I'm throwing in the towel

A project log for OPL Studio - OPL2 / OPL3 MIDI Interface

a MIDI interface for the OPL2 Audio Board and OPL3 Duo!

maarten-janssenMaarten Janssen 04/01/2023 at 12:524 Comments

Sadly this will be the end for OPL Studio unless some sort of miracle happens. As much as I love my project and all the things that it can do I'm starting to loose my sanity over all the issues with the TDA2822 amplifier and all the noise it's picking up from the screen. I simply can't make this thing work... 

Whatever I do the amplifier keeps picking up noise from the screen. This is way above my level of knowledge to fix. So after a month or two of going insane over this problem I've had enough. I'm calling it quits!


PjotrA@aliendnatronics wrote 05/09/2023 at 07:27 point

me just being silly probably, but since the only part really able to give an amount of interference to the lcd or visa versa seems to be the piezo buzzer...  i would try to place it vertical either on the spot as intended or more to the side pointing towards the user. great work btw. if I had money to spend on it I would, been thinking about getting something similar for my own home studio setup. albeit in a 19 inch rack form. good luck with your awesome cool ideas and projects. mvg Pete  ps. have not seen a pcb so my question is also are there enough ground plates?

  Are you sure? yes | no

Maarten Janssen wrote 05/09/2023 at 18:28 point

Hi Pete, thanks for your suggestions and you're right! The piezo buzzer was a big part of the problem. I've managed to get rid of the noise it produced with an additional series resistor. I've also tried different configurations for the ground. I tried a single big ground plane and a star ground where the LCD, SD card etc have separate paths to a single ground as well as the analog part of the circuit going to a single ground point. But the result was the same. After more experimenting I'm thinking that the noise is coming in through the ground of the volume pot...

  Are you sure? yes | no

dave_omahony wrote 05/07/2023 at 12:19 point

Sorry to read this, hope you found the energy to continue. Ive been watching here and your store on Tindie and Id love to pick up a built OPL Studio. I see they are back in stock - have you decided to continue? Thanks for your time and all the best for a brilliant project! Dave

  Are you sure? yes | no

Maarten Janssen wrote 05/07/2023 at 13:01 point

Hi Dave, I'm still tinkering with the all in one boards (even as we speak). But for now I will continue with the old design with the separate boards. I have a few of them left that I put in my Tindie store and ordered more PCBs from the manufacturer so in two weeks more people can get an OPL Studio. Thanks for your support!

  Are you sure? yes | no