Yesterday Mr. Huestis asked if a really quiet suction unit was
available.  If there is one made in the USA today, I have never heard
of it.  Currently available suction units have only one impeller stage,
of small diameter, rather like a vacuum cleaner blower.  So they have
to spin very fast, especially to achieve player piano vacuum levels.
They make a lot of windage noise, apart from any mechanical racket.

For reed organs, needing much lower vacuums, typically 2-1/4 inWC,
there is another possibility.  Aug. Laukhuff GmbH & Co, in Germany,
make some of their "Ventola" miniature blowers configurable for reed
organ vacuum service.

Click on http://www.laukhuff.de/ , select 'English' > 'Our products'
> 'Catalog' > 'Category 6' > and scroll to pages 28 through 32 of this
very long PDF document.  There you will find complete specs and curves
for these models:

  6-128-60; 0.12 Hp, for 3-5 reed ranks at 2-3/8 inWC,
  6-125-70; 0.18 Hp, for 6 reed ranks at 2-3/4 inWC,
  6-123-80; 0.18 Hp, for 10 reed ranks at 3-1/8 inWC.

They are really quiet -- perfectly balanced and carefully designed to
eliminate every possible source of mechanical, electrical and pneumatic
noise.  I have the pressure equivalent of 6-123-80 for my Orchestrelle,
and it sits right in the organ room without any annoyance.

But they cost between $800 and $1300!  In America, Organ Supply
Industries are the agents for Laukhuff blower products.

Also, you would need some sort of regulator.  Like any centrifugal
blower, the suction will rise on low flow, so on low organ usage, the
vacuum will increase and pull the reservoir closed.  Then the relief
pallet on the reservoir lid will open, producing its own loud noise as
the unused blower capacity is 'made up' from the atmosphere.

A clever regulator can be made from the reservoir itself, according to
the old Spencer Turbine 'Orgoblo Junior' design.  These reed organ
suction kits were connected by cutting an 6" hole in the moving board
of the reservoir.  A metal flange was screwed over this hole, and it
had a 4" nipple which was connected to the blower in the basement with
wire reinforced hose.  A spring loaded, floating valve disk was screwed
to the main, fixed board of the reservoir, opposite the nipple.  As the
reservoir was sucked closed, the valve disk cut off flow through the
hose, resulting in a constant vacuum in the organ.

Richard Vance