EQ550P | Passive Valve Two Bands Pultec Style EQ

EQ550P | Passive Valve Two Bands Pultec Style EQ
Inspired by Famous Valve Passive EQ
Hybrid Valve Class A Gain Stage
Two Band Shelf EQ Design
Separate Control for Boost and Cut
3 Frequency Settings for HF Band
3 Frequency Settings for LF Band
Vintage NOS Discrete Components
Output Coupled with Custom HRK Transformer
Class A Output Transformer Driver
JJ Electronics ECC83 Dual Triode Tube
On-Board Voltage 500 Rack PSU Filters
Direct Sale – Save on Distributors Fee!

The EQ550P is a Passive Tube based 2 Band Shelf Equaliser inspired by the famous Pultec design.

Each Band has a separate Boost and Cut Control which allows creating the sophisticated EQ curves.

Each Boost or Cut control has three different and independent frequency settings which give a total of 9 setting combinations per Band.

The Passive filter section changes the EQ curve by attenuating the signal. The ECC83 gain stage restores the signal to the nominal level adding the combination of harmonics and transients.

The EQ550P is very musical and easy to use. It can process any music material, instruments, vocal or recordings, producing amazing results.

The Valve – Discrete Transistors Hybrid circuit is the result of a long development process. It produces real Tube harmonics and reach tone while maintaining the noise on the extremely low level.

Create the Sophisticated EQ Curves!

The unique feature of Passive Equalizer is the ability to Cut and Boost at the same time.

The EQ550P can create the sophisticated EQ curves which cannot be achieved by the active shelf equalizers.

Ability to select three different frequencies independently for Cut and Boost provides countless possibilities in creating custom EQ curves.

Pictures below show a few examples of such EQ curves.

Hybrid Valve Gain Stage

“Valves can work only with high voltage” – this is the common myth repeated across the internet by self-acclaimed “experts” which have no experience in electronics.

The truth is that most of the popular valves can work with lower voltages without the problems. The key to the success is the clever solution for biasing the valve.

Specially designed discrete transistor circuit controls the biasing and forces the tube to operate as intended at the harmless anode voltage.

The result is a perfectly stable valve gain stage with standard ECC83 dual triode, which delivers 26dB of noiseless gain.

Coupled with Custom HRK Transformers

The Output of the EQ550P is coupled with specially designed custom HRK Transformers. Because of limited space in the 500 module, HRK Custom Transformers became smaller, maintaining no-compromise performance.

All HRK transformers provide the sweet-spot sonic characteristic with pristine detail reproduction. The goal of the design process was to create the transformer which will deliver a balance between the transparency and colouration typical for transformer stages.

Dicrete Transitor Class A Output Transformer Driver

The output transformer is powered by Class A, No-Feedback, DC-Coupled Discrete Driver built with NOS Transistors from ’70s.

More Info, Demo Video and Sound Samples available at:
EQ550P | PASSIVE VALVE 2 BANDS PULTEC STYLE EQ






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