Austin Audio Works

Austin Audio Works

A Delightful Headphone Amplifier
The Black Amp

I even had a full-on eargasm on Bjork's "Undo". Here's my notes from that moment: "Holycrap the heavens opened up and down came all of the angelic voices. Swirling holographic soundstage. Ooh la-la." Scott Petersen – Audio Supervisor

The Black Amp is a fully Symmetric Complimentary Class-A, Current Carrier Technology Headphone amplifier. Extraordinary detail, speed, dynamics, and resolution. Employing absolutely no global feedback and a unique bi-directional current drive. Offers exquisite layering and separation of instruments, quick and precise attack with no lingering decay. A bright, wide-open sound without harshness or fatigue, and a rendering of each musical voice in micro-detail without reducing the impact of the overall music presentation.

The remarkable sound of the Black Amp is the result of operating in the current rather than voltage domain for both gain and output.

Gain is a key to amplifiers - tube amplification started electronics about 100 years ago and tubes are voltage devices. 50 years ago transistors came along and they are current mode devices. Amplifier Designers applied transistors to tube-amplifier design concepts by controlling performance issues such as distortion, bandwidth, and noise with negative feedback. Current Carrier Technology is a technique free of this control and permits voltage gain by using matched complimentary symmetric transistors in their natural current mode acting to cancel out each other’s distortions without feedback.

Output drive to headphones is very special - moving coil and planar headphones are pure electro-mechanical transducers. They are about ampere-turns in magnet fields meaning they work on current rather than voltage (loudspeakers with crossovers have to be driven in the voltage mode). The current sourcing and sinking output of the Black Amp drives headphones as they should be, in their natural current mode.

Current mode and output allows us to design while avoiding feedback thus eliminating its dynamic music ‘muddling’ sonic signature so we get the right gain, the right drive, and the right sound.

These are the basic qualities of our amplifier designed for delightful headphone listening. The Feedback-free Current Domain of The Black Amp is an experience worth beholding and owning.

Explanation of the Specifications

1 – Output Power

The Black AMP is a current mode amplification process. Instead of the usual artificial ‘zero’ impedance output the Black Amp output is high impedance, a current source, driving the headphone transducer without an artificial effort for the amplifier to be something it is not. It is a more ‘natural’ process, the result of no global or stage feedback.

2 – Harmonic Distortion

A key technical feature of the Black Amp is that the distortion does not change with frequency. The four images below are the signal and the distortion. Note that all the distortion is second (even) harmonic energy. Even harmonics are melodic in nature as opposed to the usual distortion of feedback which is odd harmonic based and thus dissonant in sonic nature. Note the fourth image, the distortion above 50 kHz.

3 - Noise

Signal to noise is over 115 dB (weighted, that is 60 Hz limited) from a 2 volt RMS output. Noise is one of the important factors that limits resolution and the details needed for a true sound scape. The Black AMP’s unique clarity and resolution is rooted in noise between the spectral elements of the musical signal.

4 – Square-wave response

Square-waves reveal both stability and bandwidth issues. Without resorting to using feedback the Black AMP is flat and stable out to a megahertz assuring no interactions and odd-harmonic artifacts to reduce resolution and musicality. In technical terms the Black Amp behaves flawless through and pass the audio band.

The Black Amp is part of the AAW Discographer’s Auditioning System when combined with the AAW Black Swan phono preamplifier.

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