$299.00 ex. VAT

500 Units246+

Due to the Valves Shortage, only a few EQ550P are available.

Stock will be updated based on availability.

4 in stock

4 in stock


Microprocessor TLGR Meter

The CP523V is equipped with Microprocessor True Level Gain Reduction Meter.

This is a unique approach to provide the user with an ultra-accurate gain reduction reading. In most of the Compressors, the gain reduction is measured using the indirect method with an additional LDR circuit or by measuring the Side-chain voltage.

The RVGR is based on a microcontroller that measures the actual level of the signal on the input of the CP523V and the signal level on the output of the compressor stage, in real-time.

Two signal values are compared and the value of the signal reduction is calculated over 400 times every second. The results are averaged and displayed using the Gain Reduction LED Meter.

The typical error of the meter is less than -0.5dB in -1dB to -8dB gain reduction range.

CP523V Valve Class A Optocompressor TLGR Meter Demo

Play Video

Video shows how accurate the microprocessor True Level Gain Reduction is when compared to the professional lab test equipment.

HRK Active Transformer

Bart Hrk developed the propitiatory design of an Active Transformer to solve the problems of the common passive transformers.

Passive transformers are susceptible to electromagnetic interferences (50Hz Hum, RF Smog) and the frequency response dependents on load and source impedance, negatively influencing the overall performance of analogue studio equipment.

The HRK Active Transformer delivers the sound that we love, including the harmonics content and the tonal response, and removes all the hassles associated with passive transformers.

The Active Transformer produces a subtle “Air” effect and provides extended LF performance.

The Active Transfomer saturation depends on the output level. Higher output signal levels will saturate the Active Transfomer more, like in the classic studio equipment.

Pro-Grade Dual Triode Thermionic Valve

The CP523V Gain Makeup Stage is made with a Pro-Audio Grade tube, which delivers superb specification matching and a much longer operating time compared to standard thermionic valves.

Create Amazing Results!

The CP523V is easy to use even for engineers with less experience with dynamic processors.

Optocompressors are very versatile and produce smooth compression results. Any music material will benefit from the magic touch added by the CP523V.

The side-chain controls are simple and powerful providing the necessary tools for many demanding studio applications.

Add Harmonics to your Recordings or Tracks

The CP523V is suitable for recording as a part of the signal path.

It will control the dynamics of the signal from the microphone while enhancing the details and structure of the vocal or the instruments.

The CP523V can be used for tracking or mastering. Two units can be paired in stereo mode.

The Slow Attack mode and the side-chain High Pass Filter can be used very creative way in mastering applications.

Stereo Buss Operation

CP523V Stereo Bus Mix Demo – 96k HD Audio – Ratio: Medium

Attack: Slow, Sidechain HPF Engaged, Threshold: 0dB

Play Video


Clips below show the old silver plate version of the CP523V. The balck front panel version has the same sonic performance.

Female Vocal Demo

Play Video

Drums Demo

Play Video

ALL HRK Products Are Brand New - Assembled and Fully Tested

All HRK Products are tested with the industry best audio measuring equipment

Audio Precision System

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

Country / RegionShipping CostCustoms FeeVAT
All 27 European Union Countries Delivery Time: 2-7 Days– 14.99USD for orders below 299USD- FREE shipping for orders over 299USDNO Customs Fees– Yes, for personal orders- Not charged with the EU VAT number
United Kingdom Delivery Time: 3-7 Days– 14.99USD for orders below 299USD- FREE shipping for orders over 299USDNO Customs FeesNo VAT charge. HMRC collects the VAT.
USA, Canada Delivery Time: 5-10 Days– 14.99USD for orders below 299USD- FREE shipping for orders over 299USDNO Customs Fees for orders up to 800USD – charged by the USA Customs OfficeNo VAT charge.
Australia Delivery Time: 5-14 Days– 19.99USD for orders below 399USD- FREE shipping for orders over 399USDNo info available – refer to local regulations.No VAT charge.
Switzerland Delivery Time: 3-7 Days– 14.99USD for orders below 299USD- FREE shipping for orders over 299USDNo info available – refer to local regulations.No VAT charge.
Norway Delivery Time: 3-7 Days– 14.99USD for orders below 299USD- FREE shipping for orders over 299USDNo info available – refer to local regulations.No VAT charge.
Worldwide destinations Delivery Time: 3-14 Days– 29.99USDRefer to local regulations.No VAT charge.

EU Customers

The EU Customers will not pay any extra customs fees.

Business customers with valid EU VAT number will not pay the VAT tax.

Please enter your EU VAT Number at the checkout, and the VAT will be deducted from the Total Payment. The VAT number is automatically checked in the VIES database.

For personal orders from the EU, the VAT will be added at the checkout.

UK Custmers

We ship directly to United Kingdom.

UK VAT tax is collected by HRMC

Non-EU Customers

Customers from outside the EU 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 a custom invoice will be issued.

USA and Canada

Orders from the USA below 800USD are FREE from customs tax.

We ship directly to USA and Canada

Payment Options:

You can pay for your order with any Credit Card and Apple Pay!

7 Days Return Policy

Our return policy is a part of the general Terms & Conditions, which you must acknowledge at the checkout. We stand for fair rules and a win-win approach.
We understand that our customers may wish to return the product, and we provide such an option.
However, because we are a small company, we can’t afford to run a grade B outlet shop like big distributors and providing the 30 days return period. We can’t also scrap every returned unit.
We could charge our customers more to offset the cost of the returns, and this is what major distributors do. Or we can keep our prices low and hope that our customers will appreciate our policy.
This is why we provide the 7 days test period after receiving the package with the ordered items. If you wish to return the item, we will accept the return request, providing that the item is not damaged.

If the item is damaged during the transport, we will do our best to help you and provide the replacement product.