How to implement volume controls on SCPOP organ.

MIDIfication
1

To Jim Henry or anyone familiar with conventional organs.

I need some advice on how to deal with overall volume and relative balance for the SCPOP organ. I want to fall in line with normal organ design practice as far as is practical.

CURRENT DESIGN

The organ has 2 keyboards (Great and Swell) and a pedalboard.

The keyboards each have 3 groups of  sound files.

Flutes and Principals

Mixtures and Mutations

Reeds and Strings

The pedal has only one group of sound files.

There are independent “volume” controls for each keyboard group, the 3 potentiometers control the relative signal level (by Midi Control changes 07,08 and 09 between the Flutes (07), Mixtures (08)  and Reeds (09) for the lower Manual and the upper manual is dealt with in a similar way with another 3 pots.

The present design has only one potentiometer for the pedals. This controls the “volume” of the pedal sounds by employing the “expression” parameter 0B.

Each of the keyboards has an additional single pot which is used to raise or lower the composite sound levels for both of the keyboards. This uses the “expression” parameter 0B. This brings the total No of pots to 9.

It is obvious that I will need an overall volume control, a foot operated potentiometer. The current design may be fine for the PC based system.  I use my mixer analogue slider to change the overall volume. It seems to me that I should use Midi.

NEW DESIGN

I am proposing to change the design as follows:-

The relative level of the keyboard sounds will be controlled by 3 pots as before.  I will remove the “expression” pots.

I will control the pedal sounds with Midi CC 07 (volume) rather than “expression.”

The foot control pot will send identical “expression” (0B) parameters to the pedalboard and also to the 2 keyboards.

This means that there will be:-

3 pots for each keyboard sending Midi parameters 07, 08 and 09.

1 pot for the pedalboard sending Midi parameters 07 (say)

1 foot operated pot sending Midi parameter 0B to send expression to all three 'boards altering the signal levels in tandem.

Is this a practical solution?

Any advice will be welcome.

Regards Robin

 

2

As best I understand what you propose it seems workable.  As to conventional organs, the foot control (swell pedal) is most logically  Control Change 0B expression as you propose.  In a real organ this controls shutters in front of the pipes to control volume.  The control of the relative volume of ranks would fall into the realm of voicing, something that is not under the control of the organist during performance of course.  I would say you can handle voicing in any way that seems reasonable as that does not have to be something that can be used while performing and thus does not need to conform to what is conventional. 

One thing you may wish to consider is that larger organs are typically spread out into more than one chamber, each with its own swell shades and a separate swell shoe on the console.  If there are 3 or more swell shoes, there is typically a master swell shoe to the right of the chamber shoes and to the left of  the crescendo pedal.  Users of the Miditzer felt it was important to preserve the facility of multiple swell shoes.  I’d suggest limiting yourself to two swell shoes if you go this route as the larger arrangements are going to escalate the console construction costs rapidly and aren’t all that useful.

3

Dear Jim

Thanks for your input.  I have constraints imposed by the cabinet of the original Conn Organ.

The gap for the foot control is only about 8" and the present “rocker” is about 6" wide.  I dont think that the complexity of the rest of the organ designdoes will warrant  anything more complex.  I will probably  keep the mechanics of the shoe control.

I see the relative sound levels being set prior to each performance.  I will  want to add about 12 presets to store the various voice selections as well as the slider values for the Great and Swell individual levels.

It will be feasible to adjust the levels during a performance.  I suppose it depends where the faders are located on the console.

Bet Regards Robin

4

Hi,

Based on your discussion and mention of SCPOP, in classical organs there

are often uneclosed divisions with no volume control whatsoever other than

by choosing different registrations.  A three manual and pedal organ may

have only one enclosed division (swell) with a pedal to control the shades.

I suppose for residential use have a ‘master volume’ control would be useful!

                                                                                                                    —john.

5

My thanks to you John for your reply.  I am in the thick of it, at present, battling  with the programming of  the organ “stops”

Do I understand you correctly that it is often the case,  that the shoe control operates only the Swell “volume”?

Perhaps I should think of the balance controls as non- organist  presets.  The SCPOP design has a faifly elaborate scheme whereby one can couple (1)  the pedal swell and great,  (2) the swell and great (3) have individual  control  of all three.

At this stage it is a detail.  I can wait and see which is the most practical.  BTW this is a chuch organ to be played by organists (not by me).

Regards Robin

6

Do I understand you correctly that it is often the case,  that the shoe control operates only the Swell “volume”?

Yes, that would be true.

The SCPOP design has a faifly elaborate scheme whereby one can couple (1)  the pedal swell and great,  (2) the swell and great (3) have individual  control  of all three.

Pipe organs typically have similiar divisional couplers.  Of course the shoe would only

control the volume of the division it controls and not the others.  So if you were playing

on the great with the swell coupled you could control the volume of the swell only.

And note that some pipe organs will also have a crescendo pedal that controls volume

by advancing through a fixed set of registrational steps starting with the softest stops

and adding louder and louder stops until essentially full organ is reached.  But this is

different than an absolute volume control as the nature of the sound is changing not

just its volume.

You might find it interesting to read the feature list for a modern, digital, church organ

from Rodgers as you think about the features you are working on…

http://www.rodgersinstruments.com/t967_features.html

(I heard an instrument like this in concert just a week or so ago.  Pretty impressive!)

                                                                                                                —john.