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Orchestrelle, Chapter 1
Rebuilding the Æolian Orchestrelle
58-Note Player Reed Organ, 1912 Model "W"
by Richard Vance
Copyright (C) 2000 by Richard Z. Vance
rev. B, 29 July 2000

Chapter 1 - Introduction

rv01-1.jpg (92 kb)

   Recently I acquired this Orchestrelle.  I have always wanted one, and my recent retirement, plus the bargain price for this one, motivated me to stop wishing and start doing.  From time to time, I will report on the restoration progress in MMD; this is the first installment. Here is a picture of the organ as received, with only the upper part of the case removed. As you can see, it looks pretty raggedy.  Someone in the past had started to strip the beautiful walnut case, but did a poor job, and gave up before the job was finished.

     I made this diagram, shpwing the basic principles of operation, based on what I saw as I was taking down my newly acquired Orchestrelle for a complete, frame-up restoration.  It is somewhat preliminary, and does not depict everything to scale, although the relative proportions of the components are reasonably accurate.

    Unlike an ordinary American reed organ, these work on pressure of about 2-1/4 in. WC, not vacuum, .  The reeds are mounted in 6 separate rank chests, mounted one above another, above the keybed.  The ranks are mounted on six massive, vertically channeled planks, which form the backbone of the whole thing.  Five of the six ranks have variously shaped wooden resonator cavity arrays in front of the reed's sound outlet hole.  One of the ranks, the violin stop, has two sets of reeds, one above the other.  This rank has no resonators, but just two rows of round openings in the front of the valve chest.  The lower reeds are detuned slightly, and their opening is normally covered by a hinged mute strip.  When the "Æolian Harp" stop is pulled, this mute opens, and both reeds speak in Celest; the beats between the two reeds producing a wavering, tremolo like tone.  There is also another rank of thirteen 16' sub bass reeds, not shown, in the lower left side of the case.    That adds up to 419 reeds!

    The organ works as follows:

1. The roll is mounted in a spoolbox with a sliding glass door.  When closed, the spoolbox is under pressure.  As a perforation uncovers the tracker bar port,  the primary pouch is inflated.  This pouch, and its bleed, are open to the atmosphere.

2. For manual play, the key, through the linkage shown, lifts a pallet in a pressurized box, and admits pressure to the same circuit.  During hand play, an arrangement of rods with a piece of cloth stretched between them (not shown), is flipped down to cover the tracker bar.

3. The primary valve admits pressure from a small chest, to the secondary pouch.  The organ itself is much wider than the 58-note keyboard, the notes being spaced on 1" centers.  Still, there is not room for the 1-3/8" pouches in a single row, so every other pouch is on an elevated wooden cup, sort of an inverted mushroom, to form a single row of vertically staggered pouches.  (Earlier models had two rows of pouches on one board, with two separate primary valve chests, but this was hard to get to, and took a lot of space.)

4. Normally all the channels in the backplane are pressurized through the upper seat of the primary valve.  When the note is actuated, this is closed, and its channel is vented to atmosphere through the primary lower seat.

5. When the stop for any half rank (divided into bass and treble like any reed organ), pressure is admitted to the rank's chest.  This stop action is ingenious, and will be the subject for another page.

6. If any chest is pressurized, and any note's channel is vented, the pressure in the chest collapses a large, oblong pouch in the rear of the chest.  Like on the primary pouch board, there is not room for a single row of these big pouches, so every other one is on an elevated wooden block, forming a staggered array.

7. When the main pouch collapses, it pulls a pallet open, admitting wind to the reed.  It is interesting to note that the link between the wooden pouch follower and the pallet is a piece of no. 26 double-cotton-covered pipe organ hookup wire.

    Anyone who works on reed organs knows that it takes only a tiny leak at the pallet to make one of the little treble reeds speak.  To prevent this, the top 12 notes in each rank have a tiny hole, leading to atmosphere, above the reed.  Of course a trivial amount of wind is wasted through this hole when the note plays, but a small pallet leak won't cause a cipher.  Like all on Aeolian products, they thought of everything except easy maintenance access;  it would take at least an hour to unhitch everything needed to get inside any rank windchest.  This feature probably saved countless service callbacks.

     I have decided to have the finish redone professionally, and the first step was to completely disassemble the casework.  You know how Aeolian built furniture; all the pieces were finished separately, then screwed together.  I ended up with 98 pieces, large and small.  Here they are, tagged and ready to go to the stripper; the boxes in front show contain all the smaller bits.

rv01-2.jpg (18 kb)

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