Mixer
About the Mixer PCB
Mixer is an open source AVR/Arduino PCB design by rabidaudio, published on GitHub under the MIT license. It is a 4-layer board measuring 30.5 × 128.5 mm, with 91 components from 50 distinct parts.
Its main chip is the ATtiny24-20SS, from the AVR/Arduino family. Other key parts include the TL074 and DG403. By type, the board carries 27 connectors, 24 resistors, 10 capacitors, 6 switches, 5 ICs and 4 diodes.
It belongs with the audio designs in this gallery.
From the project
My custom synthesizer work
Op-amps in, round-robin sampling? Codec?
Per channel: - in jack - Fader - mute btn+led - solo btn+led - Aux send knob - Pan knob - Tone knob (center detent)
Master: - aux return jack x2 - out jack x2 - fader - Aux return knob
maybe sets of 4 channels, plus master - with ribbon - each has a single mix with direct in mixdown, allowing infinite daisy chain - -> prev in x2 - mixdown x2 -> - mute/solo bus - SPI? - Power (from master)
Main components on the Mixer
Mixer bill of materials (BOM)
91 components, 50 distinct parts.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 3 | TL074 | SOIC-14_3.9x8.7mm_P1.27mm | U1, U2, U4 |
| 1 | DG403 | SOIC-16_3.9x9.9mm_P1.27mm | U3 |
| 1 | ATtiny24-20SS | SOIC-14_3.9x8.7mm_P1.27mm | U6 |
| 1 | BSS214NW | SOT-323_SC-70 | Q1 |
| 1 | EURORACK_CONN_16 | EURORACK_16_IDC | J1 |
| 1 | AUX_OUT | Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles | J2 |
| 1 | AUX_IN_R | Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles | J3 |
| 1 | AUX_IN_L | Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles | J4 |
| 1 | MAIN_OUT_R | Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles | J5 |
| 1 | MAIN_OUT_L | Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles | J6 |
| 2 | CHANNEL_IN | Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles | J7, J9 |
| 1 | AVR-ISP-6 | IVR_PADS | J8 |
| 1 | C_BOARD_IN | PinSocket_1x08_P1.27mm_Vertical | J10 |
| 1 | INTERCONNECT1 | PinHeader_1x08_P1.27mm_Vertical | J11 |
| 1 | M_BOARD_IN | PinSocket_1x08_P1.27mm_Vertical | J12 |
| 1 | INTERCONNECT2 | PinHeader_1x08_P1.27mm_Vertical | J13 |
| 1 | C_BOARD_OUT | PinSocket_1x08_P1.27mm_Vertical | J14 |
| 1 | C_IN1 Cinch Connectivity Solutions Johnson | thonkiconn_hole | J15 |
| 1 | C_IN2 Cinch Connectivity Solutions Johnson | thonkiconn_hole | J16 |
| 1 | C_AUXSEND1 Cinch Connectivity Solutions Johnson | knob_hole | J17 |
Show 30 more
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | C_PAN1 Cinch Connectivity Solutions Johnson | knob_hole | J18 |
| 1 | C_AUXSEND2 Cinch Connectivity Solutions Johnson | knob_hole | J19 |
| 1 | C_PAN2 Cinch Connectivity Solutions Johnson | knob_hole | J20 |
| 1 | M_OUT_L Cinch Connectivity Solutions Johnson | thonkiconn_hole | J21 |
| 1 | M_AUXSEND Cinch Connectivity Solutions Johnson | thonkiconn_hole | J22 |
| 1 | M_AUX_AMOUNT Cinch Connectivity Solutions Johnson | knob_hole | J23 |
| 1 | M_OUT_R Cinch Connectivity Solutions Johnson | thonkiconn_hole | J24 |
| 2 | M_AUX_RETURN_L Cinch Connectivity Solutions Johnson | thonkiconn_hole | J25, J26 |
| 1 | M_MASTER Cinch Connectivity Solutions Johnson | knob_hole | J27 |
| 1 | C_SCREW_B Cinch Connectivity Solutions Johnson | eurorack_screw_hole | FID1 |
| 1 | C_SCREW_T Cinch Connectivity Solutions Johnson | eurorack_screw_hole | FID2 |
| 1 | M_SCREW_T Cinch Connectivity Solutions Johnson | eurorack_screw_hole | FID3 |
| 1 | M_SCREW_B Cinch Connectivity Solutions Johnson | eurorack_screw_hole | FID4 |
| 1 | B100K - AUX_RETURN_LEVEL | Potentiometer_Alpha_RD902F-40-00D_Dual_Vertical_CircularHoles | RV1 |
| 1 | A100K_MASTER_VOL | Potentiometer_Alpha_RD902F-40-00D_Dual_Vertical_CircularHoles | RV2 |
| 2 | B1M_GAIN | 3352W | RV3, RV7 |
| 2 | A100K_CHANNEL_FADER | Potentiometer_Bourns_PTA3043_Single_Slide | RV4, RV8 |
| 2 | B1M_AUX_SEND | Potentiometer_Alpha_RD901F-40-00D_Single_Vertical | RV5, RV9 |
| 2 | A100K_PAN | Potentiometer_Alpha_RD902F-40-00D_Dual_Vertical_CircularHoles | RV6, RV10 |
| 2 | MUTE_PBSW | SW_PUSH_6mm | SW1, SW4 |
| 2 | SOLO_PBSW | SW_PUSH_6mm | SW2, SW5 |
| 2 | AUX_PRE_POST_FADER_SLIDESW | Dailywell SPDT Sub-Mini Slide SW | SW3, SW6 |
| 2 | M_LED_RED | LED_D2.0mm_W4.8mm_H2.5mm_FlatTop | D1, D3 |
| 2 | S_LED_ORANGE | LED_D2.0mm_W4.8mm_H2.5mm_FlatTop | D2, D4 |
| 3 | 10u | C_0603_1608Metric | C1, C2, C3 |
| 7 | 100n | C_0603_1608Metric | C4, C5, C6, C7, C8, C9, C10 |
| 11 | 10k | R_0603_1608Metric | R1, R6, R7, R10, R11, R12, R25, R26 +3 |
| 6 | 33k | R_0603_1608Metric | R2, R5, R17, R18, R20, R21 |
| 3 | 100k | R_0603_1608Metric | R3, R14, R15 |
| 4 | 1k | R_0603_1608Metric | R8, R9, R27, R28 |
Mixer design files
The KiCad project lives in the rabidaudio/synthesizer repository on GitHub; these links point at the commit this page was built from.
- Layoutmixer/mixer.kicad_pcb
- Schematicmixer/mixer.kicad_sch
Mixer: common questions
What microcontroller does the Mixer use?
The Mixer is built around the ATtiny24-20SS, from the AVR/Arduino family.
How big is the Mixer PCB?
The Mixer measures 30.5 × 128.5 mm, has 4 copper layers and is 1.6 mm thick.
How many components are on the Mixer?
91 components, from 50 distinct parts. The full bill of materials is listed on this page.
Where can I download the Mixer design files?
From the rabidaudio/synthesizer repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.
Can I use the Mixer design in my own project?
Yes, under the terms of its MIT license, which rabidaudio chose for the repository.
Can I test firmware for the Mixer without the hardware?
Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug AVR/Arduino firmware against it before you order a PCB.
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