Ray Fairfield wrote in 000726 MMDigest:

> The longer the pipe length, the bigger the pipe needs to be.  As
> long as you can deliver the maximum amount of air the organ requires,
> at the required pressure, you should have a workable arrangement.

to which Robbie added:

>[ It hasn't been clear in the discussions whether the pressure
>[ regulator is located at the blower or by the pipe chests.

Sorry for the bit of confusion.  In those theatre organ installations,
including the San Francisco Orpheum Theatre cited as an example, the
regulators were _always_ placed as close to the pipes as possible, so
that any conductor-induced impedance mismatch would be negated by the
regulator.

In that particular case, the wind line from the blower was made 12"
diameter, which would have sufficed for a much larger division, had
it not been so far from the blower.  The only time that a wind
conductor was deliberately left longer rather than shorter was in the
case of wind lines to tremulants, which take advantage of air's natural
elasticity to create the proper 'bounce'.  In those cases, the wind line
was often 'tuned' to get a good [tremulant] sound.

Regards,
Bob Loesch, in beautiful Lake County, California, USA
http://www.jps.net/rrloesch