A Balanced Passive Preamp
The LDR1B.V25 Balanced Passive Preamplifier is a remote controlled balanced audiophile grade passive preamp (attenuator) with 1 single XLR input and 2 parallel XLR outputs. The LDR1B provides true balanced attenuation with independent attenuation of both phases in each stereo channel. Also, being a true passive preamp, the LDR1B is a unity gain preamp with no amplification or buffering.
The LDR1B.V25 is an updated version of our popular LDR1B.V2 model and its design closely parallels our single-ended LDR3.V25. The updated LDR1B incorporates our new and improved V25 preamp controller that uses LDRs (Light Dependent photoResistors) for exceptional audio performance.
Enthusiasts who value a dead quiet preamp with a deep dark background between the notes, exceptional transparency, and pleasing dynamics, will find the LDR1B.V25 to be a very satisfying preamp rivaling many high end peamps at a fraction of the cost. And it comes with a simple remote control so you can relax and enjoy your music in comfort from your favorite listening spot.
The LDR1B.V25 comes in black or silver anodized front panel and uses high quality Neutrik XLR jacks with Neotech OCC solid copper point-to-point hookup wire.
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Colorless, transparent, neutral, articulate, clear, fuzz-free, clean, natural, high resolution, great mid-range, solid bass. These are words and phrases commonly used by both customers and reviewers to describe the LDRx passive preamplifier sound.
Compared To Other Passive Preamps
The consensus of customers and reviewers is you can expect performance that is superior to conventional passive preamps utilizing even the best audiophile grade potentiometers, stepped resistive attenuators or even most transformer based volume controls.
Compared To Active Preamps
Independent reviewers have found that the Tortuga passive preamps match the performance of high-end active preamps costing many thousands of dollars more.
Key Features Under The Hood
True Balanced Attenuation
Each phase of each channel is independently attenuated. There is conversion, conditioning, or processing of the audio signal aside from each signal phase passing through an L-Pad type voltage divider composed of 2 LDRs in a classic series-shunt configuration.
Optically Isolated Passive Attenuation
There’s no amplification or buffering of the audio signal notwithstanding the presence of a power supply used solely for photoresistor control and input switching. Audio signals are optically isolated from both the power supply and the LDR control circuitry.
4th Generation LDR Technology
Built with our most advanced V25 preamp controller which employs microprocessor controlled analog Light Dependent photoRresistors (LDRs) to provide audio attenuation and input switching with unparalleled audio quality.
Built-in LDR Calibration
Employs self-contained calibration of the 4 attenuation LDRs to maintain accurate attenuation schedule and channel balance and ensure that the preamp will hold its value over the long haul as the LDRs age.
Replaceable Plug-in LDR Modules
While the useful life expectancy of LDRs are estimated to be upwards of 50,000 hours, just like tubes, some may fail earlier or go sufficiently out of spec over time to warrant replacement. And just like tubes, our LDR Modules are socketed and easily replaceable ensuring the lasting value of your passive preamp investment.
No Relays In Signal Path
LDRs are also used for audio input switching in lieu of relays. Auto Calibration does employ relays but these are physically disconnected from the audio signal path during normal operation.
Firmware Updates via USB
If warranted, control system firmware can be easily updated by the customer via a USB port located on the rear panel. Firmware updates can downloaded from our website and uploaded into the preamp from a laptop or desktop PC (not currently compatible with MACs).
Key Changes in the V25 Model Compared to V2
- Overall smoother, quieter, and more resolving attenuation | 100 vs.70 steps
- Major improvements to LDR controls and auto-calibration of the LDRs
- Faster more powerful processor with expanded memory for future features/upgrades
- Quieter power supply design with low noise 2 stage DC-DC regulation
- Input switching integrated into main control board to minimize interface points
- Provision for future OLED graphical display & WiFi/Control module