What is the impedance of headphones for a phone? What is the best headphone impedance?

With the rapid development of information and communication technologies More and more often you can see a person with headphones in the subway, on the street, at home. If initially they were used for radio communications, then later the audio device became a mass means of information consumption. To choose the most suitable headset for your smartphone or tablet, the user needs to understand the basic characteristics of the device. Before we look at what and how resistance in headphones affects, let’s understand what impedance is. Knowing this information, you can extend the service life of equipment.

The impedance in the headphones gives input resistance. The operational and technical properties of portable devices for listening to sound depend on this characteristic. To find out how much energy the equipment requires to ensure good sound, this parameter is indicated in the passport of portable devices.

The unit of measurement of electrical resistance of a conductive element is Ohm.

For pocket audio players, modern smartphones Headphones with a nominal impedance of 16-40 ohms are suitable. This value ensures high sound of the device at a low level of outgoing signals. When connected to a headset with standard sound cards using special amplifiers choose an audio device with high impedance parameters - 120-150 Ohms. Devices with high-resistance electrical resistance are suitable for professionals who work on special equipment with a high level of outgoing voltage.

Types of equipment depending on resistance values

On the multimedia equipment market, manufacturers offer a wide range of various devices with various technical characteristics: sensitivity, impedance, frequency range. Based on the resistance the headphones provide, there are two types of equipment: high-impedance and low-impedance devices. For full-size and in-ear headsets, the separation boundary parameters are different.

1. Low impedance headset– devices whose impedance for in-channel devices is no more than 32 Ohms, for full-size devices – no more than 100 Ohms.
2. High resistance devices– impedance of which for in-channel devices is more than 32 Ohms. For full-size, the value should be more than 100 ohms.

Impedance curve for different types of devices

Let's consider what information a graph of frequency in the range from 20 to 20,000 Hz depends on resistance for various types of devices.

Based on the impedance curves, it is clear that the declared value in the headset is different from the real values.

Optimal impedance values ​​for use with various devices

To purchase devices from good range sound reproduction, resistance values ​​must be taken into account. The sensitivity of devices with high resistance is less than that of low-resistance models. Therefore time battery life technical devices does not match when using headphones with different impedances. Let's consider the optimal values ​​of the level of consumed electrical voltage for various devices.

1. Smartphone. The nominal impedance for best sounding headphones is low impedance (for example, 22 Ohms). IN in this case devices other than good sound, will consume more current. So that you can play music on your smartphone longer, choose a 32-ohm model. When using devices with iPhone, models with standard frequencies are suitable. sound ranges at 22-32 Ohms. Headphone monitors are not advisable to use without auxiliary accessories: a portable amplifier, an audio player with a powerful sound card.
2. Player. The most optimal headphone impedance for standard device– 16 Ohm. If audio players have a more powerful output (Hidisz or iHiFi), which provides a level electrical voltage more than 200 mV, choose less sensitive devices with an impedance of 32 Ohms. Such devices reduce current consumption and increase battery life.

When choosing listening equipment, consider the following points:

• in reality, single-driver reinforcement devices (Grado GR10, various models Klipsh, Etymotic) have a higher average resistance, so audio players and smartphones work with them for a long time without recharging;
• multi-driver dynamic and reinforcement technology has a lower average resistance, so smartphones or players operate for a short time without recharging.

Portable amplifier for optimal sound

High-impedance headphones are used not only by professional musicians, but also by ordinary music lovers. In order to listen to music at a sufficient volume, you need to match the power of the speakers to the device. In this case, absolutely all frequencies are reproduced, and the sound is of high quality. Helps solve this problem portable amplifier for headphones - it provides high fidelity sound reproduction.

The operating principle of the amplifier is as follows: thanks to high value impedance in headphones, the device delivers less current, which prevents frequency distortion separate cascades. The high-impedance headset has uniform amplitude and frequency characteristics due to the use of an amplifier.

To avoid deterioration in the quality of headphones and their rapid wear, when purchasing equipment, pay attention to the impedance. Which one is better depends on the devices they will interact with. This parameter must correspond to the audio equipment model and listening device. The impedance of different types of headphones affects the sound quality and performance stable operation audio devices.

They also write resistance. This article explains what it is, why it is needed, and what impedance affects.

Note: Since impedance is total resistance, which includes both its active and reactive components, you need to know that most often the first - active - value is indicated on packages. Because of this, a deviation from the declared parameters of 1-3 Ohms is considered normal.

Which option should you prefer? Which resistance indicator should you choose? What should it be like? What matters here is the type of equipment to which the headphones will be connected, and the power of its amplifier.

Why do we need different resistance values ​​for different models?

Different types of headphones differ in the quality of sound production: high-impedance ones sound a little better. But the point here is not the resistance as such, but the fact that the amplifier sends less current, and therefore distorts the frequency signal less.

For portable devices- , MP-3 players and tablets - it is better to select headphones that belong to the low-impedance type. If the headphones will be used at home, for example, connected to a PC or sound card, high-resistance models are suitable.

The fact is that portable devices have a limited voltage level at the output, but there are no restrictions on the current. Because of this, you can “boost” the gadget in order to squeeze maximum power out of it only with low-impedance headphones.

The voltage of devices that belong to the stationary type is not so limited, so you can get excellent power using high-resistance models. This option will give the amplifier a more favorable load. With headphone impedance high level in this case there will be less distortion.

Note: for a smartphone or is it better to choose an option up to 50 Ohms. A model with a larger indicator will be suitable if it has a good sensitivity margin.

Resistance itself does not affect the sound (its volume and quality), but is responsible for these parameters in conjunction with SPL. This indicator determines how loud the headphones can sound. But how much power an amplifier can produce is the prerogative of impedance.

If you take two pairs of headphones that have the same SPL values, say 110 decibels per megawatt, but one model is 16-ohm and the other is 150-ohm, and connect them to a single-voltage player, then in each of the two cases the player will sound different. different:

1. with a low-impedance model - 62 mW;
2. with high resistance - 7 mW.

Simply put, his amplifier will not be able to get the most out of a high-impedance model.

Devices from the high-resistance category are used in the Hi-End. They are connected to amplifiers or 24-bit studio sound cards. This gives a higher quality and balanced audio signal. For this reason, high-impedance models are used by film and TV sound engineers and DJs. They are also used in mastering and mixing sound recordings in project studios.

Advice: a good studio option - . In addition to decent impedance, they will delight you with excellent sensitivity and a wide frequency range. They sound balanced and detailed.

Headphone volume and source power consumption

Since the volume depends on the resistance, this value also affects the energy consumption of the carrier’s battery: if you listen to music at maximum, then high-impedance and low-impedance models will spend the energy of the battery or smartphone differently.

The higher the resistance, the longer the device’s battery will “live” on one charge, be it a smartphone, player or other gadget. This is because high-impedance headphones consume less current, and this does not depend on the final actual volume.

Users of “quiet” smartphones have an extremely limited choice of headphones, since there is only one option - low-impedance “ears”. Users with gadgets that are equipped with a fairly powerful output (at least 3 V) have the opportunity to experiment.

There are two best options here:

• low resistance but high SPL;
• less sensitive, but with higher impedance.

So, if a user changes 16-ohm headphones to 32-ohm ones (for example, sports ones), the battery of his gadget will last longer.

Headphone models can sound good regardless of the number of ohms. But a lot depends on the medium. For a smartphone, it is better to choose a low-impedance option. To make the battery last longer, a model from 32 Ohm is suitable. For audio mixing and mastering audio tracks and other studio work, it’s worth taking a closer look at full-size options with high impedance. If you connect a low-impedance model to studio equipment, the volume will, of course, increase, but the frequency balance may be disrupted.

If you've ever looked at a headphone box, you've probably come across terms such as frequency range, sensitivity, power, impedance. The meaning of the first three is known to almost every music lover, but not everyone knows what impedance is. It is this concept that will be discussed.

From the point of view of scientific terminology, impedance is the total resistance of the headphones, that is, the combination of its active and reactive components. The value of the final resistance depends on the frequency at which it was measured. Quite often, on boxes with headphones, the value is given only active resistance, occasionally complete, and then only at a frequency of 1 kHz. Unfortunately, most manufacturers do not provide accompanying measurement parameters, and you can only guess what the actual impedance of your headphones is.


For example, you have dynamic headphones. The specified values ​​are 16, 24, 32, 64, etc. Ohms only display the resistance of the speaker inductor, and the resistance of the wire itself, the soldering of the plug and contacts are not taken into account. In reality, the impedance of the headphones is 1-3 ohms higher, and it varies slightly between the left and right channels. Conscientious manufacturers usually indicate that the specified and actual impedance differ by 20-30%, and this is quite normal. Although, on the other hand, this confuses some buyers who regard the error as a disadvantage.

Low and high impedance headphones

Based on resistance, headphones are divided into low-impedance and high-impedance. Each type of headphone has certain resistance parameters. Thus, in-channel low-resistance ones have a resistance of less than 100 Ohms, high-resistance ones - more than 100 Ohms. The same principle works with full-size headphones: low-impedance - up to 32 Ohms, high-impedance - more than 32 Ohms.

Impedance of different types of headphones

In-ear headphones typically have a flat impedance curve that does not deviate by 16, 24, or 32 ohms at frequencies of 20-20,000 Hz.

With over-ear headphones dynamic type quite often there is an uneven impedance curve with a minimal rise in the high frequency region and a local rise at low frequencies Oh. The resistance can be 32 Ohms at 0 Hz (excluding the reactive component), but, as practice shows, at certain frequencies its value can be twice as high.

Irregularities (rises) in the impedance curve arise due to resonance phenomena, as well as due to the design features of the emitter itself inside the headphone housing. In life it looks like this: the headphones are on the table - the impedance curve has one value, the headphones are on the head (the space is damped) - the curve is converted to another.

Impedance of full-size dynamic headphones with a flat curve

Interestingly, not all dynamic headphones have noticeable deviations or resonances. Some of them have a relatively straight impedance line, but selecting headphones based on this principle is not recommended. After all, to achieve ideal impedance values, the manufacturer has to sacrifice other more important characteristics.

In top-class dynamic headphones, there are models with both minimal and significant deviations in the impedance curve. If there is a narrow band boost in the headphones, then the amplifier should have a low output impedance (to control the low frequencies). Accordingly, with significant climbs, you need an amplifier with high resistance.

A characteristic feature of isodynamic headphones is a strictly straight impedance line. Formally, isodynamic emitters create an ideal load on amplifiers, however, in the region of ultra-high frequencies (megahertz, gigahertz), the resistance of some of them tends to 0. Particularly unpleasant is the fact that not all amplifiers are capable of operating in this mode, and this leads to a significant deterioration in quality sound. On at the moment The following companies produce isodynamic headphones: Oppo, Abyss, Fostex, Audez’e, HiFiMan.

The impedance curve looks barely predictable in in-ear headphones with a reinforcement type emitter. Thus, single-driver models have one common feature - a local rise in the upper middle (1-3 kHz) and in the high frequencies. Thanks to local boost, almost all single-driver headphones sound clear at high frequencies.

In the low-frequency range, typical resistance is 8, 16, 24 or 32 ohms. Above 500 Hz, rises are observed in the graph. If the resistance of in-ear reinforcement headphones is 100 Ohms at 1 kHz, this does not mean that they are high-impedance. According to the readings of the multimeter, their resistance can be only 16 ohms.

In multi-driver and hybrid headphones, the impedance curve varies greatly depending on the model. It is almost impossible to predict all its inflections, especially at frequencies above 500 Hz. As for the resistance drop, it can reach up to 4 Ohms, with our 100 Ohms at 1 kHz.

General conclusions from the information presented

• The impedance of in-ear dynamic and isodynamic headphones is exactly the same as on the box;
• Resistance overhead dynamic and full-size headphones— the same as on the box, but with slight rises;
• Resistance of reinforcement and hybrid headphones- does not correspond to the values ​​​​indicated on the box.

Impedance data will help you successfully select headphones for your player or amplifier. If you decide to choose hybrid or armature headphones, be sure to look at the resistance measurement results on the Internet.

What parameters are affected by headphone impedance?

Sensitivity

The sensitivity of headphones is mainly reduced to their power, and ultimately allows you to get two characteristics at once - voltage and current. Sensitivity - comfortable final characteristic for theorists, and a confusing concept for the common consumer.

You've probably heard more than once that sensitivity = volume. Roughly speaking, this is true, but it only works with speakers. Thus, the speaker resistance value is indicated as 4 and 8 ohms.

Everything is more complicated with headphones. Just look at 11 different resistances: 8, 16, 24, 32, 64, 128, 256, 320, etc. Ohm. It turns out that in order for the sensitivity = volume relationship to really work, sensitivity should be expressed in terms of voltage, not power (for example, this is what Sennheiser does). Most headphone manufacturers do not indicate sensitivity units at all. Hence the misconception that high-impedance headphones are quiet, and low-impedance headphones are loud.

To understand how impedance affects sensitivity, let's take a simple school formula:

Then we find the power from it:

W – amplifier output power, W
U – amplifier output voltage, V
I – current strength, A

An excellent example is the Beyerdynamic DT 770 series headphones with different impedances, 32, 80, 250 and 600 Ohms (some models are discontinued).

All headphones have a single sensitivity of 96 dB/mW, which means that if we apply exactly 1 mW to the headphones, the sound pressure level will be 96 dB SPL.

At 1 mW for different models we need to apply different voltage and current ratios:

It turns out that sensitivity should be considered not to power, but to voltage. Only in this case will we be able to match the headphones in volume. Accordingly, the higher the resistance, the lower the sensitivity.

Duration of operation of the player or smartphone

The higher the resistance of the headphones, the longer the player or smartphone will work without recharging, because high-impedance headphones consume less current (provided that the headphones are listened to at “maximum”, regardless of the resulting actual volume).

If you own a quiet smartphone, then, by and large, you are deprived of the opportunity to choose headphones: in terms of sensitivity, only low-impedance headphones will suit you. However, if you have a player or smartphone with a fairly powerful output, take a closer look at highly sensitive low-impedance headphones or less sensitive ones with a higher impedance. Replacing 16 ohms with 32 ohms will reduce energy consumption by a third.

The results of the graphs showed that reinforcement headphones have a higher average resistance - with them the player or smartphone works longer without recharging. Multi-driver headphones, on the contrary, have a lower average resistance, which is why the smartphone or player will, accordingly, work a little less.

Sound quality

You've probably heard that high-impedance headphones deliver more high quality sound than low resistance ones. Although this is not about headphones at all. The amplifier simply sends less current, which ultimately reduces distortion on its part. However, this rule should not be taken as a dogma. There are situations when the amplifier operates at a voltage exceeding its permissible values, then the source of distortion in this case is voltage overload, not current.

The operation of single-driver armature headphones is based on the above principle. Thanks to the rise in the upper mid and high frequencies, there is more high quality sound on those smartphones or players where low-impedance headphones do not perform well.

Frequency response of headphones

If the amplifier's impedance is above zero, then the final frequency response will depend on changes in the impedance curve of both the headphones and the amplifier.

2014-02-16T01:32

2014-02-16T01:32

Audiophile's Software

Prologue

Headphones typically have impedances ranging from 16 to 600 ohms (and some higher). So what is the best headphone impedance value? The answer largely depends on where you are going to connect them.

Which one is better?

Are low impedance headphones better than higher impedance ones? What is the optimal impedance value? Here are some important recommendations (albeit in a somewhat simplified form):

• If you are looking for headphones for use with a portable player or laptop, you should give preference to headphones with an impedance of 16 - 32 Ohms and a sensitivity of at least 100 dB/mW. There are also higher impedance headphones, up to 80 ohms, that are sensitive enough to work with some portable devices, especially if you don't need too much volume. But in fact, the lower the impedance, the better the compatibility with battery-powered devices.
• If you don't know the output impedance of the source device, it's best to avoid using armature headphones, as they may interact undesirably with the high output impedance, resulting in downright bad sound.
• If your source complies with European maximum volume regulations (many do) modern phones, even sold outside Europe), it is all the more important to select headphones with an impedance of 16 ohms and a sensitivity of 100 dB/mW or more. European compliant devices have a lower output level than most other portable devices.
• If you're using a dedicated headphone amplifier or DAC, check its specifications or instructions for the recommended headphone impedance range.
• If you are looking towards headphones with a sensitivity of less than 100 dB/mW, read at least the first five paragraphs of this article.

Different headphone impedance

Impedance of almost all non-professional acoustic speakers lies in the range of 4 - 8 ohms. This simplifies the work of developers of amplifiers, receivers, etc., because they know almost exactly what the load impedance will be. But with headphones things are a little different. There are several standards, so impedance varies widely depending on the developer, and also depending on the devices for which these headphones are designed: portable devices, consumer, studio/professional equipment. Range - from 16 to 600 (40 times more) Ohm. This causes a significant number of compatibility issues.

Why impedance is important

Sources intended for headphones, for the most part, provide absolutely different meanings power with different headphone impedances. For example, the Clip+ portable player can deliver 16 mW into 16 ohms, but only 0.8 mW into 300 ohms. The FiiO E7 can output more than 100 mW into 16 ohms, but only 2.8 mW into 600. Some sources - for example, Mini3, FiiO E9 - are not compatible with low-impedance loads at all.

Sufficient volume

Most sources provide at least 5 mW of power into 16 ohms. For headphones with a sensitivity of 100 dB/mW (the recommended minimum for a portable), this will give 107 dBSPL (sound pressure), which is in the range of 105 dBSPL - 115 dBSPL, which is a sufficient volume level for most people. See More Power.

What impedance is considered high?

I haven't heard of any strict limits, but in most cases 100 ohms and above is defined as "high impedance". These headphones are most often not intended for portable use. Also, 32 Ohms and below can be confidently called “low impedance”; such values ​​are suitable for use anywhere. This leaves an undefined region between 32 and 100 ohms, in which other factors determine the suitability of headphones for certain purposes.

In-ear headphones with balanced armature

Many high-end in-ear monitors use balanced armature technology. Examples include in-ear models from Shure, Etymotic, Ultimate Ears, etc. These headphones typically have an impedance between 16 and 32 ohms, but their actual impedance is highly dependent on frequency. The 21-ohm Ultimate Ears SuperFi 5, for example, varies its impedance from 10 to 90 ohms. Such impedance deviations often result in undesirable interactions with the source output impedance.

Why does headphone impedance vary so much?

There are many reasons for this:

• Historical preferences- Before the advent of the first good-sounding portable devices, most high-quality headphones were connected to either a home stereo system or professional studio equipment. For reasons of simplicity and cheapness in the 60s - 80s, such devices had a high output impedance. They simply used large resistances to create a voltage drop from the outputs to the speakers (so headphones could be connected to these outputs).
• Outdated standard from 1996- In 1996, a standard for headphone output was introduced - 120 Ohms - obviously more than would be convenient for developers of the corresponding equipment. Subsequently, Stereophile expressed his opinion about this standard: “Whoever came up with this is clearly living in a dream world.”. Low output impedance offers many benefits, but the ill-conceived standard still continues to influence the design of high-impedance headphones.
• High impedance is welcome for high-end headphones- In this case, there may be several compelling arguments in favor of high impedance headphones. High impedance allows the use more turns in the speaker voice coil. This can improve the efficiency of the moving system and reduce the number of compromises required, improving the overall sound experience. Also, high-impedance headphones require less current to drive, which often leads to a reduction in various types of distortion. High impedance makes the sound of headphones less dependent on the output impedance of sources, including less sensitive to the length of a three-wire cable and the quality of the connector (jack, mini-jack, etc.). Amplifiers almost always produce less distortion on higher impedance headphones.
• The iPod Revolution Drives Impedance Reduction- As of 2009, more than 200 million iPods had been sold. Before the iPod, there were other portable devices. You could even say that taking into account music mobile phones we have more than one billion portable devices in use. This is important because battery-powered devices cannot work properly with high-impedance headphones. Thus, development was accelerated suitable headphones with low impedance. But this goes against the first three points; So we have the high-end advantages and relics of the past against the huge marketing potential of a billion portable devices.

What headphones can I use for my device?

This main question which most people ask. To answer this, you need to decide on three things:

• Power Requirements- Does the source have enough power to swing this pair headphones to a sufficient volume level? The 100 dB/mW recommendations mentioned above will most likely help answer this question. In case the headphones have lower sensitivity (or it is not specified), see the article More Power.
• Device output impedance- Finding it out is problematic, since the output impedance of most devices is unknown. But the idea is to follow the 1/8 rule described in the article on output impedance. If you multiply the source impedance by eight, you will get the minimum load impedance that is recommended to be used with this device. The FiiO E9 amplifier, for example, has an output impedance of 10 ohms. Thus, if you want to be sure of maximum quality, it should be used with headphones with an impedance of 80 ohms or higher.
• Source Distortions- Some sources have problems with low-impedance loads. Tube amplifiers without output transformers, for example, produce significantly more distortion with low-impedance headphones.

Is it possible to damage something by mistake?

Use of inappropriate of this device headphones will usually not harm anything other than the sound. However, some sources are capable of producing very large output values ​​and therefore can actually damage highly sensitive headphones. But this will only happen if you increase the volume level far beyond reasonable limits, i.e., most likely this can only happen by accident. Some headphone amplifiers have a gain switch to prevent this from happening.

When do you need a headphone amplifier or DAC?

Finally

TECHNICAL PART

Voltage and current

To understand what impedance is, it is important to have at least a basic understanding of voltage and current. Voltage is analogous to water pressure, while current is analogous to water flow (eg gallons/minute). If you run water from your garden hose without a nozzle, you will get a large flow of water and will be able to quickly fill a bucket with it, but the pressure at the end of the hose will be almost zero. If you use a small nozzle, the pressure (voltage) will be much greater, but the flow of water will be reduced (it will take longer to fill the same bucket). These two quantities are inversely related. High pressure usually corresponds to low flow, and vice versa. The same is true for voltage/current.

Hose attachments

Roughly speaking, impedance is similar to the size of a hose nozzle. High impedance headphones are like a narrow ear tip. To get more water, you need more high blood pressure(voltage). Low-impedance headphones are more likely to correspond to the case of filling a bucket without a nozzle, requiring more flow and not too high pressure. Most headphone outputs are good or for the first one, or for the second case, but not for both. That's why it's important to know what you're dealing with and choose your headphones accordingly.

Load impedance (headphones)