When Metrum Acoustics customers requested to develop a headphone amplifier, we knew that the finished product would have to be something special!
From the first digital to analogue converter ever made by Metrum Acoustics we have taken a different route to most manufacturers. Most of them use conversion chips by Burr Brown, Philips, TI or Wolfson to name a few, Metrum Acoustics selected an industrial DAC chip and claims its high speed architecture improved the conversion.
Loyal to the non-oversampling, non-filtering approach Metrum Acoustics continues to bring converters to the market, everyone better than the last.
In today’s marketplace, Metrum Acoustics is one of the most prominent manufacturers of Digital to Analogue Converters. We have experience in the field of audio dating back to 1989 and while then it was electrostatic technology that spread our brand name, we are still pushing forward with innovation.
The only difference is now we have a focus on electronics, even more specifically our non-oversampling digital circuits. While it is certainly DACs that made Metrum Acoustics to what we are today, we also have innovated amplification.
The Aurix by Metrum Acoustics is a headphone amplifier, and one not fast to be forgotten!
Not an ordinary design like many other DACS but a real improvement on existing principles. Rather than using transistors or tubes for amplification a special step-up transformer is used. Said solution solves many problems as known in regular low gain amplifier designs and provides a very transparent sound image.
Only two FET transistors are in the signal path as an impedance converter ( source follower, no amplification ) and it is this property where a FET transistor can do an extremely good job and delivers a very high bandwidth having low noise and low distortion . The first Fet is used as an impedance converter to drive the step-up transformer. The second FET is used to drive the headphone. The circuits are running in full ” Class A ” so that a relatively large heat-sink is required to flow the heat .
Besides the amplifier part we have used a lot of electronics just for creating the right conditions for the amplifier part and protecting your headphone against subsonic , offsets , pops and clicks. The result is a sound that is mainly determined by the connected source.
Because of the many requests we received from both customers and dealers we decided to focus on the development of a headphone amplifier. Since the arrival of the AURIX By Metrum Acoustics, we do not just have the headphone amplifier, but a new way to preserve the integrity of the analogue signal.
During development it proved impossible not to make concessions if the designer would have utilized one of the already established techniques. Therefore this particular route was abandoned and a design was created where voltage gain is achieved via a so-called step-up transformer, instead of transistors or tubes. Only two FET transistors are utilized to convert the signal from the step-up transformer into power, which plays into the strength of these semiconductors.
By utilizing this method the Aurix has become a design free of concessions, where the integrity of the sound of tube-amps is combined with the compact practicality of the transistors, without any of their inherent flaws.
The Aurix is a 100% class A amplifier with a very high signal-to-noise ratio and almost no distortion. Because feedback has not been implemented in the design the Aurix has no degradation of the incoming signal in terms of dynamics and imaging.
In order to ensure the Aurix is flexible and applicable for most headphones it has two gain factors so that both low and high impedance headphones can be utilized. Aside from that the Aurix is equipped with two controllable analogue inputs that, in case no headphone is connected, can loop the signal back to your set. This allows the Aurix to be permanently installed in your Hi-FI-set without you ever having to switch the cables around!
Output Max. 6 Volts RMS to 600 Ohm load
Output Max. 2 Volts RMS to 33 Ohm load
Gain of 1 or 3 (+10dB) selectable by switch
Working Principle Amplification using two transistors
and a step-up transformer
Current delivery full Class A
Non feedback design
Frequency response 5Hz to 60kHz -3dB
Distortion Max. 0.01% THD , 600 Ohm load
Max 0.5% THD 33 Ohm load
Signal to noise -120 dB related to 2 Volts RMS
Protection Start-up Offset and subsonic frequencies
Consuming power Max. 30 VA