
"The KTBK filter gives exactly what you expect from it, whether on drum tracks, brass, rhythm sections or on a effects return bus."
"It's amazing that something as simple as a HPF brings so much magic to the mix. It has become an essential tool in my day to day."
"What a great job on the unit - sounds amazing! So much fun for the mix. Thanks for the great unit!!!"

An Equalizer with Vintage Flavour for the Modern Studio
For music-quality-conscious people who enjoy the warm character of an analog filter. The King Tubby’s Big Knob (KTBK) provides the same genuine tone as an Altec 9069B, a vintage equalizer, designed in 60s, which enable a great control over the sound tone. The KTBK unit includes two additional switches, a mode selector and a resonance leveler which allows to modify the filter response for adapting it to the modern studio for different phases of the music production workflow.
- Passive LC Filter
- Replica of Altec 9069B aka Big Knob
- 3rd-Order High Pass Filter
- 10 Stepped Cut-off Frequencies
- Mode Selector and a Resonance Leveler
- 3 Modes: BELL, 600Ω, NOTCH
- Designed by Reverse Engineering techniques
- Customized Multi-Tap Inductor
- Robust DSP Validation
- Fully Analog Signal Path
- Handbuilt with Love in BCN
The KTBK filter is a very precise replica of the Altec 9069B adapted for the modern studio with new controls for impedance matching and resonance. It was designed through Reverse Engineering techniques and validated with DSP to achieve the most accurate cutoffs utilising a customized multi-tap coil.

Description and Features
Let's Design the Sound
Tweak the Big Knob to get different tones, textures and an unrivalled sound effect. Allows to remove rumble noise, the parasitic frequencies and muddy sound effect in order to reducing the masking effect and achiving a clear sound. The KTBK Variable Passive High Pass Filter has stepped frequency selection with ten unequally spaced cut-offs offering a crossover type action – 70, 100, 150, 250, 500, 1k, 2k, 3k, 5k and 7.5k. A need when it is required an accurate control of the sound tone.
Multifaceted Equalizer
Passive filters are very sensitive to the impedance matching. Originally, the Altec 9069B was designed to perform with a 600Ω impedance transfer standard and currently modern audio equipments require other values. Our unit includes a mode control switch to be adapted to any equipment, allows to reproduce the original HPF response, or to generate a resonance bell over the cut-off frequency.
Sweep and layer your sounds with the KTBK filter to get unmatched sound signature. Perfect gear to create a dynamic mix with LO-FI tones! The digitalization has changed the way to record, produce and process music. It is time to explore new ways, taking the best of analog and digital domain.
Handbuilt with Love and
a Customized Features
The assembly and subsequent validation of each unit is manually done in our workshop, sited in Barcelona. The multi-tap inductor is a custom-designed element based on various frequency response and phase distortion analyses using different cores and coil winding techniques, in order to get the most accurate cut-off frequencies. The customized stepped rotary switch offers a very smoothed rotation resistance to guarantee the creative freedom during the performance. High quality ELMA rotary switch with proven solvency in the world of professional audio equipment.
New Controls, New Curves
Passive filters are very sensitive to the impedance matching. Originally, the Altec 9069B was designed to perform with a 600Ω impedance transfer standard but currently audio equipments require other values. Our unit includes a mode control switch to be adapted to any equipment, allows to reproduce the original HPF response, or to generate a resonance bell over the cut-off frequency or a variable notch filter, we call it VARI-NOTCH because the attenuation level increases with the frequency.
KTBK Dev Details: When the quality is a must

🔊📣🔔FIRST ALBUM MIXED WITH A KTBK FILTER NOW AVAILABLE AT BANDCAMP
📣 Audio Merge presents AUDIO MERGE in DUB feat. Roberto “Lone Ark” Sanchez and Chalart58. 10 dubs LP mixed with the KTBK passive HPF filter unit.
🔥Available at Bandcamp in ALONEREGGAESHOP & LAPANCHITARECORDS DUBBING IS A MUST!

DO YOU WANT TO TRY
OUR DEMO?
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How Does the KTBK Sounds?
Drums - BELL Mode
Horns - BELL Mode
The Altec 9069B, The Influencer of the Big Knob
At the 60s, Altec Lansing launched the 9069B, a variable high pass filter designed by Arthur Davis. The 9069B was a passive inductor based T-network filter, with toroidally winded inductances which provides 18 dB/oct attenuation with 10 positions for low frequency cutoff to reproduce unmatchable sound tones. Originally it was part of the Altec 9067B unit with the LPF 9068B unit.

A Program Equalizer's Creator

Altec 9069B Passive Program Equalizer

The King Tubby's Sound Signature

The Big Knob, a Secret Weapon

Dub Around the World

The New Vintage Program Equalizer
Big Knob's Testimonials
"The strongest characteristics of the filter's sound are the discrete steps, the clicks and crunches when the frequency is switched, and the phasing effect heard when filtered signals are mixed with the unfiltered originals."
"Often used on Charleston cymbals, snare or the microphones of the voices, it cuts off the undesired frequencies, and gives a clearer sound. You can also use it to eliminate parasitic noises during voice recording, especially during speeches."
Follow our Spotify List with some examples of songs using an Altec 9069B or a KTBK unit >>>
Story
This KTBK adventure has brought us many funny, intense and priceless experiences. Indeed, we want to continue with this and other sonic adventures, and that’s why we want to encourage you to support us in a crowdfunding campaign that we will launch soon, aiming to produce the first KTBK series to you. Subscribe it and let us share with you the main events and details of our research, technical tips and other surprises!
The KTBK Challenge
Our Handmade Coil
The First Prototype
The Audio Merge's Birth
KTBK vs Altec 9069B
A Big Choice
The Crowdfunding Campaign
Team
The KTBK project is initiated by Arnau Muñoz and Xavi Lizarraga, two sound engineers and audio freaks from Barcelona-Terrassa, who decided to join their professional strengths to creating quality audio equipment and focusing on to design, ergonomics and sonic quality.