In the previous issue of RadioGazeta the article “Precision headphone amplifier” was published. It may be somewhat problematic for some radio amateurs to repeat this design due to the use of SMD elements in it. And it’s also not easy to solder the TPA6120 without special equipment and materials.
In this article, we present to you the design of a headphone amplifier, made using elements in “familiar” housings, which makes it easier for averagely qualified radio amateurs to repeat it. Nevertheless, the parameters of this amplifier are no worse than those of the design in the previous article.
National Semiconductor produces a wide range of chips for audio equipment, including top series. LME49600 chip is a current amplifier (driver) and is simply ideal for a headphone amplifier. Even in the datasheet for this chip, National Semiconductor gives an example of a headphone amplifier, which formed the basis for this development. The LME49720 operational amplifier from the same company perfectly complements the LME49600 in its parameters.
Scheme
The schematic diagram of a headphone amplifier is shown in the figure:
Click to enlarge
Since both channels are identical, let's consider the operation of one of them. The input signal goes through connector K2 to the volume control P1. From the potentiometer slider, the signal is supplied to the non-inverting input of the operational amplifier IC1A, to the output of which the LME49600 IC3 driver is connected. Resistors R5, R1, R2 form a general negative feedback circuit and determine the gain of the circuit.
Since headphones have different sensitivity and impedance, the amplification circuit may not be enough for some models. Then you should install jumper JP1, which will increase the gain from two to six.
There are no coupling capacitors in the circuit; all stages are DC coupled. Therefore, to eliminate the DC component at the output (from interference and interference, power fluctuations and other reasons), an integrator on element IC1B was added to the circuit.
Electrolytic capacitors are found only in power circuits and are not present along the signal path. This ensures minimal distortion and no phase shifts.
Test bench measurements confirm the circuit's excellent performance. Based on the listening results, the amplifier showed excellent sound quality .
The amplifier power supply circuit is shown in the figure:
Click to enlarge
The diagram is typical and does not require additional explanation. As in the previous design, thanks to the use of top-end microcircuits with low sensitivity to the quality of the supply voltage, the power supply was made simple and cheap, using standard integrated voltage stabilizers.
How to choose the right headphone amplifier?
In general, all such products can be classified according to the principle of operation: they can be tube, transistor and hybrid. The first type allows you to achieve a warm and most comfortable sound. The devices are given a special visual effect by the lamps, which also glow in the dark. If they are located outside the main body, the amplifier must be positioned so that it cannot be reached by pets or children. This is due to the fact that the lamps get quite hot during operation, so children or pets can be seriously burned. Tube amplifiers are also not installed in a confined space - they must be provided with access to fresh air.
How to choose a headphone amplifier?
Transistor-type amplifiers reproduce music accurately and clearly, they are ideally combined with low-impedance headphones. In addition, they are characterized by compact overall dimensions and consume a small amount of electricity. Hybrid devices use both lamps and transistors. These are the most versatile devices that combine the positive features of the two designs discussed above. These devices are suitable for any type of headphones, because the tubes provide the softest sound, and the transistor elements provide the necessary power.
As a rule, amplifiers are designed for a specific type of headphones - some behave well with low-impedance ones, others are suitable for highly sensitive devices. When we chose products to include in our review of the best headphone amplifiers, we relied primarily on all the points discussed above. However, we also took into account some other factors: value for money, as well as user reviews. We tried to include in the rating the most popular models that will be within the means of most of our readers.
Design
The amplifier is made on a double-sided printed circuit board measuring 68 x 140 mm. (). The location of the elements is shown in the figure:
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Drawing of the board from the elements side:
Click to enlarge
Bottom side drawing of the board:
Click to enlarge
The amplifier's input circuits are located on the left side of the printed circuit board. In the middle part there are drivers and an output connector. Unlike the TPA6120, the LME49600 has a heatsink blade on the top side of the case. It must be soldered to rectangular polygons on the printed circuit board. Doing this even with an ordinary soldering iron will not be a problem.
The power supply elements are located on the right side. The network transformer is located outside the printed circuit board and is attached either to the case or to a separate board.
Ten of the best headphone amplifiers in 2022
Fiio Q1 Mark II
It features excellent production quality and advanced functionality. In particular, with the help of this amplifier it will be possible to fully reveal the capabilities of any type of headphones, even when the main sound source is a smartphone. Despite the fact that this model is made in China, it is reliably assembled, which ensures a long period of operation. The power of the design is 0.22 W, there is a built-in battery that allows the amplifier to operate without interruption for 20 hours. Overall dimensions are 99x59x12.5 mm with a weight of 101.5 g.
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If necessary, this model can be connected to a device running on the iOS operating system without the use of adapters (they always negatively affect the quality of sound reproduction) - an original Lightning cable is supplied. The upper frequencies during playback are colored quite brightly, which is why the sound delivery becomes slightly unnatural. The mid-frequency range is heard clearly and quite naturally. The bass line and gain level can be adjusted if necessary.
Advantages:
- Quite reasonable cost;
- Compact overall dimensions;
- The kit includes a cable for connecting to Apple products.
Flaws:
- There is no battery charge indicator on the case.
- The micro-USB connector is quite tight.
Fiio Q1 Mark II Headphone Amplifier
OPPO HA-2SE
The device is placed in a thick case made of high-quality artificial leather, which gives it additional style and presentability. Belongs to the middle price group, has a power of 0.22 W, and a dynamic range of 115 dB. The design features a fairly robust 384 kHz/32-bit amplified DAC. The built-in battery allows you to use the device without interruption for 13 hours. The overall dimensions are as follows - 137x68x12 mm, the weight of the device is 175 g.
Using this amplifier, it is possible to provide high-quality processing of the PCM signal in real time. Thanks to the use of this technology, it is possible to obtain a very powerful sound that will fully reveal all the facets of the track being played. The product has a significant number of connectors, among which there are two 3.5mm ports Line In and Line Out. Due to this, the user is able to independently choose the sound quality - in the first case, the DAC does not turn on and no melody processing occurs, and in the second, the track can be pumped up and the power of the converter can be felt to the maximum.
Advantages:
- Original design of the case;
- Quite compact overall dimensions;
- You can charge other devices if necessary.
Flaws:
- There is a certain musical coloring;
- With regular use, the volume control begins to become loose.
Headphone amplifier OPPO HA-2SE
iFi micro iDSD Black Label
When using this amplifier, up to 1 W is output per channel with a resistance of 64 Ohms - this is a fairly high figure among most devices included in this review. It’s worth saying right away that the device is quite expensive, but it is capable of providing a dynamic range of 115 dB. The built-in battery can work without recharging for up to 12 hours. There is a built-in 768 kHz/32-bit DAC. The dimensions are small - 158x68x28 mm, its weight is 265 g, so it is easy to take with you on business trips, trips or hikes.
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Users give quite a lot of positive feedback about this device. The amplifier can be used both portable and as a stationary device. The presence of an original coaxial-optical input allows you to work with the output, which allows you to use the gadget as a signal converter. There is a USB connector on the side of the case, so the amplifier can be used as a charger for smartphones, players and tablets.
Advantages:
- If necessary, it is possible to provide professional sound tuning;
- Decent sound quality;
- Expanded functionality;
- You can also charge other devices from the built-in battery.
Flaws:
- Its dimensions are larger than similar devices;
- Quite expensive.
iFi micro iDSD Black Label Headphone Amplifier
M-Audio Bass Traveler
The device is one of the cheapest among all the models presented in our rating of the best headphone amplifiers. The device is manufactured in the United States using original components, which automatically indicates the high quality of production and assembly of the product. The power of the device is 0.025 W, thanks to this factor the amplifier can operate in a dynamic range of up to 90 dB. There is no DAC provided here. The gadget is one of the lightest - it weighs only 30 g with overall dimensions of 45.7x46.9x15.2 mm. In offline mode, the device can work for 8 hours.
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As the owners of such amplifiers note in their reviews, the device is optimal for owners of high-quality headphones that can sound good in combination with a personal computer or laptop, but at the same time they are not able to fully reveal their qualities if they work with a smartphone. There are two jacks for connecting headphones, so two people can listen to the same music at once, and absolutely synchronously.
Advantages:
- It is quite simple to operate the device;
- One of the cheapest models;
- There is an LED battery charge indicator;
- At the same time, if necessary, you can connect two pairs of headphones at once.
Flaws:
- The case is made of glossy plastic, which will leave marks.
Headphone amplifier M-Audio Bass Traveler
Questyle CMA-800R
Despite the fact that this model is truly the best on the world market in terms of its performance, it is characterized by a very high price. For this reason, many users are not able to afford such a purchase. The device is distinguished by increased power - 0.18 W, which is really a lot for an amplifier. The device can operate in a dynamic range of up to 118 dB. Another key point is the lack of a battery. The overall dimensions are as follows: 330x55x300 mm, gadget weight – 265 g.
For headphones, this model will truly be the best version of the amplifier, and the amplification is carried out exclusively by current, which minimizes melody distortion. Similar technology is used in video signal processing, as well as in high-speed communications. The amplifier is able to work with any type of headphones, regardless of their impedance.
Advantages:
- A significant number of different inputs and outputs;
- Ideal sound quality, almost indistinguishable from live sound;
- Perfect for high impedance headphones.
Flaws:
- Quite a high cost;
- Fully revealed only with headphones belonging to the premium class;
- There is no option to use offline.
Headphone amplifier Questyle CMA-800R
SMSL B1
It is characterized by an increased capacity of the built-in battery, thanks to which the device is able to function continuously throughout the day - this is the highest indicator among all the models presented in this review. The product is not too expensive, although it is made in Britain and is equipped with a built-in DAC. Due to the capacious battery, we had to sacrifice some of the overall dimensions, which are 81x25x70 mm and weigh 270 g.
Another important distinguishing quality of this device is the ability to transmit a signal via a Bluetooth wireless channel. The amplifier converts it into an analog version and then transmits it to headphones or speakers. There is an RCA input, the product can be used on both stationary and mobile devices.
Advantages:
- Long battery life;
- The body is made of high quality metal;
- There is a Bluetooth module;
- You can work with both stationary and mobile devices.
Flaws:
- The dimensions are small, but there is an antenna protruding beyond the body.
Headphone amplifier SMSL B1
Sony PHA3
Optimally suitable for working with headphones produced by the same manufacturer. The built-in battery can provide up to 5 hours of battery life. The product is made in Japan and is therefore distinguished by its traditionally high quality. The amplifier power is 0.1 W. The dimensions of the device are 140x80x29 mm and weighs 230 g.
The gadget appeared on the market in 2022; it can also work with balanced headphones, where each channel is connected separately. The scope of delivery is quite wide, which is why the cost turned out to be quite high. In particular, there are wires for Walkamp, speaker wires with 3.5 mm connectors, and there are rubber gaskets and rings. The sound is detailed, but there is no pronounced part of the range here.
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Advantages:
- Steel body;
- Many inputs of various types;
- Expanded equipment.
Flaws:
- The battery is fully charged within 15 hours;
- The device is quite expensive.
Headphone amplifier Sony PHA3
Sennheiser GSX 1200 PRO
In third place in our ranking of the best headphone amplifiers are products from a world-famous manufacturer of acoustic products. In general, this device was developed specifically for stationary use with personal computers. In particular, it is ideal for game lovers - you will be able to instantly hear any rustle of a creeping enemy. As is already clear, there is no built-in battery here, although the device has compact overall dimensions - 143x70x139 mm with a weight of 413 g.
Up to 8 amplifiers can be connected to this amplifier at the same time, and it is capable of supporting the latest generation of 7.1 sound. The volume can be adjusted, you can quickly switch between speaker and headset, and there is a customizable equalizer. Long warranty period – 2 years. You can use this device as an external sound card connected via USB, and no drivers are required.
Advantages:
- Works with any operating systems – Windows, Macintosh;
- Optimally suitable for fans of computer games;
- There is no need to install drivers.
Flaws:
- Battery missing;
- The length of the USB cable included is short - only 1.2 m.
Headphone amplifier Sennheiser GSX 1200 PRO
xDuoo XD-05
Although the power of this gadget is slightly lower compared to other models from our review, it is capable of working for 23 hours on a single battery charge. In addition, the amplifier has a liquid crystal display, on which basic information useful to the user will be displayed, for example, the current discredit frequency.
A smartphone and other mobile devices are connected to the device exclusively via an OTG cable. It is very important that your smartphone or tablet supports this function, otherwise you won’t be able to play music. Users in their reviews note another important fact: if the gadget runs on the Android platform, you will have to install a special USB Audio Player Pro, otherwise you will not be able to unlock all the capabilities of the amplifier.
Advantages:
- Compact overall dimensions;
- Reasonable cost;
- Availability of LCD screen;
- Long battery life.
Flaws:
- There are certain difficulties when installing software;
- There are no wireless connection channels.
Headphone amplifier xDuoo XD-05
Fostex HP-A3
The leader in headphone amplifiers is the most reliable and functional model, which can operate without failures for many years. The sound is excellent - the music is detailed, the entire frequency spectrum is heard perfectly. There is no need to switch cables: this is the additional originality of this device. Here you just need to press a button and the channel switches from the speakers to the headphones. The case is quite large, but there is no battery provided, and the amplifier weighs a fair amount.
Advantages:
- Small overall dimensions;
- Classic appearance;
- Conveniently switch between audio output devices.
Flaws:
- There is no built-in battery;
- There is no on/off button here.
Headphone amplifier Fostex HP-A3
Specifications
- Reproducible frequency range: 0 - 100 kHz;
- Distortion+noise <0.0003%;
- Recommended load resistance: 16 to 300 ohms.
A graph of distortion versus output power (at different load resistances) is shown in the figure:
Dependence of distortion on signal frequency (at different load resistances):
Even with the lowest load impedance of 16 ohms (top graph), the minimum distortion is below 0.0001%, which is an excellent value.
At a frequency of 20 kHz their level remains less than 0.001%, and for a high-impedance load it is even an order of magnitude lower.
Author of the design Alan Kraus, Free translation: Editor-in-Chief of RadioGazeta Happy creativity!
The benefits of audio amplifiers
A headphone audio amplifier can provide the user with a sufficient volume level and make the sound comfortable and rich, since noise and distortion will not come to the fore. Each instrument will be heard perfectly - drums, electric guitar, violin and synthesizer.
These two functions are important and dependent on each other. Because even at the minimum volume setting, the owner will not receive clear sound, but distortion will remain. Therefore, most connoisseurs or those who have once tried to listen to music in excellent quality prefer to buy external amplifiers that will provide comfort and purity.
Top 6. Questyle CMA-800R
Rating (2021): 4.48
- Characteristics
Average price: 99990 rub.
- Country: USA
- Power: 0.18W
- Dynamic range: 118 dB
- DAC: no
- Harmonic distortion: 0.00026%
- Battery life: —
- Dimensions and weight: 330x55x300 mm, 265 g
According to reviews from music industry professionals, the Questyle CMA-800R is also one of the best headphone amplifiers. A unique feature of the gadget is current amplification, which minimizes distortion of the reproduced sound. A similar technology is used in video processing and high-speed communications; the American manufacturer was not at a loss and adapted it for audio equipment, patenting a new product under the Questyle brand. This headphone amplifier is a luxury model, and this is echoed by the price, which is unaffordable for most users. But the price is quite justified - the gadget works with headphones with any impedance, producing a very powerful, incomparable sound.
Advantages and disadvantages
- Lots of entrances and exits
- High quality sound
- Suitable for high impedance headphones
- High price
- Fully opens only with premium headphones
- Non-portable form factor
Top 5. SMSL B1
Rating (2021): 4.55
Longest battery life This amplifier can operate on a single charge for up to 24 hours, and this is the maximum among representatives of our top.
- Characteristics
Average price: 5890 rub.
- Country: UK
- Power: 0.066 W
- Dynamic range: 96 dB
- DAC: yes
- Harmonic distortion: 0.03%
- Battery life: 24 hours
- Dimensions and weight: 81x25x70 mm, 270 g
This is an amplifier with a built-in wireless DAC. It works like this: it receives a digital signal via Bluetooth, converts it to analog and transmits it via wires to speakers or headphones. In addition, the model can also perform indirect functions: for example, be a digital source via coaxial/optical paths and act as a full-fledged DAC via an RCA input. And important: this amplifier is compact, mobile and can work on one charge for a full day. The model is ideal not only for connecting to a smartphone, but also to devices that cannot reproduce sound wirelessly. And with SMSL B1 they have such an opportunity.
Advantages and disadvantages
- Wireless DAC
- Long battery life
- Metal body
- There is an NFC module for quick connection with your phone
- Not exactly portable (small, but has an antenna sticking out)
- No LDAC support (AptX only)
Top 2. xDuoo XD-05
Rating (2021): 4.65
11 reviews from resources taken into account: Yandex.Market
- Characteristics
Average price: 18890 rub.
- Country: China
- Power: 0.5 W
- Dynamic range: 112 dB
- DAC: yes, 384 kHz/32 bit
- Harmonic distortion: 0.0025%
- Battery life: 11 hours
- Dimensions and weight: 140x23x75 mm, 270 g
A less powerful headphone amplifier compared to other participants in our rating, but cheaper and with a surprisingly long run time on a single charge. So, you can listen to truly revealed favorite tracks for 23 hours. Another important feature is the presence of a screen that displays the current frequency of discrediting. A caveat is that a smartphone can only be connected via an OTG cable, and your phone must support such a connection. The reviews also warn that all the functions of this amplifier from an Android smartphone can only be assessed using the USB Audio Player PRO.
Advantages and disadvantages
- Great price
- DSD support
- Compact dimensions
- Screen
- Difficulties installing software
- Connects to phone only via OTG
Top 7. M-Audio Bass Traveler
Rating (2021): 4.45
24 reviews from resources taken into account: Yandex.Market, DNS
Best Price This is the cheapest headphone amplifier among the best models. The next most expensive model from our rating costs 58% more than this one.
- Characteristics
Average price: 3735 rub.
- Country: USA
- Power: 0.025 W
- Dynamic range: 90 dB
- DAC: no
- Harmonic distortion: unknown
- Battery life: 8 hours
- Dimensions and weight: 45.7x46.9x15.2 mm, 30 g
Inexpensive portable headphone amplifier. An ideal option for those who have good headphones, and they sound great in conjunction with a computer, but play quietly and flatly with a smartphone. In this case, M-Audio Bass Traveler will save you. The compact device will reveal the potential of your wearable acoustics. There are two jacks for connecting headphones, so you can listen to music from 2 different models at once. There are 3 operating modes: the first increases the volume, but leaves the bass at the same level, the second increases the bass to an average level, the third adds bass to the maximum. This is the best option for use with a smartphone.
Advantages and disadvantages
- There is a charge indicator
- Simple controls
- Can connect two pairs of headphones
- Marky building
- Charging via legacy micro-USB port
