Lehmann Audio Linear II Headphone Amplifier

Lehmann Audio Linear II headphone amplifier is the latest version of the Linear, a legend amongst headphone amplifiers. Now it has become even better with the Linear II and is designed for excellent sound with detail and lucidity and gives a low-artefact reproduction.

The PCB has been designed to have a low impedance (Low-Z), and the output stage is Class A for the best distortion performance. Mundorf capacitors are used in the power supply giving a good transient response. However, the Linear II is more than just a headphone amplifier, it has a built in DAC for digital audio playback. Finally, 3S device feet ensure the best resistance to vibration. There are also two headphone outputs.

Revised analogue circuitry

The Linear II has a totally revised analogue section. The PCB traces have a low impedance, for less signal loss. Moreover, it is a class A design that gives very low distortion. The components are specially selected, and include Low loss MKP precision capacitors in the power supply. This new model delivers punchy lows, along with a high resolution sound. This reveals all of the detail in the music.

What is class A?

Class A is a type of linear amplifier that gives reduced distortion. Most amplifiers are class A/ B. This is used for power amplifiers and is a mixture of class A and Class B. Class A can be power hungry, and generates a lot of heat. However, this is less of an issue with low power devices such as headphones. As a result, many headphone amplifiers are Class A.

Class A amplifiers are single ended in that they uses only one transistor. The output transistor is always passing a current. This means that it is always operating in its linear region. Class B uses two transistors, notably, these are biased to just before conduction. This can cause crossover distortion.

Gain settings to match your headphones

Headphones come with a variety of sensitivities and impedances. As a result, the Linear II has three gain settings, so that you can best match your headphones. As well as two standard 6.3mm headphone outputs, there are also two Neutrik headphone sockets, with gold plated contacts. Additionally, there is a line level output that is muted when the left-hand output is in use. Finally, there is a line level input for connecting analogue sources.

High-end DAC chip

The Linear II is more than just a headphone amplifier, it will also process digital audio, with the built in DAC. The DAC uses a high-end ESS Sabre K2M DAC chip. Just connect a digital source via the coaxial or optical digital input. This could be from a CD player or any other digital source. Linear II can also act as a high-end digital preamplifier, if headphones are not used.

The casing is made of sturdy metal to reduce vibration and decouple any external noise. Black, silver and chrome finishes are available.

Headphone connector types

Most headphones come with a 3.5mm stereo plug. These are known as Tip Ring and sleeve (TRS). They carry an unbalanced stereo signal. However, most headphone amplifiers, including the linear II use 6.3mm sockets. Hence most headphones will need an adapter plug. There is also another, 5-connector type, that is used for balanced headphones. This is known as TRRRS and separates the two audio channels.

For example, there are two sets of positive and negative wires and a zero volts ground reference. Balanced headphone amplifiers are less common and have to be designed as such. Finally, there is another type of headphones, that use electrostatic transducers, these use a completely different type of connector.