LDR V25 Preamp Controller Scheduled for April Release

V25 Preamp Controller To Succeed the V21

February 9, 2017 – Today, Tortuga announced plans to release the LDR V25 preamp controller (the “V25”) as the successor to its popular V2/V2.1 model that has anchored its award winning line of passive preamps since first being introduced to the market back in May 2014.

The V25 is a software driven audio preamp controller, attenuator and source input selector. The V25 allows the audio hobbyist, professional designer or OEM to build exceptional high performance passive and active audio preamps that rival the best high end preamps available today regardless of price.

Like its predecessors (the V1, V2 and V2.1 preamp controller) the V25 utilizes light dependent resistors (LDRs) to control volume. Tortuga Audio’s LDR based volume control technology is now in its 4th generation and delivers a level of sound quality that once you experience it you won’t want to go back to conventional potentiometers, stepped attenuators or even transformer based volume controls.

The V25 preamp controller utilizes a software driven 32 bit digital processor to control multiple analog LDRs using multiple digital-to-analog converters (DACs). The V25’s power supply is used solely to power the processor, regulate the resistance level of the LDRs and handle the IR remote communications.

Notwithstanding that the LDRs are actively controlled, the V25 is fundamentally a passive attenuation device wherein the power supply is optically isolated from the the audio signal which only “sees” the LDRs as simple passive resistors.

The V25 is a unity gain attenuator and provides no amplification of the audio signal.

More info on the V25 can be found here.

On The Road to the V3

The V25 grew out of development work on Tortuga Audio’s next generation V3 preamp controller. The V3 is a highly ambitious design that while very far along in terms of its hardware development requires substantial additional software development before it’s ready. Rather than wait any longer for the V3, Tortuga Audio decided to adopt elements of the V3 design that are fully developed and move forward with the production of the V25.

Work on the V3 remains ongoing.

An Improved LDR Preamp Controller

The V25 is an updated preamp controller design with numerous improvements over it predecessors including:

Integrated Input Switching & Simplified Signal Path

The V25 has a simplified signal path that accommodates switching between up to 6 different sources within a single circuit board and no longer depends on an external switching board with multiple interface points.

LDRs Used As Switches

The V25 preamp controller uses LDRs in lieu of conventional electromechanical relays for all input source switching.

More Powerful Processor

The V25 employs a contemporary 32 bit ARM Cortex M3 processor which has plenty of speed and capacity to power the Tortuga Audio line of preamp controllers as they continue to evolve and improve.

Precision LDR Control with 5 DACs

The V25 employs 5 separate 12 bit DACs in an improved high precision control scheme that ensures smoother, more granular and more accurate attenuation.

Mono Mode

The V25 introduces the ability to switch between stereo and monaural listening modes.

Balanced Audio Phase Reversal

The V25 preamp controller enables the user to optionally reverse the signal phase of balanced audio sources as a means of optimizing playback of any piece of music.

A More Refined Attenuation Curve

The V25 has a more granular attenuation curve with 120 steps representing 0.5 dB per step over the 60 dB attenuation range.

Hands-off Self-Calibrating LDRs

The self-contained LDR calibration process introduced with the V2 model has been refined to operate entirely in the background in the V25 and requires no user interaction. This built-in self-calibration feature ensures the the LDRs remain calibrated and perform optimally at all times.

Improved Power Supply

Even though LDRs on the V25 are optically isolated from the audio signals they control, overall sound quality benefits from improved power supply quality with a lower noise floor.

Networking of Multiple Boards

Multiple V25 preamp controller boards can be networked in order to control more than just 2 stereo channels. Initially this will be limited to connecting a pair of V25 boards for balanced stereo audio. Further development of the firmware will enable additional boards to networked together.

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