What would be your first though when you hear the term “passive equalizer”? At first, probably you think about the airy high frequency components, the rich subs and the widely applicable cuts and boosts wich can be used alongside each other. These types of equalisers have been around since the early 50’s, the most famous Pultec EQP-1 from Pulse Techniques was the first one that provided simultaneously passive filter circuits alongside high quality line amplifiers. The downside of the EQP-1 was the lack of ability to carry out precision frequency isolation, but it was able to change any sound in its core. Many of the modern equalizers are based on the original EQP-1 in both structure and functions that could be limiting in a modern music environment and production.

Our aim in the lab was to improve the classic concept. First, we added an additional mid frequency filter between the low and high frequency filters in order to improve the versatility of the unit in the modern days music environment. We left the option of simultaneous cutting and boosting in the low and high band, so all those tricks can be done that a user normally would expect from an equalizer. Furthermore, the shift function can be used on these bands so that the mid frequency of the simultaneous cutting and boosting can be shifted relative to each other. After extensive test bench trials, using the equalizer in real life applications, the versatilty of the unit was far beyond expectation. It proved to be suitable from recording to master colouring or can be used in any equalizer task. It is fair to say that it dominates the entire frequency range and most of the time it does sounds great in extreme conditions, hence we named it to Empress.
In summary, the Empress is a dual channel passive equalizer equipped with a tube amplifier that has three bands on each side. Thanks to the compact design it only needs 2U space in the studio but it will have a significant impact on your sound.

Field of application

• Mixing

• Mastering

• Recording

• Sound Design

• Saturator

Main properties

• 2×3 band setup

• Stepped attenuator design

• Tube based gain stage

• Military grade vacuum tubes

• Nanocrystaline alloy transformers