> MERGE THIS PAGE WITH THE CONSTRUCTION GUIDE

Deux boite pour envoyer les signaux audio vers les 8 hauts-parleurs, que l'on parte d'une stereo, mono ou d'une multiphonie.

La première boite est la “Matrix Mixer”, qui permet de router et de mélanger les signaux avec ses potentiomètres. Mais aussi de normaliser les signaux avec ses buffers, régler les gains en entrée et en sortie et d'aligner les niveaux avec ses vu-mètres (dernier contrôle du volume au niveau de l'ampli).

La seconde boite est la “Spatialisatrice”, qui permet de contrôler manuellement le niveau de chaque sortie d'ampli avec ses 8 faders branchés en trimmers. C'est un élément passif qui vient se brancher comme une extension à la Matrix Mixer.

exemple passif https://mickeydelp.com/blog/passive-matrix-mixer

un autre exemple (passif ou actif avec circuit opamp) https://sound-au.com/project129.htm

The switch matrix would need input and output buffers, with potentiometers for each input, allow to avoid regular mixer is many cases.. These schematics show the power supply and 1 channel of input buffering. The output buffer would be similar.

Matrix Mixer Buffers - Kicad 7 files for PCB etching, send by Zach Poff on the 05/08/2023 » :fr:meetings_projects:spectral:portablesoundsystem:matrix-mixer-kicad_4_kicad7.zip

Improvements to Matrix Mixer Design for a v.1.1 (20.10.2023)

- space for resistors are longer to fit with most common resistors.
- position of component closer to a mirror (on vertical axis) to make it easier to assemble and understand

[INSERT “LARGE RESISTOR VERSION” KICAD FILES]

Improvements for later version (not done at this time)

- larger pads : when etching is not great, drilling removes some of the pad, and then soldering is not easy (one can always use legs of component to reach the track, but it's not so elegant)
- grouping INs and OUTs to have a better management of cables (they are currently all around the board which looks like a crazy spider)

- add connectors to Meters (on the very last stage, same as what is send to amp)
- add connectors to Spat send/receive via ethernet (before going in the buffer)

The needs of those connectors could be fullfilled with 2 other modules, which would allow to keep same design for the 2 boards of buffer (INPUT and OUTPUT of the matrix).

We realized we need a control view of the signal going to the amp as our amps don't have any. This way we prevent them entering in protection mode, or getting blown.

We used cheap ready made vu-meter from Amazon [INSERT LINK TO VU-METERS][].

Finally we opted for plasma cutting the front panel of Matrix and Spatialisatrice.

Follow Pierre Pierre Pierre personal git repo for FreeCad files : https://git.disroot.org/sigpie/WanderingSoundsystem

Not so easy to find parts that matches : fader, fader caps, screw for the fader…

• Screws to attach faders to the panel (you need to do a countersink on the panel) M3 - 4mm Tête Conique

• Only fader caps fitting were thoses one capuchons adaptés chez Farnell. 3d printing those pices was abandonned mostly because the printer got stuck in the last session.