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Wind Chest Questions...

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  • Wind Chest Questions...

    Hello! I'm relatively new to the forum, so please feel free to direct me to the proper thread if my dilemma has previously been mentioned and solved by another user - although my relatively thorough search of the forum and the internet itself has turned up no answers. I'm sure that this is just the first post of what will be several seeking your advice!

    I am in the process of updating and installing a small pipe organ that someone graciously donated to my church for our chapel. Please keep in mind that I am not a professional organ builder - in fact this is my first project of this nature. While not a skilled professional, I do have the technical knowledge needed to disassemble and reassemble the instrument, and can do most repair work myself.

    The organ has a Stopped Flute rank of 97 pipes, an Open Diapason rank of 73 pipes, and a String rank of 73 pipes. An additional rank of 61 notes (a Vox Humana) came with the organ, but was never installed, and has no accompanying wind chest - just the pipes. While I would like to install that rank, it is not a priority at this time. The organ came with 2 offset chests (I believe this is the correct term) - one chest for the lowest of the stopped flutes, and the other for the lowest notes of the diapason and string ranks. The main chest is divided properly for the remaining pipes of the 3 ranks. While I didn't take an exact measurement, I believe each of these chests to be at least 6 to 7 feet long.

    In the original installation the entire organ was under expression. I would prefer to have the Diapason unenclosed, and the remaining stops (including the Vox if I install it) would be under expression. Therefore, I will need to separate the part of the main windchest that houses the diapason. No problem - I think I can handle that part. The problem is with the length of the wind chests. If you were in our chapel looking into the sanctuary, the diapason pipes would be installed on your right, and the other ranks to the left. Because the sanctuary is relatively small, the best way to install these wind chests would be to install them "kitty-cornered." Here are some possible options that I am looking at.

    OPTION 1 - MITER THE WIND CHESTS...similar to mitering a pipe at a 45 degree angle, I could cut the wind chests in half and miter them together. My main concern is if the wind pressure would be affected with the air having to go around a sharp angle of such. Will this affect the wind pressure for those pipes after the angle? I worry not too much about the smaller pipes, but rather the larger ones...these chests are set up with the largest notes on the ends of the chest, and the smaller ones descending toward the middle - so there will be larger scale pipes at the opposite ends.

    OPTION 2 - USE A FLEX HOSE...similar to option 1, but rather than mitering the actual chests, I'd seal up the open ends (after cutting them in two), and make an opening in each to connect the two with a flex hose. This would eliminate the air needing to travel a sharp corner; but since most flex hoses are circular and most wind chests are square/rectangular, this would create the additional issue that less air may get to the second half of the much would this affect the pressure in the far end? While this option is a little bit easier than option 1, the question remains on the effect of wind pressure.

    OPTION 3 - ALTER RESERVOIR OUTPUT...If my memory is correct, there are 3 exits from the reservoir for the wind...two exits go to the offset chests (via flex hoses). The 3rd exit from the bellow goes directly into the main chest. The wind gets divided into the 3 separate areas for each individual rank just before entering the chest itself. Option 3 would entail changing the number of air outputs from the current 5 to 10. Theoretically this shouldn't have any effect on the wind pressure, because the same output is still going to fill the "square footage," it it just how it gets distributed that changes. Of course - this is just an assumption...does anyone know if my guess is right?

    Option 1 will probably add a little extra space for the air to travel: typical mitering, there isn't enough space to cut the chests at a 45 degree angle - I'd cut into some of the toe holes if I did that. So I'd have to cut it in half, then manufacture a wooden 45 degree angle. Again, it adds a little extra space - albeit not much, but with the sharp angle AND the extra space, I do need to be concerned about wind pressure. Option 2 requires using a flex hose that will be narrower than the square box the air is coming from, because the hose is round...but the angle will be smoother travel. Option 3 is the most time consuming, but may have other repercussions that I am not aware of.

    So what do you think, colleagues? Will any of these options effect air pressure? Which option is best - 1, 2 or 3...or is there a 4th option you know of? I will await your replies! Thank you, in advance, for your thoughts, advice, and sharing your expertice.

  • #2
    As I look at your description of what you intend to accomplish, two thoughts (questions) occur to me.

    1. If you think you really might use the Vox Humana, why not just get another chest to start with? That would be a whole lot easier than chopping apart the chest you have. And, if you were lucky enough to find one like we have on our church organ, with a walkway down the middle of the chests, you could easily miter it without adding any extra wood.

    2. Could the chest for the Diapason fit in front of the swell chamber, thus forming a facade for it (assuming, of course, that the Diapason pipes are suitable for open display)? This would also eliminate the miter.

    As far as your other questions, a miter should not cause any real problem in air supply, and a large enough flex hose likewise will handle all the air you need. The same size hose that handles your offsets (especially the one for the low flutes) will easily give you enough air. i am not sure what you mean by option 3. But, if you use the Vox Humana, it takes so little air that it will cause no problem for the blower.

    My home organ is a Theatre III with an MDS II MIDI Expander.


    • #3
      Hi Mike! Thanks for your response.

      As far as getting a new chest, I think that would require much more time and searching. I live in a very remote part of the country - it takes nearly 2 hours just to get to "civilization" as I am familiar with it! Given the fruitless internet searching, and the lack of local resources, I think I'd be better off building a new chest from scratch rather than trying to find a the tight budget makes purchasing less likely.

      The Diapason pipes were painted - I assume in an effort to use them as facade pipes in the past - but I wasn't planning on using any of the pipes for facade purposes. We did get approximately 15 or so other pipes that were also once facade pipes. I am planning on cutting those down to size and repainting those to use as a facade. One of the issues that I have is that the chapel has been recently renovated. We didn't want to put the organ in there and have it look as an afterthought. I have the picture in my head of what it will look like when completed...while I believe I have the skill needed to complete everything, it is daunting for a first timer, but I think I'm up to the challenge!

      As for the vox - I'm not sure if I will install it with the organ right away...I am hoping to, but that depends on how well everything else on the project goes. If it does get installed, I'm probably going to have to build an enclosure around it to soften it up a bit - since it is the only reed on the organ, I'd like to use it more as a background/chorus reed - right now it does seem to have a bit of punch to it.

      I didn't think either of my ideas would affect the wind pressure too much, if at all - but since this is a first time effort, I figured I'd seek all the advice that I can get. I've already gutted the console and installed Artisan's uMIDI system. I've had a few setbacks - it appears to be a defective uMIDI board, but I've been in contact with the company and I'm sure that the issue will be resolved very soon. Both Mark and his associate have been very helpful to me in the past. Once the console conversion is complete, then comes the wind chest conversion (to get the magnets to interact with the uMIDI system). I'm hoping to have the wind chests altered by the time that project is complete. Then comes the remainder of the assembly to make sure it all works properly - then I get to take it all apart from the hall it is currently in, and install it in the chapel! Only time will tell if this all works out well!

      I'm also working on 2 other projects - one is building a large Hauptwerk efforts on converting this organ to a hybrid will certainly help in that regard. Then I'm also working on building a small 6-8 rank tracker instrument. These two are personal projects for myself - so the chapel organ project is my "guinea pig." (Unfortunately, the church has better cash flow than I do, so I've got to work on the project I can get things accomplished on first - otherwise I'd finish one of mine to make sure my skills are up to snuff before attempting a project that is in the public's eye!)

      Thanks again for your response Mike! Any other feedback or suggestions that you have to offer me are most welcome - as are comments from other forum users. I hope the upcoming holidays are great ones for you and yours! Peace!



      • #4
        You didn't say what the action type of this organ is...electro-pneumatic or electro-mechanical, and the type of action may well determine what course of action is available to you in terms of altering existing wind chests. One suggestion I would make (aside from getting a professional to give you guidance as you progress thru this endeavor) is to DRAW out IN SCALE with exact measurements the organ as you envision it installed in the church. Included in the drawing will be all the parts of the organ, the reservoir, blower, structural elements, control system locations and wiring routing internal to the organ. Some blue painter's tape laid out on the floor of the church in the proposed location will aid you in knowing how well your plans will fit with reality. You need to plan for a location for the blower and that will include sufficient electrical supply, a discrete way to route the cables from the organ console to the controls system and wind chests. You need to plan for the cabinetry that will hide the structural support elements of the organ, even if it is a simple piece of painted plywood paneling you want to consider the visual impact that it will have.

        Rick in VA