SOLD OUT!!!
Nowadays, we are focused on the production of the 2022 KTBK series and new products. If you are interested in to purchase a KTBK, please subscribe to the KTBK Filter – Waiting List 😉👇🏽

🔊📣🔔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!
KTBK, An Equalizer with Vintage Flavour for the Present Epoch!
For music-quality-conscious people who enjoy the warm sound 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 audio equipment and to different stages of the music production.
- Passive T-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
- Handmade Multi-Tap Inductor
- DSP validated with octave deviation metric
- Handmade Assembled in BCN
Audio Merge KTBK, a Vintage Equalizer for the Modern Era
The KTBK is a very precise replica of the Altec 9069B adapted for the modern music production with new controls for impedance matching and resonance. It was designed through Reverse Engineering methods and validated with DSP techniques to achieve the most accurate cutoffs utilising a handmade customized multi-tap coil.

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
Once we made up the first prototype, we planned the strategy to validate each cutoff filter is doing what we expected to do. Inverse engineering techniques allowed us to estimate the cutoff frequency precisely. To do so, we build up our own validation tool based on DSP techniques, which enabled us to compare the KTBK response with an original Altec unit and to analyze each prototype to achieve an authentic replica. Interesting? Please, check the tabs in the following object to get more details.
Handmade Assembled with a Customized Coil
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 tests and analyses performed with our prototypes. We have analysed frequency and phase response with different cores and coil winding techniques to get the most accurate cut-off frequencies. Our last prototype achieved an average of 0.05 octave deviation for the whole filter net, which is insignificant in Hz. It was compared with an Altec 9069B unit and they were almost the same frequency response and very similar resonance bell. Check the next tabs to know the different KTBK modes!


Handmade Assembled with a Customized Coil
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 tests and analyses performed with our prototypes. We have analysed frequency and phase response with different cores and coil winding techniques to get the most accurate cut-off frequencies. Our last prototype achieved an average of 0.05 octave deviation for the whole filter net, which is insignificant in Hz. It was compared with an Altec 9069B unit and they were almost the same frequency response and very similar resonance bell. Check the next tabs to know the different KTBK modes!

Customized Cutoff Frequency Rotary Switch Selector
Smoothed rotation resistance to guarantee the creative freedom during the performance. High quality rotary switch with proven solvency in the world of professional audio equipment. Made to measure according to our specifications for the KTBK unit.
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 with accuracy the parasitic frequencies, rumble noise and muddy sound effect in order to reducing the masking effect and giving a clearer sound. The KTBK Passive High Pass Filter has stepped frequency selection with ten possible cut-offs with crossover type action (70, 100, 150, 250, 500, 1k, 2k, 3k, 5k, 7.5k), a need when it is required an accurate control of 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 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 the Sound like
a Dub Master
Sweep and layer your sounds with the KTBK 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.






DO YOU WANT TO TRY
OUR DEMO?
LEAVE YOUR EMAIL HERE
We are looking for feedback, please tell us any improvements we can make to the DEMO.
How does the KTBK sounds?
Drums - BELL Mode
Horns - BELL Mode
The Altec 9069B, 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 >>>
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.