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controlling external swell shutters

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controlling external swell shutters

Postby Meweber@verizon.net » Wed Sep 11, 2019 3:19 pm

I will be constructing a hybrid organ using the Paramount 320 and a few ranks of real pipes. I also have a set of 5 swell shutters that I would like to control. Currently they don't have any actuators on them. How do I set up HW to control these and what do I need to add to the shutters to activate them. Thank you very much for your help.
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Re: controlling external swell shutters

Postby TheOrganDoc » Wed Sep 11, 2019 7:23 pm

I would recommend that you find a "Local Pipe Organ Repair shop", and explain your quest to them, They may have used parts on hand, that they could provide you !

(find them on the internet)
There are a few "Pipe Organ Parts Company's" that sell "Swell Actions"---(or Swell Motors), But they usually only sell to Pipe Organ Repair Company's, ("Sad but true") Mel
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Re: controlling external swell shutters

Postby Meweber@verizon.net » Wed Sep 11, 2019 10:41 pm

Actually I have a swell action, but it is pneumatic and needs work, and not connected on the swells themselves. Perhaps my post was not clear. I have looked at the “swell MIDI output” on the HW paramount 320 and can’t tell if this is for sequential swells and if so how many. Since the swell action needs a lot of work I thought maybe someone would have used servo motors and a MIDI/servo control module.
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Re: controlling external swell shutters

Postby NickNelson » Thu Sep 12, 2019 5:30 am

Interesting problem/project.

Converting a MIDI swell position message to a DC voltage (at signal level) would be trivial. This could then be compared with a second DC voltage derived (probably using a potentiometer) with the actual position of the swell shutters, and a difference signal derived to drive the shutters to the new position. There are several people on this forum, myself included, who could knock up an electronics package to accomplish this apect of the work at minimal cost.

The interesting part would be the way in which the shutters are driven. From a (very brief) Googling of 'MIDI Servos' I doubt whether anything easily available would offer sufficient force to rapidly shift the mass of the swell shutters. It would probably require a medium sized DC electric motor (possibly a stepper motor) and a worm type gear train to perform the necessary movement.

On the other hand, if you have the original pneumatic motor I would be very much inclined to use this if at all possible. A lot would depend on how this was originally set up and linked to the original swell pedal, but I would have thought it should be possible to use an off-the-shelf MIDI servo to drive the pneumatics.

Just my first thoughts,

Nick
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Re: controlling external swell shutters

Postby IainStinson » Thu Sep 12, 2019 9:11 am

Swell engines (which operate the shutters) often have a number of separate stages rather than offering continuous operation. (The box open in stages.)

I have a six stage swell engine on our small pipe organ. The shutters are powered pneumatically from the wind supply. Each "stage" is essentially a pneumatic motor which when supplied with wind moves the shutters. The pneumatic motors are controlled by electromagnetic valves (actual chest magnets) - when the current is supplied to the electrical mechanism the motor stage operates. The console has an expression pedal which simply supplies current to each stage as it is pressed forward and removes power from the stages as it is closed. It is not a continuous control but a sequence of discrete switches When the box is opened each stage is engaged in turn; the previous stages remain energised: as the box is closed they are disengaged in order. This pipe organ is not controlled or linked to Hauptwerk.

If I were to connect this swell engine to Hauptwerk I would want to use a midi decoder with suitable drivers to operate the discrete magnets for the swell engine. However, I’m not aware of any facility in Hauptwerk to provide the type of control required. If I were to use HW to control this organ I would leave the swell box mechanism outside HW: I might “double up” the swell pedal to drive this mechanism and a continuous midi control for the HW digital ranks.

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Re: controlling external swell shutters

Postby rayjcar » Thu Sep 12, 2019 5:24 pm

The expression pedals in Hauptwerk are encoded as Control Changes, with values between 0 and 127. Using Midi-Ox or a similar utility, you will be able to determine the exact range that is being encoded (after auto-detecting) for each expression pedal.

The channel corresponding to the expression pedal(s) should then be looped through a midi relay such as this one:

http://www.midisolutions.com/MIDI%20Sol ... 0Relay.pdf

Refer to page 6 for an example of how you could write code to cause the relay to close corresponding to when a specific control change value is exceeded. Note that this example is backward to what you want, i.e. you want the relay to close when the value is exceeded, and open when the value is below the threshold. So you just need to modify the code string accordingly.

You will need one relay for each shade motor. Midi Solutions makes a rack mount version with 8 relays
Program each relay for a higher value of Control Change corresponding to when you want each shutter to open in succession. .

Some of our more enterprising colleagues (Nick?) could probably work up something using Arduino to cut down on the expense. Some manufacturers make expansion boards with 8 relays per board.

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Re: controlling external swell shutters

Postby rayjcar » Thu Sep 12, 2019 5:31 pm

Upon further research, here is an ideal solution. Robot Electronics (UK) makes a purpose-built board with midi in and out connectors, and 8 relays.

https://www.robot-electronics.co.uk/htm/midi-rly8.htm

It comes with a very intuitive configuration utility which will allow you to specify the Control Change value for each relay. This would allow for very simple fine-tuning to have the volume of the real pipes match the virtual pipes.

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Re: controlling external swell shutters

Postby magnaton » Thu Sep 12, 2019 6:04 pm

I have been involved with or worked on a few theatre organs with digital voice enhancements. In some cases these additions were simple; toys and percussions while others more involved with tuned percussions, bass extensions, and a few complete ranks. One of these about a 3rd of the organ was digital. All of these had speakers in the chambers intermixed with the real pipes thus volume was controlled by the swell shades. This made it difficult to distinguish (if at all) between real and digital which of course was the goal.

Maybe I'm missing the point but I agree with what Iain posted to work on getting the swell shades operational independent of Hauptwerk. So a simpler solution would be to put all speakers in the chamber, set the Paramount's virtual swell to always start in the full open position, then set the master volume and or individual rank volumes accordingly to the wind blown pipes. In this design the Paramount set is treated as a (large) digital voice enhancement.

Danny B.
Last edited by magnaton on Thu Sep 12, 2019 7:34 pm, edited 1 time in total.
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Re: controlling external swell shutters

Postby rayjcar » Thu Sep 12, 2019 6:47 pm

"So a simpler solution would be to put all speakers in the chamber, set the Paramount's virtual swell to always start in the full open position, then set the master volume and or individual rank volumes accordingly to the wind blown pipes. In this design the Paramount set is treated as a (large) digital voice enhancement."

The challenge with this approach is that swell shades affect high and low frequencies differently. The pipes sound brighter as the swell shades are opened up.. If the speakers are inside the chamber, the virtual pipes, whose sounds are effectively going through a low pass filter whose cutoff is determined by the swell shoe position, would be doubly filtered.

You would have to effectively disable the swell shoe data from altering the frequency response of the virtual pipes, and I don't know how to accomplish that. Then the virtual pipes, like the real pipes, would be sounding full bore all the time.

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Re: controlling external swell shutters

Postby magnaton » Thu Sep 12, 2019 7:32 pm

rayjcar wrote:You would have to effectively disable the swell shoe data from altering the frequency response of the virtual pipes, and I don't know how to accomplish that. Then the virtual pipes, like the real pipes, would be sounding full bore all the time.

Correct. You simply don't auto-detect the Paramount's swell shoes with anything. The swell shoe doesn't have to be MIDI encoded since its function would independent of HW. There is a HW setting that asks the position of expression pedal(s) at startup, you would set it to full (127). The volume and clarity of the virtual pipes would speak at their unfiltered, recorded level.

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Re: controlling external swell shutters

Postby Meweber@verizon.net » Mon Sep 23, 2019 11:10 pm

Thank you very much for all of the comments. I learned a lot but much of it went over my head. It seems to me that I should just rebuild the original pneumatic swell action/motor and forget the idea of using servos. It is unnecessary design work. Since I don't play well or much I will want to listen to MIDI files frequently. So I don't think that bypassing HW for the swell shutters is a good idea for me. My swell action and magnets look just like a pipe chest. I don't see why I can't just use an off-the-shelf MIDI decoder/driver to activate the individual swells. Then I need to figure out how to get the appropriate signals from HW. I think that Ray has the in-depth understanding of how to do this, I just don't know enough yet to follow it. Ray, is more hardware needed than a simple decoder/driver to do this or can everything else be done with the HW MIDI output settings? I will have one set of swells whereas the Paramount 320 has two sets. If I put my speakers inside my chamber I will lose one set of expressions. My current thinking is to leave the speakers outside of the chamber to not lose the solo expression. Thank you again for all the great suggestions and I hope to get some feedback on my design approach and questions.
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Re: controlling external swell shutters

Postby rayjcar » Tue Sep 24, 2019 4:25 pm

The midi relay board should be all that you need. Make sure you order this version:

MIDI-RLY08 - 8 relay, 0 dimmer

It consists of 8 conventional relay contacts, each capable of 250 volts at 8 amps. You have five swell shutters, so you will have three spare contacts. The magnet on the pneumatic valve will be in the range of 150 - 175 ohms, depending on the manufacturer, so the current draw will be less than 100 milliamps at 12 volts.

I have the Paramount 341 installed. By right clicking on the main swell expression pedal on the virtual console, and selecting "adjust midi/trigger settings manually for expression pedal, I confirmed that the input to Hauptwerk is classified as Control Change, with a range of 0 to 127. By looking at the bottom of window, I could see that the actual range of values determined by auto-detecting that swell pedal is 17 to 67.

To control the relay board, you need to select the primary output tab, choose the output type as Midi control changes. Then select an output port from your midi interface, and an output channel corresponding to the midi input channel of the relay controller.

To configure the relay board, use the utility supplied by the manufacturer, Set the midi channel, and check the "CC enable" box. You can then set the initial values you have chosen to set the trip point for each swell shade motor. For example, if you wanted five steps between my actual values of 17 and 67, you could set relay 1 to close at CC greater than 19, relay 2 at CC > 30, relay 3 at CC> 40, relay 4 at CC > 50, and relay 5 at CC > 60 Once you get the virtual pipes and real pipes working in tandem, you can tweak the CC trip values to match the loudness levels more exactly.

Another subtle issue to monitor is the likely difference in latency between the virtual and real pipes. Johan Liljencrants has written an excellent dissertation on the latency of electro-pneumatic and direct electric valves. You can see it at http://www.fonema.se/valvetime/valvetime.html
If you find that the virtual and real pipe latencies are too different, you can tweak the Hauptwerk latency by changing the buffer size.

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Re: controlling external swell shutters

Postby Meweber@verizon.net » Tue Sep 24, 2019 5:35 pm

Thank you very much Ray.
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