Golden Age Project Eq 81 | Vintage Style 4-band Equalizer

The class-AB circuit used in the Golden Age Project EQ-81 is similar to the EQ section in the classical 1081 module, without the high and low pass filters. The sound character is warm, punchy, sweet and musical. These classic characteristics have been heard on countless recordings through the years and it is a versatile sound that works very well on most sound sources and in most genres. The essence of this sound is now available at a surprisingly low cost, making it available to nearly everyone.

The EQ-81 has stepped frequency controls that offer a wide selection of frequencies from 33 Hz to 15 kHz. The BASS and TREBLE frequency bands are switchable between shelving and bell and the MID frequency bands are of the bell type with a switchable Hi Q setting. The control range is +/- 18dB. All four bands can be set in an off mode. The EQ-81 is not intended to be used as a standalone EQ. It is designed to be used together with one of the Golden Age Project models that has an insert jack. It can also be used with some other product that has a low level (about -18 dBu to -10 dBu) unbalanced insert connector. Combining one of the PRE-73 units and an EQ-81 and using a UNITE rack kit to mount them together, one will get a 19-inch 1081-style unit at a low cost and with a great sound.

Circuit Description

The main signal path in the EQ-81 consists of four gain stages, one for each frequency band. Each gain stage uses five transistors and a few resistors and capacitors. So, the complete signal chain contains a small number of active elements. Compare that to the big number of transistors that are usually used in one single integrated circuit! The filter circuit uses additional passive components. The mid band uses inductors and capacitors for a classic LC-style eq circuit. By designing the EQ-81 to be used with a unit with a low level insert jack, the unit did not have to be fitted with an input and output stage, reducing the cost of the unit.

Modern vs Old

It is true that there are some great IC's available today that achieve very low levels of static and dynamic distortion. The simple circuits that the EQ-81 uses, cannot match the low distortion specifications of modern IC's. It is the distortion components that impart a sound character to the audio signal and, if the distortion components are of the right sort, this is a good thing since it makes the recorded voice or instrument sound "better", more musical, more pleasing to the ear. This is one reason why vintage style units are so popular today. This is not to suggest that modern, transparent sounding audio circuits are a bad thing, sometimes they are preferred over colored ones. It's all about taste and it depends on the genre. For most modern music styles, "color" and "character" are definitely a good thing. And doesn't it feel good to use audio components built according to the old, minimalistic approach where one can follow the signal from one discrete component to another?

Features:

- Vintage Style electronics. No intergrated circuits in the signal path
- 4-band with inductor based mid frequency bands
- Stepped frequency selection
- A wide selection of frequencies from 33 Hz to 15 kHz
- Control range up to +/- 18 dB
- Each band has an off mode
- Tantalum capacitors in the signal path
- Designed to be used together with one of the models with an insert jack
- TRS jack for in-and output connection, the nominal working level is around -18 dBu
- Selectable ground lift switch
- External power supply to avoid interaction with the audio circuits
- Great sound that suits most sound sources and genres
- A solid build quality that will last many years of normal use