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. 

Customer Reviews

Based on 12 reviews

love it

Harry Do
One of the best colour modules

I'm looking forward to getting my second one to complete the set. This module is super musical and gives that feeling of rock and roll that we hear from guitar amps. It's definitely made my music sound better.

Jacob Seal
An "always on" unit?

Just got the module installed. Started out with bass guitar. Fat mode, EQ bypassed.

First, I wanted a bit more so I raised the input gain by about 25 percent.

OMG this thing rocks. I had a bass track where I used Soundtoys Little Radiator for some tube grit. I replaced it in the chain with Pentode....and Pentode crushed! It is smooth and subtle or really obvious....but always pleasant with good harmonics and the subtle clipping that good saturation should have.

Also sounded great on kick. On snare I am not sure it did enough extra to be worth it....but I only tried it on a Slate sample which is basically already processed. It may work better on a from scratch mix.

I will be installing switches so I can access the jumpered features. So far I have not tried the EQ or the rich mode.

I can't wait to try this on vocals.

On bass I was really liking the Neve color about 50 percent with 4.7k on, directly into Pentode. Beautiful sound!!

Sounds good on.. everything?

Rocking the fat setting with a tiny high boost and tiny low cut to balance out the 15ips I have next in the chain. Tracking guitar and bass through this has made recording so much more fun. Together with the 15ips, they compress everything so nicely and are just the sound I was looking for. Stoked.

Versatile, glue-like

Compared to some of the other modules this might be one of the more "invisible" ones as the core sound goes- and yet, I've found it can do a super great job of getting guitars, snares, even vocals to sit. Pushed, it definitely compresses, and pushed super hard the tube starts to show though leans brighter. It's a little more obvious in the fat setting, but most of my testing has been in rich, which is my preference overall for the sources listed above. I imagine it's probably amazing with bass on the fat setting. The Bax EQ is also super useful and wonderfully musical sounding- m/s processing it can really widen or open things up a bit. Over the master bus it performs an amazing glue and I will be committing all my mixes through it henceforth. I don't have a lot of outboard gear, and I heavily recommend anyone who's in a similar position grab this for some of the 3D-ness soft stuff can't seem to replicate.. though in a bunch of chromas or mister focus' I could see studios of any size benefitting. Gain staging with this one is very important (as is for all of them but y'know.)

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