Proposal: Multi-Part Support and Virtual Mixer for miniDexed

[Banana71]

Ever since @soyersoyer introduced the parts for the miniDexed #950 , a few thoughts have been going through my head that I would like to share with you.

miniDexed – Mixer Extension

Definitions:

• TG = Tone Generator
• Part = a group of 8 TGs

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Preparing for Multiple Parts

Parts:

• Part 1 = TG1–TG8
• Part 2 = TG9–TG16
• Part 3 = TG17–TG24
• and so on.

Each part gets a global MIDI channel that can be changed via the UI:

GlobalMIDIChannelPart1 = 1  
GlobalMIDIChannelPart2 = 2  
GlobalMIDIChannelPart3 = 3  

To allow all parts to use the same performances, they must have different MIDI channels.

Performances would need a placeholder MIDI channel that can either inherit the global MIDI channel or still work in older versions.
MIDI channel 17 could act as OMNI in older versions. In a future version, if MIDIChannel = 17, the system could internally replace it with the part’s Global MIDI Channel.

Example:

• Part 1 loads a performance

• In that performance, the active TGs are assigned to MIDI channel 17

• If MIDIChannel = 17, assign the TG the value of GlobalMIDIChannelPart1

These global settings should be stored in a separate file (e.g. Global.ini). This file could also hold other global user-defined parameters, such as MasterVolume or other values currently in minidexed.ini.

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Virtual Mixer for miniDexed

To capture the TX816 vibe, an 8-channel mixer would be ideal.

• Inputs: 8 channels, grouped into 4 stereo busses

• Each TG can freely select a bus and route to its left/right stereo input via PAN

• Each bus has:

• • Volume control
• • 3-band EQ
• • 2 effect send paths

• The four busses are summed, pass through a Limiter, and then go to Audio Out

• For each bus, two effects can be chosen from a small set (Chorus, Delay, Reverb, …)

• Mixer data would be saved within the Performance.ini

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Another Idea for Multiple Parts: ALL/ODD/EVEN

The original DX7 could be set to ALL, ODD or EVEN note mode to increase polyphony — playing only odd or only even notes.

Example:

Part1MIDIReceive = Odd    # (All, Odd, Even)  
Part2MIDIReceive = Even  

Loading the same performance in both parts would nearly double the effective polyphony.

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It’s not easy to put all these ideas into words, so please feel free to ask for clarification if anything is unclear.

Peter

[probonopd]

Hi Peter, so you would prefer having multiple parts with 8 voices each over having e.g., one performance with up to 16*4 voices (16 voices, each of which up to 4 times detuned and panned)? That is what I have running currently in my experimental Linux, macOS, Windows, FreeBSD, and Embedded Linux version.

[soyersoyer]

Thanks for thinking on this and writing it down.

Each part gets a global MIDI channel that can be changed via the UI:

There are some performances that use multiple MIDI channels (Mkii Strgs+F3, Floating, Weekend, Flutter). Maybe it would be better to set an offset?

Part1ChannelOffset = 0 
Part2ChannelOffset = 3

To allow all parts to use the same performances, they must have different MIDI channels.

If someone wants to layer another performance, they can use the same one.

Inputs: 8 channels, grouped into 4 stereo busses

Good idea. Maybe 4 reverbs won't fit into the rpi3's performance, but it's worth a try.

The performance file new parameters could be:

TG1Bus=1

Bus1EQEnable=1
Bus1EQLow=level
Bus1EQMid=level
Bus1EQHigh=level
Bus1SendFx1SendLevel=level
Bus1SendFx2SendLevel=level
Bus1Level=level

Bus1SendFx1Type=Chorus
Bus1SendFx1Level=level
Bus1SendFx2Type=Reverb
Bus1SendFx2Level=level

Bus1SendFx2ReverbSize=size
Bus1SendFx2ReverbHighDamp=hd

...

Which word fits here better? The Bus or the Chain?

I would love to do these, but I would have to integrate the previous PRs. I wonder where :)

Another Idea for Multiple Parts: ALL/ODD/EVEN

If someone wants high polyphony, they can set the number of TGs to 8 and the polyphony to 32 and that's it.

That is what I have running currently in my experimental Linux, macOS, Windows, FreeBSD, and Embedded Linux version.

Where is the source?

[Banana71]

There are some performances that use multiple MIDI channels (Mkii Strgs+F3, Floating, Weekend, Flutter). Maybe it would be better to set an offset?

Thanks for the tip. Except for the MKii Strg+F3 should set the MIDI channel to 1 for all performances. I'll correct that.

Peter

[soyersoyer]

Thanks. It's cleaner that way.

Meanwhile, I realized that offset is mostly used by programmers, so it's not a good idea.
And if only the MIDI channel is specified, it can still work the same way.

So I think this is fine:

Part1MIDIChannel=1
Part2MIDIChannel=4
...

(MKii Strg+F3 loads on Part2 to channels 4 and 7.)

I saw that you already saved the performances in the new TG Compressor format. With older MiniDexes (or the current one), the compressors will not be turned on.

A solution to this integration issue would be nice.

Shall we start a fork?

[Banana71]

I saw that you already saved the performances in the new TG Compressor format. With older MiniDexes (or the current one), the compressor will not be turned on.

A solution to this integration issue would be nice.

Right, compressors are a good tool. However, FM synthesis is characterized by its very dynamic capabilities, and therefore I use compressors very carefully so as not to lose the FM character.

I hadn't even thought about the modified Performance.ini at the time. What happens to the older versions when they load a Performance.ini with compressors? I assume all compressors are disabled then, right?

Edit: You already wrote it yourself.

[Banana71]

I don't know how you feel about it, but so far you've always done it this way. I would prefer to expand the project in small steps.

e.g.
Stage 1: 8 TGs with the compressors -> lead to a 2-channel mixer (L/R) with 3-band EQ and volume control -> and then to the limiter and audio output
Stage 2: Stage 1 + two effect sends (including the original reverb + e.g., delay and/or chorus)
Stage 3: Stage 2 + expansion to 8 channel Mixer
Stage4: Stage 3 + expansion to multiple parts
Or in a way that makes sense from a programming perspective. Too many changes at once quickly overwhelm you when testing and troubleshooting.
This way you could also test the functionality of the extensions on RPi 2, 3, and Zero 2.
Stage 3+4 would probably only be possible with RPi 4 and higher.

Should we start a fork?
As I understand @probonopd, a fork would be the right step right now. This way, everyone can work on their own ideas. And then we'll definitely come together again later.

Hi Peter, so you would prefer having multiple parts with 8 voices each over having e.g., one performance with up to 16*4 voices (16 voices, each of which up to 4 times detuned and panned)?

I actually prefer one part (TG1 - TG8) with the highest possible polyphony. But I think we could be very flexible and offer a suitable environment for every user.
e.g.
Performer Mode:
I didn't describe my suggestion for the ODD/EVEN function precisely enough. The goal is to achieve up to 64-fold polyphony with just one part (+ shadow part). It's essentially a mirrored part: TG9 = TG1, TG10 = TG2,.... Part 1 is ODD and Part 2 is EVEN.

Performer Mode:
4 parts with 8-fold polyphony

Combo Mode:
Part 1 with 32-fold polyphony, Part 2 with 8-fold polyphony, Part 3 drums with 2-fold polyphony if the engine allows it.

Of course, these are all just wild ideas; I have no idea what can actually be implemented. Ultimately, I'm very satisfied with the way the miniDexed already is, but I would never want to slow down @soyersoyer in his work and am looking forward to what's to come :-)

Peter

[soyersoyer]

DreamDexed is almost at Stage 2 (compressors, EQ, 2 effect chains with chorus, delay, reverb).

[soyersoyer]

DreamDexed is at Stage 2! It has a cool CloudSeed2 ambient reverb also!
Sound demo

[soyersoyer]

Thanks to @Banana71, DreamDexed now has 9 new, excellent performances in Bank4 that take advantage of the new FXsends and effects options. It's worth checking out!

[soyersoyer]

DreamDexed is near Stage 4. Pi 4 has 3 buses (parts), Pi 5 has 4 buses. Very cool!
DreamDexed#55

[soyersoyer]

And it finally merged :)