New Engine: Aeolus (Pipe Organ Emulator)

Hi @zynthianers!

I just merged with master and the new Aeolus (Pipe Organ Emulator) engine is now “official”.
A simple “Update Software” from the Admin menu should do the trick :wink:

From the Aeolus Web Site:

Aeolus is a synthesised (i.e. not sampled) pipe organ emulator that should be good enough to make an organist enjoy playing it. It is a software synthesiser optimised for this job, with possibly hundreds of controls for each stop, that enable the user to “voice” his instrument. First presented at the 2nd LAD conference in Karlsruhe, end of April 2004.

Main features of the default instrument: three manuals and one pedal, five different temperaments, variable tuning, MIDI control of course, stereo, surround or Ambisonics output, flexible audio controls including a large church reverb.

Aeolus is not very CPU-hungry, and should run without problems on a e.g. a 1GHz, 256Mb machine.
The current release is 0.9.0, available on the downloads page.

Enjoy!! :kissing_heart:


It is beautiful, @jofemodo !

Great implementation ! :+1:

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Am I going crazy? I can’t find this in the list of Synth Layers any more. It used to be there 'cos I played with it. Is it missing for anyone else?

Aeolus needs channels 1-4. If you already have a layer using one of this channels, aeolus is removed from the list. It’s not very nice, but it was the fast&dirty solution i implemented. In a perfect world, aeolus should be configured for using the available channels, and of course, it can be done if enough interest is expressed. Until then, please, simply create Aeolus layers before any other … :wink:

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Ah! Understood. Ironically I was only adding it to see if I was interpretting the code that limited it to MIDI channels 1-4 correctly!!! I may take a look at this whilst I have the bonnet (hood) up. :slight_smile:

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23 posts were split to a new topic: Accessibility for sight impaired users

More from the article @

The pipes have to be physically located within a reasonable distance
of each other. What constitutes a reasonable distance varies with the size and nature of
the acoustic environment. If the pipes are located sufficiently far apart, their perceived
onsets may not be simultaneous, which is required for them to blend (Sandell, 1991, p7).
The temporal acuity of humans can be as little as 2ms (Green, 1973). Onset differences
of between 10 and 30ms, while they will not be perceived directly by the listener, will
suggest the presence of two tones rather than one (Rasch 1978).

Makes some interesting reading for our occasional latency threads … :slight_smile:

that’s where with the organnery distro, we are using ambisonics amongst other ersources for spread, delay compensation, windchest panning, etc, it’s not just a straight forward organ emulation anymore. it’s being expanded on and all I can say is, can’t wait to put this in to place.


depending on what you’re using for hardware, Aeolus (especially in the Organnery distro) supports more than 4 channels, it has to. You can run 6 manuals, pedalboard, stop jambs, pistons and sequencer functions based on encoder configurations. The limitation seems to be on how Zynthian interacts with Aeolus and not the other way around. :slight_smile:

Hi there,

old thread, I know. But currently it’s the first time I need a church organ for the choir of my wife and I have some problems. I am using Aeolus “out of the box” on a Z5 (latest stable OS).

1.) How can I disable the massive reverb?
2.) Is there a way to use the sustain pedal like it is used for piano (I need the hands free for some times)?

TIA, Holger

Hi @C0d3man !

In current version, none of this features is available. Sustain is not a “standard” feature of pipe organs and reverb control is unavailable for MIDI control.
Anyway, @riban has improved aeolus engine, including reverb and sustain controls. among other improvements. It’s available in the development branch “chain_manager”, but be adviced that this branch it’s not suitable for production yet and if you change to it, there is not return path, use another SD-card if you want to test.


Sure, but would be very helpful if you have to give signs to a choir while playing :grin:

Hmmm… I am not sure if I want to test a development branch when having about 100 listeners/spectators… perhaps for the next concert.


If you are going to use only Aeolus, perhaps it’s no so risky. Indeed, “chain_manager” is quite stable, although there are some issues here and there, all the basic functionality is working. Give it a try if you have some time to test it :wink:


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Ok, thanks for the hint! Additionally Pianoteq is only used (in stage mode). I will give it a try.

I have problems with Aeolus and chain_manager. I ca load the organ and MIDI events are arriving at my Z5, but no sound is coming out. Using PT on anaother chain works fine.

BTW: Where is the mode selection (stage, studio)?

I also tried to enable VNC on the stable tree and lowered the level for the reverb via VNC but this seems to be buggy. You can lower the reverb level but seems to work like the master volume for the chosen manual. No way to remove the reverb.

It seems that the aeolus engine has not been upgraded correctly. I will take a look.
BTW, did you update from testing?

Global stage/multi-timbral flag has been dropped in chain_manager and testing branches.
Now, it can be adjusted by device: bold-click in the MIDI capture screen. Yes, this workflow is suboptimal and it’s being improved right now by @riban :wink:

I remember having adjusted the reverb in the Aeolus GUI and it worked for me, but this was a long time ago. I will check again.