Hafler PH50 Phono Stage

The Hafler PH50 is an ultra-linear phono stage for moving magnet (dynamic 47k-Ohm) cartridges that exhibits less than 0.5dB deviation from 10Hz to 100kHz and boasts a well defined RIAA curve to preserve and transmit the original program material with minimal coloration. Particular attention has been applied to reducing noise, a problem common to the 33 RPM recording chain, resulting in a low -82dB noise floor with greater than 91dB of dynamic range and less than 0.002% distortion.

The design begins with a 14 gauge steel casing to shield the low level signals from external magnetic fields and RF contamination. Gold-plated input and output RCA connector pairs are employed that will not tarnish over time, thus optimizing signal flow. Inside, the solid-state circuit and military grade PC board have been optimized by carefully positioning parts for minimal self-noise and cross-talk and then supplemented with a ground plane to reduce susceptibility to RF and external magnetic fields. An external supply further reduces noise by removing the power transformer from inside the casing.

Front panel controls include a power on-off switch and a variable low-cut filter that may be inserted into the signal path when needed. The fully djustable low cut (high-pass) filter enables the user to reduce low frequencies that can cause resonance and feedback when playing music at higher levels. This helps eliminate both airborne and solidly coupled transmission of vibrations that can disrupt the stylus and cause feedback, rumble and distortion.

Compact yet 'plug and play' easy to use, the PH50 follows Hafler's 50 year tradition of building the very finest audio products.

Features:

• Phono stages for moving magnet cartridges
• Ultra low noise transformerless design
• Variable high-pass filter to eliminate rumble
• Plug and play easy to set up and use

Dial In

1. Power

Turns on the PH50

2. Low Cut

Inserts low cut filter into signal path

3. Variable Low Cut Filter

Eliminates rumble from excessive bass

 

Connect

1. RCA Inputs

Connects from the turntable to the PH50. Features 47k-ohm standard input for moving magnet cartridges. Gold plated to eliminate tarnishing and ensure optimal signal transfer.

2. RCA Outputs

Line level output connects to preamp or receivers' -10dB line input. Gold plated to eliminate tarnishing and ensure optimal signal transfer.

3. Ground Lug

Standard round spade connector for the turntable ground attachment. Features knurled stainless steel thumbscrew for easy manipulation.

4. Power

Connection for the external 15V power supply. Features cable lock for added security. The power supply is included.

 

Inside

1. Low-noise, Ultra-linear Circuit

To optimize signal transfer, the PH50 employs metal-film resistors along with full-sized capacitors that are hand inserted to deliver the very best audio quality.

2. Double Sided PCB

Through-hole solder points combine with a military spec circuit board for greater durability. A full surface ground plane reduces susceptibility to radio frequency interference.

3. Extra Durable Switches

Ultra high quality switches and potentiometers employ steel casings and metal shafts for long-term reliability. Switches rated at over 20,000 cycles.

4. Steel Casing

Made from virgin steel, the folded U-shape design provides a solid frame for the sensitive PC board to eliminate torque, which could lead to premature cold solder joints. Also provides excellent shielding against RF and tray magnetic fields.

 

Specifications

Audio circuit type:	Active operational amplifier
Frequency response:	RIAA curve
Total harmonic distortion (THD+N):	0.008%
Dynamic range:	91dB
Input impedance:	47K Ω
Maximum input:	-21dBu
Gain:	35dB
Clip level - output:	+12dBu
Output impedance:	400 Ω
Equivalent input noise:	-79dBu
Noise floor:	-79dBu
Intermodulation distortion:	0.04%

Features

Controls:	Low pass cut off
Switches:	Low pass ON, power
Low-cut filter:	20Hz to 500Hz
Filter Slope:	12dB / Octave