Pentode is the first module to bring true tube saturation to the Colour format. True to the spirit of the Colour format, Pentode employs minimal, carefully selected components to achieve a coveted, vintage tone. A single NOS tube running at its true plate voltage is overdriven to produce the musical saturation that can only be described as "tube color."

Design Notes

-Brad McGowan, Designer, Louder Than Liftoff

MKII Improvements

Pentode MkII intensifies vibrant color in the source by adding musical second- and third-order harmonic distortion. Expanding on the design of the original Pentode Colour, the user may now select between one of two tube bias settings to fine-tune the harmonic spectra. The RICH setting presents a lively blend of both even and odd order harmonics, which enhances presence and pulls the sound forward in a mix. This setting configures the tube to deliver the original Pentode tone many have grown to love, especially on guitars and vocals. A new FAT bias setting configures the tube for mostly second-order order harmonics for a thicker, rounder tone. It evokes a more vintage vibe that some may associate with classic tube equipment using triodes.

You can further sculpt the sound and sonic texture with the new two-band Baxandall EQ, which follows the tube stage. The elegant simplicity of this circuit has attracted hi-fi and pro audio designers since its invention in 1952. Revolutionary for its time, it still remains a classic due to its effortless tone bending powers. In our implementation, the Bass and Treble curves, and their unique interaction were inspired by an obscure 1960's tube mixer. We tweaked by ear for optimum musical synergy with the rest of the circuit.

Features

• NOS Raytheon 6418 subminiature tube
• Two bias settings (via jumper): Rich and Fat
• Regulated DC filament supply
• 2-band Baxandall EQ inspired by vintage 1960's tube mixer
  1. Bass and Treble bands individually bypassable via jumper
  2. EQ gain adjustable via trim pots: +/-8 dB
  3. Recommended applications: subtle tube frequency contouring, bus sweetening, mix-ready vocal and guitar presence, big bass
• Class A biased buffers using audiophile grade op amps
• Wima MKP film caps
• Compatible with DIYRE Colour

Pentode is offered fully assembled and tested by Louder Than Liftoff. It and LTL's other Colours will not be available as DIY kits.

Note on Tube Microphonics

There is a real vacuum tube in this thing. One thing that real tubes have that emulations don't is microphonics. Due to the vibration sensitive nature of the 6418 tube, some units may experience a low-level ringing for a couple seconds when the unit is bumped or the bypass/engage switch is pushed. 

Samples

Resources

• Operation Manual