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Pipe Organ "Front End"

Building organ consoles for use with Hauptwerk, adding MIDI to existing consoles, obtaining parts, ...

Pipe Organ "Front End"

Postby Coenraads » Thu Feb 07, 2019 3:00 pm

When a four rank positif pipe organ was delivered unannounced to the shop of the local organ builder, he asked me to look after the electrical end of things. The organ, originally a tracker, had been unsuccessfully converted with electric pull downs. We removed these and used direct electric action instead. Fortunately the organ came with four of Roman Sowa's decoder/pipe drivers. I daisy chained these and assigned each rank to a different channel. Using a Midi controller with selectable channels we were able to test each rank.

But for voicing, we needed to be able to play ranks together and try the ranks at different pitch levels for some judicious unification. And although the owner intended to connect the positif to a larger pipe organ, I thought it would be nice if he could play the organ as a standalone right away by simply plugging in any old 61 key DIN Midi keyboard. I wanted to do this without building a stop rail, so I installed an Arduino based pipe organ "front end" inside the organ with a single Midi IN.

Those of you who are also faced with controlling a small pipe organ from a VPO console may find my solution to how I implemented the stop action interesting and useful.

Basically it involves giving up top C on the keyboard. Pressing that key causes a general cancel to occur and turns the top octave into stop selection mode. Up to 12 stops can be assigned to this top octave. Pressing these keys turns those stops on. (Shades of Hammond) When finished selecting stops one can simply start playing anywhere outside this octave which immediately causes the top octave (except for top C) to revert back to its normal playing function.

The code for this can be found on my website.

https://sites.google.com/site/casavantopus400/

If you study this, you will also see how I implemented the borrowing of the bottom octave from an eight foot step to extend a four foot stop. And while I was at it, when one runs out of pipes at the top, (possible with unification) I just "folded" those notes back an octave.

John
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Re: Pipe Organ "Front End"

Postby organtechnology » Thu Feb 07, 2019 9:37 pm

and this is related to Hauptwerk software how?
Complete VPO systems powered by Hauptwerk™. Real Wood Consoles, PC or MAC Computer Sound Modules, Audio for Home or Church.
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Re: Pipe Organ "Front End"

Postby Coenraads » Fri Feb 08, 2019 2:59 pm

The author of the preceding, who asks the question, "and this is related to Hauptwerk software how?" deserves an answer. And the answer is, "It isn't."

But I take exception to the implication that therefore this does not belong on the HW Forum.

First of all, this was posted on that part of the site dealing with DIY consoles/MIDI. MIDI consoles are not software specific. I am confident that many DIYers who cannot afford HW and use Jeux d'Orgues on an iPad or some other software, visit this site for information and ideas.

Secondly, I apologize for not making clear why this idea of "piggybacking" pipe organ stop data onto the back of a MIDI data stream could be useful to someone using HW. Let me use myself as an example. I have been a HW user from the very beginning, but recently I acquired some pipes which I am using to build a small pipe organ. Someday I dream of building a proper console for it, but in the meantime I will play it from my HW MIDI console. I.e., I will have a hybrid instrument.

The pipes will be located some distance from the console and I really don't want to build a stop rail which will only be discarded later. Since the pipe organ will be run using the same MIDI data stream as HW, I thought that this technique of piggybacking the stop control data might be of use to others facing a similar situation.

John
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Re: Pipe Organ "Front End"

Postby murph » Fri Feb 08, 2019 5:09 pm

I'm quite liking the different approach to coding being shown.
I really like using the mega to do 2 keyboards, with nothing else. Most other projects use additional multiplexers, which I have always thought superfluous to a simple design.
Personally, I would have put the swells on the micro in this design, to keep cables short. (I'd probably add toe-pistons too down there.....)
Not sure about the de-bounce, but that can be edited.

Please keep it up John!

Tony.
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Re: Pipe Organ "Front End"

Postby jkinkennon » Sat Feb 09, 2019 1:27 pm

The techniques used are easily transferable to Hauptwerk projects that lack stop controls. I for one would like to see more technical interaction on this forum. As an example a local organist asked if I could develop a capture system for a 4-rank Moller unit organ. He had wanted to add Hauptwerk voices originally but the expenses had not been approved. Now that he has the benefit of quick registration changes he is playing music that he had previously avoided and adding more color to the liturgical style service.

The congregation has noticed the changes and I am now proposing they add Hall Effect sensors to the manuals, a change that will maintain the ability to turn off the capture system without interfering with the Moller's original operation. Suddenly Hauptwerk is easily within reach.

This is a Teensy project by the way at a fraction of the cost of commercially available solutions. We used recycled SAMs and pistons from previous projects and custom built a new piston rail and stops panel. I'd be happy to share the design.
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Re: Pipe Organ "Front End"

Postby engrssc » Sat Feb 09, 2019 5:16 pm

You might want to check out:

https://almorse.net/content_OrganUpgrade.html

There's quite a bit to it to do it right.

Rgds,
Ed
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Re: Pipe Organ "Front End"

Postby Coenraads » Sat Feb 09, 2019 6:08 pm

I like John Kinkennon's thinking. If I understand him correctly, he is suggesting that the data stream from VPO to HW could be intercepted by an Arduino and massaged to make HW do things that might normally be difficult to set up. E.g., one push of a button (or top C) could temporarily turn a keyboard, or part of a keyboard, into a stop rail or piston rail.

And thanks for your willingness to share information about your combination action project. I recently advised a friend on using a single Arduino Mega to implement a combination action on his home pipe organ. (15 ranks, 30 stops, 3 manuals, 12 pistons and 16 memory levels). A neat touch was having the Arduino monitor the MIDI out of the Syndyne switching system to determine the position of the drawknobs.

John
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Re: Pipe Organ "Front End"

Postby jkinkennon » Sun Feb 10, 2019 4:15 pm

engrssc wrote:You might want to check out:
https://almorse.net/content_OrganUpgrade.html
There's quite a bit to it to do it right.


Once one understands that a capture system is merely providing a set of perhaps 24 to 30 dry contacts to replace the original Moller controls (not SAMs in this case) then it becomes quite straightforward to set up a system that does not interact at all with the Moller electrical circuits. The dry contacts (no voltage) on the usual Reisner SAM do not connect to the activating coils except for the grounded frame of the SAM. This means the capture system can be turned off without affecting the Moller.

I did add high impedance sensor connections to follow the state of the SAMs for easy combination setting and for eventual HW compatibility. Again, that is not rocket science.

Future HAFKA sensors from midi-hardware.com may be added in the future. This happily coexists with the Moller as there is NO connection to the keys.

Sometimes we over-think things until we end up doing nothing and learning nothing.
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Re: Pipe Organ "Front End"

Postby Coenraads » Mon Feb 11, 2019 3:23 pm

To Tony: Thank you for the kind words about my code. I think you are referring to the Arduino Mega code I used for the Galanti project. You talk about not being sure about the debounce code and that it might be edited out. I would caution anyone from doing so, since I believe it to be a better part of the code.

I started with the debounce code I had successfully used with pedal board reed switches, but the Galanti, which uses a delicate tightly wound spring to contact a bus bar, bounced so badly that I kept getting spurious messages. So I solved that by adding an array which keeps track of which notes are already on or off.

When the scan loop finds a note being turned on, it simply increments a counter by one for that note and continues scanning. Only when the count reaches 6, is the note actually turned on and only then, if it is not already on. Turn off reverses the procedure until the count returns to zero. The key of course is to never stop the scan while performing a debounce.

My Midi Tool iPad app now shows the output from the Galanti to be absolutely clean, which gives me confidence that this routine is now bomb proof.

The Arduino is actually blindingly fast, so even if this all seems too elaborate, in fact it doesn't impact the response time. So try the code as is. I think you will like it.

John
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Re: Pipe Organ "Front End"

Postby murph » Mon Feb 11, 2019 7:16 pm

Hi John,
I wasn't saying there was anything wrong with the de-bounce in this instance. I was just questioning the effectiveness of waiting for x amounts of on triggers in other, better circumstances.
In those circumstances, it would be annoying.......

Having said that, I might start with your code, a couple of gold wires and a good wrapping of tin-foil on the wood to try and add contacts to my sets of Ivory keys.
It'd be a lot cheaper that hall/optical.


Tony.


p.s. Only joking about the tin-foil. The Kimber-Allen pair (which I like, nice tracker touch springs!) have wipers.
Unfortunately, they are a different width to the 4 sets of Comptons, which don't have tracker or wipers.
I'll probably use the KA pair with a straight pedal-board and the 4-manual set with the RCO board. (If I ever get around to it all... The Yamaha keys just work for now.)
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Re: Pipe Organ "Front End"

Postby Coenraads » Mon Feb 11, 2019 11:22 pm

Hi Tony

Having just replaced all the keyboard switches on a three manual Rodgers hybrid instrument with Kimber Allen gold-on-gold switch blocks, I think of them as the "Gold Standard" but unfortunately expensive. Don't neglect the possibility of going optical. I've just spent a day experimenting with them and the results were promising. At a dollar per optical switch, the cost is very reasonable and I was surprised by how well they integrated with an Arduino using virtually the same code I always use. (See my latest post). I can't vouch for how well this will work in a full scale setup, but my experiments were very promising.

You are absolutely right of course, using a debounce count of 6 is a bit ridiculous and I usually only use 3 or 4. Either way, you are not going to notice any delay.

Good luck with your project,
John
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