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Newbie questions about blower and pipe mounting to improve Mk I instrument

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  • Newbie questions about blower and pipe mounting to improve Mk I instrument


    I'm a musician and am new to the world of pipe organs but I've just taken the plunge and made a 60-note pipe organ. To be accurate, I've actually adapted one that's already up and running - one made by parts salvaged by another more experienced maker. I did so to learn about pipe organs and design something that fits into my own performance. I've stripped and rewaxed and reguilded the pipes, laid them out how I want them, made a new windchest to my own design and put the electrics back in again. I've attached a photo of the Mk I of the new version of the organ.

    The organ, which uses solenoid valves, runs very well but there are one or two deficiences I need to sort out. I'm really hoping some of you here will be willing to share some of your expertise so I can improve things on the Mk II:

    - I don't think the pipes are getting enough air pressure as I have to turn the blowers up a lot to get a good tone from the pipes. I assumed that if I had the same pipes as the old organ used - and played the same number of pipes simultaneously as I did before - then changing the volume of the windchest would make no difference. This assumes there are no leaks. It's just a bigger reservior but the same amount of air is going out every second so no more oomph is needed from the blowers. Have I assumed wrongly? i.e. if you increase the size of the windchest but keep the pipes the same size, do you stumble on problems?

    - I know I don't have very good coupling to my pipes. Do you have any cross-sectional images showing how you've mounted pipes above holes in the windchest to get a good connection? Some of mine don't directly connect with the hole that's connected to the solenoid. They fit snuggly - there are no leaks around the sides - but due to the design there's a small reservoir of air under them all the time. I have a feeling this was a mistake as it's creating losses (maybe due to impedence mismatches?). I can hear too much hiss in the note and the notes aren't as strong as I'd hoped. If I knew how experienced organ builders usually mount their pipes that would be great.

    Incidentally, I work quite a bit with Arduinos and sensors and realised I can make a cheap air pressure sensor that can live in the organ. So if any of you have any tips on the above, I can experiment with a live readout of the pressure inside the winchest. Might be an interesting way to accelerate R&D.

    Any advice gratefully received!


  • #2
    If you have to turn the blower all the way up, that can also indicate that the wind pressure you started with isn't the right one for the pipes. Pipes are voiced (regulated) for a given wind pressure. If that is too low they will hardly sound if it is very much less or sound 'thin'. If the pressure is too high they can overblow.

    That has not much to do with the size of the windchest. Normally a large windchest is an advantage as it stabilises the wind pressure (less variation). Normally after the blower comes a regulator and a reservoir bellows. Take a look at this book (probably you can see more tha I can over here in europe) Starts at page 18 for the bellows and regulation.

    To make contact the windchest is mostly a half-round dimple or conical and the pipe is also slightly domed at the foot. The dimple in the wood is charred with a red-hot tool to make it smooth and remove tool markings. Purpose is to make a line contact.


    • #3
      Where the heck did you get that odd set of pipes with the copper, open midrange?

      Winding an organ has been called "the black art." You can do everything according to the book and still have seemingly inexplicable problems.

      "as I have to turn the blowers up a lot to get a good tone" Real organ blowers are either on or off. There is no turning them up or down.

      Bellows. Four kinds:
      1. Reservoir: Holds a quantity of wind. Largely obsolete. These are typically seen in 19th century organs and usually very large often taking up the entire bottom of the organ. This is because wind in those days was raised by human effort via #2
      2. Feeder: Like a large fireplace bellows. Usually two were placed on the bottom of a reservoir and compressed alternately, connected by a beam - not unlike the "walking beam" on a steamboat.
      3. Regulator: The most common and usually erroneously called a reservoir. These are made up of a top which rises and falls with pressure connected to a valve which regulates the amount of wind. The top can be like an accordion with ribs and gussets or it can be a simple diaphragm. As the top rises, the valve closes and vice versa.
      4: Concussion. Often called a "winker." this is more or less a shock absorber to steady the wind. It is much like a fireplace bellows with a spring.

      Quite frankly I think you need to rethink your wind system. I have no idea what you are using for a blower. Were I doing this I would use either a Ventus blower or a Meindinger blower. They both make small models. The Meidingers are noisier than the Ventus but a lot cheaper. BOBCO also made small blowers and there are also the Spencer Junior blowers if you can find one - they haven't been made in decades.

      I would build a blower box to muffle the noise and would build in a static regulator bellows. One trick that the pros know is that you can not change wind pressure more then a few inches at a time without trouble. The static regulator will bring the pressure down to where your final regulator can use it.

      With a small windchest like this I would build the regulator right into the bottom with a style known as a "schwimmer". This takes up a lot less space and is common practice with compact, portable organs.

      You have a manometer, right? That's an essential piece of kit.

      The regulation of the pipes can be tricky. They need to be at least close to whatever pressure they were originally voiced on. There are two types of pipes when it comes to regulation; open and closed toe. Those wooden pipes are certainly closed toe. The open metal can go either way. Wooden pipes, if they are old enough, are sometimes regulated by hammering wooden wedges into the toe. Around 1910 they started putting lead toe points on them where the hole could be reamed out or tapped closed. You have to be sure that those stoppers are nice and airtight too. Otherwise, they just won't work right.

      That's all I can tell you for now. Building even a small pipe organ is fraught with a thousand little pitfalls that you would never think of. It sure looks nice though. Good work on that part.


      • #4
        Thanks for such a detailed reply - it's really helpful. I'm going to look into these details. And yes, I have a manometer which I use as the organ is operating so a good way to help.
        (PS Those pipes aren't copper - they're lead and we've painted them with Ardenbrite copper paint).

        - - - Updated - - -

        Hello Havoc
        Thanks so much for this - it's really helpful. Plenty to think about here and I'm going to look up that reference.