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Herron Audio VTPH-2 Tube Phono Preamp
The Herron VTPH-2 phono preamplifier was created to address the retrieval of musical information from vinyl LPs without any compromise. The original design was only intended for use by a few dedicated music lovers in their cutting edge audio systems. The design was so good, and the demand so high, that the unit was refined and engineered to meet the requirements for a more durable unit manufactured in larger quantities. In the process, important refinements were developed and discoveries were made about tolerances and the threshold of human hearing limits.
Cartridge Loading Details
The moving-coil inputs can be loaded to a particular cartridge specification by externally connecting the appropriate resistors using the "MC LOAD" RCA connectors on the back of the unit, or they can be internally soldered at the MC INPUTS circuit board (this should only be done by a competent technician). The moving-coil inputs have no load resistors installed unless specified by the customer when the unit is ordered from Herron Audio. We recommend trying the VTPH-2 in the no-load configuration as the unit is supplied for most moving-coil cartridges. 47,000(47k)ohm RCA load plugs are supplied with the unit for optional use. Additional user specified loading plugs can also be purchased with the unit. The moving-magnet inputs are factory loaded at 47,000(47k)ohms, 100pF (standard loading for moving-magnet cartridges).
Herron VTPH-2 Features
Switchable moving-coil and moving-magnet operating modes with separate input connectors for each
Additional RCA connectors for external moving-coil loading
Cartridge biased moving-coil input stage allows for infinite load resistance (operation with MC cartridge totally unloaded)
Class A operation
Passive RIAA equalization for accurate phase and amplitude response
Reversing power line (AC) polarity switch for minimizing line-to-chassis reactive currents and noise pickup
Low plate operating currents and controlled warm-up for cool operation and extended tube life
Low noise
No mechanical switches in the signal path
Zero feedback, no feedback loops in the audio circuitry
Gold plated RCA and ground connectors
Audio path capacitors are high quality film type
Hand-picked components for accurate response
Automatic muting at startup, shutdown, and mode selection
Four levels of high voltage regulation
Regulated soft-start DC filament and high voltage supply
Regulated tube bias supply
Toroidal power transformer
Front panel indicators for power, voltage, and output (mute release)
Available in silver or black
Herron VTPH-2 Specifications
Tube complement: (2x12AX7, 3x12AT7) or (4x12AX7, 1x12AT7)
Gain MC Mode: (2x12AX7, 3x12AT7) 64dB or (4x12AX7, 1x12AT7) 69dB
Gain MM Mode: (2x12AX7, 3x12AT7) 43dB or (4x12AX7, 1x12AT7) 48dB
Frequency response: RIAA 20Hz to 20kHz ±0.1 dB
Signal-to-Noise Ratio: 80dB, A weighted
Output impedance: 500ohms nominal (12AT7 "V5" dependent)
Input impedance: infinite with no load resistors connected
Note: load resistors can be connected externally via RCA connectors or soldered internally
Absolute polarity: non-inverting (all modes)
Power requirements: standard IEC connector, most international voltages available
Overall dimensions: 17.6"Wx4"Hx10"D
Warranty: 3 years, parts and labor; tubes: 90 days
HiFi Review of Herron VTPH-2
The Herron VTPH-2 gives listeners all the benefits of a tube unit with few of the failings and a text-book technical performance to boot. It offers a level of vacuum-tube engineering (carefully combined with solid-state circuitry) that's rare at any price, unheard of at this one.
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