Doesburg, Martinikerk Walcker Organ

The Walcker organ of the Martinikerk in Doesburg, Netherlands

The great four manual organ of Oscar Walcker was built as his opus 1855 for the church Nieuwe Zuiderkerk in Rotterdam in 1914-1916. The construction of the church and the organ was sponsored by brothers Bos who were organists themselves and who had certain predilection for the organbuilding techniques represented by the lastest achievements of German organbuilders. For this reason, the modern organ with an electro-pneumatic action was commissioned to the Walcker and Co.  When the church had been demolished in 1968, the organ was sold to the Doesburg parish and transferred to the Martinikerk. This church lost its own organ during the bombardment of the 2nd World War when its spire was destroyed. Although different (neobaroque) organ fashion was governing at that time, the authorities of the church made the fortunate decision to acquire the Walcker organ which is now pride of the town and a true historical monument, because there are only few large Walcker organs preserved without major  rebuilding.

The organs of the Walcker company bear many characteristics which we usually call "romantic" today: predominance of 8' stops carefully selected to provide the widest possible differeciation of the sound color as well as smooth dymanic layering, absence of aliquoteslower number of reeds,use of darker mixtures, the contrast between the division based on dynamics rather than on timbre, tracker allowing comfortable and light touch and virtuoso playing technique, plenitude of couplers and other playing aids.

Nevertheless, the opus 1855 exhibits also the influence of the Alsace organ reform after Emil Rupp. The elements of this sound concept were: more reeds in the French fashion after Cavaillé-Coll, large swell divisions (there are three swell boxes available), brighter mixtures and cornets after Silbermann - the builder proudly engraved the name of the Freiberg master to the largest pipes of the stops made according to the Silbermann scales. An extraordinary feature of the organ which brings the idea of brighter sound color further is the treble rank extensions. Although the compass of manuals is already large - five full octaves, there is a sixth treble octave available for many stops and comes into use when the octave coupler is engaged.

Originally, the organ had an echo division positioned above the vault of the Rotterdam church while the sound was driven through 22 meters long channel into the church nave. This feature was not rebuilt in Doesburg, but the echo division is not lost. It is now seated on top of the organ case in a swell box.

The organ allows historically accurate reproduction of the organ music written during the Romantism and later.

Further reading: Orgelreform in Nederland. Het orgal van de Grote of Martinikerk te Doesburg. Willem Jan Cevaal (ed.), Walburg Pers, 2003. ISBN 90-5730-265-9.



The Hauptwerk version: This organ model requires Hauptwerk version 5 or higher. Only the advanced version of Hauptwerk is suitable for running this virtual model.

Sample Quality

The samples are offered in 24bit/48kHz quality, multiple releases (3 levels). The sample set is encrypted and dongle protected. The reverberation time is up to 6 seconds for the ambiental version. The sample set is offered in the surround (six channels) variant. The dry version (two channels) is also available for use with an external reverb.

The organ offers a wide range of dB, from pianissimo to a great fortissimo. The audio level is set as default so as not to overload the soundcard output when reasonable tutti is played. If the volume is turned up considerably beyond the default setting, there could be a danger of blowing the speakers.

 The Compass

The original compass of the manuals is 61 keys, i.e. 5 octaves. Most stops have an internal extension to 73 tones (6 octaves) to be used with the super octave couplers. The same compass is available in the virtual model. The pedal compass is 30 tones, the extended pedal compass of the virtual organ model is 32 tones (C-g1).  


Many ranks offer recorded tremmed samples (recorded tremulants). These special tremmed ranks can be identified by the word "tremmed" in the rank description. Load these special ranks together with the normal ranks to get the correct behavior with the tremulant engaged. On the rest of the ranks, the Hauptwerk tremulant model is active.

Pipe Coupling

Pipe coupling feature is introduced with this sample set. Great enhancement of the realism of the sample set. Read about it more.

Variants of the sample set

  • Surround: the surround recording uses 6 independent channels for each virtual pipe. The sound of the organ pipes is captured by the front microphones, the church response by the rear microphones.  There are 4 front channels (dry and diffuse) used to supply the sound of the organ to the front speakers, while the 2 other channels (rear) offer the response of the church. You can use these 2 channels to feed your surround (rear) speakers. Please note, that at least 4 speakers are needed to reproduce the surround sample set variant. 
    Tip: In the church where the organ was built originally, the IVth manual was an Echo division (Fernwerk). It may be a good idea to swap the front and rear channels for the ranks of the IVth manual so that you get the effect of an Fernwerk. 
    • CPU: polyphony of 10.000 required, 15.000 or more recommended.
    • RAM requirements
      • 16-bit: 23.8 GB
      • 20-bit: 41,9 GB
      • 24-bit: 45,5 GB
    • HDD space occupied: approx. 60 GB.
  • Dry: The dry channels solo may be used for special purposes only. An addition of external reverb is necessary! If used in large reverberant spaces (such as churches) a lot of user voicing will be necessary to match the sound of the virtual pipes to the acoustics of the venue.  
    • CPU: polyphony of 1.500 simultaneous pipes required.
    • RAM requirements
      • 16-bit: ca.  5.4 GB
      • 20-bit: ca.  7.6 GB
      • 24-bit: ca.  9.2 GB
  • Wet: For use in headphones or other 2-channels environment: please disable all the ranks marked by the word "rear" and "dry" in the rank audio output dialog when loading the organ for the first time. The diffuse ranks solo form a 2-channel wet sample set.
    • CPU: polyphony of 3.000 required
    • RAM requirements (diffuse channels solo, full load using the memory compression):
      • 16-bit: ca.  10 GB
      • 20-bit: ca.  18 GB
      • 24-bit: ca.  20 GB



  • The dry channels mixed into the to the diffuse and rear perspectives provide considerable amount of detail to the result. Thus, the "presence" of the audio is greatly enhanced. Do not exaggerate the amplitude of the dry channels in the mix, or the result may start sounding unrealistic.
  • It may be good idea to route the dry channels through a separate output bus, while adding a bit of suitable convolution reverb to the dry channels, before mixing them back to the diffuse channels.
Man. I Man. II Man. III Man. IV Pedaal Zwelwerkpedaal
Prinzipal 16' Bourdon 16' Lieblich-Gedackt 16' Quintatön 16' Grand Bourdon  32' (a) Gedecktbass 16' (f)
Gross-Prinzipal 8' Flöten-Prinzipal 8' Geigen-Prinzipal 8' Nachthorn 8' Prinzipalbass 16' Echobass 16' (g)
Bourdon 8' Syntematophon 8' Lieblich-Gedackt 8' Echo-Bourdon 8' Subbass 16' Bourdon doux 8' (h)
Viola di Gamba 8' Doppel-Gedackt 8' Konzert-Flöte 8' Echo-Gamba 8' Harmonikabass 16' Bassflöte 8' (i)
Jubal-Flöte 8' Flute-harmonique 8' Quintatön 8' Vox-Angelika 8' Contrabass 16' (b) Violoncello 8' (j)
Gemshorn 8' Salicional 8' Viola d'amour 8' Spitz-Flöte 4' Flötenbass 16' Bassonbass 16' (k)
Dulciana 8' Cello 8' Aeoline 8' Glockenton IV-III Oktavbass 8'  Clairon harmonique 4' (e)
Praestant 4' Harmonika 8' Vox-Coelestis 8' Vox-Humana 8' Flötenbass 8' (c)  
Rohr-Flöte 4' Prinzipal 4' Liebes-Geige 4' Echo-Trompete 8' Choralbass 4'  
Oktave 2' Orchesterflöte 4' Flauto-Dolce 4'   Quintbass 10 2/3'  
Kornett III-V (Silbermann) Piccolo 2' Flautino 2'   Mixtur V (d)  
Mixtur V (Silbermann) Kornettino III-IV Sesquialtera II   Bombardon 32'  
Trompete 8' Nasard 2 2/3' Cymbel III-IV (Silbermann)   Posaune 16'  
  Gross-Mixtur V-VII (Silbermann) Klarinette 8' (free reeds)   Tuba 8'  
  Basson 16'        
  Trompete harmonique 8'        
  Orchester Oboe 8'        
  Clairon harmonique 4'        
  tremolo tremolo tremolo    
  • (a) - acoustique, Contrabass + Quintbass.
  • (b) - transmission from Man. I. Prinzipal 16'.
  • (c) - transmission from Man. I. Jubalflöte 8'.
  • (d) - transmission from Man. I. Mixtur.
  • (e) - transmission from Man. II. Clairon harmonique 4'.
  • (f) - transmission from Man. III. Lieblich Gedackt 16'.
  • (g) - transmission from Man. IV. Quintatön 16'.
  • (h) - transmission from Man. IV. Echo Bourdon 8'.
  • (i) - transmission from Man. III. Konzertflöte 8'.
  • (j) - transmission from Man. II. Cello 8'.
  • (k) - transmission from Man. II. Basson 16'.



normal pedal melodie bassmelodie suboctave superoctave
II - I


I - P II - I P - I II - I II - I
III - I II - P I - II P - II III - I III - I
IV - III   IV - III     II - P

Other playinig aid

Unison off for Man. I

General Coupler


Rücklauf für Crescendo (hardware device to run the Crescendo backwards, omitted)

Couplers off from the Crescendo (one by one)

General Coupler off from the Crescendo 

Combinations P., Mf., F., Tutti without mixtures and reeds, Tutti 

Automatic Piano Pedal (the user can pre-set different registrations for the pedal. Such a preset is engaged automatically whenever the specified keyboard is touched. Thus, the pedal stops are automatically and quickly changed whenever the user "jumps" with his hands to a different keyboard.)

Handregister off, reeds off, mixtures off, Manuaal 16' stops off, crescendo off.

4 free combinations (omitted since there is large number of free combinations available)

Calcant (no functionality on the original instrument, the sample set uses this switch as a blower switch)



  • Manuals: 5 octaves, 61 tones. Most stops have an internal treble extensions (6th octave) for the super-octave couplers (73 pipes in total for each stop).
  • Pedal: 30 tones (C - f1). The virtual model extends the compass to 32 keys.





Screenshots explained

 Console view:

this is the general console view. It serves to define the keyboard MIDI inputs for all the divisions. The only active part of this view are the manuals and the pedal. Specifying the MIDI inputs is done by right-clicking on the desired manual or pedal. All the other screen components are image-only. 

 Bellows view:

this is the view of the wind ways of the instrument, the base for the Hauptwerk wind model. In the upper part, there are 11 hand pumped wedge bellows, the red indicator shows how full/empty the bellow is, the gauge on the side shows the inner pressure inside the bellows. The switches above each bellow show the operation of the bellows. The upper one served to enable or disable the bellows completely (you can run only several bellows if you wish - attention, the organ can become short of air quickly). The lower two buttons show whether the bellows is inflating (left button) or deflating (right button).

The small "windows" under each set of bellows show how air is going from the bellows to the windchests of the organ. If it is closed, no air is going to windchests, if it is open, air is passing from the bellows to the windchests.

In the lower corner of this view, there are gauges to measure the pressure each of the windchest (some divisions have split windchests).

 Left+Right Jambs view:

for dual touch screens, split jambs were created. They allow for portrait or landscape orientation, according to the orientation of the touch screens.

 Left + Right Jambs Vertical view:

the dual stop jambs offer vertical (portrait) orientation as an alternative.



Single Jamb:

for a single touch screen, this is the stop jamb to be used. All the stops of the organ can be found there. This view allows for landscape and wide landscape orientantion, according to the size of the touchscreen used. Please note, that the foot levers found on the original organ were not reproduced, since they only duplicate hand drawstops which are available. All features of the organ can be controlled by the drawstops, hence the foot levers were omitted. You may, however, attach your MIDI foot pistons to any drawstop to imitate the behavior of the original organ. The attaching of the physical piston to a button on screen is done by right-clicking on the button. You may attach more than one MIDI physical switch to any of the drawstops on the screen.

Note to the right click: The Single jamb, the Split Jambs and the Simple jamb, all allow for right-click to attach a specific MIDI hardware button to any of the software switch. This is done so that several different MIDI hardware buttons can operate one single software switch, so that the user can operate one stop or one and the same coupler with more than one hardware pistons.

 Pedal Matrix:

Dynamic routing of the ballanced pedals is possible via this pedal matrix tab. Click the button to connect the hardware pedal to the swell/crescendo of the sample set.


The mix of the perspectives (dry, diffuse, rear) may be adjusted and saved into one of the three memory buttons. Blower and tracker noise level can be adjusted here, too. In the right lower corner, there is a slider to control the amount of the Pipe Coupling effect. Dragging the slider all the way down (value 1) makes the organ without any pipe coupling effect, bringing it to the maximum value makes the effect most prominent.

 Simple Jamb:

simplified version of a single jamb to allow for more readable version of the stop names on small LCD touch screens.

 Simple Jamb - portrait alternative.




Automatic Piano Pedal

For each manual, specific combination of Pedal stops can be prepared. When hands play on any specific manual, the corresponding combination of Pedal stops is engaged automatically. In this way, different pedal registrations can be used to accompany each of the manuals. If two manuals are being played exactly simultaneously, the higher manual has precedence for the piano pedal.



 Crescendo Programming

For each crescendo state (1-64), the state of any stop can be set in the three last screens of the ODF layout. Each coupler can be disengaged from the crescendo temporarily using the corresponding "Auslöser der Coppl. aus Crescendo" button.




Doesburg, vol.0, 2.01 update:

Piccolo middle D release corrected.

  1. Doesburg Walcker Surround Sample Set (Vol. 0+1+2)

    Doesburg Walcker Wet and Surround Sample Set. Version 2. Volumes 1 + 2. Includes Dry, Diffuse and Rear perspectives.

    Hauptwerk v.5 or higher required. The sample set is encrypted, dongle protected.


    Excl. Tax

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  2. Doesburg Walcker Dry Sample Set (Vol. 0+1)

    Doesburg Walcker Dry Sample Set. Version 2. Volume 1. Includes Dry perspective.

    Minimum Hauptwerk version: 4.2. (Also works in all higher versions.). Not encrypted.


    Excl. Tax

    Detail & order

  3. Doesburg Walcker Sample Set Trial (Vol. 0+1+2)

    Doesburg Walcker Wet and Surround Sample Set. Version 2. Volume 0+1+2. 6-channel demo sample set. Hauptwerk 5 or higher required, dongle protected. Full sample set 7 days trial. The licence expires after 7 days!

    The price of the trial code is subtracted from the price of the full product when purchased (trial for free).
    Price: Excl. Tax: €9.00 Incl. Tax *: €10.89 Excl. Tax

    Detail & order

  4. Doesburg Walcker Sample Set Demo (Vol. 0)

    Doesburg Walcker Wet and Surround Sample Set. Version 2. 6-channel demo sample set. Hauptwerk 4.2 or higher required, no dongle protection.

    Price: Excl. Tax: €0.00 Incl. Tax *: €0.00 Excl. Tax

    Detail & order