• OPL Studio v2.1.0 Software

    Maarten Janssen6 days ago 0 comments

    Time for another software update! The new synthesizer code v2.0.0 that I introduced for the all-in-one hardware was a great improvement of what was there before, but it also contained some unfortunate bugs. The biggest issue being that it completely broke when putting OPL Studio in OPL2 only mode. This has now been fixed as well as v2.1.0 containing the long awaited support for pseudo 4-OP patches.

    Pseudo 4-OP Patches

    So what are pseudo 4-OP patches? They are like 4-OP patches, but using two 2-OP patches to produce a richer sound to emulate a 4-OP patch. Since we're emulating 4-OP patches it means that these kinds of instruments can be used both on OPL2 and OPL3 hardware. Back in the day this would be a great fit for example on older SoundBlaster cards or Adlib cards to enhance the audio. For example DOOM uses this trick with some of its instruments.

    IMO after playing around with pseudo 4-OP patches for a while they may even sound better that regular 4-OP patches! especially when playing with the finetune for the second voice you can get some beautiful sounds.

    Updated Patch Editor

    Supporting Pseudo 4-OP patches introduces some additional parameters that need to be exposed through the patch editor. So it has been updated to add the controls for transpose and finetune of the second voice. Finetune is now also available on regular 2-OP and 4-OP patches, by the way.

    There is now support for DMX instrument banks in the form of *.OP2 files, such as those used in DOOM, that include pseudo 4-OP instruments and the OPL Studio session files *.OPS also support pseudo 4-OP now.

    The new software can be downloaded from the OPL Studio release page https://github.com/DhrBaksteen/OPLStudio/releases

    And now back to those MIDI CC to synthesizer CC mappings!!

  • OPL Studio is now available on Tindie!

    Maarten Janssen05/30/2024 at 18:40 0 comments

    Just a short project update this time to announce that after more than year of struggling with bad hardware designs, mistakes and frustrations the new OPL Studio is now available in my Tindie store for everyone!

    The new units improve upon the existing OPL Studio design. I've taken into account the feedback and wishes that I've received from many users over time as well as my own wished to create the ultimate OPL2 MIDI synthesizer!

    The 'old' kits will also remain available for everyone who already owns an OPL3 Duo or OPL2 Audio Board and wants to expand its capabilities, or for those who want to customize OPL Studio to their own liking.

    Find out more on my Tindie page

  • The Home Stretch

    Maarten Janssen05/19/2024 at 12:47 0 comments

    Right now I'm putting together the first production units of the new OPL Studio. It's the final step and it can sometimes be frustrating since I'm extremely happy that finally units are working well and I'm almost able to share them with the rest of the world, but also it's where I find all the little problems that I want to fix before putting the new all-in-one OPL Studios in my Tindie store. 

    Now is the time when I figure out what is the best way to assemble each unit, what to look out for during assembly, what to test, and how to fix the inevitable mistaks that I'm going to make during assembly.

    Some parts turn out to be easier than expected. The ZIF connector for the LCD with all of its tiny pins was the most nerve wracking component at first. But after surprisingly few times I got the hang of soldering it and now I no longer break a sweat. 

    On the other hand, for the enclosure I've found lots of little mistakes that I needed to fix. I ended up redesigning most of the enclusure over the past couple of weeks. This resulted in an enclosure that's simpler to 3D print and wich is much sturdier than the design I had before. The LCD bezel was the final pice of the enclosure puzzle that I needed to solve, as it was too easy to come loose. It now clamps into the LCD mount so it won't come loose so easilly anymore.

    For now I'm putting together a small stock pile of units and awaiting a few more components that I ordered too few of, but then after a very, very long time the new all-in-one OPL Studio will be available!

    OPL Studio Software v2.0

    With the new hardware also comes new software. The OPL Studio software v2.0 is the first release to support the all-in-one as well as the existing kit versions of OPL Studio. No changes are needed, the software detects the hardware during start up and fully supports both models. 

    Support for the new hardware is not the only new thing in the 2.0 software. In this release all of the OPL3 synthesizer code has been rewritten. It no longer relies on my Arduino OPL2 library and that makes it much more flexible toward the future.

    This was a huge undertaking that I really underestimated. It has taken me several months and from a feature perspective the 2.0 software may look like nothing new has been added, but it lays the ground work for some very exciting new things coming soon!
    • DMX and WOPL instrument patches with support for pseudo 4-OP patches
    • Routing of any MIDI CC to any synthesizer parameter.
    • Patch effects like the macros from Adlib Tracker

    The new software is already available on GitHub. The OPL Studio website I will update next week.

  • The All In One hardware

    Maarten Janssen03/23/2024 at 14:43 0 comments

    The hardware for OPL Studio with integrated OPL3 Duo! is ready!!! It has taken many months with lots of frustrations and times where I just wanted to give up, but now it's finally here :)

    I've put together a quick video to show the first images of the all in one OPL Studio in action. It's playing a simple MIDI tune running an inbetween version of the old and upcoming re-write of the synthesizer code. The audio is a direct capture from the line out. You can hear some exagerated vibratos that I had hardcoded while experimenting with the new synth code, it does sound nice on this tune I think.

    The enclosure is also almost ready, so in a couple of weeks the new OPL Studio will be finally available from my Tindie shop!

  • The Good News Project Log

    Maarten Janssen02/14/2024 at 19:12 0 comments

    Finally I have good news to report on the all-in-one OPL Studio! 

    This design is like a night and day difference compared to previous prototypes. The audio is clear, the line out has a higher output level and the speaker out has a much, much lower noise floor. There is no more noise on the line out and on the speaker out there is only very slight noise from the LCD if you're listening through headphones and the OPLs are silent.

    There is light at the end of this very long tunnel now!

    Mistakes With The LCD

    Is it all good? No! Of course I did find more mistakes. The biggest one being the LCD connector. At one point during the design I had rotated the footprint, but I fell into 'a trap for young players' and I forgot to also reverse the order of the pins! So the LCD was dead. After realizing this I was a bit hesitant about fixing it, because it was tricky enough to solder the connector the first time and desoldering it and soldering it back after rotating was a good challenge! Also because there was no room. I had to solder the connector back at an angle and let it rest on some resistors and capacitors. To my surprise I managed to do it! 

    The LCD showed some signs of life, but still no clear image. It only showed a garbled mess of gray pixels. So I was sure that I messed up when soldering the connector. But to my surprise, when I added a connector for one of the old LCD modules, it was showing the same mess of pixels. This confused me and took me a while to figure out. It turned out to be the reset signal. On the kit design I had not used it, but for the all-in-ones I intended to use it. Turns out that I had not given the LCD controller enough time to properly reset. Problem solved after a simple software fix. Even the touch screen worked on the first try.

    The brightness is still a bit of an issue, because it doesn't work as it did on the old design. The screen is very dim, so that's still something I need to fix.

    Other Small and Easy Fixes

    There are other small things that need fixing. Transistor footprints that are not quite right, the MIDI status LED being too bright, the 3D printed LCD mount that needs some tweaking.

    All small thing that I will be working on in the next two weeks and get another few PCB prototypes made to check what should be the production version of OPL Studio. 

  • All-In-One Prototype Assembly

    Maarten Janssen02/06/2024 at 17:09 0 comments

    All-In-One Prototype

    All the parts to assemble the fist new All-In-One prototype have arrived and I have now put together the first board!

    The LCD connector was especially difficult and exciting cause of the teeny tiny pins and I wanted to be careful not to melt the plastic while soldering the part with hot air. There were a few bridges that I managed to fix with the soldering iron, some flux and carefully dabbing the excess solder with some desoldering braid. I'm happy with the result and it seems that at least there are no shorts.

    Of course I did make some mistakes when I ordered the components... :)

    • I ordered mono jack sockets instead of stereo ones
    • My BoM had the same Mouser part # for 10nF caps as I had for the 2200pF caps. Oops! I must've copy pasted the parts without updating the reference, so for now 0.1uF will have to do instead of 10nF
    • The shaft of the volume pot is too short, though I think this one is on Mouser for getting me the wrong part since I did order one with a 20mm shaft, but no worries for the prototype I'll just 3D print an extension for the shaft
    • My biggest mistake is with the two level shifters that I intended to use with the LCD. I must've forgotten to check the footprints, cause these parts aren't available as SOIC-16, what I used on the PCB. I ordered TSSOP-16s without checking and that will not fit! So for now I omitted the level shifters. They are probably not really needed since the breakout boards I was using before also don't have them. I used some tiny single strands of copper wire that I cut from a stripped wire to connect the data lines

    I haven't yet tested the board. I need to make some software changes to accomodate the different pinouts on this board. This is what I'll do during the course of this week and hopefully the prototype works as expected!

    MIDI Controller Update

    While I was waiting for the new PCBs and components I continued working on the MIDI and OPL controllers in the software. The audio part has been completely reworked to allow for exciting new features such as pseudo 4-OP instrument patches, patch effects and MIDI control mapping. 

    Right now the MIDI control mapping is finished, except for the UI. You can now map any incoming MIDI CC to a synthesizer control. For example map MIDI CC 54 to a software vibrato, software tremolo or patch parameter such as operator output level.

    Next up will be to implement support for pseudo 4-OP patches...

  • A New All-In-One Prototype

    Maarten Janssen01/14/2024 at 11:27 0 comments

    Now the sequencer has been updated and after a few day where I added additiona file support to the media player it's time to get back to the hardware of OPL Studio!

    The media player now supports DOSBox raw OPL (*.DRO), id Music Files (*.IMF) and Video Game Music (*.VGM)

    Another All-In-One Prototype

    Before my christmas holiday I spend a lot of time breadboarding parts of a new all-in-one design and experimenting with a previous prototype that has now become a Frankenstein setup with many loose wires, replaced components and failed experiments. The goal was to fix the issues that existed with the previous prototypes. Whether this is now the case I'll not comment about. I have been disappointed a few times before after getting excited about new PCBs.

    So another round of prototypes is now going to get manufactured where I made some drastic changes that I left out of previous prototypes:

    • The LCD screen is no longer a breakout module, but now attaches directly to the mainboard using a ribbon cable. All circuitry to drive the LCD is now also on the mainboard. This is scaring me the most since I couldn't breadboard this part
    • The little TDA2822 amplifier is also gone. Now there is an amplifier build out of discrete components
    • The status LEDs hadve moved left of the screen
    • The power button doubles as panic button
    • The line and speaker jacks are now 6.3mm jacks
    • There is a real volume knob now and the A and B rotary controls have moved for better looks and operation

    In The Mean Time: Software Refactoring

    While I wait for the new PCBs I will continue working on the next major update of the software. The code that handles MIDI and controls the OPL3 chips will be refactored to allow for some cool new tricks:

    • Pairing two 2-OP channels to make a pseudo 4-OP channel and support for OPL patch files duch as *.DMX that allow this
    • MIDI control mapping so you can map any MIDI control to an OPL Studio control. For example to have the volume slider control the output level of an OPL channel, to name something stupid
    • More advanced instrument patch effects like those used by various trackers to create more convincing drum sounds or to emulate the sound of the Loudness OPL2 music from games such as Fuzzy's World of Golf

  • New Sequencer Nearing Completion & All In One Update

    Maarten Janssen11/14/2023 at 13:57 0 comments

    The new sequencer is nearing completion. All functionality has been implemented and many bugs have already been fixed. The newest additions since the last log are:

    • A revert function that works as a rudimentary undo for any changes made to the sequence since it was opened.
    • The option to copy and paste sequences.
    • There is a transpose function to change the pitch of all notes or to shift all notes left or right in time.
    • The piano roll editor now has the controls to set the velocity and panning of new notes that are added by hand.
    • You can now also drag and drop events in the details panels. For example you can long press the volume graph to add a new volume event and you can drag it to change its position and value.
    • Many, many tweaks and bug fixes

    Drum sequences are still not using the new sequencer and I will definitely leave that until after the new software update. I now just want to release this thing after a few more days of testing to capture as many bugs as I can.

    Next to the sequencer update there will be a fun little secret hidden in the new software ;)

    Update On The All In One Units

    I have some good news on the all in one units this time. When using the line out the audio is now fine. No more excessive noise from the different components. The amplifier to the speaker out is still a problem, but I think I also have that mostly covered now. I've been working on a different amplifier design using a different chip that as far as I've been able to test sounds promising. I have a little test amplifier breakout board on the way to test my new design before I integrate it into the main PCB.

    For the LCD module I also have some new plans. So far I've been using complete modules for the LCD and touch panel that also include an SD card socket. The problem I'm having with these modules is that too often they are of questionable quality where some have brightness issues, some of them have misaligned touch screen panels, others have issues with adhesion of the different layers of the LCD and so on. This means that for every OPL Studio I've been shipping so far I've been hand picking the LCD modules to make sure they function correctly. This also means that I've been rejecting far too many modules (around 25%) and then I'm not even counting all modules that arrive broken due to aweful packaging done by vendors. Anyway, to get a better grip on LCD quality I will change to building the modules myself or rather I will use the loose LCD + touch panels that connect to the main PCB using a ribbon cable and I will build the interface myself. I have a few panels on the way to test this out.

    Finally the enclosure will also get an update, though it will keep the same dimensions and overall look as the current units.

  • Detailed Editing Panels In The New Sequencer Module

    Maarten Janssen10/08/2023 at 14:55 0 comments

    Time for another sequencer update! 

    I had a little break in between to attend the 2023 Eindhoven Maker Fair with the OPL Studio and some other projects of mine. It was a lot of fun to see and talk to everyone there and have lots of people and especially kids play around with all the synths I brought! Lots of good energy to continue work, so there has been a lot of progress over the last couple of weeks. 

    The sequencer is now at a point where it's fully functional and includes all the panels that allow you to edit all sequence details.

    In the previous log I wasn't sure yet how I could facifitate editing sequence details such as note properties, volume, modulation, etc. I was thinking to add a little panel with tabs below the piano roll, but since most of the screen was already taken this would be way too small. Still sticking with the tabs seemed like the only viable option, although still the screen is too small since I need 6 tabs and this wouldn't leave any room to show any labels on the tabs. This meant that it was time to expand the UI with a new component: a tabs ribbon! The ribbon now allows me to scroll through a list of tabs if there are too many to fit on screen.

    The 'Sequence' tab is the main tab of the sequencer where you create your sequences by recording MIDI or using the drag and drop piano roll and where you do all your basic editing. The other tabs go into more details of the sequence and allow you to tweak all the tiny details. Something the old sequencer really was lacking!

    The first tab shows the note details. It shows a graph of the full sequence and all of the notes. Using the spinners and rotary controls you can now navigate through the sequence note by note and change parameters such as note velocity, panning and start and duration up to MIDI tick level. Quantization is also done in this tab, plus there is a handy feature to equalize the velocity and / or panning of all sequence notes. By clicking the equalize button a dialog will open that allows you to set a default velocity and panning. Handy if your fingers don't always hit the keys with the right pressure.

    The next tabs allow you to change volume level, panning, pitch and modulation. They all function in a similar way. Again the sequence graph is there to show you the parameter values over time, with the notes of the sequence in the background (in dark grey). In these panels you can tweak existing events that you may have recorded from MIDI, you can add new events and of course delete them. A handy reature is to interpolate between the values of two events when you're adding them manually. 

    For now the sequencer has all the basic functions that I want it to have. Some things that are still missing are more controls to add, delete, copy and paste notes, to transpose the sequence and to configure the MIDI channel. This will be added in the coming weeks as well as more improvements and streamlining of the code while I work and play around with the sequencer. Whether or not I'll also replace the current drum sequencer with this new one in the same release is something I'm not yet sure of. Eventually I will, but it depends a bit on how much memory I will have left on the Teensy and on how much effort it takes to finalize the sequencer.

  • A New Sequencer

    Maarten Janssen08/20/2023 at 16:18 0 comments

    It's been quiet here for a while regarding updates, but I think that today I have a nice one. 

    Ever since I had the melody sequencer in OPL Studio I never really liked it. It's ok for just the basic stuff, but it's a pain to really get serious about editing your sequences, because it only shows you if one or more notes are active on a step. You can't easilly change existing notes, let alone change any other properties such as modulation, panning, etc after recording.

    This is now going to change. I've had the idea to implement a piano roll style editor for a long time and finally now is the time to show the progress I'm making with it.

    The new sequencer is a more conventional piano roll style editor that you may be familiar with from other MIDI editing software. You can add notes to a sequence by simply drawing them onto the piano roll. This is also a welcome improvement for when you don't have a MIDI device to record from, but still want to play with the sequencer. You can drag new notes up and down to set their pitch and left and right to change their length. As you drag the notes around they will play.

    Existing notes can be dragged across the piano roll to change pitch and location. You can grab the end point of notes to change the start and end points. Or long press to delete individual notes from your sequence. While dragging the notes around, the piano roll will automatically scroll.

    The little piano on the left hand side of the view shows you the range of the musical scale where you're editing and you can press the keys to get a note preview.

    The piano roll has a green playhead to indicate the current playback position. As you play the sequence the piano roll will start to scroll to show you the notes that are being played. Scrolling can be disabled by disabling the scroll lock on the bottom right of the view.

    When you are in recording mode the playhead will turn red and show you where the next note will be recorded in the sequence. All existing recording functionality still exists in the new sequencer: direct MIDI recording, step recording and the ability to set up a trigger to start recording as soon as a note on event occurs.

    It took quite a lot of code to get this all working, but it was well worth it I think! The piano roll makes the sequencer much more user friendly and powerful. But, we're not done yet... Moving notes around is just one thing, but as the tabs at the bottom of the screen may be giving away already, there will also be options for more detailed editing. Changing note velocities, volume, panning, pitch, modulation etc. 

    The detailed editing is something I haven't fully figured out yet how to make it work in the UI on this tiny screen. It also leaves no room for the 'menu' buttons that I have on some of the other app modules to, for instance, copy & paste. I'm sure I'll figure it out as I go...

    Below you can see a demo of the sequencer in action.