The Hauptwerk Virtual Pipe Organ Projects
OPUS II - A New Virtual Pipe Organ
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Back to: How it all started OPUS I - The first organ!
This page: OPUS II - a New Hauptwerk Project
YOU HAVE SEEN OPUS I - My First Hauptwerk Virtual Pipe Organ

I built my first Hauptwerk Virtual Pipe Organ project in 2007-2008. It has lasted me for almost nine years. Over several years, it grew: it gained multiple channel audio, which gives it truly impressive sound which amazes everyone who hears and plays it. It gained three new PCs over those years, each with more powerful CPUs, more RAM and then increased fixed disc storage until it had 2 x 3TB in a RAID array. Then it gained a pair of Novation LaunchPads, which greatly increased the flexibility of control.
However, OPUS I was always seen as a proof of concept, because it lacked the refined playing-aids that professional organists who visited and played the instruments expected. And so, over several years, a plan for the design and  building of a major new instrument started to crystallise in my mind.

OPUS II - A New Hauptwerk Virtual Pipe Organ is finished!

And so, I decided to build a second console using all that experience I have gained with the first organ. As mentioned already, OPUS II has some of the playing aids that professional organists and recitalists who have played OPUS I (as my first organ is now named) have missed on the first organ.


1.1 The Console
First, we have a new console. I have improved the look of the new console by using clear varnish rather than dark stain. That makes it take on a more modern appearance. OPUS I was stained in Walnut, a choice which I regretted on completion, as I considered that the unstained natural wood, light in colour, had a better appearance.
The console is also somewhat heavier, as the spruce/pine frame is constructed in thicker wood, and the panels are 9mm ply rather than 3.00-5.00mm. This makes the console more stable, and stronger.
The platform/keyboard stack support is wider and more substantial. Unfortunately the decorated engraved and embossed mouldings which I used to such good effect (my mitring of the mouldings has been often admired) are no longer available, and so a plain edging has been used along the platform.
My new book:
"All about Hauptwerk"
is available now from:
All about your Computer
A full explanation of how to setup and use Hauptwerk: keyboards/ pedalboard/  expression pedals/ and controller accessories.
There are designs for a pedalboard and console
Multi-channel audio setup, convolution reverb setup, tuning and temperament are also covered.
YouTube Video
showing the book

1. The console frame base

2. The console frame
(The aperture is for expression pedals)

3. The console frame (front elevation)

4. The console frame and front panelling

6. The console almost complete, varnished, and with the keyboard platform fitted.

5. Console frame with mouldings and toe pistons
These images show how a frame was constructed from spruce and pine, beginning with the base.
The front of the base has a battens of sufficient width to encompass the pedalboard.
The frame is also equipped with a space which forms a niche for the two expression pedals, and a sloping panel on which toe pistons can be mounted.
Decorative mouldings round off the construction and provide a neat edge surrounding the expression pedal aperture.

1.2 The Pedalboard
The pedalboard used in OPUS I was obtained from a deconsecrated Methodist Chapel in Loughborough, as you'll already know if you have read the account of OPUS I. It was about 110 years old, and was MIDIfied using reed switches and a 32-switch parallel MIDI Encoder from MIDI Gadget Boutique - see the OPUS I page for details. I decided that OPUS II would warrant a new pedalboard.
After some investigation I opted to have the pedalboard constructed in Italy. It was quite an expensive exercise, but it was reasonably promptly executed. However, there was a failure to meet the full specification of the RCO pedalboard design, and its derivative AGO. Resolving that error would have required a return of some of the pedalboard parts - that is not convenient, and I am still thinking about that, but I may put the error right myself. Apart from that (quite significant issue) the pedalboard is very usable, and well made. It has slightly thicker pedal sticks than did my original OPUS I pedalboard, in line with modern practice.
I do not like the short cables with which the pedalboard connects to its MIDI controller, and will alter that arrangement in due course to make it easier to connect, and also to see the LEDs that indicate the status of the controller during configuration.
The pedalboard has two expression pedals of standard design, but using Hall Effect transistors and neodymium button magnets. These work very well, and have the advantage of stability, and simplicity compared with optical systems, and of being completely free from the effects of wear suffered by potentiometer systems.
Above the pedalboard, I have mounted a set of six toe pistons, five with an LED active indicator, and a sixth as a pedal divisional cancel.

1. The pedalboard parts (unassembled)

2. Pedalboard detail
(Toe end: showing damping pads and springs)

3. The pedalboard assembled

4. Left access door & part of pedalboard
6. The console, varnished, with the pedalboard in situ.

5. Right access doors & part of pedalboard
These images show the pedalboard, how it is constructed, and fitted into the console frame..
The front of the console base has a batten on each side of sufficient width to encompass the pedalboard.
The two expression pedals mounted on the pedalboard frame fit into the niche, and six toe pistons are mounted on a sloping panel.
Hinged doors one each side provide access to the computing and electronics of the organ.

1.3 The Keyboard Stack
I decided to make the keyboard stack a major feature of the new organ. Therefore, I specified a set of three brand new, especially built high quality keyboards in the "Baroque style" with tracker action, cherry naturals and ebony sharps & flats and beech key cheeks.
The keys would get their feel from having a full length key-stick, enabling a traditional balance point to be used, rather than the very short keys associated more recently with many keyboards. In the event, the three-manual keyboard stack weighed in at 50kg! I was glad I didn't decide to have a four-manual stack.
There would also be a full set of 37 divisional and general thumb pistons, using illuminated buttons. six of the thumb pistons would enable control of a fourth manual division, enabling the upper manual to function fully with a Swell and a Solo division in larger instruments.
Unfortunately I failed to specify exactly how the thumb piston MIDI parameters for MIDI IN (senses the engagement of a thumb piston) and MIDI OUT (illuminates the selected LED) should be matched (i.e. same MIDI channel and Note ON) to ease Hauptwerk configuration. Release of the source code for the Arduino controller was refused, and the only correction option offered was a return of the Arduino PCB for reconfiguration. I did not regard this as satisfactory as it would mean dismantling on the keyboard to extract the controller.

1. The traditional keyboard bases
(in workshop)

2. The baroque-style keys in construction
(in workshop)

4. The keyboard stack mounted on its platform

3. The keyboard stack (in workshop)
The music desk was not actually used.
These images show the keyboard stack, it's features, and how it fitted onto the console keyboard platform.

1.4 The Control Section
I wanted to make the operation of this instrument as independent of the computer keyboard, mouse and monitor screen as possible. In fact, the keyboard, mouse and monitor are required only for logging into the PC and installing or configuring a sample set.
The entire organ, including the computer can be turned on and off from the control section, and the 2x16 character LCD display shows loading status of the organ during loading, and the name of the currently loaded combination set.
Recording of MIDI and Audio can be started (both simultaneously if required) and stopped using push buttons (on the right) and LEDs indicated when recording is taking place.
There is also an illuminated combination setter switch on the right.
An Arduino Teensy micro-controller is used to operate most of these control functions. I wrote the code in C, after reading an article by Tim Howard on his WordPress Blog.

The Control Section
This image shows the Control Section.

On the far left, there are power switches for the Audio & MIDI and for starting up the PC. A push button also enables the PC to be shut down from the console.
Next is a 2-line LCD display which can show the currently loaded Organ, Combination Set and Temperament.
Four Push button switches enable selection and loading of any installed Organ, Combination Set and Temperament.
Centrally, the 16 lit rocker switches enable control of the couplers.
On the right of the rocker switches, four push buttons enable sequenced selection of registrations, whilst a fifth button allows combination selection.
On the far right, three push buttons allow MIDI and Audio recording to be switched on and off. The lower button on that group closes the Hauptwerk software.

1.5 The Stop Jambs
In Phase I of my OPUS I console organ stops were controlled by a touch screen. I found that the touch screen was a little subject to bounce, or would sometimes miss the touch. Subsequently, in Phase II of OPUS I I fitted two Novation LaunchPads for stop control (and for control of a number of other functions, including coupler control, MIDI and Audio recording, and PC shutdown). These were, and remain excellent. However, for OPUS II I decided to attempt to use a mechanism a little more like that used in most real pipe organs.
Solenoid actuated moving stop jambs were discounted as they cost in the region of £40-44, and I decided to have 120 stops!
After investigation I settled on illuminated push buttons, as commonly used in arcade machines. These have a micro-switch enclosed in a switch housing with an LED, and can be obtained at a very low-cost from several sources. The fact that they make an audible click on operation was not seen as a disadvantage, as electro-magnetic action draw stops also make quite a noise in action.
There would be a left and right stop jamb, bearing 60 switches each. There would be a MIDI encoder and a MIDI decoder board in each stop jamb.
1. The uncut stop jamb panels with buttons fitted

2. The stop jamb panels are cut and housed

3. stop jambs ready for wiring

4. Right hand stop jamb wired
These images show the construction of the two stop jambs.
There are 120 illuminated stop switches in six columns of twenty, vertically staggered.
The space at the top of each jamb allows a label to be placed giving the organ name and builder.
There is a space between each column for a strip bearing the names of the stops to be inserted.


2.1 The Component Shelf
A component shelf, accessible from behind the organ, supports the devices associated withy the organ. The apparent simplicity of the layout rather belies the complexity of the setup!
The device shelf carries the electronics and computing components.
The components, from left to right, are:
 Far Left: MIDI Hub. Carries 4 MIDI-IN and 4 MIDI-OUT cables for the Pedalboard and Expression Pedals and for the Left and Right Stop Jambs
 Inner Left: 7-way USB Hub. Carries Keyboard Stack and Thumb Piston, Pedalboard Controller Power, Control Section (x2), Touchscreen and Hauptwerk dongle
 Centre: 16 channel USB Audio Device, Currently 3 Stereo Pairs, a Subwoofer and Stereo Headphone output occupy about half of the available channels
 Inner Right: PC Unit - Intel Skull Canyon. i7 CPU, 32GigaByte RAM, 2 Terabyte SSD disc
 Far Right: PC Power Supply

2.2 The Music Desk and Lamp
A music desk and lamp sit on top of the control section, whilst the two stop jambs sit on either side of the keyboard stack, in a conventional layout.

1. The control section and music desk, with lamp
3. The Completed Console

2. The control section with stop jambs in place
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(c) KA Spencer 2018