Aum Acoustics LDR Based
Passive Preamplifier
With 5V USB Power Circuit

 

LDRbw1

The Finest Passive Preamplifier Available Today!

CUSTOM, HAND BUILT, EXQUISITE, REMOTE CONTROLLED, LED DIGITAL DISPLAY, LDR BASED, 2 INPUTS, 2 OUTPUTS, SINGLE-ENDED WITH FURUTECH FP-901 CHASSIS JACKS, SILVER, GOLD, & PLATINUM WIRING – VERY UNIQUE STATEMENT QUALITY SOUND

These truly are collectors items. It takes about 60 hours to build one of these units. It also has taken about $4,000 in R&D cost to explore the parts and wire used for this build.

I’ve been building custom tube and solid state amplifiers for many years. My greatest roadblock has been the lack of a transparent high quality volume control. I’ve used carbon pots, stepped attenuators, transformer based, resistor based, and finally LDR based volume controls. Finally, I’ve created the volume control unit that I’ve been dreaming of! This unique passive preamplifier far exceeds my aspirations and I now have a volume control design that can be used to improve the sound quality of most any audio system. That was my goal and I also wanted to share this success with a few additional people. This is the reason for investing time and money to create these four units for sale.

THE LACK OF A HIGH QUALITY VOLUME CONTROL IS THE LARGEST ROADBLOCK IN HIGH END AUDIO

No matter how good a power amplifier circuit, it’s biggest limitation is and has been the restriction imposed by a carbon pot, a stepped attenuator, a digital volume control, or most any other method of adjusting volume.With the introduction of the Aum Acoustics Version 2 Volume Control unit, this stumbling block has been eliminated. You will not find a cleaner, more transparent, and more detail exposing volume control anywhere (active or passive). Unless there is a substantial impedance mismatch between this volume control and your power amp, you will not find a better volume control solution.

I’ve included information below regarding the research and design that has led up to the release of this upgraded Version 2 unit. Please let me know if you have any questions. You can find the design, R&D, and build story for this preamplifier on this webpage: Aum Acoustics Preamplifier Story. The key to the incredibly superb sound of this unit is a combination of it’s unique chassis design (using extruded aluminum panels that are 1/8″ thick with 1/2″ wide integrated ribs for strength and vibration control, the use of 4 pairs of Furutech FP-901 RCA chassis jacks (providing an increase in quality over typical rhodium or gold plated brass slug jacks), and a unique combination of three exotic metal wire types used for connecting all internal components in this unit.

Through the inclusion of gold, silver, and platinum wire, a sonic presentation is made available that is unique to the Aum Acoustics volume control unit. Nothing comes close to the positive sound quality presentation of this combination of exotic metals.

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SPECIFICATIONS

SELLING PRICE = $2,995

  • Chassis outside dimensions are 12″ wide x 8″ deep x 2 1/4″ high without feet
  • LDR based volume control circuitry using Tortuga Audio’s master controller board, encoder board, LED display and switching IO board. Total cost for these 4 components is $380
  • Chassis is solid 1/8″ thick custom CNC’d aluminum – very heavy vibration damping design
  • Side walls are extruded aluminum with ribs for increased strength and vibration control
  • All chassis parts are black hard anodized aluminum
  • Chassis AUM logo and RCA jack labels are engraved into the black anodized coating
  • High quality volume knob can be upgraded if desired (6mm shaft, guitar style knobs)
  • 2 chassis compartments to keep power supply isolated from sensitive input & output circuitry
  • 2 switchable inputs (via encoder volume knob or Apple remote control wand)
  • 2 outputs – one solid silver and gold wiring & one with solid silver, gold, and platinum wiring
  • 4 pair of Furutech FP-901 chassis jacks – the absolute best sounding best built jacks in the world
  • All internal hookup wire (deluxe output jack pair includes platinum wire) is either high purity solid silver (cotton covered ) or 7N purity OHNO cast solid silver mixed with gold wire (in air dialectic not Teflon) plus solid custom 99.999% bare platinum wire.
  • Custom and fully tweaked 12VDC supply for powering the LDR circuitry
  • Custom and fully tweaked 5VDC supply for providing clean USB power to an external USB to S/PIDF converter. (This circuit “snips” the 5VDC power that comes from your computer’s USB cable shunts it to ground through a 500 ohm resistor and then inserts (into the 2nd USB out cable) the clean 5VDC power that comes from the custom internal power supply included in this unit. The data from your computer’s USB cable is routed from the USB IN to the USB OUT cables untouched. It is the super clean power coming from this power supply (inserted into the 2nd USB OUT cable) that makes the huge sonic difference when then connected to an Audiophilleo AP2 USB to SPIDF converter, a SOtm USB to SPIDF converter, or other converter that is powered via the USB cable. Or, you can just clean your USB power if you’re connecting a USB cable direct to a DAC’s USB port. Connecting a converter is optional but recommended for many DACs.
  • One USB IN (Male A) and One USB OUT (Male B) for USB power supply connection
  • Very high quality side mounted 20 amp LTW bright red push style on/off switch
  • On/Off, input selection, balance, brightness all controlled by either encoder knob or hand held remote
  • Front panel LED display (standard is yellow but optionally available in other colors)
  • Apple aluminum hand held remote is required for remote operation but not included
  • Vibration damping feet are 3/4″ high x 1 1/4″ wide and half sphere in shape
  • 10K output impedance will match most any power amplifier (solid state or tube). This can be custom adjusted by Tortuga if desired.