iCathedral Organ iSymphonic Orchestra

Advanced Usage

The following instructions are intended for users who are already familiar with the iSymphonic Orchestra App and who are interested in more in-depth topics regarding this app. If you are using iSymphonic Orchestra for the first time, then please refer to the introductional chapter of this manual first.

External MIDI Devices

iSymphonic Orchestra automatically connects to all external MIDI devices (i.e. keyboards, foot switches, slider/button controls) attached to your iPad / iPhone. So there is no software configuration required to receive MIDI data from your external MIDI equipment.

On the very top left of your screen you see a number which is reflecting the current amount of external MIDI devices attached to your iPad / iPhone. You can use this as a quick visual indicator whether your external MIDI device(s) are correctly connected with your iOS device. If the number is less than the amount of external MIDI devices attached to your iOS device, then in most cases a physical connector problem is usually the cause. In such cases please try to disconnect and re-connect the respective device's connectors and cables. Find out more ...

You may encounter that the number of external MIDI devices is showing 1 even though you have no external MIDI equipment attached to your iPad / iPhone at that moment. This is not an error. Usually that means you used iOS's so called Network MIDI feature before, which will remain visible like a regular MIDI hardware device for the entire system. In such cases, when you attach one external MIDI keyboard, the number shown should thus be 2.

If the amount of external MIDI devices is displayed correctly and the app is still not reacting as expected by you, then please also check following configuration topics:

  1. Make sure you read the notes about the multi-part feature of this App.
  2. Check whether the MIDI channel of the respective part is configured correctly.

You may also use our free MIDI monitor app MIDI Wrench to check which external MIDI devices are exactly connected to your iOS device, and to check what kind of MIDI events they are sending on which MIDI channel. This tool is very helpful to resolve MIDI connection issues quick and efficiently.

Velocity Response Curve

You may adjust the so called velocity response with the velocity response curve editor, as shown on the left. The velocity response curve defines the relation between MIDI note-on velocity values (0 ... 127) and the resulting instrument's volume (0 ... 1). In other words: it controls the precise volume depending on how fast you trigger a key on your external MIDI keyboard. This is commonly used to adjust the feeling of individual MIDI keyboards according to your prefered playing style and taste.

Simply place one finger onto the curve and drag your finger around on the screen to bend the velocity response curve to the desired shape. You hear the result of the velocity curve change as soon as you lift up your finger from the screen.

You may save the current velocity response curve as preset by tapping on the "Save" button. A popup will appear on your screen: enter a name for the new preset and confirm saving the new preset.

To restore a previously saved velocity response curve preset, select one preset from the combo box (available on the very top of the velocity response curve editor). As soon as you tapped on an item from the velocity response preset list, that preset becomes immediately audible.

To restore the velocity response curve to its default setting (a neutral linear), tap on the "Reset" button. The change becomes immediately audible.

To delete a previously saved velocity response curve preset, select the preset with the preset combo box first, then tap on trash can button on the upper left side of the velocity response curve editor.

Hermode Tuning

Multi-voiced western music is based on combinations of 3rds and 5ths. For an optimal musical performance it is necessary to tune these intervals and chords as accurately as possible to a so-called just intonation. Fixed frequencies cannot meet this requirement completely. Equal Temperament, which is commonly used by keyboard instruments, has acceptable 5ths, but its 3rds are quite detuned. This leads to undesired acoustic interferences: major triads - in particular - they sound sharp and weak. In contrast to this, musicians as members of string and wind ensembles or of qualified choirs are educated to fine-tune their tones. They shadow upwards or downwards the pitch of the performed notes according to their harmonic function. In this way they achieve a close approach to just intonation. The result is a lively musical performance with much more gloss in the heights and significant more warmth in the basses than with Equal Temperament. Find out more about Musical Tuning and Temperament ...

The Hermode Tuning algorithm imitates this tuning behavior of professional musicians automatically for you in the background of this app, and controls the tuning in real-time while you are playing as usual.

By default the Hermode Tuning algorithm is disabled, so by default your music will be performed with Equal Temperament.

To activative Hermode Tuning, open the Hermode Tuning control screen by tapping on the "hmt" button. Then select one of the available Hermode Tuning presets from the combo box on the very top of the Hermode Tuning screen.

As soon as the Hermode Tuning algorithm is activated, the frequency corrections of the individual notes will be shown by moving beams in real-time. The horizontal middle line reflects the neutral basis of Equal Temperament. A beam moving upwards the neutral line indicates that the respective note was pitched higher than its usual frequency of Equal Temperament, a beam moving downwards the neutral line indicates the respective note was pitched negatively, that is to a lower frequency than its usual one of Equal Temperament. On the left hand side you find a vertical scale ranging from -64 cents to +64 cents, which you can use to read the precise tuning of the individual notes in cents.

Active notes are displayed as red beams, white beams instead reflect notes that were released and are currently inactive.

Currently the following two Hermode Tuning presets are available:

On the very left you will find a vertical slider, which you can use to control the tuning intensity of the Hermode Tuning algorithm. If the slider is at top position (default) then the individual notes are corrected with max. tuning intensity. If the slider would be at its lowest position, then this would result in no detuning at all, so effectively this would mean Equal Temperament tuning. A slider value of about 70% is recommended when making music together with additional musical instruments which are tuned to Equal Temperament.

To disable the Hermode tuning algorithm, select "Disabled" from the Hermode Tuning preset combo box.

The Hermode Tuning algorithm is consuming hardware resources. With very old devices (i.e. iPad 1 or iPhone 4) this may lead to performance issues. If you encounter any issues, then please disable the Hermode Tuning algorithm on such devices. For more recent iOS devices there should be no negative impact using Hermode Tuning.


For each note you trigger, a certain amount of so called voices are spawned by the app's audio engine. A voice is one instance of an engine internal sound generating object, each streaming its own sample data, having its own synthesis states, its own envelopes, its own filters and so on. Certain sounds / instruments require only one voice per note, more complex sounds / instruments though may consume 4 voices per note or even more. Since each voice consumes hardware resources, the amount of voices that may be played simultaniously by your iPad / iPhone is limited. The precise maximum amount of voices depends especially on your iOS device model being used. Find out more ...

The amount of voices in use are displayed in real-time on the very top right of your screen. By default automatic polyphony is turned on. That means the app tries to find an appropriate maximum amount of voices for you, depending on various factors, for example the exact iPad / iPhone / iPod touch model being used, the currently selected latency setting, but also depending on whether you are using certain effects or are using Inter-App Audio mode. Because there are a variety of factors that have an impact on overall resource consumption of your device and thus the maximum amount of voices your device may handle depends on numerous circumstances. Due to this it is recommend to leave the app in automatic polyphony mode. As long as automatic polyphony mode is on, the "Voices" row from the settings screen is read only, that is it will only show you the currently selected maximum polyphony as being decided by the app for the moment for you.

If you rather want to have more control over the app's maximum polyphony, then you may switch off automatic polyphony. In this case it is up to you to select an appropriate value for the maximum amount of voices. You may want to do so for example when you are using several other audio apps at the same time, and want to reserve a certain amount of resources for those other apps, so in this case you might want to reduce the maximum amount of voices so that iSymphonic Orchestra reduces hardware resource consumption (i.e. CPU usage and SSD bandwidth). Another reason might be that you want to fine tune this setting for a recent iOS device model, especially since automatic polyphony usually selects the respective amount of max. voices under pessimistic aspects. In such cases you might increase max. voices manually to achieve a higher overall polyphony. When setting the maximum voices manually, please review the following guideline:

  1. If you encounter noise, artificial artifacts or stuttering audio while playing with the app, then the maximum amount of voices is too high. Reduce max. voices until those undesired audio artifacts disappear while playing.
  2. If you hear that notes got cut off unexpectedly or if overall sound seems to be too "thin", then you might want to increase the max. voices setting.
  3. Keep in mind that whenever you change your audio setup (i.e. when you decrease the latency setting, turn on effects or start using other apps simultaniously) this might require you to adjust your manually selected maximum polyphony setting each time.
  4. On doubt, re-enable automatic polyphony again.
  5. If you still encounter undesired audio artifacts even when automatic polyphony is turned on, then please check whether other audio apps are running in the background. And if so, stop those other audio apps from running in the background.


There is always a certain amount of delay involved when playing with an electronical instrument. The time that passes between triggering a note on your keyboard and the time when you actually hear its result on your audio speakers is called latency. In a digital system - like with this app - the amount of latency is mostly defined but the digital audio buffer size the system (or app) is working with. This is configurable, and hence its latency is configurable. If the overall latency is too high (that is if the delay is too long), then it will obviously have a negative impact on your playing. On the other hand, when using a very small latency setting, this comes with a price: The digital system has to work with tiny buffer sizes and CPU usage increases substantially; not anti-proportional to the buffer size, but in fact with complex digital systems (like this app) even exponentially. As a result, the maximum polyphony that may be delivered with your device shrinks substantially with smaller buffer sizes. Most musicians are fine with a latency of 23ms, and that's why this is the default latency setting with all our apps. There are however also some musician who are very sensitive to even lowest latencies of less than 5ms. So as a musician you have to make a trade-off and decide by yourself what an appropriate latency is for your playing style. How much latency can you bear, how much polyphony do you need, and how much resources do you probably need for other apps running on your device at the same time.

You may configure the amount of latency on the settings screen of iSymphonic Orchestra, as shown on this screen shot. On the very top of the screen you can always read the current latency of the app. This value does not simply display the latency setting you selected, instead it always displays the real, effective latency as measured by the app in real-time. So it adds additional control whether the latency is actually the one desired by you, and whether that latency is stable (that is retaining at constant latency amount).

The measured latency displayed on top of the screen, and the amount of latency configured by you may differ. This is usually an indication that your system is overloaded. In such cases iOS automatically steps back latencies requested by apps, in order to keep them at least running stable, without causing audible glitches. In such cases, check whether other apps are running in the background and stop them from running in the background.

Run App in Background

By default this app will automatically be suspended (stopped) whenever you press the home button at your iPad / iPhone, or when you switch to another app. Sometimes you may want the app though to continue running in the background, for example when you are using another app to display scores while you are playing orchestra sounds on your keyboard with iSymphonic Orchestra. To do so, go to the settings screen of this app, which you can reach by tapping on the small gear wheel icon top right on the main screen of this app. At section "Audio / MIDI Driver" you find a switch called "Run App in Background". Enable this switch to keep the iSymphonic Orchestra app running in the background, even when it is not visible on the screen.

See also: Background Apps.

You do not need to enable the "Run App in Background" setting when using this App in either Inter-App Audio mode, JACK mode or Audiobus mode. In those modes the app will automatically continue to run in the background, and as soon as the app is no longer used in one of those three modes, the app will automatically stop running in the background. So the mentioned setting here is just intended to control the background running behavior while using iSymphoic Orchestra as stand-alone audio app. You should disable the "Run App in Background" setting as soon as you don't need the iSymphonic Orchestra app anymore. Otherwise it will constantly reserve hardware resources and may drain your battery.

Built-in MIDI Recorder

Refer to the MIDI Recorder manual for information about the built-in MIDI Recorder of iSymphonic Orchestra.

That manual also covers all Recorder specific settings that you can find on the settings screen of this app.

Document Updated:  2016-11-28  |  Author:  Werner Mohrlok, Christian Schoenebeck