The Fair Organ Preservation Society Discussion Forum

Information to start a new project.
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Author:  kevyn [ Sun May 22, 2011 8:14 pm ]
Post subject:  Information to start a new project.

Hi all, I have built a couple of John Smith projects in the past and last year completed a MIDI organ. I am now getting brave and will shortly be starting a new 65 key venture. I have discovered that John uses the Pell register system but appears to have adapted in his plans. Can some one explain to me how I might be able to use the register system as Alan designed it as I would like to be able to control more registers than the plans show. What I mean by this is that I saw a 30 note Pell at Hollycombe last weekend and it was able to control single bordons or violins independantly of each other, my previous organ cant do this as the bordons play all the time either with or without celeste. I want to understand how the Harmidi system self cancel without using a command just for that purpose which is how John shows it.

My work can be seen on youtube under the name of kwaigoneginn.

Author:  Rob Barker [ Mon May 23, 2011 6:51 am ]
Post subject:  Re: Information to start a new project.

Hello Kevyn,

Welcome to the forum.

The Pell register system features auto cancel (auto declanche) which means that the arranger only has to select the register he or she wants without worrying about previously set registers, or including a cancel signal. This is all handled by the hardware on the Harmidi system.

However, if you are using a J. Omega board or similar to control your magnets, there is a register control board available from a couple of sources (including John Smith). It is simply wired into the existing system. It can control all the registers, including the multiplexed tremulant signal. The only limitations are the number of magnet ranks, as they are driven by single driver chips instead of a dedicated driver for each rank. This limits you to about 3 ranks depending on what magnets you use. However the problem is easily overcome if you want lots of ranks.

I hope this helps.


Author:  kevyn [ Mon May 23, 2011 3:19 pm ]
Post subject:  Re: Information to start a new project.

Hi Rob,

Thanks for the reply so quick, I assume you are referring to the CMOS type register board John talks of? I looked up the MIDI map for Alans scale over the weekend and noticed that Alans has midi44 as Violin and john has it as single bordon and midi 46 as Bordon and john has celeste (reset) and wanted to try and get away from the permanantly on bordon to one as Alans arrangements intended. I assume you mean the harmidi system itself copes with the declanche control signal rather than use midi 46 as the reset?

Not fully understanding register control wont stop me from starting though as I need to make all the pipes and windchests yet and I can cross this bridge later or ensure the chest can be wired accordingly.

Thanks again Kev.

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