Dual-YM2612 hardware synthesizer

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djf26
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Post by djf26 » Mon Mar 30, 2015 5:22 pm

Hello everyone, and thanks for all of the interesting information here. I am having an issue with the code and I am hoping someone can assist me.

I have the circuit breadboarded, and am currently designing a single sided PCB for my uses. I am pretty confident that the circuit is all hooked up properly. When a MIDI signal is sent to the Teensy, I am getting a vague grumbling noise out. Usually means that the MIDI signal is being processed, but no data is being actually sent. I think that my problem lies in flashing the EEPROM.

I have no experience with Python, so that is most likely where the issue lies. When I run the python script, it runs, and nothing happens. Kind of hangs there. Will there be some sort of completion message, or any indication that the EEPROM has been flashed? I know that I have it pointing to the right COM port, and it is communicating with the Teensy board. When I connect my MIDI device to test, however, there is no sound other than that grumble.

Maybe the issue is with the code? I believe that I have uncommented the appropriate areas, but maybe foobat or someone can direct me to the specific lines of the Teensy code that are required for the flashing process?

I know that this is out of the blue on an old thread, and I know that everyone is very busy and this is on the backburner, but I am very excited about the project. Just a little concerned about committing the time and energy to etching and populating a board if I cannot get the coding working.

Thank you to foobat for his efforts though, I have been eagerly planning this project for about a year now.

Cheers.

foobat
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Post by foobat » Sun Apr 12, 2015 1:30 pm

Oh yeah if the eeprom doesn't have any voices in it it'll do that

Uncomment the //flashEEPROM() line in setup() and start up the device with it plugged into the USB port. Then you should be able to run tserial.py. Afterwards, re-comment the flashEEPROM() line.

tserial.py looks for the "eeprom.pak" file in its directory to send and tries to send it to /dev/ttyACM0 (even if that device node is wrong or doesn't exist).

Sorry it sucks so bad, I hope to get around to finishing up the last 5% on this project one of these ...years.

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Aly James
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Post by Aly James » Thu May 07, 2015 6:26 pm

Just a quick info, I had finally found some hours to dig the code and reprogram the baby a bit, stripping of the LCD thingy, switching to separate channel control and started to implement proper FMDrive CC, works great so far!
it shouldn't be too long to finish once I have some extra time :)

I should also implement legato playing for mono channel (with previous key remembering) because straight mono is a bitch when you play live on a keyboard ;)

Best
AJ

foobat
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Post by foobat » Fri Jul 10, 2015 7:38 pm

oh awesome dude

I still haven't had time to do *anything* since we last talked via email. One of these days...

uprock7
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Re: Dual-YM2612 hardware synthesizer

Post by uprock7 » Tue Apr 19, 2016 4:00 pm

Hey all, I have a teensy2.0++, a few YM2612, and some 7.68Mhz dip-14 oscillators on the way. Im looking to build something pretty similar and I have a few questions.

1) Why is there a dual power source for +5V and Vdd? Does the YM2612 a.Vcc use a lot of power?
2) Could the teensy's +5v from usb power the YM2612?
3) What happens if you dont supply power to the a.Vcc pin?
4) If I wanted to use an external amplifier, could I just connect the MOL and MOR straight to that?
5) Is there a complete part list anywhere for the components for this project?

thanks in advance.

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Re: Dual-YM2612 hardware synthesizer

Post by foobat » Fri Apr 22, 2016 5:15 am

1) to keep the power source to the YM2612 and LM386es as noise-free as possible
2) yes but not the way I have it laid out (the LM317s need higher voltage to be stable). You will get switching noise when you manipulate the data bus and change pin states on the Teensy if you do that, and it can't be easily filtered without affecting the audio output to my knowledge (ymmv, IANAEE)
3) the YM2612s will be undervolted and won't work with this schematic
4) you can, but this will pull too much current from the YM2612 and will slowly damage it over time. You want to have at least an op amp voltage follower. You also need a mixer if you have two of them (I did this by amplifying each signal individually and combining them with resistors but I'd do something more complex if I did it again)
5) I didn't make a BOM but there aren't many components and they're labeled fairly clearly, I can make a BOM if you need one but idk when I'll get around to that

uprock7
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Re: Dual-YM2612 hardware synthesizer

Post by uprock7 » Fri Apr 22, 2016 8:36 pm

All that makes so much more sense now, which means I have a new round of questions! Im toying with the idea of using YM3438's instead.

1) Is the voltage divider resistors not needed on the MOL/MOR of the 3438 ? Just the pulldown resistor and the coupling cap?

2) Would you use a LM715 with the output going back into the negative in as a voltage follower for the 3438?

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Re: Dual-YM2612 hardware synthesizer

Post by foobat » Sat Apr 30, 2016 7:04 am

1) I have no idea what those 12k and 220k resistors are for. I suspect I didn't when I made the amplifier either. The twiddly bits don't make music come out of the scoochers if those parts are populated. ¯\_(ツ)_/¯

2) idk, try it and report back. I think it's kind of hard to get an op amp set up to work with a 0v/+5v supply if you don't know what you're doing because they usually want +/-6v or similar.

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Re: Dual-YM2612 hardware synthesizer

Post by foobat » Fri Oct 06, 2017 5:29 am

webserver went down awhile ago and the sources for this have been offline, they should be back up now at http://namakubi.net

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