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Precio SOUND (IVA Inc.):
H-1500 II PLUS LCR Phono Stage
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.
⊙ 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)