DACS MicAmp 2 Clarity Two Channel Microphone Amplifier
Winner of 1998 SSAIRA for Outboard Pre-amplifiers voted for by readers of Studio Sound
"Does it sound good?" The answer in tests has been an unequivocal "YES!"
- 2 channel discrete-component-based microphone amplifier
- Ultra low noise, ultra low distortion
- Unmatched transparency of sound coupled with sonic punch
- Gain settings in 6dB steps, from +20dB to +62dB, with a 0dB to +10dB trim control
- Separate non-Phantom Power input coupled directly to gain stage for dynamic, ribbon and valve mics
- Flat frequency response from below 20Hz to above 48kHz
- Tri-segment LED display for clear metering
Easy to set up and use, the DACS Clarity MicAmp produces an
extraordinarily clear, uncoloured, detailed and complete sound for
recording everything from voice and acoustic instruments to overheads on
drums, with bomb proof input stage and optional in line pad. Users
universally describe it as one of the finest microphone amplifiers in
the world.
Technical Specifications
The DACS MicAmp is a very high
performance unit. At this level we believe that every effort must be
made to avoid compromising the quality of the signal path. We have
examined every aspect of the process, from the power supply to wiring to
external connectors. Probably the changing of any one factor would make
no noticeable or measurable difference, but cumulatively we believe
that the attention to detail is worthwhile, particularly in long-term
performance and reliability. Below are some notes regarding the
technical aspects of the MicAmp, which we believe make this unit one of
the best Microphone Amplifiers available.
Power Supply Unit
The Dual Rail supply used in all our products uses LM317 variable
regulators. These have been shown in a number of tests to be lower noise
than standard 78/9 series regulators. We have also implemented
additional ripple reduction circuitry. In addition most capacitors are
Tantalum, not standard electrolytic. The main smoothing capacitors are
4700µF per rail. The Phantom Power Supply is an op-amp based regulator
giving extremely stable regulation.
Power distribution uses a star system to minimise any interaction between circuit elements.
Earthing
The unit uses a star earth system where all earths go to the 0V terminal using heavy cable.
Wiring and Fixing
Where connections are crucial we have soldered directly to the PCB.
This forms a more reliable long-term connection than plugs. All cables
are loomed and firmly cable tied to the board. The audio cable is OFC,
again producing a small benefit over the long term. No external
connectors are PCB mounting. This ensures long-term reliability.
Components
The input DC decoupling capacitors are metallised polyester of 5%
tolerance. The input is protected by four ultra fast diodes. The
transistors are stacked to improve thermal coupling and reduce lead
length. They are mounted in a turned pin socket. The gain switching
uses a self-cleaning rotary switch which is screwed to the PCB, then
soldered, and the switching shaft is fixed to the screwed down portion
of the switch body so that there is little or no mechanical stress on
the PCB. The pot (conductive plastic tracks) is also mounted on a
bracket to minimise PCB stress. The filter stage uses 5% metallised
polyester capacitors too, to give accurate and stable filtering. The
amplifier stage is decoupled from the filter and trim stage by a 100uF
bi-polar electrolytic capacitor. The trimmers are all low noise trimmers
with a wide track. Throughout we have used Burr Brown OPA604s which are
extremely high specification op-amps optimised for audio applications.
In listening tests they have been preferred to NE5532s.
Noise and distortion
EIN is -133dB relative to a maximum output of +22dBu. Distortion is
very low, with THD+N figures of around .00025% @ 1kHz (measured in the
audio frequency range). Input impedance is ca 1kOhm.
Frequency response
-3dB point at 48kHz, roll off at 6dB/octave Flat to less than 20Hz on
phantom with subsonic roll off at 6dB/octave, DC coupled on non phantom
inputs.
