Search found 16 matches

On the setup, I noticed frequency instability (quite frank) caused by the use of Digital Potentiometers. This happens even at rest when there are no signals on the INC, UD pins.

When disconnecting ...

Wow, amazing project! How did you learn all this stuff? Very Happy

Yes it's fun to do, indeed.

As for the learning process, I've done some engineering in college, then I went into IT as a sys admin and ...

The two XR-2206 IC version of the synth is now controlled by an Arduino Due.
computes faster, and has plenty of SRAM that was going low on the Arduino Mega 2560.

Also, added a Winbond Flash 32 mbi ...

A little follow-up on the PWM by LFO using XR-2206 self keying.
As I said earlier last year, I made the decision to use a DAC for fine frequency control (using a DAC offset) with a superimposed DAC w ...

Added Github project page :
https://github.com/rodv92/synth1
----
I finally managed to dynamically autotune the self-keyed oscillator. (for pw modes / saw modes)

The trick was to tune the subosc ...

I have a bit of time to explore VCO autotune and frequency correction used in big commercial synths.
Synths teardown videos are quite sparse and commercial synths service manuals seem hard to find fo ...

that's all I can say for now untill I've invested more time in it.

one question though; are those original XR2206 chips ? I know you can get them pretty cheap from china these days
and ...

I managed to improve the auto tuning based on the cd4046 pll chip.
Since the phase shift comparator 1 output basically measures the beat frequency between the oscillator and the reference pwm frequen ...

Ok, so I implemented an autotune system based on chips at hand.

I have CD4046 pll available so I decided to analyse the phase comparator I output signal.

When a reference signal and the VCO squa ...

synth arp sample... quite detuned because of one subosc that needs recalibration.

Quick update.

The areas of development I am working on :

The truth table for all the oscillators sync. and retrigger mode switches so I don't miss anything.

The XR-2206 amplitude modulation ...

Here is the schematic for anyone interested.
This is only the Dual VCO Stage with Hardsync and waveform selection.
The VCA will be on another board, but it is a mix of a simple 555 envelope and Vint ...

Update.

I added the pitch mod JFET and inadvertently shunt the R1 and R2 XR-2206 pins to ground.
Damn.. !
It seems to have fried the chip for the triangle / saw output.

I managed to get some s ...

A quick update.

Now that MIDI is working, I put the synth to test in order to check that the digital pots were working ok.

The potential problem with them is that they do not give feedback on th ...

Attachments to the project

Hi, I am currently designing a double VCO XR-2206 based synth.
It works pretty well.

Instead of controlling the osc. frequency by CV,
i decided to use discrete R levels for pins 7 and 8, implemen ...

Author	Message
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Thu Aug 19, 2021 2:59 am Subject: follow-up Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	On the setup, I noticed frequency instability (quite frank) caused by the use of Digital Potentiometers. This happens even at rest when there are no signals on the INC, UD pins. When disconnecting ...
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Fri Aug 06, 2021 2:47 pm Subject: XR-2206 Arduino Digitally Controlled Dual VCO Project Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	Wow, amazing project! How did you learn all this stuff? Yes it's fun to do, indeed. As for the learning process, I've done some engineering in college, then I went into IT as a sys admin and ...
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Tue Aug 03, 2021 9:01 am Subject: Some samples... Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	The two XR-2206 IC version of the synth is now controlled by an Arduino Due. computes faster, and has plenty of SRAM that was going low on the Arduino Mega 2560. Also, added a Winbond Flash 32 mbi ...
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Tue Jun 29, 2021 1:32 am Subject: XR-2206 : PWM by LFO Follow-up Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	A little follow-up on the PWM by LFO using XR-2206 self keying. As I said earlier last year, I made the decision to use a DAC for fine frequency control (using a DAC offset) with a superimposed DAC w ...
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Fri Dec 11, 2020 1:43 pm Subject: Autotune follow-up Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	Added Github project page : https://github.com/rodv92/synth1 ---- I finally managed to dynamically autotune the self-keyed oscillator. (for pw modes / saw modes) The trick was to tune the subosc ...
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Sat Oct 31, 2020 8:09 am Subject: VCO.frequency stability control Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	I have a bit of time to explore VCO autotune and frequency correction used in big commercial synths. Synths teardown videos are quite sparse and commercial synths service manuals seem hard to find fo ...
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Fri Oct 30, 2020 1:27 pm Subject: XR-2206 Arduino Digitally Controlled Dual VCO Project Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	that's all I can say for now untill I've invested more time in it. one question though; are those original XR2206 chips ? I know you can get them pretty cheap from china these days and ...
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Fri Oct 30, 2020 12:33 pm Subject: auto tuning follow-up Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	I managed to improve the auto tuning based on the cd4046 pll chip. Since the phase shift comparator 1 output basically measures the beat frequency between the oscillator and the reference pwm frequen ...
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Sun Oct 25, 2020 6:48 am Subject: Autotune follow-up Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	Ok, so I implemented an autotune system based on chips at hand. I have CD4046 pll available so I decided to analyse the phase comparator I output signal. When a reference signal and the VCO squa ...
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Wed Oct 07, 2020 10:54 am Subject: XR-2206 Arduino Digitally Controlled Dual VCO Project Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	synth arp sample... quite detuned because of one subosc that needs recalibration.
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Sun Oct 04, 2020 11:32 am Subject: XR-2206 Arduino Digitally Controlled Dual VCO Project Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	Quick update. The areas of development I am working on : The truth table for all the oscillators sync. and retrigger mode switches so I don't miss anything. The XR-2206 amplitude modulation ...
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Mon Sep 28, 2020 3:14 am Subject: XR-2206 Arduino Digitally Controlled Dual VCO Project Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	Here is the schematic for anyone interested. This is only the Dual VCO Stage with Hardsync and waveform selection. The VCA will be on another board, but it is a mix of a simple 555 envelope and Vint ...
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Sat Sep 26, 2020 5:41 am Subject: XR-2206 Arduino Digitally Controlled Dual VCO Project Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	Update. I added the pitch mod JFET and inadvertently shunt the R1 and R2 XR-2206 pins to ground. Damn.. ! It seems to have fried the chip for the triangle / saw output. I managed to get some s ...
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Sun Sep 20, 2020 5:01 am Subject: XR-2206 Arduino Digitally Controlled Dual VCO Project Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	A quick update. Now that MIDI is working, I put the synth to test in order to check that the digital pots were working ok. The potential problem with them is that they do not give feedback on th ...
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Fri Sep 18, 2020 8:30 am Subject: XR-2206 Arduino Digitally Controlled Dual VCO Project Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	Attachments to the project
Topic: XR-2206 Arduino Digitally Controlled Dual VCO Project
rodv92 Replies: 22 Views: 15038	Posted: Fri Sep 18, 2020 5:22 am Subject: XR-2206 Arduino Digitally Controlled Dual VCO Project Subject description: First prototype of a fully digital potentiometer Arduino controlled Synth Forum: DIY Hardware and Software » Developers' Corner
rodv92 Replies: 22 Views: 15038	Hi, I am currently designing a double VCO XR-2206 based synth. It works pretty well. Instead of controlling the osc. frequency by CV, i decided to use discrete R levels for pins 7 and 8, implemen ...