ST596 | Analog Harmonics Processor – Matched Pair

$699.00 $499.00 ex. VAT

Easy to Use Analog Harmonics Processor

  • Mix and Match HRK 500 Products!
  • Buy VAT FREE with EU VAT Number
  • NO VAT for Orders from Outside EU
Promo Qty Discount
500 Mix & Match 2 - 3 10%
500 Mix & Match 4 - 5 15%
500 Mix & Match 6 + 20%


ST596 | Harmonics Analog Saturation Processor and Tape Emulator

  • Adds Harmonics and Saturation
  • Analog Modeling Discrete Circuitry
  • Germanium and Silicon Transistors Tape Emulator
  • Custom Coupled Inductors – Tape Head Emulation
  • Independent DRY and WET Controls
  • Tape Mix Control
  • High Frequencies Cut Filter
  • Low Frequencies Safe Feature
  • Custom HRK Transformer Output
  • Class A Discrete Transformer Driver
  • High-Quality ALPS Potentiometers
  • Studio-Grade Low Noise Opamps
  • Balanced Input
  • Compatible with API 500 Format
  • Direct Sale – Save on Distributors Fee!

The ST596 is an Analog Harmonics Processor dedicated for professional music producers and studio engineers.

The ST596 adds harmonics and saturation to any music material providing the full control of the harmonics amount and the Dry and Wet signal level.

The ST596 is based on the Custom HRK Analog Modeling circuitry built with discrete components, which produces a complex spectrum of harmonics.

The ST596 does not significantly change the overall peak level of the processed waveforms, nor distort the source signal, like in the common saturation studio hardware.

The ST596 is easy to use and intuitive controls make the tracking, reamping or mastering a quick and satisfying job.

ST596 – The End of Your Struggle!

Did you try countless DAW plugins to get the “true sound” and “analogue warmth” of the vintage studio preamps or consoles? Have you noted that all plugins sound similar and if you add more plugins the result is only less satisfying?

It is not much you can do about it… The DAW plugins are the only emulation of the analogue circuits and your computer is not capable to calculate the mathematics involved in complex physical processes which happen every nanosecond in the analog hardware.

Have you tried to patch the signal through the clone of the “vintage” mic preamp or compressor, only to battle with noise, hum and ground loops for hours?

You won’t win with laws of physics. Every time you add the gain the noise floor will rise and every cable conducts the electric current, which may create the ground loop…

The ST596 is a solution for all above and many other problems which almost every music producer or studio engineer has encountered.

Learn more about how the ST596 can help you to enjoy your work.

The Analog Modeling Circuitry

The ST596 Analog Harmonics Processor uses the custom-designed Analog Modeling discrete circuitry which produces the complex harmonic content without the usual problems associated with digital or hardware saturation.

The common way of producing the harmonics is to overdrive the signal with analog hardware. Usually, the gain has to be increased to achieve the desired results, which also raise the noise and hum levels, normally residing below the audible threshold.

Hardware components such as the thermionic valves, transformers and discrete circuits produce the harmonic distortions and this process can be described by the mathematical equations.

Simplified equations are used by the computer programs, the audio plugins, to simulate the properties the analogue hardware. More advanced plugins use expensive DSP cards to offload the main CPU and deliver more realistic results.

The term Operational Amplifier, which is the most common electronic component today, has its roots in the long-forgotten past when the mathematical calculations were done by the analogue computers built with amplifiers capable of conducting mathematical operations. Hence the name.

The Analog Modeling Circuitry used in the ST596 does the math of generating harmonics in the real-time analogue domain. No digital approximation, no latency, no CPU bottleneck!

The ST596 does not increase the gain of the processed signal keeping the noise as low as possible. It just adds the harmonics to the source signal.

Although the processed signal can be perceived as louder due to the higher harmonics content, the peak level of the signal remains almost the same.

The Analog Tape Emulator

The ST596 Analog Tape Emulator circuitry is based on the discrete germanium and silicon transistors, including FET transistor, and delivers the subtle final touch to the processed signal.

Custom coupled inductors act like the write and read tape heads, adding harmonics of the tape recorder.

The level of the tape saturation can be controlled by the level of the signals sent from the WET and DRY knob.

The tape harmonics can be blended with the Tape Mix knob.

The LF Resonant circuit can be engaged with the onboard jumper, which is useful for vocals and the lead instruments.

Intuitive Control and Workflow

The ST596 is easy to use. The number of knobs and switches are limited to a minimum to provide the hassle-free operation.

The Drive knob controls the amount of harmonics produced by the Analog Modeling circuit. Only the harmonics are added to the source signal.

The Wet knob sets the level of harmonics added to the source signal.

The Dry knob controls the level of the source signal and the total output level when the ST596 is engaged.

The Tape Mix knob allows the blending between the signal processed by the Tape Analog Emulator and the signal from the previous stages.

The HFC switch cuts off the high frequencies to remove the air harmonics content. This feature helps with vocals and other HF rich signals. It can be used also in a creative way.

The LFS switch blocks the LF content passed to Analog Modeling circuit, preventing the lows from being overdriven. This feature helps with LF rich signals such as drums, bass guitar, bass synths and bass tracks.

Tape-In switch engages the Tape Emulator circuit. The Process switch works as the bypass switch.

Simplified Signal Flow Diagram

ST596 Bass Guitar Demo

ST596 Drums Demo

ST596 Stereo Synth Demo

ST596 Drum Machine Demo

ST596 Accoustic Guitar Demo


User Manual:

Please read the User Manual before the use of the ST596.

ST596 User Manual

ST596 Recall Sheet

The ST596 is fully compatible with API 500 Format


The Main FAQ Section

Item Condition

Brand New, Assembled and Tested.

Every single HRK product is carefully tested with Audio Precision test equipment before the shipping to ensure hassle-free operation.

Payment & Shipping


All Items are dispatched from the European Union within 1-3 working days.

We offer fast worldwide UPS shipping with tracking.

FREE delivery is available for orders over the 249USD to EU, USA and Canada.

FREE delivery is available for orders over the 299USD to Australia, New Zeland, Japan and other destinations.

Please check the shipping cost during the checkout.

Delivery to other WorldWide destinations – 24.99USD

EU Business Customers

All prices exclude the VAT Tax.

If you have the EU VAT number you can purchase the products available in the Bart HRK Shop with no VAT Tax.

Please enter your EU VAT Number at the checkout and the VAT will be deducted from the Total Payment.

Non-EU Customers

Customers from outside the EU can purchase the items with no VAT.

Please select the destination country and the VAT will be removed automatically.

If the VAT is not removed, please email customer service via the contact form and custom invoice will be issued.

Orders from the USA below 800USD are customs tax-free.

Payment Options:

You can pay for your order with any Credit Card



Input impedance: 10kOhm

Output impedance: 100R

Phase inverse: none

Gain: 0dB

All HRK Colour Modules are fully compatible with DIYRE Colour Format

All HRK Colour Processor and Preamps fully compatible with DIYRE Colour Format

All HRK 500 products are fully compatible with API 500 Format

You may also like…