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PH50B Phono Stage with Balanced Outputs

  • Phono stage for moving magnet cartridges
  • Extremely low noise transformerless design
  • Variable low cut filter to eliminate rumble
  • Balanced pro audio +4dB XLR outputs

The Hafler PH50B is a high performance phono stage for moving magnet (MM) cartridges, with the ability to easily connect to HIFI playback systems or pro audio recording and playback equipment. It features a well-defined RIAA curve to preserve the source material and an exceptionally low noise profile for quiet distortion-free operation.

The PH50B is housed in a 14-gauge steel enclosure to shield against radio and electromagnetic interference, with gold-plated input and output RCA connectors that ensure optimal signal transfer and won’t tarnish over time. XLR output connectors provide balanced +4dB professional line level signals for connection to recording interfaces or pro audio systems, so you can digitize your vinyl collection without needing an additional gain stage. Solid state circuitry and a military grade circuit board provide minimal self-noise and cross-talk, and 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 adjustable low cut 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. Lastly, a ground lift switch helps eliminate buzz and hum from ground loops when using the XLR outputs.

The Hafler PH50B is compact, reliable and versatile, with outstanding audio quality that allows you to easily connect to HIFI systems or pro audio recording equipment.

Dial In

  1. Power
    Turns on the PH50B
  2. Low Cut
    Inserts low cut filter into signal path
  3. Variable Low Cut Filter
    Eliminates rumble from excessive bass
  4. Lift
    Activates a ground lift on the XLR outputs to remove buzz and hum

Connect

  1. RCA Inputs
    Connects from the turntable to the PH50B. 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. XLR Outputs
    Balanced XLR outputs allow for connection to pro audio systems and recording interfaces. Selectable between -10dB and +4dB using an internal push-switch.
  4. Ground Lug
    Standard round spade connector for the turntable ground attachment. Features Knurled stainless steel thumbscrew for easy manipulation.
  5. Power
    Connection for the external 15V power supply.

Inside

  1. Low-noise, Ultra-linear Circuit
    To optimize signal transfer, the PH50B 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 are 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 solder joint failure. Also provides excellent shielding against RF and stray magnetic fields.
  5. Adjustable Gain
    The balanced outputs can be set between two different output levels. The default +4dB can be adjusted to -10dB with the switch pushed in.

Specs

Audio circuit type:Active operational amplifier
Frequency response:RIAA curve
Total harmonic distortion (THD+N): 0.008%
Dynamic range:95dB
Input impedance:47K Ω
Maximum input:-21dBu
Gain - RCA:34dB
Gain - XLR:40dB
Clip Level - RCA:+10dBu
Clip Level - XLR:+16dBu
Output Impedance - RCA:400 Ω
Output Impedance - XLR:200 Ω
Equivalent Input Noise:-119dBu
Noise Floor:-84dBu
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

Resources

FAQ

Can I connect a moving coil cartridge to the PH50B?

No. The PH50B is designed for moving magnet cartridges. For moving coil designs, the Hafler PH60B is the proper choice.

What is the advantage of the PH50B over a built-in phono stage?

Unlike most built-in phono stages that are ‘side attraction to the main show’, the PH50B was conceived from the ground up to deliver great sound with low noise for a more exciting and natural experience. The PH50B also features balanced XLR outputs which allow you to connect to a recording interface or a pro audio system for playback.

Can I bypass the RIAA equalization curve inside the PH50B?

No. It is built into the PH50B and is part of the circuit board.

Should I be concerned with the length of the cables I use?

High impedance RCA cables are generally more prone to picking up noise from radio frequencies and magnetic fields. Thus keeping the cables shorter is beneficial. As a rule, try to keep the RCA output cables from the PH50B under 2 meters (6') in length. The balanced XLR outputs on the PH50B are designed to connect to the inputs of a recording interface or a pro audio playback system, with cables up to 100m (300') long.

Why does the Hafler PH50B employ an external power supply?

The low output from a turntable requires a lot of gain to bring it up to a suitable level. This also makes the circuit much more prone to noise. The transformer in a power supply generates hum which if not kept in check can generate noise; moving the power supply outside the casing significantly reduces the problem.

Can I connect the PH50B to my recording interface to transfer my albums?

Absolutely, the balanced XLR outputs of the PH50B can be connected directly to the line level inputs of a recording interface, for easy digital transfer of your vinyl collection.

Does the impedance on my moving magnet cartridge matter?

No. Standards have been established for years with moving magnet cartridges so that they all work within a prescribed range. You simply plug in and you are set to go.