Abacus LDR V2 Passive Preamplifier with Dual Display

Passive preamplifier based on the latest Tortuga Audio LDR3xV.2 board with Auto Calibration, replaceable LDR’s, and USB port for software updates. It uses pairs of microchip controlled Silonex LDR’s to achieve the best in signal attenuation with perfect balance.

Specifications

• Preamplifier Type: Passive unity gain without buffer | attenuation via light dependent resistors (LDRs) in an LPad configuration
• Attenuation Range: -60 dB  to 0 dB in a 70 step attenuation schedule
  
  
• Compatible Amplifiers:  Works best with tube or solid state amps having input impedance of 20k ohms or higher
• Nominal Input Impedance: 20k ohms
  
  
• Control System: Software based (updateable) 8 bit digital micro-controller driving 12 bit digital-to-analog volume control
• Software :  Updateable via download from website and upload via USB cable from PC
• Auto Calibration:  User enabled/disabled self-contained auto calibration of LDRs to correct for drift/aging
• Replaceable LDR Modules: Similar to tubes, LDR modules can be easily unplugged and replaced if warranted
• Display:  Dual numerical displays (blue) providing volume and status information
• Control Methods & Functions:  Remotely  controlled via the elegantly simple Apple Remote | Front panel control via rotary encoder with integral push button switch
  
  
  • Power on/off toggle
  • Volume raise/lower
  • Mute/UnMute (with smooth ramping of volume)
  • Channel balance adjust & reset
  • Display brightness raise/lower
  • Channel input select
  • Auto calibration start/stop
  • Remote pairing (enabled via encoder bush button only)
  
  
• Input Switching:  Audio signal switching done via high quality relays
• Power Supply: 12V DC Wall-wart type universal power supply
  
  
• 12 Volt Trigger Out: Heavy duty chrome plated through-hole threaded phone jack provide 12 volt signal when unit turned on
• USB Port:  For updating control software if warranted.
• Inputs/Outputs: 
  
  
  • Inputs: 3 unbalanced RCA inputs
  • Outputs: 1 parallel unbalanced RCA outputs
  
  
• Audio Connectors: Nerve Audio Copper RCA
• Audio Wire: #24 silver coated Teflon wire.
  
  

1 year limited Abacus Music warranty.

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