Get Additional -10% OFF with the Promo Code: PEN9EJWU
⏳ Limited Time Offer! ⏱️
zł1,136
- Mix & Match HRK 500 Products!
| 500 Units | 2 | 4 | 6+ |
| Discount | -10% | -15% | -20% |
- Free Shipping for Orders $299+
- Handmade in HRK Workshop
- Fully Assembled and Tested
- Express Delivery to Europe │ USA │ UK │ Canada
- Inspired by Famous Valve Passive EQ
- Adds Harmonics and analog warmth
- enhances the sound stage and content separation
- Pro-Grade NOS Dual Triode
- perfect for tracking and stereo bus processing
- Intuitive dial-Until-You-Like operation
- Designed and built for stereo use
- Hybrid Tube Class A Gain Stage
- Two Bands Shelf EQ Operation
- Separate Control for Boost and Cut
- 3 Frequency Settings for HF Band
- 3 Frequency Settings for LF Band
- Coupled with Custom HRK Active Transformer
- On-Board Voltage 500 Rack PSU Filters
- Direct Sale - Save on Distributors Fee!
Stereo Buss Operation
- Our improved production process ensures stereo matching between units
- If you purchase two units in one order, both units are matched for stereo operation, bus processing and mastering.
The unique feature of Passive Equalizer is the ability to Cut and Boost at the same time.
The EQ550P can create sophisticated EQ curves which cannot be achieved by the active shelf equalizers.
The ability to select three different frequencies independently for Cut and Boost provides countless possibilities in creating custom EQ curves.
The plots below show a few examples of such EQ curves.
Like any other equalizer, the EQ550P can be used to cut or boost the shelf frequencies.
The plots below show the maximum cut and boost for each band and frequency settings.
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 interference (50Hz Hum, RF Smog) and the frequency response is dependent on load and source impedance, negatively influencing the overall performance of analogue studio equipment.
The HRK Active Transformer solves the problems of the passive transformer while preserving and even enhancing the positive trades of the transformer output stage, including the harmonics content and the tonal response.
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.
EQ550P Demo Videos
The demo video presenting the older version of the EQ550P with a Silver front panels.
The current Black front panel version is delivers the same performance as the units presented in the video.
All videos are server hosted to insure the best quality of sound without the YouTube compression or normalization.
| EQ550P Specification | ||
| Input Type / Input Impedance | Balanced Electronic | 20k |
| Output Type / Output Impedance | Balanced HRK Active Transformer | Less than 10R |
| Initial Gain | 0dB | All controls set to flat response |
| Max Output Level | +25dBu@1%THD | Balanced Signal |
| Power Consumption | 180mA max. | |
| Format | API 500 Format | |
| Phase Reverse | No | 0 deg. |
| Static Noise | -89dBu@10Hz-22kHz | All controls set to flat response |
| Thermionic Valve | NOS Dual Triode | High Quality NOS Selected Tube |
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
- Our improved production process ensures stereo matching between units.
- If you purchase two units in one order, you can be sure that both units are matched for stereo operation, bus processing and mastering.
All Items are dispatched from Poland in the European Union within 1-3 working days.
| Country / Region | Shipping Cost | Customs Fee | VAT |
| All 27 European Union Countries Delivery Time: 2-7 Days | – 14.99USD for orders below 349USD- FREE shipping for orders over 349USD | NO 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 349USD- FREE shipping for orders over 299USD | NO Customs Fees | No VAT charge. HMRC collects the VAT. |
| USA, Canada Delivery Time: 5-10 Days | – 14.99USD for orders below 349USD- FREE shipping for orders over 349USD | NO Customs Fees for orders up to 800USD – charged by the USA Customs Office | No VAT charge. |
| Australia Delivery Time: 5-14 Days | – 19.99USD for orders below 449USD- FREE shipping for orders over 449USD | No info available – refer to local regulations. | No VAT charge. |
| Switzerland Delivery Time: 3-7 Days | – 14.99USD for orders below 349USD- FREE shipping for orders over 349USD | No info available – refer to local regulations. | No VAT charge. |
| Norway Delivery Time: 3-7 Days | – 14.99USD for orders below 349USD- FREE shipping for orders over 349USD | No info available – refer to local regulations. | No VAT charge. |
| Russia, Belarus – NOT AVAILABLE | NOT AVAILABLE | NOT AVAILABLE | NOT AVAILABLE |
| Worldwide Destination Delivery Time: 3-14 Days | – 29.99USD | Refer 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
If the item is damaged during the transport, we will do our best to help you and provide the replacement product.
The Impact of Switched-Mode Power Supplies used in 500 Racks on Analog Audio Circuitry
Switched-mode power supplies (SMPS) are ubiquitous in modern electronics due to their efficiency and compact size. However, they can cause issues with analog audio circuitry. The primary reason is that SMPS operates by rapidly switching on and off, typically at high frequencies. This operation can generate noise and harmonics across a wide frequency spectrum, which can infiltrate sensitive analog audio circuits and degrade audio performance. This issue is often termed as “switching noise.”
The ripple voltage, which is the residual periodic variation of the DC voltage, can also be a source of concern. In an audio system, this ripple voltage can couple into the audio path, leading to audible noise or hum.
The Solution: HRK Advanced On-Board Active SMPSU Filter
The problems caused by SMPSU can be mitigated by implementing an additional active PSU filter. This filter works by suppressing the switching noise and reducing the ripple voltage. It does so by providing a low impedance path at the switching frequency, which effectively ‘shorts out’ the noise, preventing it from entering the audio circuitry.
Moreover, it can improve the Power Supply Rejection Ratio (PSRR), a measure of how well an audio device rejects noise coming from the switched-mode power supply. A higher PSRR means the circuit is less susceptible to power supply noise, thereby improving the overall sound quality of the analog audio system.
Therefore, HRK Active PSU filter is an effective solution to ensure the integrity and quality of audio in analog systems powered by switched-mode power supplies.
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