Reference 1956 Equalizer
Table of Contents
Introduction
The “low-end trick” is a classic: boosting and cutting the bass at the same time on a “Pultec”-style equalizer. But that’s not the only reason this type of EQ is still in use today, 70 years after its inception. The passive design is minimum-phase and extremely musical: broad strokes, big tone. Cuts and boosts are achieved with resistors, capacitors, and chokes. No op-amps or transistors. Just passive electronics, with a beautiful tube amp stage on the output.
This plug-in is based on a modern hardware that adds stereo functionality and additional frequency selections while maintaining the true nature of the original design. The transformers provide a thick low-end character, which can be exaggerated using the “Headroom” control in the lower “Extended Features” panel.
On top of that, we added built-in Mid/Side functionality and separate gain controls for the two channels.
User Interface
Each channel is divided into three main parts: low shelf, mid bell, and high cut.
Low Shelf
- Boost
- Increases the gain of the low-shelving filter.
- Cut
- Decreases the gain of the low-shelving filter.
- Frequency
- Sets the frequency of the low-shelving filter.
Mid Bell
- Boost
- Boosts the bell filter. The actual boost in dB depends on the Bandwidth of the filter—around 18 dB at the narrowest setting and about 10 dB at the widest.
- Bandwidth
- Sets the sharpness of the bell filter.
- Frequency
- Sets the center frequency of the bell filter.
High Attenuation
- Cut
- Sets the amount of high-frequency attenuation.
- Frequency
- Sets the center frequency of the cut.
Mid Section
- Gain
- Sets the output gain for the left/mid or right/side channel.
- Unlink/Link
- Links or unlinks the left/mid and right/side controls.
- L/R, M/S
- Sets the equalizer to operate in Left/Right or Mid/Side mode.
Credits
Fredrik Jansson – DSP and UI development
Niklas Odelholm – Modeling, product design
Johan Bremin – Quality assurance
Ulf Ekelöf – 3D rendering