EA-200 Phono Preamplifier By Phasemation

The Phasemation EA-200 builds on the original EA-5 model. The sound quality was improved further by refining the circuits, upgrading the power supply, and creating a new sophisticated design of the exterior.

The design is a class A circuit with zero-feedback, and using all discrete parts. Amplifying with zero-feedback increases the cost but the results are spectacular. A load feedback amplifier compares the input and output signals and the difference (supplement signal) is amplified as an input signal which makes it possible for amplification at a low cost. However, a zero-feedback circuit amplifies the input signal itself, which makes a big difference. In terms of sound quality, with music impression, dynamics, and shading expressions, there’s no substitute for zero-feedback, so all Phasemation phono preamplifiers use this approach.

Amplifier Details
High Gm FETs (field-effect transistor) are used to create a voltage-current converter with extremely low noise. Then, the stable RIAA equalizer circuit has excellent transient response characteristics. For the output buffer, an inverted Darlington circuit is adopted to ensure a high input impedance and low output impedance, which strongly drives the device in the next circuit.

a) Solid chassis structure
A phono signal is weak by nature, so care must be taken to ensure it’s not influenced by outside signals. The chassis base and top cover are made from a 1.6 mm steel plate, and copper coated. A small chassis size allows for a reduction of magnetic distortion that maintains high strength and rigidity.

b) Dual mono circuitry
1) A dual monaural circuit actualizes a uniformity of the left and right channels at a high level. A high-performing power supply provides power without any common power impedances due to left/right individual powers and accomplishes channel separation of 90dB or more (20Hz to 20kHz).

Introduction of High-Quality Parts

The following evaluated high sound quality parts and so on are used for the RIAA impedance elements and the power supply, which strongly influence phono sound quality.

1) Metal film resistors with some margin of the rated value
2) High-quality film capacitor
3) Fast recovery diodes
4) Low noise Zener diodes

Stereo Sound
BEST BUY COMPONENTS 2013-14 Phono Equalizer Amplifier 3rd Prize

Ongen Publising
Audio Excellence Award 2013 Bronz Prize

Ongen Publising
analog Grand Prix 2014 Gold Award

Seibundo-shinkosha
2013 MJ Technology of the Year Analog Components Excellent award