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AudioUnit hosting on iOS!


Deep Expressor for iOS is not released yet: it was only exposed in the first betas.

Midi control functions in MIDI Guitar on iOS are more limited as on the full desktopversion.
What kind of midi controls do you wish to have over a loaded AU?

If all slots on guitar channel are “none”, there is no direct sound. To have clean guitar without fx you can load DIRECT to have the guitarsound enabled.

Split will route the synth to one channel and guitar to the other. This is a nice option for creative use or on stage.


I’m puzzled about Deep Expressor not being released yet - wasn’t it in 2.5? If I load your patch Deep Clean Pipes, for example, it puts Deep Expressor in the first guitar FX slot. This is one of my favourite sounds as it comes close to some of the V-Guitar sounds on my Roland guitar synths.

AU synths have different MIDI controls for functions according to the developer. In AUM you can see these exposed when an AU instrument or effect is loaded in a channel and so link them to hardware MIDI controls or other apps. When MIDI Guitar is added as an IAA in AUM, any Audio Units loaded with MG do not have their MIDI controls exposed. As a result, I still prefer to use MGs external MIDI output to drive an AU synth or FX in a separate AUM channel. That’s still the only way to drive IAA synths, of course.

The main MG controls I’d like to see exposed to MIDI would be the MIX and MASTER level controls so they could be controlled by a foot pedal for example. Not essential as the same result can be achieved by hosting MG in AUM.


Deep Expressor was only in the beta, before the 2.5 release. It has some simularity with some Roland hex cosm fx yes ( I do own a lot of that stuff too…), but I discovered this kind of sound more by fooling around with midi and filters, like 10 years ago. Gladly I could use this experiment lateron. We’ll introduce it lateron officially, you managed to “steal” it out of the beta, so you can use it anyway for now, just copy the patch to a new one if you need another patch with it… :wink:

When MIDI Guitar is loaded into a host like AUM, it is natural to have the synths loaded in AUM, not inside the MG IAA plugin. (this is simular to desktop situation)
The loading of AU’s inside MG is targeted on having a simple host, remote controllable, with a very guitarfx kind of setup. For many, using a extra host is too much hassle.
For complexer setups, there is allways AUM and AB, but we can not really guide users there: there is just so many thing to know about e.g. the differences between IAA and AU, if you want to use it succesfully, especially with midi program changes for recalling patches.
Our AU option just offers the simplest possible solution to invoke a synth in a live setup.

MIX and MASTER would be good candidates for remote control, agreed…

The stuff that is shown in a host from AU plugins are “automation parameters”. they are not midi, but hosts often offer options to attach them to incoming midi. On desktop these params are the ones you can attach an envelop to in the track.


Thanks for the clarification, Paul, I’m pleased to have ‘stolen’ the beta version of Deep Expressor! I’d be happy for it to be an IAP in a future release, assuming there are no technical reasons holding back its inclusion.

Obviously catering for all the permutations of hosting MG is potentially a nightmare and I appreciate your aim of simplicity for live use. I’m trying to come up with a reliable set up for live use myself and AUM fits the bill for me as it also allows a lot of flexibility for recording individual parts for subsequent remixing. Most of my music tracks are recorded live, just not with an audience, but I spend a lot of times configuring the apps in AUM and would like to be able to do this on the fly using MIDI controllers. Hence the interest in MG hosting AUs and being able to recall a relatively complex patch with a single program change. For me the missing link in using MG standalone would be accessing those MIDI automation parameters as AUM does. However, there are so many IAA synths that are not yet available as Audio Units, such as Animoog and the M3000 mellotron, that will bring me back to using AUM.

I’ve hardly touched my Roland/Boss guitar synths for over a year since using MG2, both the desktop and iOS versions. Keep up the good work!


The fact is that with Garage Band in my XR the UI is much better and it has a button to show more parts of the UI, thats why I though that MG or the host can do something more. From my ignorance of course.
And yes I tried with the aspect ratio parameter but it only seems to get worse and have less space.


Version 2.6.5 is up on TestFlight.

We’ve tried further to improve hosting and make it easier to set the aspect ratio of the AU’s user interface. Unfortunately, this AudioUnit standard is very undocumented by Apple, and i’m not even sure Apple has decided upon a specification. Clearly, some plugins (like SynthMaster Player) will not layout themselves based on the window size, even though that’s certainly part of Apples idea with this. But in these latest versions you can go the the “plugins” section and specify what kind of window size you want for each plugin. So far I found a match for all plugins tested on iPads and iPhones I’m testing here.

It may be a bit tedious to find the right window size this way, but I think that’s still better than AUM where you get a resizable window to adjust every time you load a plugin. And SynthMaster Player doesn’t fit in AUM on an iPhone 6s no matter what you do.

Generally we should just try to follow Garageband which has probably set the standard for most plugins.

lovejazz, please let us know how it goes on iPhone XR and everyone else, please post screenshots of plugins along your iPad/iPhone hardware information if you notice anything strange.



First Synthmaster is the same more or less, changing the ratio other than the default does not provide any better view. Im comparing to the stand alone UI where there are more buttons, not sure how it is expected to be shown according to the manufacturer.
Second, Zeeon now is MUCH better, it seems to be correct atm.
Thanks for your effort.


Great. Then I think its all good!

I think you misunderstood about SynthMaster then - its supposed to layout knobs differently when it runs as AudioUnit compared to Standalone, in order to fit a smaller window.
To me it looks identical in MIDI Guitar, AUM, AudioBus3, etc…


We’ve submitted this latest beta to Apple and so official update will be out in a day or two.


The eagle has landed!


Yes, the eagle is in the wild now.
Apple has a system where the eagle will fly around for 7 days and land on all the different devices out there. If he didn’t arrive to your device yet, you can call him up in App Store.


I am running Midi Guitar 2.6.5 on an iPad Pro 9,7 / 256GB / iOS12.2 and on an iPhone6+ / 128GB / iOS12.2. I have purchased and unlocked all IAPs.

Unfortunately on both devices the app freezes/crashes during the 'scanning for plugins" process. I happen to have a lot of AU effects (approx 90) and instruments (approx 100) on my devices that are not giving any issues in any of my DAWs or AU hosts, but MG2 seems to choke on them or maybe the amount…

After a couple of reboots of the app and additional attempts to scan the plugins it manages to complete and i am able to select them in the fx slots. I see a complete list of my AU instruments and FX there. However when i click the "plugins’ tab to get to the page with an alphabetical overview of all the scanned plugins, i get an incomplete list of them which ends halfway with the letter M. “MIDI BUS [AU]” is the last item in the list that it shows and everything after that is not displayed. I can keep scrolling down further but the screen wil be black and not show any more names. Which means i also am unable to set the Window Aspect/Size for those Audio Units that come after the letter M.

During scanning i have noticed an error with the Ape Matrix audio units. For instance ‘Mood’ synth gave me an error message. so i removed that app and have tried to rescan the plugins again. it still froze a few more times during scanning but i have not seen any other error messages that might indicate that there was a problem with another AU.

i don’t know if it is possible for me to help and narrow down the above mentioned issues and get into the beta testing process or if it is possible to share crash logs with you guys to see if we can fix these crashes or find out which apps might be the culprits? It is not feasible for me to manually remove and test for each individual AU since i have so many of them plus i don’t wish to lose my settings/presets for those apps.

Please let me know in what way i can help/contribute to hopefully fix some of these AudioUnit hosting issues in MG2.

Did anyone else run into these problems as well, or have tested Apesoft’s Mood synth successfully in MG2?



In additional to my earlier findings:

  1. On my iPhone6+ the Plugins page only shows 36 plugins in the list and won’t show me anything after the letter F while many more AUs are actually installed.
    My iPad Pro shows 56 plugins until it stops halfway the letter M while more plugins are installed.
    And on my old iPad Air (running iOS12.2 as well) I also only get to see no more than 56 plugins on the Plugins page although there are more installed.
    56 somehow seems be the limit of plugins it will display on my iPads on the plugins settings page.

  2. I have managed to successfully run Apesoft’s Mood synth as an AU in MG2 on my iPhone6+, so it might not necessarily be a bad AU causing the problems. My iPad Pro allows me to use Sunrizer as an AU in MG2, on my iPad Air however Sunrizer is not found in MG2 although it is installed as well on that device. iPad Air gives me an error when scanning Synthmaster One and won’t allow me to use it in MG2 while Synthmaster One runs perfectly fine in MG2 on my iPad Pro without giving me any error messages.
    So it all seems a bit random which Audio Units might work on one device while not being accepted by MG2 on another device. It doesn’t seem that particular Audio Units are causing the issues but more like random behavior.

Not sure if any of the above is in any way helpful, but these were just some observations i have made while comparing MG2’s AU hosting behavior on three of my i-devices. I thought i would mention them here nevertheless. Thanks!


Thank you Dutchee, for the detailed reports!

There seems to be problems indeed when you have so many plugins. We are fixing this now, and aim to send an update to Apple tomorrow.


Update 2.6.6 is out, might take an hour or so before your App Store notice.
Scanning should now be lightning fast and it will list all of them.
Please let us know if it still skip any of your plugins.


I tested the update on all my devices and all issues are resolved. Indeed scanning lightning fast now and successfully loads all my AUs and properly shows them all on the plugins page as well. Thanks a lot for this fast fix!