Question : What are the key features of the AT-BHA100 Headphone Amp?

Answer : With the release of the AT-BHA100 Balanced Headphone Amplifier, we wanted to highlight some of the key features of this new product. But before we get to those, we should probably answer a few general questions, such as, “What is a headphone amplifier?” and “When should I use one?”

As indicated by its name, a headphone amplifier amplifies (increases) the signal from the audio source, then outputs that increased audio source to the headphones. To do this, voltage (or power) is added to the signal by means of vacuum tubes, power transistors, or a mixture of both. When an amplifier uses both tube and transistor technology to amplify the signal, we refer to it as a hybrid amplifier. This is the case with the AT-BHA100, which uses JJ Electronics ECC83S vacuum tubes in the preamp section, and transistors for the power section. The preamp tubes deliver superb depth and sense of presence, while the power transistors are capable of high-power performance to handle the wide dynamic range of sound sources.

A headphone amplifier may be needed to get the desired volume level for the listener, or it may be needed for the headphones operate to their full potential. While volume level may be subjective in nature, as loudness can be perceived differently from person to person, many consumer electronics, such as smartphones, computers, and tablets, have relatively low-quality built-in headphone amplifiers. Due to this, many of these headphone amplifiers have low power and impedance. Impedance can best be described as the effective resistance of an electrical circuit. This is usually not an issue, as most consumer headphones don’t require much power to operate and have an impedance between 30–50 ohms. However, headphones that have a higher impedance will have issues with these amplifiers. For example, the ideal headphone impedance should be 8–10 times larger than that of the source. Many consumer headphone amps found in smartphones have an impedance of 4.5 ohms, which means the ideal headphone impedance is in the 40-ohm range. If you have headphones with a high impedance (100+ ohms), then the smartphone will have trouble powering these headphones. This is when a higher-powered headphone amplifier is needed.

Now that we’ve covered the basics on headphone amplifiers and their purposes, let’s turn our attention to the AT-BHA100. This balanced headphone amp has two balanced outputs, as well as two standard 6.3 mm (1/4") outputs. The desired output can be selected via the OUT button on the front of the unit to switch between the balanced and unbalanced outputs. The balanced outputs on the AT-BHA100 support 4.4 mm TRRS and 4-pin XLR, which are common balanced connections found on audiophile headphones. With balanced connections, the audio signal is sent to each driver independently, which can have the benefit of increasing power, reducing distortion, and preventing cross talk due to the elimination of a common ground. Balanced outputs may also allow for quicker dynamics and more refined detail.

The AT-BHA100 implements four independent amplifier circuits to help suppress cross talk, and the high-quality New Japan Radio MUSES8820 operational amplifier highlights the depth and warmth found in vacuum-tube amplifiers. The AT-BHA100 also supports Direct Stream Digital (DSD) and other high-definition formats.

On the rear panel of the AT-BHA100, there are balanced XLR inputs, as well as unbalanced RCA line inputs and outputs. These inputs can be selected via the IN button on the front of the amplifier. The line output will allow the signal to pass through to powered speakers if needed. Lastly, there is a LOW/HIGH gain switch, which allows the amplifier to support a wide range of headphones with varying sensitivities and can support headphones with impedances from 16–600 ohms.

If you have additional questions regarding the AT-BHA100 or other headphone amplifiers, please contact our Audio Solutions Team for further assistance.