ACCUPHASE AD-2820

              

                  
Gramofonový ekvalizační zesilovač
    

          

    
                

                        

                                
                    
                      ACCUPHASE AD-2820
                    
                                         
                      
                                    
                            

              
              

                      

        

          

                        
 

                                    

              

                                

                  
                  
                  
                  
                  
                                      

                      Číslo produktu: 
                      
                            7030
                        
                      
                    

                    
                      
                

                              

            

            

          

        

              

    

    

        
    

              
            

    
          

          
    

    
    

    

    
The AD-2820 uses printed circuit boards made from glass cloth  fluorocarbon resin, housed in a sturdy aluminum enclosure to minimize  any kind of external influence. The input terminals are connected to the  amplification circuitry by the shortest possible route, realizing  outstanding signal/noise ratio. The use of a DIN standard connector for  the link to the host component provides enhanced reliability.


    

  • The AD-2820 is a modular unit designed for use in the C-2820 preamplifier.
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  • All functions are controlled from the front panel of the C-2820.
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  • The INPUT SELECTOR allows selection of AD-1(OP) or AD-2(OP).
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  • The AD switch allows gain selection of MM 30 dB, MM 40 dB, MC 60 dB, or MC 70 dB.
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  • The MC LOAD (OHMS) switch allows setting the MC cartridge  load impedance to 10, 30, 100, or 300 ohms. The selected position is  stored in an internal memory for each switch.
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Guaranteed Specifications [Guaranteed specifications are measured according to EIA standard RS-490] (installed in C-2820)


Frequency response


MM/40dB, MC ?20?20,000Hz ±0.2dB


MM/30dB        ?20?20,000Hz ±0.3dB


AD maximum input voltage (1 kHz, 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 18 dB 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-2820 circuit diagram (one channel)

AD-2820 circuit diagram

A major feature of the AD-2820 is the use of a  balanced configuration for 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 (Q1, Q2, Q3,Q4, Q5, Q6). By contrast, the MC input needs  to handle very low-level signals with a low input impedance. This is  realized by the use of a differential input circuit with low-noise  bipolar transistors (Q7 to Q10) together with a low-impedance NFB loop,  resulting in playback with minimal noise. The MC input impedance can be switched to 10, 30, 100, or 300 ohms,  while the MM input impedance is fixed to 47 kilohms. In addition, 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 the host  component. Operation convenience therefore is exactly the same as when  using a preamplifier with built-in phono equalizer.


Printed circuit boards

Printed circuit boards used in the AD-2820





Compatibility


Compatibility with other phono equalizer units (AD-2810/AD-2800 etc.)


The AD-290V/AD-290 designed for the C-290V/C-290,  as well as the AD-2810/AD-2800 designed for the  C-2810/C-2800/C-2410/C-2400 can be used as is in the C-2820. However, selecting the 300 ohm position for the MC impedance will have  no effect, because this function is not supported by the older products.  Also, the actual gain will be different from the indication of the AD  gain selector knob, as follows. MC: 62 dB, 68 dB, MM: 30 dB, 36 dB.


Compatibility with other preamplifier models (C-2810/C-2410 etc.)


The AD-2820 can also be used in the models  C-2810/C-2800/C-2410/C-2400/C-290V/C-290. However, the 300 ohm position for the MC impedance cannot be used,  because there is no corresponding selector position on the front panel  of these models. Also, the actual gain will be different from the  indication of the AD gain selector knob, as follows. MC: 60 dB, 70 dB,  MM: 30 dB, 40 dB.




Specifications and design subject to change without notice for improvements.
    

  



    
  
  

    
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