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Digital Polyphonic Synthesizer with DreamBlaster X2 module - v2

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ixtern
Veteran Wiggler
Posts: 512
Joined: Mon Jan 22, 2018 4:34 am

Digital Polyphonic Synthesizer with DreamBlaster X2 module - v2

Post by ixtern »

This is second version of my synthesizer based on the DreamBlasterX2 module.

Main differences between v1 and v2:
- v2 has only one display (LCD 40x2), LED display from v1 generated big electrical noise, OLED display noise also was hearable,
- v2 version has designed and manufactured PCBs (gerber files will be attached).

v2 synthesizer was made with the same concept as v1: mainboard and modules.
Please notice that this is a (working) prototype and ther may be some errors here and there.

0. Photos of whole synthesizer
Outside:
DreamBlasterX2_synth_front.jpg
Inside:
DreamBlasterX2_synth_inside.jpg
1. Block diagram
block_diagram_v2.png
2. Mainboard
mainboard.sch.png
ArduinoMidiPolySynthMainboard_Sch.pdf
(183.72 KiB) Downloaded 16 times
ArduinoMidiPolySynthMainboard_pcb.pdf
(46.42 KiB) Downloaded 10 times
eee_SynthMainGerbers.zip
(230.48 KiB) Downloaded 11 times
to be continued...
Attachments
ArduinoMidiPolySynthMainboard_pcb.pdf
(46.42 KiB) Downloaded 12 times
ixtern
Veteran Wiggler
Posts: 512
Joined: Mon Jan 22, 2018 4:34 am

Re: Digital Polyphonic Synthesizer with DreamBlaster X2 module - v2

Post by ixtern »

MIDI Board

MIDIboard has two MIDI inputs and six MIDI outputs. Both inputs (MIDI1 In and MIDI2 In) may control the synthesizer.
Six MIDI outputs are divided as follows:
- one for MIDI Out (duplicated MIDI output for DreamBlastedCX2 board)
- one for MIDI2 Through
- four for MIDI 1 Through.

There are also three LED indication outputs - one for MIDI1 In, one for MIDI2 In and one for MIDI Out.
DreamBlasterX2_synth_midi.jpg
DreamBlasterX2_synth_midi.jpg
ArduinoMidiPolySynthMidi_Sch.pdf
(62.56 KiB) Downloaded 10 times
ArduinoMidiPolySynthMidi_Parts_Dim.pdf
(14.03 KiB) Downloaded 11 times
eee_synth_midi_gerber.zip
(68.62 KiB) Downloaded 7 times
to be continued...
Attachments
midi_board_sch.png
ixtern
Veteran Wiggler
Posts: 512
Joined: Mon Jan 22, 2018 4:34 am

Re: Digital Polyphonic Synthesizer with DreamBlaster X2 module - v2

Post by ixtern »

Buttons Encoder

Buttons encoder based on the good ols 74C922 serves not only as an encoder but also as a debouncer.
Saves data lines and processor time. To check that any button is pressed only DA line needs to be tested.
DreamBlasterX2_synth_buttons_encoder.jpg
buttons_encoder.png
ArduinoMidiPolySynthButtonEnc_Sch.pdf
(30.5 KiB) Downloaded 8 times
ArduinoMidiPolySynthButtonEnc_Parts_Dim.pdf
(8.75 KiB) Downloaded 9 times
eee_button_enc_gerber.zip
(32.23 KiB) Downloaded 6 times
ixtern
Veteran Wiggler
Posts: 512
Joined: Mon Jan 22, 2018 4:34 am

Re: Digital Polyphonic Synthesizer with DreamBlaster X2 module - v2

Post by ixtern »

Audio Board

As DreamBlasterX2 has stereo output, audio board is also stereo. It consists output (unbalanced) and headphone amplifiers.
TS972 op amp may be replaced by any rail-to-rail low-noise op amp working good for audio with +5V supply.
TS922 op amp may be replaced by any rail-to-rail op amp with little larger output current (up to 80 mA) working good for audio with +5V supply.
DreamBlasterX2_synth_audio.jpg
audio_board_sch.png
AudioMidiPolySynthAudiov2_Sch.pdf
(87.67 KiB) Downloaded 10 times
AudioMidiPolySynthAudiov2_Parts_Dim.pdf
(38.4 KiB) Downloaded 7 times
eee_audiov2_gerbers.zip
(167.87 KiB) Downloaded 7 times
ixtern
Veteran Wiggler
Posts: 512
Joined: Mon Jan 22, 2018 4:34 am

Re: Digital Polyphonic Synthesizer with DreamBlaster X2 module - v2

Post by ixtern »

Encoders Board

Here were used encoders with pushbutton. Type: Bourns PEC11R-4215F-S0024.
DreamBlasterX2_synth_encoders_s.jpg
encoders_sch.png
ArduinoMidiPolySynthEncoders_Sch.pdf
(44.11 KiB) Downloaded 6 times
ArduinoMidiPolySynthEncoders_Parts_Dim.pdf
(12.03 KiB) Downloaded 9 times
eee_encoders_gerbers.zip
(60.45 KiB) Downloaded 6 times
weasel79
Common Wiggler
Posts: 145
Joined: Mon May 06, 2019 7:42 am

Re: Digital Polyphonic Synthesizer with DreamBlaster X2 module - v2

Post by weasel79 »

hey man, i can't stop coming back to your posts. really great work. as i told you i also ordered some dreamblaster boards from serdaco, they arrived a couple days ago and i will start with some prototyping soon. i will probably try and use one of the fv1 boards to add some more fx...

the "sound board" as your schematics call it, is mostly like a proper output stage? for the headphone amp? did you make the 1/4" output jacks symmetrical/balanced?

the dreamblaster seems to be receiving only one pin for midi, correct? i didn't look at serges documentation for dreamblaster yet, i assume the pinheader midi in also goes through the onboard optocoupler?

and thanks for the hint at the 74C922, seems like a great solution with the internal debouncing...
ixtern
Veteran Wiggler
Posts: 512
Joined: Mon Jan 22, 2018 4:34 am

Re: Digital Polyphonic Synthesizer with DreamBlaster X2 module - v2

Post by ixtern »

weasel79 wrote: Tue Jan 25, 2022 7:58 am hey man, i can't stop coming back to your posts. really great work. as i told you i also ordered some dreamblaster boards from serdaco, they arrived a couple days ago and i will start with some prototyping soon. i will probably try and use one of the fv1 boards to add some more fx...

the "sound board" as your schematics call it, is mostly like a proper output stage? for the headphone amp? did you make the 1/4" output jacks symmetrical/balanced?

the dreamblaster seems to be receiving only one pin for midi, correct? i didn't look at serges documentation for dreamblaster yet, i assume the pinheader midi in also goes through the onboard optocoupler?

and thanks for the hint at the 74C922, seems like a great solution with the internal debouncing...
The soundboard is an output stage and headphone amplifier also (separate). Unfortunately, it is only unbalanced (fully balanced is complicated and simple balanced is only an additional resistor).

There is only one pin for midi, yes. I don't think there is a optocoupler on board as it was a computer-targeted module (Waveblaster compatible).

DreamBlaster pinout:
connector.png
connector.png (22.08 KiB) Viewed 150 times
old Waveblaster pinout:
WaveBlasterConnectorPinout.png
WaveblasterPinout.pdf
(172.45 KiB) Downloaded 5 times
ixtern
Veteran Wiggler
Posts: 512
Joined: Mon Jan 22, 2018 4:34 am

Re: Digital Polyphonic Synthesizer with DreamBlaster X2 module - v2

Post by ixtern »

Buttons Board.

As the buttons, Highly PB61304BL-5 LED-illuminated buttons were used.
DreamBlasterX2_synth_buttons2.jpg
DreamBlasterX2_synth_buttons_back.jpg
buttons_sch.png
ArduinoMidiPolySynthButtons_Sch.pdf
(35.47 KiB) Downloaded 8 times
ArduinoMidiPolySynthButtons_Parts_Dim.pdf
(12.22 KiB) Downloaded 9 times
eee_buttons_gerbers.zip
(24.29 KiB) Downloaded 6 times
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