Garash G.404 - ten band graphic equalizer in 500 series format

G.404 eqalizer is an ammage of the rare and narrowly known vintage Aengus 404 eq or also known as the Aengus thumbwheel eq.

This is a fairly rare device. A graphic 8 band eq created in the mid 70's. Silvia Massey and Ros Hogarth have a number of similar ones, thanks to which it probably has a certain hype.
Dan Probst got me interested in the idea of creating a similar eq to Aengus. While studying it I came across a post on the site about 404 eq and decided to join the study of this device. After a certain amount of research and emulating the circuit in the LTspice app I came to the conclusion that it’s not possible to recreate it in the fully original form. The reason is the specific thumbwheel gain switches around which the circuit is created. The solution was a systematic research, emulation of the characteristic features of the bands and bandwidths. Aengus and earlier created by me G.TEN have similar equalization principle based on the gyrator filters.
To get as close as possible to the sound of the Aengus (but using slider potentiometers) I completely recalculated the gyrator filters to the 404 specs and this gave exactly the same bands and bandwidth values. A prototype was built, which underwent modifications while testing and listening to opinions from colleagues and soundengineers. This is how prototype was built

An unexpected benefit was that the Aengus has eight octave bands (with pretty broad Q) and I have ten. Opinions on the remaining two were divided, especially heated arguments were for an additional band on top. In the end a shelf band at the bottom was added, as well as selectible 20kHz bell band OR top shelf band. By using both shelfs it is actually possible to do some sort of a tilt filter. The choice of top band functionality is selected either at the stage of module installation into the 500 series lunchbox or through a special small hole on the front panel. Yes, you will need a bent paper clip for this). It is not the most technological solution, but this solution turned out to be convenient from the point of view of device unification and allowed to produce serial units in reasonable time without the cost of cardinal technical changes.
This is how G.404 was born!

- standard 500 series VPR module size
- balanced input and output
- true relay bypass with a led status indicator
- 8 broad Q bell bands
- proportional-Q bell bands
- two additional low shelf and 20K / high shelf bands
- 12dB of boost/cut (with 3dB gain change mark lines)
- custom ordered center detent slide potentiometers
- 2520 style DOA output buffer
- our own designed and manufactured output transformer

G.404 is available as an assembled unit or as a diy kit.
For purchasing contact us directly or through our distributor: