8 things to know about Simple EQ

4 HP | 25mm deep | 20mA
Designed March 2014

Modular Grid |
Github | Schematic

Available from Thonk

1. Learn SMD soldering by building two channels of the kind of tone controls you'd find on an old hifi.
2. The top channel has Baxandall bass and treble controls
3. The bottom channel has a 'tilt' control like the one on Quad 44 hi-fi amps in the 70s. To the right, it gently boosts signals above 1kHz, cutting below. To the left it gently boosts below 1kHz, cutting above.
4. Like the Graphic Eq, this module uses NE5532 op-amps, and is based on a design in Douglas Self's masterful 'Small Signal Audio Design'. It's a clean, simple circuit with very little noise.
5. The circuit is set up so that if you push a full-range (10v point-to-point) sine wave though it at a frequency that's being boosted, it will clip. Otherwise there's a reasonable amount of headroom and a lot of boost. In other words, just enough range to push sounds into distortion. Works well in a feedback loop.
6. Constructed with a handful of (relatively large) 1206 capacitors and resistors, it's the perfect first project if you want to learn SMD soldering, and it comes with a detailed build guide from Thonk.
7. Here is a nice illustrated build guide and demo from Mesomesona in Tokyo.
8. This is a fairly simple build, but if you have any issues, the best way to get help is to check the GitHub Issue List, and remember to check closed issues as well as open ones.