Doepfer A-101-6 Opto FET VCF/Phaser
Doepfer A-101-6 Opto FET VCF/Phaser Overview
The Doepfer A-101-6 Opto FET VCF/Phaser is an 8HP multi-mode filter module for Eurorack synthesizers. Designed with a hybrid Opto-FET circuitry, the A-101-6 is extremely stable under high voltage levels, providing you with a robust and responsive filtering effect that can create FM-style modulation with near-zero distortion. Internally built with six 6dB/oct serial slopes, the Doepfer A-101-6 offers a wide range of different filtering types from Low-pass, High-pass and two types of All-pass filters.
On the reverse of the unit, the A-101-6 houses jumper circuits to alter the filter type as well as a small potentiometer to trim the level of the slope and maximum resonance. Ideal for tailoring the response of your module to your source, you can adjust the harmonic content and saturation levels of the Feedback control. Anything from clean and smooth to raspy and overdriven resonance is achievable with ease, offering a wide tonal palette for your filtering.
Full Description
Flexible and versatile filtering
Comprised of six serial 6dB/Oct filter stages, the A-101-6 can work in four different selectable modes. Low-pass, High-pass and two All-pass modes offer flexible filtering for virtually any signal source. The obvious choices for a multi-mode filter module, low-pass and high-pass provide you with the ability to design the sound of your signal to tame the extreme ends of the frequency spectrum to fit within a mix or to be used for creative effect to add suspense. The magic of the A-101-6 however lies within the two All-pass filter modes. All-pass filters are in essence a short frequency-dependent delay. High frequencies and low frequencies contain vastly different energy levels and therefore move at different rates. The All-pass filter can be used to change the phase relationships of different ends of the frequency spectrum to create interesting FM modulation such as Phaser.
Hidden on the reverse of the unit, there are a few tricks up the sleeve of the A-101-6. Here, you will find both jumpers and a small trim potentiometer. These allow you to select the filter type and adjust the maximum resonance/feedback levels and slope strength on your A-101-6. This can be particularly useful for controlling the maximum level of the resonance on your module. Resonance is controlled by the feedback control and when set at nominal levels can be driven into self-oscillation. Cranking the Feedback into self-oscillation can be used to great creative effect when in the All-pass mode, allowing you to create a unique focussed distorted sound at a targetted frequency range to cut through any mix.
Opto FET circuitry
Comprised of Opto FET circuitry, the Doepfer A-101-6 produces a unique sound amongst multi-mode filters. Similar to Vactrols, but using light dependent field-effect transistors (FETs) instead of light depending resistors (LDRs). Where the circuitry differs from traditional FET circuits is that the A-101-6 combines FETs and LED (Light-emitting diode), creating a significantly faster response time. This improved response allows for faster attack and decay characteristics of your signal and even opens up FM effect possibilities such as Phasers.
The design of the A-101-6 is susceptible to distortion when driven with higher-level signals to the input. Ideal for a multi-mode filter, you can create crunching and thunderous low-end that's ideal for bass lines in traditional Acid House-style music or even transform lead lines into searing overdrive territory when filtering out the lows to cut through a dense mix with ease.
Features
- 3U Eurorack module, 8HP wide
- Multi-mode filter module with Low-pass, High-pass and All-pass filter types
- Six 6dB/oct filters working in series
- OPTO Fet circuitry provides fast response, emphasising attack and release characteristics of your signal
- Adjustable feedback level
- Circuit board jumpers for altering configuration and filter slope
Specifications
- Width: 8HP
- Depth: 65 mm
- Current:
- +40mA (+12V)
- -40mA (-12V)
- Product code: A-101-6