The class-A circuit used in the EQ-573 is made to be similar to the legendary Neve 1073 EQ module. Additional frequencies have been added to the mid and high frequency sections, and only discrete components are included in the signal's path giving the EQ-573 a warm, punchy, sweet and musical characteristic that has been heard on countless recordings through the years. The EQ-573 is also very versatile and will work on most sound sources in almost any genre.

The EQ-573 has stepped frequency controls that offers a wide selection of frequencies from 33 Hz to 20 kHz. Each section can be switched off individually. There is also a master bypass switch for easy comparisons.

The low and high frequency bands are shelving and the mid frequency band is of the bell type. The control range is +/-15 dB for the two lower bands and +/- 18dB for the high frequency band. The high pass filter is of the inductor type with a slope of 18 dB / octave.

The PRE-573 has a dedicated insert connector at the back allowing it to interface with other GAP 500 modules. The insert can be activated by removing a jumper connector at the back of the module.

The second Golden Age Project module for the api 500 rack is the EQ-573. The EQ-573 consists of the inductor based high pass filter section and the 3-band eq section from the classic 1073 module with some added frequencies. These two modules together offer a fully fledged 1073-module in a compact format at a very low cost.

There is a second jumper at the back of the module that selects 600 ohm termination on the output. The standard mode is termination on, since it gives the flattest response when the PRE-573 is used with modern line inputs that typically has an input impedance of 10 kohm or more. The user can chose to remove the jumper and deactivate the termination resistor, this will increase the level above 10 kHz and create a peak in the response for an even more pronounced "Air" effect.

The output is transformer balanced and fully floating and can drive a 600 ohm load up to level of about 28 dBu.

Vintage Style electronics, no integrated circuits in the signal path

3-band with a dual inductor based mid frequency band

Inductor based high pass filter

Stepped frequency selection

Control range up to +/- 18 dB

A wide selection of frequencies from 33Hz to 20kHz

Each section can be switched off individually

Master Bypass switch

Tantalum capacitors in the signal path

Circuit board star grounding scheme

Great sound that suits most sound sources and genres

A solid build quality that will last many years of normal use

Designed to be used together with the Golden Age Project PRE-573