LDR1B.V25K Balanced Passive Preamp Kit

LDR1B.V25K Balanced Passive Preamp Kit

Price: $1,095

This is a legacy product and is no longer produced or sold by Tortuga Audio.

The LDR1B.V25K is a complete balanced passive preamp kit built around a pair of Tortuga Audio V25 preamp controller boards, orderable with either a single XLR input & dual outputs, or dual inputs & a single output. All circuit boards are provided fully built and tested — no soldering of components to circuit boards required. The kit includes everything needed to assemble a complete audiophile grade balanced passive preamp: enclosure, front/rear panels, graphic OLED display, XLR jacks, power supply, manual encoder/knob, remote, and wire.

The kit is sonically identical to the LDR1B.V25 Balanced Passive Preamp that Tortuga Audio sold as a finished product, built around the same V25 preamp controller board — that page is the technical reference for the electronics themselves.

Kit vs. finished unit

The differences between the base kit and the non-kit LDR1B.V25 are:

  • Front panel — the kit’s is acrylic, where the finished unit uses brushed anodized aluminum with an acrylic inlay

  • Hookup wiring — the kit uses MilSpec silver-coated stranded copper wire (Neotech UP-OCC available as a paid upgrade), where the finished unit uses Neotech UP-OCC solid copper hookup wire standard

What’s included

Qty Item

2

LDR.V25 preamp controller board

1

2.95" x 6" x 8" black powder coated extruded aluminum enclosure box

1

0.25" x 2.95" x 6" see-through dark acrylic front panel, cut for the encoder and knob

1

0.08-0.10" x 2.95" x 6" black anodized rear panel, cut for jacks

1

Knurled black enameled Fender Telecaster-style encoder control knob

4

Peel-and-stick urethane rubber feet

3 pair

XLR jacks (1 input & 2 outputs, or 2 inputs & 1 output)

1

DC power jack

1

12 VDC trigger-out phono jack

8

Sets of socket head black oxide sheet metal screws with washers (front/rear panel)

1

External "wall-wart"/"brick" 12 VDC power supply, 120 or 240 VAC

1

4-conductor cable, encoder to display module

1

Ribbon cable, display module to V25 board

1

Rotary encoder module with nut and washer

1

Blue master display board with IR receiver module soldered in place

1

Blue slave display board

1

Ribbon cable, master to slave display module

1

Display module mounting bar (plastic angle)

4

Sets of nylon threaded rods with nuts & washers for the master display mounting bar

1

USB cable, V25 USB port to rear panel

10 ft

White #24-26 gauge silver-coated copper wire (audio hookup)

1 ft

Red #20 gauge silver-coated copper wire (power hookup)

1 ft

Red #26 gauge silver-coated copper wire (trigger hookup)

1 ft

Black #20 gauge silver-coated copper wire (power hookup)

1 ft

Black #26 gauge silver-coated copper wire (trigger hookup)

3 ft

Green #20 gauge silver-coated copper wire (audio ground hookup)

1

0.060" x 5.7" x 8" FRP mounting board

10

#4 threaded hex stand-offs (mounting the V25 board and ground bar)

20

#4 screws for the mounting stand-offs

2

#4 screws for mounting the display bar to the board

2

#4 nuts for mounting the display bar to the board

1

Apple remote

4

Power connector wire crimps

2

2-pin power connector shells

Optional: 5 ft of Neotech 26AWG UP-OCC solid copper wire, in place of the standard hookup wire.

Not a difficult kit to build, but balanced wiring takes care

On a scale of 1-10 (10 being expert level), this kit was rated around a 4-5 difficulty level — higher than the single-ended LDR3.V25K, because getting the point-to-point XLR wiring right requires care. It’s straightforward, but the complexity of balanced wiring can trip up a novice (and an expert whose mind wanders).

In addition to the kit itself, building it requires:

  • Solder

  • Soldering iron

  • Allen (hex) wrench for the socket head screws that attach panels

  • Wire strippers

  • Wire cutters

  • Small screwdrivers (regular and Phillips) for stand-off screws, encoder knob, etc.

  • Wrenches and/or sockets for tightening the jack nuts

Assembly instructions specific to this balanced kit were never published — only instructions for the very similar single-ended LDR3.V25K kit, most of which apply here too.