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Hello friends. I am Rolf and I would like to share my latest DIY project "Jeannie" with you. It is an 8 voices polyphonic synthesizer based on a Teensy 4.1 board.

I started doing it last summer. Now I have built an effects circuit for the synthesizer.

"Jeannie" DIY Synthesizer


Effect circuit



The Fx menu in the synth is almost ready. The new one is still missing Display of the parameter values after a program change.

There are more videos on my youtube channel: https://www.youtube.com/channel/UCXQSpP0qn5MXSkyDo6PZ4Cw

Greetings from germany. Rolf

Edited by rolfdegen
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Hello and have a nice Sunday smile.png

There are a few changes in the circuit diagram. The DAC output (PT8211) on the Teensy Board has an active 32KHz LowPass filter. This reduces high-frequency interference signals at the input of the effect chip.



The OTA (IC5a / b) for the volume control of the effect signal (MIX) has now been moved to the output of the effect chip. This means that the noise floor at the synthesizer output is a little lower at low effect levels.


Greetings Rolf

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Hello Friends..

Our progress cannot be stopped. This time we really accelerate.

The Fx PCB is ready. Now we has started to route the "Jeannie" mainboard. I'm curious..

Fx board




This is the first draft of the "Jeannie" mainboard. There will still be some changes such as the Teensy processor module (left).

This is moved further down so that the USB socket can be used from the outside.

Greetings Rolf

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  • 2 weeks later...
Posted (edited)

The 1st draft in 3D



The board is roughly the size of a laboratory card in euro format (160 x 100).

The Fx module is simply plugged onto the back.



The current prototype


Greetings from germany. Rolf

Edited by rolfdegen
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Hi @rolfdegen. Thanks for sharing.

Overall this project looks good and sounds cool! The Teensy v4 is clearly a capable MCU with it's fast ARM Cortex-M7.

I'd be curious to hear about what motivated you to get started with this project and to build off of the Electrotechnique TSynth v4 foundation (http://electrotechnique.cc/)?

You also chose to use a minimal control surface, so I'm guessing you're envisioning more of a sequenced, MIDI CC message type of interaction, rather than a live, interactive performance?


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