Which is better: 4-ohm or 8-ohm speakers?

Hey everyone, today we will discuss a classic question in the audio industry:

Which are better, 4-ohm speakers or 8-ohm speakers?

We have encountered some customers who prefer 8-ohm speakers because they believe that 4-ohm speakers have too low of an impedance for their amplifiers. They express concerns about the influence of back electromotive force and feel that 8-ohm speakers are easier to drive with an amplifier, whereas 4-ohm speakers may be more challenging to power. Consequently, many people assume that 8-ohm speakers must sound better than 4-ohm speakers.

Of course, many people hold opposing views on this issue.

Let's discuss Aperion Audio's perspective on the topic for your reference. You are encouraged to share your thoughts in the comment section.

No.1 Common Misunderstandings About Speaker Impedance

Misunderstanding 1: 8 ohm speakers are often perceived to provide "better sound quality" than 4 ohm speakers, or vice versa. 

Aperion: Sound quality is not directly related to impedance; it depends on factors such as speaker design and crossover adjustment. Some high-end speakers are designed to be 4 ohms to optimize sensitivity or frequency response, while 8 ohm speakers can also offer top-level sound quality.

Misunderstanding 2: 8 ohm speakers are more power-efficient. 

Aperion: A speaker's actual power consumption depends on the volume level of playback. 4 ohm speakers can be more efficient at the same volume because the amplifier outputs more current at a lower voltage. However, when fully loaded, 4 ohm speakers may consume more total power than 8 ohm ones.

Misunderstanding 3: Impedance mismatch will damage the amplifier. 

Aperion: As long as the amplifier supports the nominal speaker impedance (such as 4–8Ω) and is not overloaded, it generally will not be damaged. However, dangerous situations arise when using a 4Ω amplifier to drive an 8Ω speaker, resulting in insufficient power, or when using an 8Ω amplifier to drive a 4Ω speaker, leading to overload and overheating.

Ultimately, there is no absolute distinction between the quality of 4Ω and 8Ω speakers. The most critical factors are matching the amplifier's performance with that of the speakers and considering the specific requirements of your usage scenario.

No. 2: Many people are concerned that 4-ohm speakers are challenging to drive with amplifiers. 

First, it's essential to understand that there are industry standard requirements for speaker impedance.

Speaker Impedance Standards:

The impedance of 8-ohm and 4-ohm speakers is equivalent to resistance. While a 4-ohm speaker does exhibit back electromotive force, an 8-ohm speaker does as well, but the effects may vary based on specific conditions.

It's essential to understand the speaker industry standards regarding impedance. According to these standards, a speaker's minimum impedance cannot be lower than 80% of its rated impedance. This means that the minimum impedance for an 8-ohm speaker is 6.4 ohms, and for a 4-ohm speaker, it is 3.2 ohms.

Most power amplifiers on the market can effectively drive speakers with an impedance above 3 ohms. However, when a speaker's minimum impedance drops below 2 to 2.5 ohms, most amplifiers struggle to operate correctly, leading to potential short-circuit issues.

No.3 Why are many HiFi speakers rated 8 ohms instead of 4 ohms?  

The amplifier's output power and the speakers' maximum sensitivity are the main reasons.  

But why does this relate to the amplifier? It's simple—speakers need an amplifier to produce sound. Therefore, when comparing 8-ohm and 4-ohm speakers, it's essential to consider the amplifier you will use with them.

We assume that the specifications of a two-channel amplifier are as follows:

• 160 watts RMS per channel at 8 ohms; frequency response of 20 Hz – 20 kHz; total harmonic distortion (THD) < 0.1%.
• 250 watts RMS per channel at 4 ohms; measured at 1 kHz; THD < 1%.

The amplifier delivers different power outputs at 8 ohms compared to 4 ohms. Typically, the power output at 4 ohms is significantly higher than at 8 ohms.

Let’s consider an example. If a speaker has a sensitivity of 86 dB at both 8 ohms and 4 ohms, we can calculate the difference in maximum sound pressure level (SPL) after adding the amplifier. 

The formula for maximum power calculation is:  
MAX SPL = 10 log10(amplifier power in watts) + speaker sensitivity (SPL in dB)
8ohm: 10log160W+86=22+86=108dB
4ohm: 10log250W+86=24+86=110 dB

Thus, the maximum SPL for the speaker would be 108 dB at 8 ohms and 110 dB at 4 ohms.

It is clear that a speaker's higher total impedance results in lower maximum sensitivity and reduced sound output. When the sound volume decreases, it becomes more challenging to notice flaws in the speaker's sound, background noise from the amplifier, and other undesirable factors.

Additionally, many speakers on the market overlook impedance issues in their design, focusing primarily on achieving a flat frequency response curve. As a result, they often fail to meet industry standards. One can observe significant dips when measuring the impedance curve alone, with some measurements dropping well below the required 80%. 

8-ohm speakers are generally acceptable since their impedance remains sufficiently high, typically not falling below 3 ohms. However, 4-ohm speakers can pose a serious risk. If their design is flawed, the impedance can drop below 2.5 ohms, which may cause problems for amplifiers that lack sufficient load capacity, rendering them unable to function correctly.

In other words, designing and producing 4-ohm speakers is generally more challenging than designing and producing 8-ohm speakers. 

For a long time, this has led many people to believe that 8-ohm speakers are easier to drive than 4-ohm speakers. This is the reason.

No.4 Key Selection Suggestions:

1. Review the Nominal Parameters of the Amplifier:
   - An amplifier labeled "4-8Ω" is compatible with speakers of both 4Ω and 8Ω impedances. However, be aware of power matching; for instance, power output is halved when using 8Ω speakers.
   - Avoid connecting 4Ω speakers to amplifiers that only support 8Ω, such as older AV amplifiers.

2. Consider the Listening Environment and Purpose:
   - For small home spaces, 8Ω speakers are more stable and manageable for the amplifier to drive, generating less heat.
   - Combining 4Ω speakers and a high-current amplifier is more efficient for large spaces or high-volume requirements.

3. Multi-Speaker System Considerations:
    Calculate the total impedance when connecting speakers in series or parallel to avoid exceeding the amplifier's load limit. For example, connecting two 4Ω speakers in parallel results in a total impedance of 2Ω, so the amplifier must be capable of supporting a 2Ω load.

No.5 Summary:

- Advantages of 4Ω Speakers: They offer a higher power potential, making them suitable for professional high-volume scenarios, but require high-performance amplifiers.

- Advantages of 8Ω Speakers: They offer strong compatibility and high stability, making them ideal for home and entry-level audio systems.

   Core Principles:
   Impedance matching > Nominal power matching > Listening preference.
  
Whether you choose 4Ω or 8Ω speakers, ensure that your amplifier can consistently drive the speakers and maintain a 20% power margin.

Some people ask Why does Aperion Audio primarily use a 4-ohm design for our speakers instead of an 8-ohm design?

First, it's important to note that fewer people listen to HiFi audio, and the market is shrinking. Most individuals tend to listen to music while watching movies at the same time. Watching movies requires speakers with higher sensitivity, so we opt for a 4-ohm design instead of an 8-ohm one.

Secondly, we have tremendous confidence in our speaker design and production processes, adhering strictly to IEC standards. Even with our 4-ohm speakers, the minimum impedance will not drop below 3.2 ohms, ensuring they work well with commonly available power amplifiers. Additionally, the speaker drivers and crossover designs of Aperion's speakers are highly compatible, allowing for an excellent listening experience, even for HiFi music.

That's all for this time. We hope you have a great time!

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