H-1500 II PLUS RIAA Phono stage

◈ PRINCIPAL FEATURES

⊙ LCR TYPE RIAA EQUALIZATION

  RIAA Equalization is specification for the correct playback of vinyl records, established by the
  Recording Industry Association of America.  The purpose of the equalization is to permit longer
  playback times, and improve sound quality.

  RIAA equalization is a form of pre-emphasis (in the recording process) and de-emphasis on
  playback.

  A record is cut with low frequencies reduced ( to conserve groove width and allow greater
  the surface noise also).  The result is a flat frequency response.  There are four types of de-
  emphasis method on playback.

   A. Active filters (Negative feedback type)

     ● Different quantity of negative feedback applied.  Deeper feedback to high frequencies
        and shallower to low frequencies.
     ● Improved S/N Ratio, low cost and consistent operation.
     ● Looser bass reproduction and possible a pinched and compressed high frequency
        playback due to excess feedback ratios.

   B. Passive filters (CR type)

     ● The frequencies filtered to fit that of the RIAA by varying the amount of attenuation
        at different frequencies through a complex resistor-capacitor network.
     ● No voltage overload, purer reproduction form no feedback, and more accurate RIAA
        compensation.
     ● No gain, insertion loss and impedance matching problems.

   C. Hybrid filters (CR and Nega type)

     ● Use of two type filters to low and high frequencies separately (Active filter to low
        frequencies and passive to high frequencies).
     ● The advantages and disadvantages of two types shown up at the same time.

   D. LCR filters of H-1500 II SE

     ● Two pieces of linear reactor (a kind of choke coil) comprises main parts, assisted
        by precise RC filters to lower impedances and insertion loss.
     ● In vacuum tube circuits, active and passive filters usually are operated on hundred
        some kilo ohms of impedance, LCR RIAA filter's impedance is 600 ohms constant!
        Lower the impedance, more dynamic and more detailed reproduction.
     ● Furthemore, LCR RIAA filter's series resistance, less than 13 ohms (Tango's 31 ohms)
     ● But LCR RIAA unit drawbacks are high cost, difficulty of impedance matching which
        has been the hindrance of commercialization of superb unit and its phono stage
        amplifiers.
     ● ALLNIC manufactures itself the LCR RIAA Unit of high quality and develops
        the 600 ohms impedance matching method even without coupling transformer, the result
        is the H-1500Ⅱ SE Phono Stage.
     ● For the higher signal to noise ratios the H-1500Ⅱ Plus  is equipped with high speed
        automatic voltage regulator of pure vacuum tubes for each channel and with separate
        power supplying unit.
     ● For MM/MC dual Input, high quality MC Step-up Transformer with Permalloy PC core
        included.
     ● Patent pending Tube Damper sockets are used for perfectly blocking any vibration
        or any microphonic noise.
     ● Non-negative feedback circuit secures pure sound reproduction without coloration.

 ⊙ Two MC inputs and two MM inputs.
   You can connect four cartridges at a time.

◈ SPECIFICATIONS

⊙ Frequency[RIAA] : 20Hz ~ 20KHz (±0.3db)

⊙ Voltage Gain : +40db (1KHz) MM
                +66db (1Khz) MC

⊙ Input Impedance : MC upto 117Ω
                MM 47kΩ

⊙ Maximum Input Voltage (MM, Non-clipping) : 20Hz / 30mV
                                     100Hz / 100mV
                                     1KHz / 240mV
                                     10KHz / 280mV

⊙ THD (Total Harmonic Distortion) : Less than 0.17% (1KHz, Output 1V)

⊙ Output Impedance : 430Ω(On - off method)

⊙ S/N Ratio : -86db (CCIR, 1KHz)

⊙ Tube : 5842 Ⅹ 6, E282F Ⅹ 2
         7233 Ⅹ 2, 6485 Ⅹ 2 (Automatic Voltage Regulator)
         5AR4 Ⅹ 1 (Rectifier)

⊙ Dimensions : Amp / 430mm Ⅹ 275 Ⅹ 118 (WⅩDⅩH)
              Power supply / 170mm Ⅹ 275 Ⅹ 118 (WⅩDⅩH)

⊙ Power Consumption : 70W / 220V / 60Hz

⊙ Weight : Amp / 6.8Kg
           Power supply / 6.0Kg