Phono Equalizer Unit AD-2850

Phono Equalizer Unit AD-2850

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Phono Equalizer Unit AD-2850

AD-2850 is the dedicated phono equalizer unit. Analog records can be reproduced with high quality by installing AD-2850 in a rear-panel slot. The AD-2850 features separate input circuitry for MC and MM cartridges to ensure optimum matching and realize outstanding S/N ratio. 2 sets of analog-player input jacks, the AD1 and AD2 are equipped, and their selections are switchable with the INPUT selector of pre-amplifiers.

  • Differential amplifier circuit with ultra low noise bipolar-transistors for MC cartridges.
  • Differential amplifier circuit with ultra low noise junction-FET for MM cartridges.
  • Differential RIAA equalizer circuit is designed to provide super accurate RIAA equalization characteristics.
  • MC Load settings are selectable from among 4 values “10Ω/30Ω/100Ω/300Ω”. The input impedance for both MM settings is 47kΩ.
  • Storing separate MC Load and/or AD GAIN settings for each installed AD input (AD1 and/or AD2) is available, and it enables the smooth switching of 2 kinds of analog players or tone arms.
  • The printed circuits are made from glass cloth fluorocarbon resin.

 

Guaranteed Specifications [Guaranteed specifications are measured according to EIA standard RS-490] (Specifications installed in C-2850)

 

FREQUENCY RESPONSE

MM/40dB, MC

20~20,000Hz ±0.2dB

MM/30dB 

20~20,000Hz ±0.3dB



AD MAXIMUM INPUT VOLTAGE (1kHz, 0.005% THD)

MM/30dB INPUT   310mV
MM/40dB INPUT 96.5mV
MC/60dB INPUT 9.5mV
MC/70dB INPUT 3.2mV

 

GAIN (GAIN SELECTOR SET TO 18dB POSITION, 12/18/24 dB SETTINGS AVAILABLE)

 

AD[MM:30/40dB]INPUT → BALANCED/LINE OUTPUT 48/58dB
AD[MM:30/40dB]INPUT → REC OUTPUT : 30/40dB
AD[MC:60/70dB]INPUT → BALANCED/LINE OUTPUT : 78/88dB
AD[MC:60/70dB]INPUT → REC OUTPUT : 60/70dB



 

INPUT SENSITIVITY AND IMPEDANCE

Input Input Sensitivity Input Impedance
For Rated Output For 0.5V Output
AD-MM/30 dB INPUT 8.0 mV 2.0 mV 47 kilohms
AD-MM/40 dB INPUT 2.5 mV 0.63 mV 47 kilohms
AD-MC/60 dB INPUT 0.25 mV 0.063 mV 10/30/100/300 ohms, switchable
AD-MC/70 dB INPUT 0.08 mV 0.02 mV 10/30/100/300 ohms, switchable
BALANCED/LINE 252 mV 63 mV

40/20 kilohms, switchable

 


SIGNAL-TO-NOISE RATIO

Input Input shorted (A weighting) EIA S/N
S/N ratio at rated output
AD-MM/30 dB INPUT 94 dB 86 dB
AD-MM/40 dB INPUT 85 dB 86 dB
AD-MC/60 dB INPUT 80 dB 86 dB
AD-MC/70 dB INPUT 73 dB 87 dB
BALANCED/LINE 111 dB 110 dB


AD-2850 CIRCUIT DIAGRAM (ONE CHANNEL)

A major feature of the AD-2850 is the use of a balanced configuration or the internal circuitry. Separate input stages optimized for MC and MM cartridges respectively bring out the best performance from every cartridge. When using the MM input, high output impedance matching is achieved by means of a low noise FET configuration. By contrast, the MC input needs to handle very low-level signals with low input impedance. This is realized by the use of a differential input circuit with low-noise bi-polar transistors together with a low-impedance NFB loop, resulting in playback with minimal noise. Also, the built-in differential RIAA equalizer circuit with using high-precise components for both feedback side and ground side is designed to provide super accurate RIAA equalization characteristics. The MC input impedance can be switched to 10, 30, 100, or 300 ohms, while the MM input impedance is fixed to 47 k ohms. In addition, the gain can be set to 60 or 70 dB for MC and to 30 or 40 dB for MM. All of these functions are controlled with switches on the front panel of pre-amplifiers. Operation convenience therefore is exactly the same as when using a pre-amplifier with built-in phono equalizer.

                             

            Printed circuit boards used in the AD-2850

 


COMPATIBILITY

COMPATIBILITY WITH OTHER PRE-AMPLIFIERS (C-2820/C-2420 etc)

The AD-2850 can be used in the models C-2820/C-2810/C-2800/C-2420/C-2410/C-2400/C-290V/C-290. However, the 300 ohm position for the MC impedance can be used only in the models C-2850/C-2820/C-2420, because other models have no corresponding selector position on the front panel. Also, the actual gain will be different from the indication of the AD gain selector knob as follows. MC: 60dB, 70dB, MM: 30dB, 40dB.

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