such as 2 ohms per channel in normal operation, the 4 ohm requirement for bridged mode is determined by the total impedance of both channels.

Therefore, when selecting subwoofers and considering the bridged operation of your amplifier, ensure that the combined impedance of the subwoofers matches or exceeds the minimum 4 ohms requirement specified by the manufacturer. This will help you utilize the bridging capability of the amplifier effectively and avoid potential issues related to impedance mismatching.

Using multiple subwoofers in series vs parallel

DIAGRAM – Series vs parallel subwoofer power comparison

diagram showing how power is shared between subwoofers series vs parallel

When connecting multiple speakers to a single output channel, it’s important to understand that the available power will be shared among the speakers. Here are some key points to remember:

  • Parallel Connection: When you connect speakers in parallel, their total impedance decreases. For example, if you connect two 4-ohm speakers in parallel, the total impedance becomes 2 ohms. In this configuration, each speaker will receive half of the amplifier’s rated power output at 2 ohms.
  • Series Connection: When you connect speakers in series, their total impedance increases. For example, if you connect two 4-ohm speakers in series, the total impedance becomes 8 ohms. In this configuration, the total power output to all the speakers will be lower compared to parallel connection, and each speaker will receive half of that power.

It’s important to note that connecting multiple speakers to one output channel involves a compromise. Car amplifiers are typically designed to work optimally with one or two speakers per channel. If you try to connect speakers in a way that doesn’t match the amplifier’s specifications or impedances, you may not achieve the maximum power output or risk damaging the amplifier or speakers.

To avoid any issues, it’s advisable to plan ahead and consider the speaker impedance, whether they are single voice coil (SVC) or dual voice coil (DVC), and ensure they are compatible with the amplifier before making a purchase. By doing so, you can optimize the performance and power delivery of your audio system.

What about dual voice coil subwoofers?

how to wire a dual coil coil speaker diagram

Dual voice coil (DVC) subwoofers offer flexibility and convenience, especially if you plan to make changes to your audio system in the future. Here are some important points to remember when using DVC subwoofers:

  1. Wiring Configuration: Whenever possible, choose DVC subwoofers with an impedance that allows you to wire all the coils in parallel. This configuration will result in a lower impedance, matching the minimum ohms load specified by your amplifier.
  2. Single Voice Coil (SVC) Use: DVC subwoofers can be used with only one voice coil if necessary, but it’s not ideal. Each voice coil may have different parameters and may not handle heat or power as effectively as when both coils are used.
  3. Avoid Mixing Ohms Ratings: It’s generally not recommended to mix DVC subwoofers with different ohms ratings. This can lead to suboptimal overall impedance, either too high or too low, and may result in some voice coils remaining unused.
  4. Single Channel Use: If necessary, you can use one amp channel per voice coil. However, it’s best to use a mono (non-stereo) input to both of the amplifier’s RCA inputs. This ensures that both channels receive the same signal and avoids any differences that could cause sound cancellation or imbalance.

By selecting the correct DVC subwoofers and configuring them appropriately, you can achieve various impedance loads, such as 4 ohms, 2 ohms, or even 1 ohm, depending on your needs. When using a mono amp with multiple subwoofers, it may require additional consideration, but many car stereos or signal processors offer a mono signal output specifically for driving one voice coil per channel.

4 ohm vs 2 ohm car speakers

2 ohm vs 4 ohm car speakers section image

There are some coaxial, woofer, and component speaker sets available on the market with impedance ratings of 3 ohms or even 2 ohms. While these options may seem appealing for full-range music, it’s important to consider the following factors:

  • Bridging Amp Channels: If you have a minimum 4-ohm requirement to bridge your amp channels for more power, using a lower impedance speaker set can pose a challenge. You may find yourself unable to bridge the channels unless you opt for a higher impedance speaker set.
  • Parallel Speaker Usage: Lower impedance speakers may restrict your ability to use tweeters or additional speakers in parallel. This limitation can be problematic if you have space constraints, budget limitations, or if you’re waiting to purchase a second amp. Many people prefer using a 2-ohm minimum amp to drive two speakers in parallel, such as tweeters and coaxial speakers. Choosing a lower impedance option would not be compatible in such a setup.
  • Power Output Considerations: If your amplifier offers more power per channel at 2 ohms for your main speakers, you can certainly go for it. However, keep in mind that you will need a dedicated channel for each speaker to accommodate the lower impedance.

When deciding on speaker impedance, it’s crucial to ensure compatibility with your amplifier’s specifications and the intended configuration of your audio system.

Basic Physics of Subwoofers

When comparing 2-ohm and 4-ohm subwoofers, an important factor to consider is their resistance or impedance ratings, depending on the type of current flowing through them. Resistance or impedance refers to the level of resistance offered by the subwoofer against the flow of electric current. This resistance plays a crucial role in regulating the sound quality produced by the subwoofer.

A subwoofer with low resistance allows electric current to flow easily, resulting in higher power generation and louder sound output. However, this also means that the subwoofer primarily focuses on handling higher-intensity frequencies, making it more challenging to reproduce lower frequencies effectively. As a result, the bass quality produced by speakers or subwoofers with lower resistance ratings may be compromised, despite their ability to generate higher power and volume.

Conversely, subwoofers or speakers with higher resistance ratings operate with a lower flow of current, leading to comparatively lower volume levels. However, they can produce a more refined bass output because they are better equipped to handle lower frequencies. Although they may not be as loud as their low-resistance counterparts, their ability to handle low frequencies effectively contributes to improved bass performance.

When selecting between 2-ohm and 4-ohm subwoofers, it’s essential to consider the specific requirements of your audio system and the desired balance between power, volume, and bass quality.


Frequently Asked Questions (FAQs)

Can I utilize a car radio to power both 2-ohm and 4-ohm speakers?

Yes, you can use your car radio to power both 2-ohm and 4-ohm speakers. However, it’s important to note that playing 2-ohm speakers on a 4-ohm amplifier will require more power than usual. This is because 2-ohm speakers require more power to reach the same volume level as 4-ohm speakers.

Which subwoofer is better for a car, 2-ohm or 4-ohm?

The choice between a 2-ohm or 4-ohm subwoofer depends on your preferences and requirements. If you desire louder bass and more powerful sound, a 2-ohm subwoofer paired with a powerful amplifier would be suitable. However, if you prioritize budget and clarity, a 4-ohm subwoofer would be a better choice.

How does impedance affect sound quality?

The impact of impedance on sound quality is minimal and typically only noticeable to audio experts. In general, there isn’t a significant difference in sound quality between 2-ohm and 4-ohm speakers. However, 2-ohm speakers tend to produce louder sound, while 4-ohm speakers often provide clearer sound quality.

Can you upgrade from 4 ohms to 2 ohms without changing the amplifier?

Whether you can upgrade from 4-ohm speakers to 2-ohm speakers without changing the amplifier depends on the specifications of your current amplifier. If your amplifier is designed for 4-ohm speakers, you cannot upgrade to 2-ohm speakers without changing the amplifier. However, if your amplifier supports 2-ohm speakers, then you can switch to 2-ohm speakers.

What is the most common impedance of car speakers?

The most common impedance for car speakers is 4 ohms. However, there are also lower impedance options available, such as 3-ohm and 2-ohm car speakers. According to Ohm’s law, lower impedance allows for easier electrical flow. In other words, a 2-ohm speaker requires less power from your amplifier to produce the same volume as a 4-ohm speaker.

What does “ohm” mean in car speakers?

In car speakers, “ohm” refers to the impedance rating, which measures the resistance the speaker presents to the flow of current. Lower impedance speakers require less power from the amplifier to reach the same volume level as higher impedance speakers.

Can you connect 4-ohm speakers to a 2-ohm amplifier?

Technically, you can connect 4-ohm speakers to a 2-ohm amplifier. However, the volume will be lower compared to connecting the same 4-ohm speakers to a 4-ohm amplifier.

How do you wire a 4-ohm speaker to a 2-ohm amplifier?

The recommended way to wire 4-ohm speakers to a 2-ohm amplifier is by wiring the speakers in parallel. This configuration results in a 4-ohm load on the amplifier, which is the recommended load for most car amplifiers. It’s important to note that this method is common for subwoofers, unless you use two separate 4-ohm speakers per each 2-ohm channel in the amplifier.

Which is better, 2-ohm or 4-ohm speakers?

The preference between 2-ohm and 4-ohm speakers varies among individuals. Some people prefer the bass response of 2-ohm speakers, while others prefer the treble response of 4-ohm speakers. The choice ultimately depends on personal preference and the specific characteristics of the amplifier being used.

Can you mix 2-ohm and 4-ohm speakers?

You can mix speakers with different impedances, but not within the same pair of channels. For example, you cannot connect a 2-ohm speaker to the left channel and a 4-ohm speaker to the right channel. Mixing different impedance speakers is similar to the concept of car wheels where you do not put different wheels on the same axle. However, it is possible to use 4-ohm speakers at the front and 2-ohm speakers at the back of the car, but they need to be connected to different amplifiers. One multichannel amplifier cannot simultaneously support 4-ohm and low impedance speakers. If you want to run 4-ohm speakers at the front and 2-ohm speakers at the back, you will need two amplifiers, one for each set of speakers.



Getting the kind of bass you want in your car is not a matter of hooking up just any subwoofer you come across in the market. There is a lot more that matters. The kind of resistance that the sub has will determine the loudness and quality of bass you’ll get. It’ll also determine the amount of power the sub will demand from the car amplifier or head unit. Basically, a 2 ohm subwoofer demands less power from the amp and tends to deliver louder bass. On the contrary, a 4 ohm subwoofer will demand more power from the amp and deliver less loud but higher quality bass. Thus, make your choice depending on the kind of bass you want.

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