Prog Organ - a VPO
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Updated: 9 December 2021


  Prog Organ A Virtual Pipe Organ  


Hear Prog Organ - this links to a page with many music files played on many different simulated organs

Also see this YouTube video for more information about the system


Prog Organ is a digital 'virtual pipe organ' (VPO) system using a PC as described in the article Digital organs using off-the-shelf technology, and used in the article Re-creating Vanished Organs.  Many different organs have been simulated and examples of their sounds can be heard here.  It is essentially a very fast software 'relay' which takes the signals from all the usual controls on a standard organ console (keys, stops, couplers, pistons, swell pedals, etc) and maps them into a form compatible with an arbitrary number of MIDI-controlled music synthesisers such as computer sound cards or software synthesisers.  Provided Windows recognises a device as a MIDI synth, it can be used with Prog Organ.  When first developed it was offered as freeware, but it was later withdrawn because the effort involved in supporting it for a growing user base became impractical. 


The most important aspect of Prog Organ, as with any other VPO or digital organ, is the quality of the sound samples loaded into it.  This is because it was designed to be a musical instrument rather than merely a software toy.  Furthermore, it was designed so that its operation would be completely transparent to the performer, in particular by not significantly increasing the latency (time delay) of whatever synthesisers are used with it.  This is achieved by a feature unique to Prog Organ in which the console contacts are scanned using one of the standard ports on the PC rather than the computer merely acting as a passive receiver for MIDI messages as the organ is played.  This enables the entire console to be scanned at a constant rate of several hundred times per second, meaning that the additional delay contributed by Prog Organ itself is below five milliseconds even for the 'densest' music consisting of heavy chords played using many stops and octave couplers at high speed.  The scan rate is independent of computer speed.  By contrast, MIDI is an inherently slow system whose latency increases as the demands placed on it by the performer increase.  Together with fast hardware synths such as those in good quality sound cards, the overall latency of the system is maintained well below 20 milliseconds with a medium-performance PC and therefore it is not subjectively noticeable.  This can be compared to the latency of a good pipe organ electric action, which is not below 50 milliseconds.  However MIDI can also be used as an alternative input option if desired.




This shows Prog Organ in a church where it was being demonstrated to and played by a gathering of organists and organ builders.   The loudspeakers were separate from the console and they were placed in various positions in the building during the course of the day.  Nine entirely different simulated organs were demonstrated (more are now available), and these can be heard here.



The console in the picture above is a test bed rather than a finished piece of furniture.  However it is fully functional, of standard dimensions and it can be played in the usual manner.  It can be easily dismantled in less than an hour and transported to other venues by a single person in flat pack form, thus removing doubts as to whether it will go through doors, how much 'muscle' is required to lift it, etc.  Reassembly is similarly easy.  This makes it particularly useful for demonstrations such as that pictured above, or when assessing how well a particular simulation will sound in a building.  A closer view of the keyboards and stop panel is shown below.




Close-up of the keyboards and stop panel.  The stop keys are conventional Kimber Allen motorised (magnetically operated) units, operated by the departmental and general thumb pistons which can be seen together with toe studs which are out of shot.  A capture combination system with ten memories is available, the desired memory being called up using the thumb wheel switch sited centrally below the stops.  The tabs themselves are blank, with the stop names for a particular simulated organ hung on brass pegs above each group of stop keys.  This simple method removes the need for unconventional alternatives such as touch screens, mice, etc.  Similarly, there are no fixed departmental names - either of the keyboards can be given any notional title desired such as Great, Swell, Hauptwerk, Brustwerk, etc.  Thus at the console the stops are grouped into four categories labelled  'upper', 'lower', 'pedal' and 'other' purely to assist the player.  Indeed, the physical limit of two keyboards can be extended by defining as many 'floating' divisions as desired which can be played from either manual.  The keys themselves are good quality wooden ones by Herrburger Brooks, not the nasty plastic mouldings one often gets with digital organs.  Two oak-finished swell pedals by Kimber Allen, as used in pipe organs, are incorporated.  Thus the playing experience is entirely standard to any organist, who is thereby free to concentrate on making music the moment s/he gets onto the bench.


It is extremely easy and quick to switch between the various simulations.  When Prog Organ starts it asks which simulation is required, and if it is not the one used last time, the user is able to select from a list of names.   A shot of the start up screen is shown below.




Prog Organ start up screen.  The user can select the desired simulation by choosing another configuration file name from a list which appears if the  'No' button  is clicked.  The sample set for that simulation is then loaded.  The only other operation is then to replace the stop names above the stop keys as appropriate, as no further interaction with the computer is required.  The information seen in the background is displayed for information only to confirm that the system was set up correctly when installed.



The system has been updated continuously since it was first developed around 2005 and many articles elsewhere on this site provide more of the background, as below:



General interest


Hear it - several hours of recordings of Prog Organ played on many different simulated organs ranging from Arp Schnitger to WurliTzer


Digital organs using off-the-shelf technology - an early article describing the genesis of Prog Organ and virtual pipe organs in general since they began to appear in about 2000


Choosing a Virtual Pipe Organ - some issues affecting the choice between the several VPOs currently (2015) available


Digital Organs Today - a transcript of an article originally published in Organists' Review in November 2009



More details about specific simulations


Re-creating Vanished Organs - details of many of the pipe organs simulated by Prog Organ and some issues encountered in simulating them


A digital simulation of the 1935 Rutt theatre organ at the St Albans organ theatre


A digital simulation of the 1933 WurliTzer at the St Albans organ theatre


A digital simulation of the organ at Malvern Priory


The organ Cavaillé-Coll never built! - a detailed description of the extended Cavaillé-Coll simulated organ originally at Bellahouston parish church in Glasgow


Digitising an old lady - a detailed description of the historic 1858 simulated Walker organ at St Mary Ponsbourne, Hertfordshire



Information aimed at those building their own VPO


A simple console for a virtual pipe organ


Console-building hints and tips


Re-using old stop tabs in Virtual Pipe Organ consoles



Detailed articles covering some specific technical issues


Creating Sample Sets for Digital Organs from Sparse Data


Console scanning, MIDI & PIC microcontrollers for Virtual Pipe Organs


Signals, Noise and Bit Depth in Virtual Pipe Organs


Wet or Dry Sampling for Digital Organs?


Tremulant Simulation in Digital Organs