Louder Than Liftoff

Pentode Tube Saturation Colour


  • Fully Assembled

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

There something so visceral and satisfying about listening to audio reproduced by a tube circuit. Pentode increases the perceived loudness of your source by saturating the transients (audio sorcery!) and adding musical 2nd and 3rd order harmonic distortion. As the ratio of RMS to peak energy grows by turning up Colour's Saturation knob, sonic density is magnified, volume is increased, and the sound becomes gigantic. That's why we like to call Pentode a Gigantifier!

-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.


  • 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. 

Real analog plugins.

Colour is a new format for analog audio gear designed for and by the DIY community. We took our favorite sounding analog circuits and put them on modules that are small, affordable, and swappable.

The Colour format consists of Colours and Palettes:

Colours are ultra-compact, pluggable analog circuit blocks that impart various types of analog color. Check out our ever-growing selection of Colours. Colours can be designed and released by anyone.

Palettes provide controls, power, and support circuitry for Colours. We currently offer the Colour 500 Palette and CP5 Mic Preamp with Colour.

Customer Reviews

Based on 7 reviews
Not sure about the tone on this one

Was excited to see a tube colour module, however after spending a good amount time with a pair of these, I decided to sell them. I find that the tone is on the harsher side than many triode circuits that I've heard, most of which have that nice round midrange sound. It will reduce dynamics without dramatically coloring the signal, but when pushed I find the sound harsh rather than warm. I honestly can't say if this is due to pentode vs. triode, available power, or the physical size of the tube compared to say, a 12AX7.

Rob schnapf
Pentode is my favorite colour

I think I own 6 different colour modules now and this one is my favorite.
Slowly dial in the sweet spot for each track.
As you start to saturate it it darkens nicely.
Love it in the mic pre and really dig it in the new colour modules with the transformer.
For me It really seems to be the most flexible of the modules as it has such a wide range of sonic usefulness.
It's not just a distortion box. It is a very capable module and I'm glad I got two of them.....

Top notch

I got two and they sit in my busses since the first day. Drums, bass, keys, horns...
Adds fatness and presence at moderate drive levels and a nice growl without harshness when fully driven.
Everything sounds better through this


This module works on almost anything in a positive way. Even when it is pushed it still won't sound ugly. It has this really cool way of smoothing over the high end while still adding a nice sparkle to things. Try it on mandolin. Do it.

My favorite colour so far

This tool is now my secret weapon to warm about anything. Works perfectly on about 90% of the sounds I get through it (I tried pretty much anything you can think of, electronic basslines, analogue drumachines, acoustic percs, flute, voice... It's always that little touch that is required once you've cleaned and compressed your sound. Im glad I've ordered 2 of th'em along with greyhill switchs, I will be able to work on stereo bus (and therefore save so much time) with this baby as soon as my second channel is assambled. If you are wondering what 3 colours you will choose first, that pentode one should be at the top of your priority list. I would also recommend the (red) cinemag for sure. I am still getting used to the implode Fet comp, I think I will need to move the knobs were I can use them to really unleash it's power. Fun time around anyway, but seriously, you want that one. Now what would be very nice sitting next to the pentode, would be another (bigger) tube that fatten the basses, so you get a bit like a tube pulteq EQ setup.

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