The Altec 9069B Replica:
King Tubby Big Knob
Passive High Pass Filter
King Tubby Big Knob
Passive High Pass Filter
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 and composed of a 3rd order High Pass Filter with 10 stepped cut-off frequencies which enable a great control over the sound tone. Besides the frequency selector, our KTBK unit includes two additional switches, non-existent at the Altec design, 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. At this time, we aim to produce the first KTBK’s series and we are preparing a crowdfunding campaign to be launched soon for this. Join us to be the first to know!
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.
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. Validated with DSP techniques to achieve the most accurate frequency response utilising a handmade customized multi-tap coil.
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.
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 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.
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.
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!
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.
* Gracias a Chalart y La Panchita Records por proporcionar estos sonidos.
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.
This KTBK adventure has brought us to 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!