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A set of modular PCBs that can be used to create a custom configuration for a Matrix Mixer. A Matrix mixer allows you to mix you any input to any output at the same time.
If you have for example a 4x4 Matrix Mixer, you have 16 knobs with each controlling a how much of a given input signal (`1-4`) will be mixed into a given output (`A-D`):
For example by turning up the knob at the intersection between Input `2` and Output `B` we can mix all of the signal present at the input to the output. If we turn up another knob at another intersection, the signal will be present at both outputs:
<img src="images/matrix-examples.png" height="auto" width="600px">
This makes Matrix mixers extremely flexible and allows for many possible combinations and use cases.
# Modules
The 4x4 matrix above consists of:
- 2x MAMI-INPUT Module
- 2x MAMI-OUTPUT Module
- 4x MAMI-QUAD Module
The modules are designed in a way they can be connected via wires or jumpers to each other, so multiple configurations are possible (e.g. 2x2, 2x4, 4x2, 8x8, 10x6 etc.).
Here an example 8x8 setup consisting of 4 Input modules, 4 Output modules and 16 Tiles:
## Input Module [MAMI-INPUT]
The Input Module has two 3.5mm Mono Input Jacks and two (On)-Off-On Switches that allows muting individual inputs (or momentarily/permanently switching them on).
| Top | Bottom | 3D | Dimensions |
| ---- | ------ | --- | ------ |
| <img src="gerbers/MAMI-INPUT_Combined_Top.png" width="200px"> | <img src="gerbers/MAMI-INPUT_Combined_Bottom.png" width="200px"> | <img src="images/3d-input.png" width="200px"> | <img src="images/board_input.png" height="200px"> |
Mixes two inputs onto two outputs using 4 Potentiometers.
| Top | Bottom | 3D | Dimensions |
| ---- | ----- | --- | ------ |
| <img src="gerbers/MAMI-QUAD_Combined_Top.png" width="200px"> | <img src="gerbers/MAMI-QUAD_Combined_Bottom.png" width="200px"> | <img src="images/3d-quad.png" width="200px"> | <img src="images/board_quad.png" height="200px"> |
Provides two 3.5mm Mono output jacks, with a Jumper (or switch) each row of tiles can be switched between unipolar and bipolar attenuation.
| Top | Bottom | 3D | Dimensions |
| ---- | ------ | --- | ---- |
| <img src="gerbers/MAMI-OUTPUT_Combined_Top.png" height="200px"> | <img src="gerbers/MAMI-OUTPUT_Combined_Bottom.png" height="200px"> | <img src="images/3d-output.png" height="200px"> | <img src="images/board_out.png" height="200px"> |
The summing section looks like this and allows a jumper (`J_ATT1` and `J_ATT2`) or a switch (2.54mm lead spacing) to be used to switch between unipolar and bipolar attenuation for each row seperately.
<img src="images/schematic_summing.png" height="auto" width="600px">
## Envelope Follower Module [MAMI-ENV]
A dual Envelope follower that can be hooked up to a `MAMI-OUTPUT`-Module. Has two output jacks in the same 25mm spacing as the output module and two LEDs that correspond to the output levels.
| Top | Bottom | 3D | Dimensions |
| ---- | ------ | --- | --- |
| <img src="gerbers/MAMI-ENV_Combined_Top.png" height="200px"> | <img src="gerbers/MAMI-ENV_Combined_Bottom.png" height="200px"> | <img src="images/3d-env.png" height="200px"> | <img src="images/board_env.png" height="200px"> |
### Erata Output Module rev. 1.0 (has been fixed in 1.1)
- Silkscreen for Vee and Vcc is swapped!
- `R4` and `R8` should have a value of 100 Ω not 100 kΩ (or bridge it with solder)
- Connector `J_W` was flipped by 180° (this however depends on which side you want your outputs). Solve it like this (just make sure the silkscreen labels connect to the right bus): <img src="images/bus-wiring.jpg" height="auto" width="600px">
Constructing a panel is straightforward: drill holes for all potentiometers, switches and jacks.
There are example panels for a 8x8 Matrix (with and without envelope outputs) in the [panels](panels) directory.
Use the python code in [calculate-parts.ipynb](https://code.hfbk.net/sdiy/mami/blob/master/calculate-parts.ipynb) to calculate the needed parts for your variant of the MAMI
# Power-Supply
The MAMI needs a fitting ±12V Power supply. This obviously depends on the size you are going for and which opamp you use – one Output-Module with 2 channels and a LME49720 draws ~20mA. Anything up to 10x10 should be able to be powered by the [3WPSU](https://code.hfbk.net/sdiy/3wpsu) with a USB-B Phone Charger, as the 3WPSU is able to deliver up to 125mA per rail.